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1

Comparison of MISR and Meteosat-9 cloud-motion vectors  

NASA Astrophysics Data System (ADS)

Stereo motion vectors (SMVs) from the Multiangle Imaging SpectroRadiometer (MISR) were evaluated against Meteosat-9 cloud-motion vectors (CMVs) over a one-year period. In general, SMVs had weaker westerlies and southerlies than CMVs at all latitudes and levels. The E-W wind comparison showed small vertical variations with a mean difference of -0.4 m s-1, -1 m s-1, -0.7 m s-1 and corresponding rmsd of 2.4 m s-1, 3.8 m s-1, 3.5 m s-1for low-, mid-, and high-level clouds, respectively. The N-S wind discrepancies were larger and steadily increased with altitude, having a mean difference of -0.8 m s-1, -2.9 m s-1, -4.4 m s-1 and rmsd of 3.5 m s-1, 6.9 m s-1, 9.5 m s-1at low, mid, and high levels. The best overall agreement was found in marine stratocumulus off Namibia, while differences were larger in the Tropics and convective clouds. The SMVs were typically assigned to higher altitudes than CMVs. Attributing each observed height difference to MISR and/or Meteosat-9 retrieval biases will require further research; nevertheless, we already identified a few regions and cloud types where CMV height assignment seemed to be the one in error. In thin mid- and high-level clouds over Africa and Arabia as well as in broken marine boundary layer clouds the 10.8-?m brightness temperature-based heights were often biased low due to radiance contributions from the warm surface. Contrarily, low-level CMVs in the South Atlantic were frequently assigned to mid levels by the CO2-slicing method in multilayer situations. We also noticed an apparent cross-swath dependence in SMVs, whereby retrievals were less accurate on the eastern side of the MISR swath than on the western side. This artifact was traced back to sub-pixel MISR co-registration errors, which introduced cross-swath biases in E-W wind, N-S wind, and height of 0.6 m s-1, 2.6 m s-1, and 210 m.

Lonitz, Katrin; HorváTh, ÁKos

2011-12-01

2

Motion filter vector quantization  

Microsoft Academic Search

Motion-compensated prediction of video is formulated as a novel vector quantization scheme called motion filter vector quantiza- tion (MFVQ). In MFVQ, the motion vector and the pixel-intensity interpolation filter are combined into a motion filter and the en- tire filter is vector quantized. A codebook design algorithm is proposed for designing unit gain and entropy constrained MFVQ codebooks. The algorithm

Dariusz Blasiak; Wai-yip Chan

2002-01-01

3

The effect of the arbitrary level assignment of satellite cloud motion wind vectors on wind analyses in the pre-thunderstorm environment  

NASA Technical Reports Server (NTRS)

The impact of satellite-derived cloud motion vectors on SESAME rawinsonde wind fields was studied in two separate cases. The effect of wind and moisture gradients on the arbitrary assignment of the satellite data is assessed to coordinate surfaces in a severe storm environment marked by strong vertical wind shear. Objective analyses of SESAME rawinsonde winds and combined winds are produced and differences between these two analyzed fields are used to make an assessment of coordinate level choice. It is shown that the standard method of arbitrarily assigning wind vectors to a low level coordinate surface yields systematic differences between the rawinsonde and combined wind analyses. Arbitrary assignment of cloud motions to the 0.9 sigma surface produces smaller differences than assignment to the 825 mb pressure surface. Systematic differences occur near moisture discontinuities and in regions of horizontal and vertical wind shears. The differences between the combined and SESAME wind fields are made smallest by vertically interpolating cloud motions to either a pressure or sigma surface.

Peslen, C. A.; Koch, S. E.; Uccellini, L. W.

1985-01-01

4

Wind estimates from cloud motions: Phase 1 of an in situ aircraft verification experiment  

NASA Technical Reports Server (NTRS)

An initial experiment was conducted to verify geostationary satellite derived cloud motion wind estimates with in situ aircraft wind velocity measurements. Case histories of one-half hour to two hours were obtained for 3-10km diameter cumulus cloud systems on 6 days. Also, one cirrus cloud case was obtained. In most cases the clouds were discrete enough that both the cloud motion and the ambient wind could be measured with the same aircraft Inertial Navigation System (INS). Since the INS drift error is the same for both the cloud motion and wind measurements, the drift error subtracts out of the relative motion determinations. The magnitude of the vector difference between the cloud motion and the ambient wind at the cloud base averaged 1.2 m/sec. The wind vector at higher levels in the cloud layer differed by about 3 m/sec to 5 m/sec from the cloud motion vector.

Hasler, A. F.; Shenk, W. E.; Skillman, W.

1974-01-01

5

Motion vector coding using decoder-side estimation of motion vector  

Microsoft Academic Search

The H.264\\/AVC standard employs the predictive motion vector coding technique using the median predictor of spatially neighboring three motion vectors. Although the median is effective in reducing redundancy, it is not always optimal in minimizing bits. To solve the matter, a new motion vector coding scheme, known as, MV competition in which decoder is signaled on the selected optimal PMV,

Kwanghyun Won; Jungyoup Yang; Byeungwoo Jeon

2009-01-01

6

Correlation-Based Motion Vector Processing With Adaptive Interpolation Scheme for Motion-Compensated Frame Interpolation  

Microsoft Academic Search

In this paper, we address the problems of unreliable motion vectors that cause visual artifacts but cannot be detected by high residual energy or bidirectional prediction difference in motion-compensated frame interpolation. A correlation-based motion vector processing method is proposed to detect and correct those unreliable motion vectors by explicitly considering motion vector correlation in the motion vector reliability classification, motion

Ai-Mei Huang; Truong Nguyen

2009-01-01

7

Study to determine cloud motion from meteorological satellite data  

NASA Technical Reports Server (NTRS)

Processing techniques were tested for deducing cloud motion vectors from overlapped portions of pairs of pictures made from meteorological satellites. This was accomplished by programming and testing techniques for estimating pattern motion by means of cross correlation analysis with emphasis placed upon identifying and reducing errors resulting from various factors. Techniques were then selected and incorporated into a cloud motion determination program which included a routine which would select and prepare sample array pairs from the preprocessed test data. The program was then subjected to limited testing with data samples selected from the Nimbus 4 THIR data provided by the 11.5 micron channel.

Clark, B. B.

1972-01-01

8

A Fourier approach to cloud motion estimation  

NASA Technical Reports Server (NTRS)

A Fourier technique is described for estimating cloud motion from pairs of pictures using the phase of the cross spectral density. The method allows motion estimates to be made for individual spatial frequencies, which are related to cloud pattern dimensions. Results obtained are presented and compared with the results of a Fourier domain cross correlation scheme. Using both artificial and real cloud data show that the technique is relatively sensitive to the presence of mixtures of motions, changes in cloud shape, and edge effects.

Arking, A.; Lo, R. C.; Rosenfield, A.

1977-01-01

9

GLOBAL ATMOSPHERIC MOTION VECTOR INTERCOMPARISON STUDY  

Microsoft Academic Search

Atmospheric Motion Vectors (AMVs) are amongst the data assimilated routinely by a number of weather prediction centers. The AMV data disseminated by the producers around the world undergo a thorough quality control including quality indicator (QI) and\\/or recursive filter function (RFF) threshold- based AMV pre-selection, blacklisting, thinning of the data, etc.. Until now there has been a lack of an

Iliana Genkova; Regis Borde; Johannes Schmetz; Jaime Daniels; Chris Velden; Ken Holmlund

10

Fourier transform techniques for the inference of cloud motion  

NASA Technical Reports Server (NTRS)

The development and evaluation are reported of phase shift techniques based on the Fourier transform for the estimation of cloud motion from geosynchronous meteorological satellite photographs. An alternative approach to cloud motion estimation, involving thresholding, was proposed and studied.

Lo, R. C.; Rosenfeld, A.

1974-01-01

11

Motion Vector Refinement for High-Performance Transcoding  

Microsoft Academic Search

In transcoding, simply reusing the motion vectors extracted from an incoming video bit stream may not result in the best quality. In this paper, we show that the incoming motion vectors become nonoptimal due to the reconstruction errors. To achieve the best video quality possible, a new motion estimation should be performed in the transcoder. We propose a fast-search adaptive

Jeongnam Youn; Ming-ting Sun; Chia-wen Lin

1999-01-01

12

Comparison of MISR and Meteosat 9 Cloud Motion Winds  

NASA Astrophysics Data System (ADS)

A detailed investigation of cloud motion winds from the Multi-angle Imaging SpectroRadiometer (MISR) against atmospheric motion winds from a geostationary satellite was essentially needed. Previously, MISR winds have only been compared to limited radiosonde and wind profiler datasets, or forecast models. Those comparisons already showed relatively good agreements. This study offers the most detailed evaluation of cloud motion winds from MISR to date. Its purely geometric stereo technique retrieves cloud motion and height simultaneously, and is potentially more accurate than traditional satellite winds relying on ancillary information for height assignment. Here, we have analyzed one year of MISR and state-of-the-art Meteosat 9 wind retrievals, producing robust statistics based on 225,155 coincident wind pairs. Retrieval differences have been investigated as a function of quality control metrics, geographic location, season, surface type, cloud elevation, MISR stereo matching technique, and Meteosat 9 height assignment method. We have found that MISR winds have no substantial speed bias compared to Meteosat 9; however, the meridional (MISR along-track) wind components show significantly larger rms differences than the zonal (MISR cross-track) components. There is also a land-ocean contrast with vector differences being larger over land. In general, the worst agreement between wind retrievals is observed in the Tropics. Contrarily, MISR wind heights are systematically larger by 450 m on average than Meteosat 9 heights. Case studies for the Southeast Atlantic Ocean demonstrate that height differences can often be traced to a low bias in the Meteosat 9 brightness temperature height assignment method, which puts winds unreasonably close to the surface, especially in broken cloud fields. Investigating cloud-free land scenes, we have established the minimum error characteristics, and the relationship between along-track wind error and height error in MISR retrievals. Applying these findings to cloudy scenes, we have identified large geographic areas where the observed MISR-Meteosat 9 height differences cannot possibly be explained by MISR height errors alone. Based on our results, we conclude that the MISR wind product, although probably inadequate for weather prediction purposes due to its limited spatial coverage, can still be very useful pinpointing particular situations where geostationary height assignment methods face serious difficulties and, hence, need further improvement. In the future, MISR-like retrieved cloud motion winds over a much wider swath could even be used in numerical weather prediction models to cover e.g. higher latitudes, where no observational data are yet utilized.

Lonitz, K.; Horvath, A.

2009-12-01

13

Improvement of cardiac CT reconstruction using local motion vector fields.  

PubMed

The motion of the heart is a major challenge for cardiac imaging using CT. A novel approach to decrease motion blur and to improve the signal to noise ratio is motion compensated reconstruction which takes motion vector fields into account in order to correct motion. The presented work deals with the determination of local motion vector fields from high contrast objects and their utilization within motion compensated filtered back projection reconstruction. Image registration is applied during the quiescent cardiac phases. Temporal interpolation in parameter space is used in order to estimate motion during strong motion phases. The resulting motion vector fields are during image reconstruction. The method is assessed using a software phantom and several clinical cases for calcium scoring. As a criterion for reconstruction quality, calcium volume scores were derived from both, gated cardiac reconstruction and motion compensated reconstruction throughout the cardiac phases using low pitch helical cone beam CT acquisitions. The presented technique is a robust method to determine and utilize local motion vector fields. Motion compensated reconstruction using the derived motion vector fields leads to superior image quality compared to gated reconstruction. As a result, the gating window can be enlarged significantly, resulting in increased SNR, while reliable Hounsfield units are achieved due to the reduced level of motion artefacts. The enlargement of the gating window can be translated into reduced dose requirements. PMID:19097853

Schirra, Carsten Oliver; Bontus, Claas; van Stevendaal, Udo; Dössel, Olaf; Grass, Michael

2009-03-01

14

Motion vector coding algorithm based on adaptive template matching  

Microsoft Academic Search

Motion estimation as well as the corresponding motion compensation is a core part of modern video coding standards, which highly improves the compression efficiency. On the other hand, motion information takes considerable portion of compressed bit stream, especially in low bit rate situation. In this paper, an efficient motion vector prediction algorithm is proposed to minimize the bits used for

Wen Yang; Oscar C. Au; Jingjing Dai; Feng Zou; Chao Pang; Yu Liu

2010-01-01

15

Wind estimates from cloud motions: Preliminary results from phases 1, 2, and 3 of an in situ aircraft verification experiment  

NASA Technical Reports Server (NTRS)

Low level aircraft equipped with Inertial Navigation Systems (INS) were used to define the vertical extent and horizontal motion of a cloud and to measure the ambient wind field. A high level aircraft, also equipped with an INS, took photographs to describe the horizontal extent of the cloud field and to measure cloud motion. The aerial photographs were also used to make a positive identification in a satellite picture of the cloud observed by the low level aircraft. The experiment was conducted over the tropical oceans in the vicinity of Florida, Puerto Rico, Panama and in the Western Gulf of Mexico. Results for tropical cumulus clouds indicate excellent agreement between the cloud motion and the wind at the cloud base. The magnitude of the vector difference between the cloud motion and the cloud base wind is less than 1.3 m/sec for 67% of the cases with track lengths of 1 hour or longer. The cirrus cloud motions agreed best with the mean wind in the cloud layer with a vector difference of about 1.6 m/sec.

Hasler, A. F.; Shenk, W. E.; Skillman, W. C.

1975-01-01

16

The role of the harmonic vector average in motion integration  

PubMed Central

The local speeds of object contours vary systematically with the cosine of the angle between the normal component of the local velocity and the global object motion direction. An array of Gabor elements whose speed changes with local spatial orientation in accordance with this pattern can appear to move as a single surface. The apparent direction of motion of plaids and Gabor arrays has variously been proposed to result from feature tracking, vector addition and vector averaging in addition to the geometrically correct global velocity as indicated by the intersection of constraints (IOC) solution. Here a new combination rule, the harmonic vector average (HVA), is introduced, as well as a new algorithm for computing the IOC solution. The vector sum can be discounted as an integration strategy as it increases with the number of elements. The vector average over local vectors that vary in direction always provides an underestimate of the true global speed. The HVA, however, provides the correct global speed and direction for an unbiased sample of local velocities with respect to the global motion direction, as is the case for a simple closed contour. The HVA over biased samples provides an aggregate velocity estimate that can still be combined through an IOC computation to give an accurate estimate of the global velocity, which is not true of the vector average. Psychophysical results for type II Gabor arrays show perceived direction and speed falls close to the IOC direction for Gabor arrays having a wide range of orientations but the IOC prediction fails as the mean orientation shifts away from the global motion direction and the orientation range narrows. In this case perceived velocity generally defaults to the HVA. PMID:24155716

Johnston, Alan; Scarfe, Peter

2013-01-01

17

Rapid ray motions in barium plasma clouds and auroras  

NASA Technical Reports Server (NTRS)

On two evenings in 1968, anomalous field-aligned brightenings or emission enhancements of up to 3X were observed to move rapidly through three different Ba(+) clouds over Andoya, Norway. Similar effects were observed in Ba(+) clouds released from rockets launched from Poker Flat, Alaska, on March 21, 1973 and on March 22, 1980. On these occasions, auroras on or near the Ba(+) L shell also exhibited active rapid ray motions, which prompts the assumption that the two phenomena are related and the expectation that an explanation of the rapid ray motions in the Ba(+) clouds would lead to a better understanding of the physics of auroral ray motions and the auroral atmosphere. Seven possible mechanisms to produce the observed moving emission enhancements are discussed. The observations provide strong evidence for the existence of transient electric fields of order 100 mV/m at altitudes as low as 200 km during active aurora with rapid ray motions.

Wescott, E. M.; Hallinan, T. J.; Stenbaek-Nielsen, H. C.; Swift, D. W.; Wallis, D. D.

1993-01-01

18

Proper Motion of the Magellanic Clouds using SPM  

NASA Astrophysics Data System (ADS)

Absolute proper motions are determined for stars and galaxies to V = 17.5 over a 450 square-degree area that includes the Magellanic Clouds, using photographic and CCD observations of the Yale/San Juan Southern Proper Motion program. Multiple, local relative proper motion measures were combined in an overlap solution using photometrically selected galactic disk stars to define a global relative system that is then transformed to absolute using external galaxies and Hipparcos stars to tie into the ICRS. The resulting catalog is used to derive the mean absolute proper motions of the Magellanic Clouds: (?_{?}^{} cos &delta,; ?_{?}^{})_LMC=(+1.88, +0.37)±(0.27, 0.27) mas yr^-1 and (?_{?}^{} cos ?, ?_{?}^{})_SMC=(+1.05, -1.03)±(0.30, 0.29) mas yr^-1, based on best-measured samples of 3822 LMC stars and 964 SMC stars. A dominant portion of the formal errors is due to the estimated uncertainty in the inertial system of the Hipparcos Catalog. A more precise determination was made for the proper motion of the SMC relative to the LMC; (?_{{? cos ? }}^{}, ?_{?}^{})_{SMC-LMC}=(-0.91, -1.49)±(0.16, 0.15) mas yr^-1. This differential value is used to estimate of the total velocity difference of the two clouds to within ±54 km s^-1. The absolute proper motion results are consistent with the Clouds' orbits being marginally bound to the Milky Way, albeit on an elongated orbit.

Vieira, K.; Girard, T.; van Altena, W.; Zacharias, N.; Casetti, D.; Korchagin, V.; Platais, I.; Monet, D.; López, C.

2014-06-01

19

Fast full search motion estimation algorithm using early detection of impossible candidate vectors  

Microsoft Academic Search

To reduce the amount of computations for a full search (FS) algorithm for fast motion estimation, we propose a new and fast FS motion estimation algorithm. The computational reduction of our FS motion estimation algorithm comes from fast elimination of impossible motion vectors. We obtain faster elimination of inappropriate motion vectors using efficient matching units from localization of a complex

Jong-Nam Kim; Sung-Cheal Byun; Yong-Hoon Kim; Byung-Ha Ahn

2002-01-01

20

The real time calculation of cloud motion in infrared image sequences using mathematical morphology operations  

Microsoft Academic Search

The real time calculation of local cloud motion may be useful in aiding the discrimination of small targets from backgrounds by infrared search and track systems. While the apparent motion of clouds in image sequences can be considered to be optical flow, the standard methods of optical flow calculation are not suited to real time calculation of cloud motion. In

R. C. Warren

1999-01-01

21

Digital video steganalysis using motion vector recovery-based features.  

PubMed

As a novel digital video steganography, the motion vector (MV)-based steganographic algorithm leverages the MVs as the information carriers to hide the secret messages. The existing steganalyzers based on the statistical characteristics of the spatial/frequency coefficients of the video frames cannot attack the MV-based steganography. In order to detect the presence of information hidden in the MVs of video streams, we design a novel MV recovery algorithm and propose the calibration distance histogram-based statistical features for steganalysis. The support vector machine (SVM) is trained with the proposed features and used as the steganalyzer. Experimental results demonstrate that the proposed steganalyzer can effectively detect the presence of hidden messages and outperform others by the significant improvements in detection accuracy even with low embedding rates. PMID:22781241

Deng, Yu; Wu, Yunjie; Zhou, Linna

2012-07-10

22

An efficient gray search algorithm for the estimation of motion vectors  

Microsoft Academic Search

Motion vector estimation plays an important role in motion-compensated video coding. An efficient and fast search algorithm is proposed for the estimation of motion vectors. With the help of gray prediction, the algorithm can determine the motion vectors of image blocks quickly and correctly. Since the proposed algorithm performs better than other search algorithms [e.g. the three-step search (TSS), cross-search

Jau-Ling Chen; Pei-Yin Chen

2001-01-01

23

An Efficient Motion Vector Coding Scheme Based on Prioritized Reference Decision  

Microsoft Academic Search

In the latest video coding frameworks, efficiency of motion vector (MV) coding is becoming increasingly important because of the growing bit rate portion of motion information. However, neither the conventional median predictor, nor the newer schemes such as the minimum bit rate prediction scheme and the hybrid scheme, can effectively eliminate the local redundancy of motion vectors. In this paper,

Dajiang Zhou; Jinjia Zhou; Satoshi Goto

2009-01-01

24

Atmospheric motion vector retrieval using improved tracer selection algorithm  

NASA Astrophysics Data System (ADS)

Tracer selection is the fundamental step in the retrieval of atmospheric motion vectors (AMVs). In this study, a new technique for tracer selection based on extracting the corner points in an infrared (IR) image of a geostationary satellite for the retrieval of AMVs is developed. Corner points are frequently used in computer vision to identify the important features of an image. These points are usually characterized by high gradient values of the image intensity in all directions and lie at the junctions of different brightness regions in the image. Corner points find application in computer vision for motion tracking, stereo vision, mosaics, etc., but this is the first time that the information from corners is used for tracer selection in AMV retrieval. In the present study, a commonly used Harris corner (HC) detection algorithm is followed to extract corners from the image intensity of an IR image. The tracers selected using the HC method are then passed on to the other steps of the retrieval algorithm, viz., tracking, height assignment, and quality control procedures for the retrieval of AMVs. For the initial development of the HC, Meteosat-7 IR images are used to derive AMVs for July and December 2010. The AMVs retrieved using HC are validated against collocated radiosonde observations, and the results are compared with the local anomaly (LA) method as reference. LA is used for tracer selection in operational AMV retrieval algorithm from the Indian geostationary satellite Kalpana-1. AMVs retrieved using HC have shown considerable improvement in the AMV accuracy over the AMVs derived using LA.

Kaur, Inderpreet; Deb, S. K.; Kishtawal, C. M.; Pal, P. K.; Kumar, Raj

2014-02-01

25

Context-based motion retrieval using vector space model  

E-print Network

Motion retrieval is the problem of retrieving highly relevant motions in a timely manner. The principal challenge is to characterize the similarity between two motions effectively, which is tightly related to the gap between ...

Zhang, Zhunping

2008-01-01

26

Atmospheric Motion Vectors Derived via a New Nested Tracking Algorithm Developed for the GOES-R Advanced Baseline Imager (ABI)  

NASA Astrophysics Data System (ADS)

A new Atmospheric Motion Vector (AMV) nested tracking algorithm has been developed for the Advanced Baseline Imager (ABI) to be flown on NOAA's future GOES-R satellite. The algorithm has been designed to capture the dominant motion in each target scene from a family of local motion vectors derived for each target scene. Capturing this dominant motion is achieved through use of a two-dimensional clustering algorithm that segregates local displacements into clusters. The dominant motion is taken to be the average of the local displacements of points belonging to the largest cluster. This approach prevents excessive averaging of motion that may be occurring at multiple levels or at different scales that can lead to a slow speed bias and a poor quality AMV. A representative height is assigned to the dominant motion vector through exclusive use of cloud heights from pixels belonging to the largest cluster. This algorithm has been demonstrated to significantly improve the slow speed bias typically observed in AMVs derived from satellite imagery. Meteosat SEVERI imagery is serving as an important GOES-R ABI proxy data source for the development, testing, and validation of the GOES-R AMV algorithms given its similarities (spectral coverage, pixel resolution, and scanning rate) and performance (spectral noise, navigation/registration) to the future GOES-R ABI. The new GOES-R AMV algorithm is also being applied to the instrumentation on the current operational GOES series of satellites and is expected to replace the heritage AMV algorithm being used in NESDIS operations today. Plans at NOAA/NESDIS also include using the new GOES-R AMV algorithm to generate AMVs from the future VIIRS instrument on the NPP satellite. Details of the GOES-R ABI AMV algorithm and the validation results will be presented and discussed.

Daniels, J.; Bresky, W.; Wanzong, S.; Velden, C.

2012-12-01

27

Vector subtraction using visual and extraretinal motion signals: A new look at efference copy and corollary  

E-print Network

distributions of activity from visual motion sensors and from an extraretinal source such as a pursuit signal from motion in the world has a long history. The earliest recorded description of the problem canVector subtraction using visual and extraretinal motion signals: A new look at efference copy

Krauzlis, Richard J.

28

The Proper Motion of the Magellanic Clouds. II. New Results for Five Small Magellanic Cloud Fields  

NASA Astrophysics Data System (ADS)

We present new results from a ground-based program to determine the proper motion of the Magellanic Clouds (MCs) relative to background quasars (QSOs), being carried out with the Iréneé du Pont 2.5 m telescope at Las Campanas Observatory, Chile. The data were secured over a time base of seven years and with eight epochs of observation "As measured" (field) proper motions were obtained for five QSO fields in the Small Magellanic Cloud (SMC): QJ0033-7028, QJ0035-7201, QJ0047-7530, QJ0102-7546, and QJ0111-7249. Assuming that the SMC has a disklike central structure, but that it does not rotate, we determined a center-of-mass (CM) proper motion for the SMC from two of these fields, QJ0033-7028 and QJ0035-7201, located to the northwest and west of the main body of the SMC, respectively. Combining these latter proper motions with the CM proper motion presented by Costa et al. (hereafter CMP09) for the SMC (from the field QJ0036-7227, located to the west of the main body of the SMC), we obtain a weighted mean of ?? cos ? = +0.93 ± 0.14 mas yr-1 and ?? = -1.25 ± 0.11 mas yr-1. This CM proper motion is in good agreement with recent results by Piatek et al. and Vieira et al., and we are confident that it is a good representation of the "bulk" transverse motion of the SMC. On the contrary, the results we obtain from the fields QJ0047-7530 and QJ0102-7546, located to the south of the main body of the SMC, and the field QJ0111-7249, located to the east of its main body, seem to be affected by streaming motions. For this reason, we have not used the latter to determine the SMC CM proper motion. These streaming motions could be evidence that the SMC was tidally disrupted in a close encounter with the Large Magellanic Cloud (LMC). Complementing the SMC CM proper motions given here and in CMP09, with the currently accepted radial velocity of its center, we have derived its galactocentric (gc) velocity components, obtaining a weighted mean of V gc,t = +289 ± 25 km s-1 and V gc,r = +14 ± 24 km s-1. These velocities, together with the galactocentric velocity components given for the LMC in CMP09, imply a relative velocity between the LMC and SMC of 67 ± 42 km s-1 for V rot,LMC = 50 km s-1 and of 98 ± 48 km s-1 for V rot,LMC = 120 km s-1. Despite our large errors, these values are consistent with the standard assumption that the MCs are gravitationally bound to each other.

Costa, Edgardo; Méndez, René A.; Pedreros, Mario H.; Moyano, Maximiliano; Gallart, Carme; Noël, Noelia

2011-04-01

29

THE PROPER MOTION OF THE MAGELLANIC CLOUDS. II. NEW RESULTS FOR FIVE SMALL MAGELLANIC CLOUD FIELDS  

SciTech Connect

We present new results from a ground-based program to determine the proper motion of the Magellanic Clouds (MCs) relative to background quasars (QSOs), being carried out with the Irenee du Pont 2.5 m telescope at Las Campanas Observatory, Chile. The data were secured over a time base of seven years and with eight epochs of observation 'As measured' (field) proper motions were obtained for five QSO fields in the Small Magellanic Cloud (SMC): QJ0033-7028, QJ0035-7201, QJ0047-7530, QJ0102-7546, and QJ0111-7249. Assuming that the SMC has a disklike central structure, but that it does not rotate, we determined a center-of-mass (CM) proper motion for the SMC from two of these fields, QJ0033-7028 and QJ0035-7201, located to the northwest and west of the main body of the SMC, respectively. Combining these latter proper motions with the CM proper motion presented by Costa et al. (hereafter CMP09) for the SMC (from the field QJ0036-7227, located to the west of the main body of the SMC), we obtain a weighted mean of {mu}{sub {alpha}} cos {delta} = +0.93 {+-} 0.14 mas yr{sup -1} and {mu}{sub {delta}} = -1.25 {+-} 0.11 mas yr{sup -1}. This CM proper motion is in good agreement with recent results by Piatek et al. and Vieira et al., and we are confident that it is a good representation of the 'bulk' transverse motion of the SMC. On the contrary, the results we obtain from the fields QJ0047-7530 and QJ0102-7546, located to the south of the main body of the SMC, and the field QJ0111-7249, located to the east of its main body, seem to be affected by streaming motions. For this reason, we have not used the latter to determine the SMC CM proper motion. These streaming motions could be evidence that the SMC was tidally disrupted in a close encounter with the Large Magellanic Cloud (LMC). Complementing the SMC CM proper motions given here and in CMP09, with the currently accepted radial velocity of its center, we have derived its galactocentric (gc) velocity components, obtaining a weighted mean of V{sub gc,t} = +289 {+-} 25 km s{sup -1} and V{sub gc,r} = +14 {+-} 24 km s{sup -1}. These velocities, together with the galactocentric velocity components given for the LMC in CMP09, imply a relative velocity between the LMC and SMC of 67 {+-} 42 km s{sup -1} for V{sub rot,LMC} = 50 km s{sup -1} and of 98 {+-} 48 km s{sup -1} for V{sub rot,LMC} = 120 km s{sup -1}. Despite our large errors, these values are consistent with the standard assumption that the MCs are gravitationally bound to each other.

Costa, Edgardo; Mendez, Rene A.; Moyano, Maximiliano [Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago (Chile); Pedreros, Mario H. [Departamento de Fisica, Universidad de Tarapaca, Casilla 7-D, Arica (Chile); Gallart, Carme [Instituto de Astrofisica de Canarias, Tenerife 38200, Islas Canarias (Spain); Noel, Noelia, E-mail: costa@das.uchile.cl, E-mail: rmendez@das.uchile.cl, E-mail: mmoyano@das.uchile.cl, E-mail: mmoyano@mpia-hd.mpg.de, E-mail: mpedrero@uta.cl, E-mail: carme@iac.es, E-mail: noelia@mpia-hd.mpg.de [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, 69117 Heidelberg (Germany)

2011-04-15

30

Quality Assessment of Atmospheric Motion Vectors Over the Indian Ocean  

NASA Astrophysics Data System (ADS)

Because conventional observations over the oceans are not available, especially during tropical cyclones, multi-spectral atmospheric motion vectors (AMVs) estimated from geostationary satellites are routinely assimilated in the numerical weather prediction models at different operational centres across the globe. The derived AMVs are generally validated with radiosonde observations available over land at synoptic hours; however, over the ocean there is a limited scope to assess the quality of AMVs. Over ocean, AMVs can be validated with radiosonde data available from opportunistic ships or using dropsonde data available from aircrafts. In this study, the accuracy of the AMVs derived from the geostationary satellites Kalpana-1 and Meteosat-7 is evaluated over the oceanic region. Radiosonde data available from a ship cruise held in the Bay of Bengal during the period 09 July-08 August 2012 and from the Cal/Val site situated at Kavaratti Island (72.62°E, 10.57°N) in the southern Indian Ocean are used to assess the AMV accuracy. In this study, 83 radiosonde profiles are used to validate the Kalpana-1 AMVs, to allow a better understanding of AMV errors over the Indian Ocean. The RMSVD of Kalpana-1 AMVs for the high-, mid- and low-levels are found to be 7.9, 9.4 and 5.3 m s-1, respectively, while the corresponding RMSVD for Meteosat-7 AMVs are 9.1, 5.5 and 3.7 m s-1. A similar accuracy is observed when the AMVs are validated against the NCEP analyses collocated with the nearest radiosonde locations. The high RMSVD and bias for Kalpana-1 AMVs at the mid-level and Meteosat-7 AMVs at the high-level are associated with the limitation of satellite winds to resolve the upper-level easterly jet in conjunction with errors in the height assignment. This study could help the numerical modellers to assign appropriate observation error over this region during the assimilation of AMVs into the NWP models.

Kaur, Inderpreet; Deb, S. K.; Kishtawal, C. M.; Pal, P. K.

2014-09-01

31

T-vectors make autonomous mobile robot motion planning and self-referencing more efficient  

Microsoft Academic Search

A motion planning and self-referencing approach has been developed, simulated and applied to an actual robot. Although there are several novelties to these approaches, the fact that both are based on traversability vectors (t-vectors) is one aspect of this research that is unique. Through their application it has been found that t-vectors enhance the detection of path obstructions and geometric

J. A. Janet; Ren C. Luo; Michael G. Kay

1994-01-01

32

University Navstar Consortium GPS Site Motion Vector/Crustal Velocity Archive  

NSDL National Science Digital Library

The University Navstar Consortium (UNAVCO) Boulder facility has developed a Global Positioning System (GPS) Site Motion Vector Archive. Precise motions of points on the Earth, made with continuous or episodic GPS measurements, are being used to study tectonic processes including plate motions, plate boundary zone deformation, earthquakes, and volcanic eruptions. This archive of GPS velocities contains project information, maps, links, data, and metadata from both regional and global GPS analyses and showcases the work conducted by university and other research investigators. The archive also contains a global plate motion model velocity calculator and an interactive map tool. Velocity data are also accessible via a Distributed Ocean Data Sets (DODS) server.

2007-03-26

33

Insitu aircraft verification of the quality of satellite cloud winds over oceanic regions  

NASA Technical Reports Server (NTRS)

A five year aircraft experiment to verify the quality of satellite cloud winds over oceans using in situ aircraft inertial navigation system wind measurements is presented. The final results show that satellite measured cumulus cloud motions are very good estimators of the cloud base wind for trade wind and subtropical high regions. The average magnitude of the vector differences between the cloud motion and the cloud base wind is given. For cumulus clouds near frontal regions, the cloud motion agreed best with the mean cloud layer wind. For a very limited sample, cirrus cloud motions also most closely followed the mean wind in the cloud layer.

Hasler, A. F.; Skillman, W. C.

1979-01-01

34

Turbulent fluid motion 2: Scalars, vectors, and tensors  

NASA Technical Reports Server (NTRS)

The author shows that the sum or difference of two vectors is a vector. Similarly the sum of any two tensors of the same order is a tensor of that order. No meaning is attached to the sum of tensors of different orders, say u(sub i) + u(sub ij); that is not a tensor. In general, an equation containing tensors has meaning only if all the terms in the equation are tensors of the same order, and if the same unrepeated subscripts appear in all the terms. These facts will be used in obtaining appropriate equations for fluid turbulence. With the foregoing background, the derivation of appropriate continuum equations for turbulence should be straightforward.

Deissler, Robert G.

1991-01-01

35

Cloud morphology and motions from Pioneer Venus images  

NASA Technical Reports Server (NTRS)

The horizontal and vertical cloud structures, atmospheric waves, and wind velocities at the cloud top level were determined by the Pioneer Venus photopolarimeter images in the UV from January through March 1979. The images indicate long-term evolution of cloud characteristics, the atmospheric dynamics, and rapid small changes in cloud morphology. The clouds show a globally coordinated oscillation relative to latitude circles; retrograde zonal winds of 100 m/s near the equator are determined from the tracking of small-scale cloud properties, but two hemispheres show important variations. The zonal wind velocity in the southern hemisphere is reduced toward the poles at a rate similar to solid body rotation; the midlatitude jet stream noted by Mariner 10 is not observed.

Rossow, W. B.; Del Genio, A. D.; Limaye, S. S.; Travis, L. D.; Stone, P. H.

1980-01-01

36

Steady-State Pursuit Is Driven by Object Motion Rather Than the Vector Average of Local Motions  

NASA Technical Reports Server (NTRS)

We have previously shown that humans can pursue the motion of objects whose trajectories can be recovered only by spatio-temporal integration of local motion signals. We now explore the integration rule used to derive the target-motion signal driving pursuit. We measured the pursuit response of 4 observers (2 naive) to the motion of a line-figure diamond viewed through two vertical bar apertures (0.2 cd/square m). The comers were always occluded so that only four line segments (93 cd/square m) were visible behind the occluding foreground (38 cd/square m). The diamond was flattened (40 & 140 degree vertex angles) such that vector averaging of the local normal motions and vertical integration (e.g. IOC) yield very I or different predictions, analogous to using a Type II plaid. The diamond moved along Lissajous-figure trajectories (Ax = Ay = 2 degrees; TFx = 0.8 Hz; TFy = 0.4 Hz). We presented only 1.25 cycles and used 6 different randomly interleaved initial relative phases to minimize the role of predictive strategies. Observers were instructed to track the diamond and reported that its motion was always coherent (unlike type II plaids). Saccade-free portions of the horizontal and vertical eye-position traces sampled at 240 Hz were fit by separate sinusoids. Pursuit gain with respect to the diamond averaged 0.7 across subjects and directions. The ratio of the mean vertical to horizontal amplitude of the pursuit response was 1.7 +/- 0.7 averaged across subjects (1SD). This is close to the prediction of 1.0 from vertical motion-integration rules, but far from 7.7 predicted by vector averaging and infinity predicted by segment- or terminator-tracking strategies. Because there is no retinal motion which directly corresponds to the diamond's motion, steady-state pursuit of our "virtual" diamond is not closed-loop in the traditional sense. Thus, accurate pursuit is unlikely to result simply from local retinal negative feedback. We conclude that the signal driving steady-state pursuit is not the vector average of local motion signals, but rather a more vertical estimate of object motion, derived in extrastriate cortical areas beyond V1, perhaps NIT or MST.

Stone, Leland S.; Beutter, B. R.; Lorenceau, J. D.; Ahumada, Al (Technical Monitor)

1997-01-01

37

Adaptive quarter-pel motion estimation and motion vector coding algorithm for the H.264/AVC standard  

NASA Astrophysics Data System (ADS)

We present an adaptive quarter-pel (Qpel) motion estimation (ME) method for H.264/AVC. Instead of applying Qpel ME to all macroblocks (MBs), the proposed method selectively performs Qpel ME in an MB level. In order to reduce the bit rate, we also propose a motion vector (MV) encoding technique that adaptively selects a different variable length coding (VLC) table according to the accuracy of the MV. Experimental results show that the proposed method can achieve about 3% average bit rate reduction.

Jung, Seung-Won; Park, Chun-Su; Ha, Le Thanh; Ko, Sung-Jea

2009-11-01

38

COMPARISON OF ATMOSPHERIC MOTION VECTORS AND DENSE VECTOR FIELDS CALCULATED FROM MSG IMAGES  

E-print Network

, initially for the tracking of solid objects from a pair of images : optical flow estimation methods infrared (IR 10.8 µm) channel. Adaptations of the method consist in using a cloud classification at subsatellite point, 15 min standard time interval, 12 channels for MSG satellites). The progress on tracking

Szantai André

39

Considering polarization in MODIS-based cloud property retrievals by using a vector radiative transfer code  

NASA Astrophysics Data System (ADS)

In this study, a full-vector, adding-doubling radiative transfer model is used to investigate the influence of the polarization state on cloud property retrievals from Moderate Resolution Imaging Spectroradiometer (MODIS) satellite observations. Two sets of lookup tables (LUTs) are developed for the retrieval purposes, both of which provide water cloud and ice cloud reflectivity functions at two wavelengths in various sun-satellite viewing geometries. However, only one of the LUTs considers polarization. The MODIS reflectivity observations at 0.65 ?m (band 1) and 2.13 ?m (band 7) are used to infer the cloud optical thickness and particle effective diameter, respectively. Results indicate that the retrievals for both water cloud and ice cloud show considerable sensitivity to polarization. The retrieved water and ice cloud effective diameter and optical thickness differences can vary by as much as ±15% due to polarization state considerations. In particular, the polarization state has more influence on completely smooth ice particles than on severely roughened ice particles.

Yi, Bingqi; Huang, Xin; Yang, Ping; Baum, Bryan A.; Kattawar, George W.

2014-10-01

40

Arctic PBL Cloud Height and Motion Retrievals from MISR and MINX  

NASA Technical Reports Server (NTRS)

How Arctic clouds respond and feedback to sea ice loss is key to understanding of the rapid climate change seen in the polar region. As more open water becomes available in the Arctic Ocean, cold air outbreaks (aka. off-ice flow from polar lows) produce a vast sheet of roll clouds in the planetary boundary layer (PBl). The cold air temperature and wind velocity are the critical parameters to determine and understand the PBl structure formed under these roll clouds. It has been challenging for nadir visible/IR sensors to detect Arctic clouds due to lack of contrast between clouds and snowy/icy surfaces. In addition) PBl temperature inversion creates a further problem for IR sensors to relate cloud top temperature to cloud top height. Here we explore a new method with the Multiangle Imaging Spectro-Radiometer (MISR) instrument to measure cloud height and motion over the Arctic Ocean. Employing a stereoscopic-technique, MISR is able to measure cloud top height accurately and distinguish between clouds and snowy/icy surfaces with the measured height. We will use the MISR INteractive eXplorer (MINX) to quantify roll cloud dynamics during cold-air outbreak events and characterize PBl structures over water and over sea ice.

Wu, Dong L.

2012-01-01

41

COMPARISON OF MSG DENSE ATMOSPHERIC MOTION VECTOR FIELDS PRODUCED BY DIFFERENT METHODS  

E-print Network

COMPARISON OF MSG DENSE ATMOSPHERIC MOTION VECTOR FIELDS PRODUCED BY DIFFERENT METHODS Szantai A on optical flow techniques have been applied to a dataset of Meteosat Second Generation (MSG) images Second Generation - MSG - in particular), with better spatial and temporal resolution of the images

Szantai André

42

Suggested Courseware for the Non-Calculus Physics Student: Measurement, Vectors, and One-Dimensional Motion.  

ERIC Educational Resources Information Center

Evaluates 16 commercially available courseware packages covering topics for introductory physics. Discusses the price, sub-topics, program type, interaction, time, calculus required, graphics, and comments of each program. Recommends two packages in measurement and vectors, and one-dimensional motion respectively. (YP)

Mahoney, Joyce; And Others

1988-01-01

43

Secondary School Mathematics, Chapter 21, Rigid Motions and Vectors, Chapter 22, Computers and Programs. Student's Text.  

ERIC Educational Resources Information Center

Transformation geometry topics are covered in one chapter of Unit 11 of this SMSG series. Work with translations, reflections, rotations, and composition of motions is included; vectors are briefly discussed. The chapter on computers and programming deals with recent history and uses of of the computer, organization of a digital computer, an…

Stanford Univ., CA. School Mathematics Study Group.

44

Stratiform clouds and their interaction with atmospheric motions  

NASA Technical Reports Server (NTRS)

During the 1987 to 1988 academic year, three projects were finished and plans were made to redirect and focus work in a proposal now being reviewed. The completed work involves study of waves on an equatorial beta-plane in shear flow, investigation of the influence of orography on the index cycle, and analysis of a model of cloud street development in a thermally-forced, sheared environment. The proposed work involves study of boundary layer circulations supporting stratocumulus decks and investigation of how the radiative effects of these clouds modulate larger-scale flows such as those associated with the index oscillation.

Clark, John H. E.; Hampton, N. Shirer

1989-01-01

45

Water vapor motion signal extraction from FY-2E longwave infrared window images for cloud-free regions: The temporal difference technique  

NASA Astrophysics Data System (ADS)

The aim of this study is to calculate the low-level atmospheric motion vectors (AMVs) in clear areas with FY-2E IR2 window (11.59-12.79 ?m) channel imagery, where the traditional cloud motion wind technique fails. A new tracer selection procedure, which we call the temporal difference technique, is demonstrated in this paper. This technique makes it possible to infer low-level wind by tracking features in the moisture pattern that appear as brightness temperature ( T B) differences between consecutive sequences of 30-min-interval FY-2E IR2 images over cloud-free regions. The T B difference corresponding to a 10% change in water vapor density is computed with the Moderate Resolution Atmospheric Transmission (MODTRAN4) radiative transfer model. The total contribution from each of the 10 layers is analyzed under four typical atmospheric conditions: tropical, midlatitude summer, U.S. standard, and midlatitude winter. The peak level of the water vapor weighting function for the four typical atmospheres is assigned as a specific height to the T B "wind". This technique is valid over cloud-free ocean areas. The proposed algorithm exhibits encouraging statistical results in terms of vector difference (VD), speed bias (BIAS), mean vector difference (MVD), standard deviation (SD), and root-mean-square error (RMSE), when compared with the wind field of NCEP reanalysis data and rawinsonde observations.

Yang, Lu; Wang, Zhenhui; Chu, Yanli; Zhao, Hang; Tang, Min

2014-11-01

46

A Convective Vorticity Vector Associated With Tropical Convection: A 2D Cloud-Resolving Modeling Study  

NASA Technical Reports Server (NTRS)

Although dry/moist potential vorticity is a useful physical quantity for meteorological analysis, it cannot be applied to the analysis of 2D simulations. A convective vorticity vector (CVV) is introduced in this study to analyze 2D cloud-resolving simulation data associated with 2D tropical convection. The cloud model is forced by the vertical velocity, zonal wind, horizontal advection, and sea surface temperature obtained from the TOGA COARE, and is integrated for a selected 10-day period. The CVV has zonal and vertical components in the 2D x-z frame. Analysis of zonally-averaged and mass-integrated quantities shows that the correlation coefficient between the vertical component of the CVV and the sum of the cloud hydrometeor mixing ratios is 0.81, whereas the correlation coefficient between the zonal component and the sum of the mixing ratios is only 0.18. This indicates that the vertical component of the CVV is closely associated with tropical convection. The tendency equation for the vertical component of the CVV is derived and the zonally-averaged and mass-integrated tendency budgets are analyzed. The tendency of the vertical component of the CVV is determined by the interaction between the vorticity and the zonal gradient of cloud heating. The results demonstrate that the vertical component of the CVV is a cloud-linked parameter and can be used to study tropical convection.

Gao, Shou-Ting; Ping, Fan; Li, Xiao-Fan; Tao, Wei-Kuo

2004-01-01

47

A Directional & Adaptive Diamond Search by Adaptive Pattern Switching with a Predicted Motion Vector  

Microsoft Academic Search

ABSTRACT Wepropose,a simple ,fast block-matching ,algorithm (BMA) based ,on the ,direction of the ,predicted motion vector called directional & adaptive diamond search by adaptive pattern switching (DADS-APS). The proposal method has two sequential search steps, including 1) an initial search, and 2) a refinement search for the local area. Adaptive pattern switching (APS) is proposed,for the initial search and a

Jong-ho Kim; Byung-gyu Kim; Suk-kyu Song; Chang-sik Cho

2006-01-01

48

Kinematic differential geometry of a rigid body in spatial motion using dual vector calculus: PartI  

Microsoft Academic Search

In the present paper, the geometrical properties of a line trajectory in spatial motion are researched by using dual vector calculus. The invariants of a line trajectory generated by spatial motion are represented by that of the dual curve on the dual unit fixed sphere. Meanwhile the dual curvature theories or the dual geodetic Euler–Savary analogue is set up.Some special

Ö. Köse

2006-01-01

49

Transverse motion of high-speed barium clouds in the ionosphere  

NASA Technical Reports Server (NTRS)

Simulation results, based on a field-line-integrated, two-dimensional, electrostatic model, are presented for the motion of a barium cloud injected transverse to the geomagnetic field in the ionosphere at high speeds. It is found that the gross evaluation of injected plasma clouds depends on the initial conditions, as well as the nature of the background coupling. For a massive (mass of about 10 kg), orbital (velocity of about 5 km/s) release in the F region (350-450 km), it is found that plasma clouds can drift tens of kilometers across the magnetic field in tens of seconds after ionization. This type of release is similar to those which are planned for the Combined Release and Radiation Effects Satellite mission.

Mitchell, H. G., Jr.; Fedder, J. A.; Huba, J. D.; Zalesak, S. T.

1985-01-01

50

Characterizing uncertainty in the motion, future location and ash concentrations of volcanic plumes and ash clouds  

NASA Astrophysics Data System (ADS)

Forecasting the location and airborne concentrations of volcanic ash plumes and their dispersing clouds is complex and knowledge of the uncertainty in these forecasts is critical to assess and mitigate the hazards that could exist. We show the results from an interdisciplinary project that brings together scientists drawn from the atmospheric sciences, computer science, engineering, mathematics, and geology. The project provides a novel integration of computational and statistical modeling with a widely-used volcanic particle dispersion code, to provide quantitative measures of confidence in predictions of the motion of ash clouds caused by volcanic eruptions. We combine high performance computing and stochastic analysis, resulting in real time predictions of ash cloud motion that account for varying wind conditions and a range of model variables. We show how coupling a real-time model for ash dispersal, PUFF, with a volcanic eruption model, BENT, allows for the definition of the variability in the dispersal model inputs and hence classify the uncertainty that can then propagate for the ash cloud location and downwind concentrations. We additionally analyze the uncertainty in the numerical weather prediction forecast data used by the dispersal model by using ensemble forecasts and assess how this affects the downwind concentrations. These are all coupled together and by combining polynomical chaos quadrature with stochastic integration techniques, we provide a quantitative measure of the reliability (i.e. error) of those predictions. We show comparisons of the downwind height calculations and mass loadings with observations of ash clouds available from satellite remote sensing data. The aim is to provide a probabilistic forecast of location and ash concentration that can be generated in real-time and used by those end users in the operational ash cloud hazard assessment environment.

Webley, P.; Patra, A. K.; Bursik, M. I.; Pitman, E. B.; Dehn, J.; Singh, T.; Singla, P.; Stefanescu, E. R.; Madankan, R.; Pouget, S.; Jones, M.; Morton, D.; Pavolonis, M. J.

2013-12-01

51

Pacific-North American plate motion from very long baseline interferometry compared with motion inferred from magnetic anomalies, transform faults, and earthquake slip vectors  

NASA Technical Reports Server (NTRS)

Geodetic VLBI measurements were used to test whether the Pacific-North American plate velocity averaged over several years of direct observation (1984-1987) equals that averaged over millions of years. It was also tested whether this velocity parallels the San Andreas fault, transform faults and earthquake slip vectors in the Gulf of California, and earthquake slip vectors along the Queen Charlotte fault, along the Alaskan peninsula, and along the Kamchatkan peninsula. The VLBI data provide an estimate of the direction of plate motion that is independent of estimates from fault azimuths and earthquake slip vectors. The Euler vector determined from VLBI was found to be nearly identical to the Euler vector of plate motion model NUVEL-1, which is based on the trends of transform faults, earthquake slip vectors, and spreading rates from marine magnetic anomalies that average motion since 3 Ma. The velocity between the Pacific and North American plates averaged over the past several years equals or nearly equals its velocity averaged over the past several million years, the difference along their boundary nowhere exceeding 4 + or - 7 mm/yr.

Argus, Donald F.; Gordon, Richard G.

1990-01-01

52

The primer vector in linear, relative-motion equations. [spacecraft trajectory optimization  

NASA Technical Reports Server (NTRS)

Primer vector theory is used in analyzing a set of linear, relative-motion equations - the Clohessy-Wiltshire equations - to determine the criteria and necessary conditions for an optimal, N-impulse trajectory. Since the state vector for these equations is defined in terms of a linear system of ordinary differential equations, all fundamental relations defining the solution of the state and costate equations, and the necessary conditions for optimality, can be expressed in terms of elementary functions. The analysis develops the analytical criteria for improving a solution by (1) moving any dependent or independent variable in the initial and/or final orbit, and (2) adding intermediate impulses. If these criteria are violated, the theory establishes a sufficient number of analytical equations. The subsequent satisfaction of these equations will result in the optimal position vectors and times of an N-impulse trajectory. The solution is examined for the specific boundary conditions of (1) fixed-end conditions, two-impulse, and time-open transfer; (2) an orbit-to-orbit transfer; and (3) a generalized rendezvous problem. A sequence of rendezvous problems is solved to illustrate the analysis and the computational procedure.

1980-01-01

53

Bio-signal analysis system design with support vector machines based on cloud computing service architecture.  

PubMed

Today, many bio-signals such as Electroencephalography (EEG) are recorded in digital format. It is an emerging research area of analyzing these digital bio-signals to extract useful health information in biomedical engineering. In this paper, a bio-signal analyzing cloud computing architecture, called BACCA, is proposed. The system has been designed with the purpose of seamless integration into the National Taiwan University Health Information System. Based on the concept of. NET Service Oriented Architecture, the system integrates heterogeneous platforms, protocols, as well as applications. In this system, we add modern analytic functions such as approximated entropy and adaptive support vector machine (SVM). It is shown that the overall accuracy of EEG bio-signal analysis has increased to nearly 98% for different data sets, including open-source and clinical data sets. PMID:21096347

Shen, Chia-Ping; Chen, Wei-Hsin; Chen, Jia-Ming; Hsu, Kai-Ping; Lin, Jeng-Wei; Chiu, Ming-Jang; Chen, Chi-Huang; Lai, Feipei

2010-01-01

54

The application of cloud texture and motion derived from geostationary satellite images in rain estimation - a study on mid-latitude depressions  

Microsoft Academic Search

This paper presents the preliminary results of a rain rate estimation system that utilizes a combination of cloud appearance and motion that can be derived from Meteosat7. The proposed rain rate estimation system consists of three steps: feature selection, rain estimation and validation. In feature selection, cloud textural information is extracted and cloud motions are derived by a modified optical

Aimamorn Suvichakorn; Adrian Tatnall

2005-01-01

55

Vector subtraction using visual and extraretinal motion signals: a new look at efference copy and corollary discharge theories.  

PubMed

The question as to how the visual motion generated during eye movements can be 'canceled' to prevent an apparent displacement of the external world has a long history. The most popular theories (R. W. Sperry, 1950; E. von Holst & H. Mittelstaedt, 1950) lack specifics concerning the neural mechanisms involved and their loci. Here we demonstrate that a form of vector subtraction can be implemented in a biologically plausible way using cosine distributions of activity from visual motion sensors and from an extraretinal source such as a pursuit signal. We show that the net result of applying an 'efference copy/corollary discharge signal' in the form of a cosine distribution is a motion signal that is equivalent to that produced by vector subtraction. This vector operation provides a means of 'canceling' the effect of eye movements. It enables the extraretinal generated image motion to be correctly removed from the combined retinal-extraretinal motion, even in cases where the two motions do not share the same direction. In contrast to the established theories (efference copy and corollary discharge), our new model makes specific testable predictions concerning the location (the MT-MST/VIP areas) and nature of the eye-rotation cancellation stage (neural-based vector subtraction). PMID:19146325

Perrone, John A; Krauzlis, Richard J

2008-01-01

56

A vector-dyadic development of the equations of motion for N-coupled rigid bodies and point masses  

NASA Technical Reports Server (NTRS)

The equations of motion are derived, in vector-dyadic format, for a topological tree of coupled rigid bodies, point masses, and symmetrical momentum wheels. These equations were programmed, and form the basis for the general-purpose digital computer program N-BOD. A complete derivation of the equations of motion is included along with a description of the methods used for kinematics, constraint elimination, and for the inclusion of nongyroscope forces and torques acting external or internal to the system.

Frisch, H. P.

1974-01-01

57

Cloud speed sensor  

NASA Astrophysics Data System (ADS)

Changing cloud cover is a major source of solar radiation variability and poses challenges for the integration of solar energy. A compact and economical system that measures cloud motion vectors to estimate power plant ramp rates and provide short term solar irradiance forecasts is presented. The Cloud Speed Sensor (CSS) is constructed using an array of luminance sensors and high-speed data acquisition to resolve the progression of cloud passages across the sensor footprint. An embedded microcontroller acquires the sensor data and uses a cross-correlation algorithm to determine cloud motion vectors. The CSS was validated against an artificial shading test apparatus, an alternative method of cloud motion detection from ground measured irradiance (Linear Cloud Edge, LCE), and a UC San Diego Sky Imager (USI). The CSS detected artificial shadow directions and speeds to within 15 and 6% accuracy, respectively. The CSS detected (real) cloud directions and speeds without average bias and with average weighted root mean square difference of 22° and 1.9 m s-1 when compared to USI and 33° and 1.5 m s-1 when compared to LCE results.

Fung, V.; Bosch, J. L.; Roberts, S. W.; Kleissl, J.

2013-10-01

58

Vectors  

NSDL National Science Digital Library

This lesson was created by Larry Friesen and Anne Gillis for Butler Community College. It will help physics and calculus students differentiate between the uses of vectors in mathematics vs. physics. This website provides two PDF documents that give detailed lessons about vectors, including an overview of terminology, sample problems, and an HTML worksheet is also provided. For educators or students, this site offers well laid-out lessons and/or practice with vectors.

Friesen, Larry; Gillis, Anne

2008-04-18

59

vectors  

NSDL National Science Digital Library

The word vector comes from the Latin term vehere, to carry. In Biology, a vector is an agent which carries disease, such as a mosquito carrying infected blood from one patient to the next. In physics, a vector is a quantity which has both a magnitude and a direction associated with it. The most commonly used example of vectors in everyday life is velocity. When you drive your car, your speedometer tells you the speed of your car, but it doesn't tell you where you are going. The combination of both where you are going and how fast you are going there is your car's velocity.

Joiner, David; The Shodor Education Foundation, Inc.

60

Impact of Kalpana-1 retrieved atmospheric motion vectors on mesoscale model forecast during summer monsoon 2011  

NASA Astrophysics Data System (ADS)

The atmospheric motion vectors (AMVs) retrieved from multi-spectral geostationary satellites form a very crucial input to improve the initial conditions of numerical weather prediction (NWP) models at all operational agencies throughout the globe. With the recent update of operational AMV retrieval algorithm using infrared, water vapor, and visible channels of Indian geostationary meteorological satellite Kalpana-1, an attempt has been made to assess the impact of AMVs in the NWP models. In this study, the impact of Kalpana-1 AMVs is assessed by assimilating them in the Weather Research and Forecasting (WRF) model using three-dimensional variational data assimilation method during the entire month of July 2011 over the Indian Ocean region. Apart from Kalpana-1 AMVs, the other AMVs available from Global Telecommunications System (GTS) are also assimilated to generate the WRF model analyses. After the initial verification of WRF model analyses, the 12-h wind forecasts from the WRF model are compared with National Centers for Environmental Prediction Global Data Assimilation System final analyses. The assimilation of Kalpana-1 AMVs shows positive impact in 12-h wind forecast over the tropical region in the upper troposphere. Similar results are obtained when other AMVs available through GTS are used for assimilation, though the magnitude of positive impact of Kalpana-1 AMVs is slightly higher over tropical region. The 24-h rainfall forecasts are also improved over the Western India and the Bay of Bengal region, when Kalpana-1 AMVs are used for assimilation against control experiments.

Kaur, Inderpreet; Kumar, Prashant; Deb, S. K.; Kishtawal, C. M.; Pal, P. K.; Kumar, Raj

2014-06-01

61

ON THE INTERPRETATION OF RECENT PROPER MOTION DATA FOR THE LARGE MAGELLANIC CLOUD  

SciTech Connect

Recent observational studies using the Hubble Space Telescope have derived the center-of-mass proper motion (CMPM) of the Large Magellanic Cloud (LMC). Although these studies carefully treated both rotation and perspective effects in deriving the proper motion (PM) for each of the sampled fields, they did not consider the effects of local random motion in the derivation. This means that the average PM of the fields (i.e., the observed CMPM) could significantly deviate from the true CMPM, because the effect of local random motion cannot be close to zero in making the average PM for the small number of fields ({approx}10). We discuss how significantly the observationally derived CMPM can deviate from the true CMPM by applying the same method as used in the observations for a dynamical model of the LMC with a known true CMPM. We find that the deviation can be as large as {approx}50 km s{sup -1} ({approx}0.21 mas yr{sup -1}), if the LMC has a thick disk and a maximum circular velocity of {approx}120 km s{sup -1}. We also find that the deviation depends both on the total number of sampled fields and on the structure and kinematics of the LMC. We therefore suggest that there is a possibility that the observed CMPM of the LMC deviates from the true one to some extent. We also show that a simple mean of PM for a large number of LMC fields ({approx}1000) can be much closer to the true CMPM.

Bekki, Kenji [ICRAR, M468, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009 (Australia)

2011-03-20

62

Parallel Implementations of Block-Based Motion Vector Estimation for Video Compression on Four Parallel Processing Systems  

Microsoft Academic Search

Parallel algorithms, based on a distributed memory machine model, for an exhaustive search technique for motion vector estimation in video compression are being designed and evaluated. Results from the execution on a 16,384 processor MasPar MP-1 (an SIMD machine), a 140 node Intel Paragon XP\\/S and a 16 node IBM SP2 (two M IMD machines), and the 16 processor PASM

Min Tan; Janet M. Siegel; Howard Jay Siegel

1999-01-01

63

THE PROPER MOTION OF THE MAGELLANIC CLOUDS. I. FIRST RESULTS AND DESCRIPTION OF THE PROGRAM  

SciTech Connect

We present the first results of a ground-based program to determine the proper motion of the Magellanic Clouds (MCs) relative to background quasars (QSO), being carried out using the Irenee du Pont 2.5 m telescope at Las Campanas Observatory, Chile. Eleven QSO fields have been targeted in the Small Magellanic Cloud (SMC) over a time base of six years, and with seven epochs of observation. One quasar field was targeted in the Large Magellanic Cloud (LMC), over a time base of five years, and with six epochs of observation. The shorter time base in the case of the LMC is compensated by the much larger amount of high-quality astrometry frames that could be secured for the LMC quasar field (124 frames), compared to the SMC fields (an average of roughly 45 frames). In this paper, we present final results for field Q0557-6713 in the LMC and field Q0036-7227 in the SMC. From field Q0557-6713, we have obtained a measured proper motion of {mu}{sub {alpha}}cos {delta} = +1.95 {+-} 0.13 mas yr{sup -1}, {mu}{sub {delta}} = +0.43 {+-} 0.18 mas yr{sup -1} for the LMC. From field Q0036-7227, we have obtained a measured proper motion of {mu}{sub {alpha}} cos{delta} = +0.95 {+-} 0.29 mas yr{sup -1}, {mu}{sub {delta}} = -1.14 {+-} 0.18 mas yr{sup -1} for the SMC. Although we went through the full procedure for another SMC field (QJ0036-7225), on account of unsolvable astrometric difficulties caused by blending of the QSO image, it was impossible to derive a reliable proper motion. Current model rotation curves for the plane of the LMC indicate that the rotational velocity (V {sub rot}) at the position of LMC field Q0557-6713 can be as low as 50 km s{sup -1}, or as high as 120 km s{sup -1}. A correction for perspective and rotation effects leads to a center of mass proper motion for the LMC of {mu}{sub {alpha}} cos{delta} = +1.82 {+-} 0.13 mas yr{sup -1}, {mu}{sub {delta}} = +0.39 {+-} 0.15 mas yr{sup -1} (V {sub rot} = 50 km s{sup -1}), and to {mu}{sub {alpha}} cos{delta} = +1.61 {+-} 0.13 mas yr{sup -1}, {mu}{sub {delta}} = +0.60 {+-} 0.15 mas yr{sup -1} (V {sub rot} = 120 km s{sup -1}). Assuming that the SMC has a disk-like central structure, but that it does not rotate, we obtain a center of mass proper motion for the SMC of {mu}{sub {alpha}} cos{delta} = +1.03 {+-} 0.29 mas yr{sup -1}, {mu}{sub {delta}} = -1.09 {+-} 0.18 mas yr{sup -1}. Our results are in reasonable agreement with most previous determinations of the proper motion of the MCs, including recent Hubble Space Telescope measurements. Complemented with published values of the radial velocity of the centers of the LMC and SMC, we have used our proper motions to derive the galactocentric (gc) velocity components of the MCs. For the LMC, we obtain V {sub gc,t} = +315 {+-} 20 km s{sup -1}, V {sub gc,r} = +86 {+-} 17 km s{sup -1} (V {sub rot} = 50 km s{sup -1}), and V {sub gc,t} = +280 {+-} 24 km s{sup -1}, V {sub gc,r} = +94 {+-} 17 km s{sup -1} (V {sub rot} = 120 km s{sup -1}). For the SMC, we obtain V {sub gc,t} = +258 {+-} 50 km s{sup -1}, V {sub gc,r} = +20 {+-} 44 km s{sup -1}. These velocities imply a relative velocity between the LMC and SMC of 84 {+-} 50 km s{sup -1}, for V {sub rot,LMC} = 50 km s{sup -1}, and 62 {+-} 63 km s{sup -1} for V {sub rot,LMC} = 120 km s{sup -1}. Albeit our large errors, these values are not inconsistent with the standard assumption that the MCs are gravitationally bound to each other.

Costa, Edgardo; Mendez, Rene A.; Moyano, Maximiliano [Departamento de AstronomIa, Universidad de Chile, Casilla 36-D, Santiago (Chile); Pedreros, Mario H. [Departamento de Fisica, Universidad de Tarapaca, Casilla 7-D, Arica (Chile); Gallart, Carme; Noel, Noelia [Instituto de AstrofIsica de Canarias, Tenerife 38200, Islas Canarias (Spain); Baume, Gustavo [Facultad de Ciencias Astronomicas y GeofIsicas de la UNLP, IALP-CONICET, Paseo El Bosque s/n, La Plata (Argentina); Carraro, Giovanni [European Southern Observatory, Alonso de Cordova 3107, Santiago (Chile)], E-mail: costa@das.uchile.cl, E-mail: rmendez@das.uchile.cl, E-mail: mmoyano@das.uchile.cl, E-mail: mmoyano@mpia-hd.mpg.de, E-mail: mpedrero@uta.cl, E-mail: carme@iac.es, E-mail: noelia@iac.es, E-mail: gbaume@gmail.com, E-mail: gcarraro@eso.org

2009-05-15

64

Geodesy by radio interferometry - Determination of vector motions for sites in the western United States  

NASA Technical Reports Server (NTRS)

The use of VBLI to study plate tectonic motion, plate boundary deformation, earth dynamics, and the crustal motions in the western U.S. is discussed. Results from dual frequency (S and X band) mobile VLBI experiments between October 1982 and February 1987 are presented. It is suggested that significant northwest motion is occurring well east of the San Andreas fault.

Gordon, David

1988-01-01

65

Clouds  

NSDL National Science Digital Library

This lesson combines science, English and art to teach the students information about clouds and to encourage abstract thinking through writing and painting. Students will first read and discuss the information about clouds. Next, they will choose a type of cloud and write a composition about it. Then they do a painting of their cloud and attach their composition.

1998-01-01

66

Airborne Doppler wind lidar to evaluate cloud and water vapor motion vectors from GIFTS  

NASA Astrophysics Data System (ADS)

Planning is in progress to launch a much improved temperature and moisture sounder called GIFTS- Geosynchronous Imaging Fourier Transform Spectrometer. The IPO of the NPOESS had developed an Airborne Sounder Test bed, NAST, to simulate GIFTS data products. The IPO has also developed an airborne Doppler wind lidar (Twin Otter Doppler Wind Lidar - TODWL) to provide accurate wind profiles over the oceans to enable evaluation of the GIFTS and other space-based wind observing systems. This presentation reports on the first in a series of TODWL under flights of the NAST flown on NASA"s ER-2.

Emmitt, G. David; Smith, William L., Sr.

2003-12-01

67

Roll tracking effects of G-vector tilt and various types of motion washout  

NASA Technical Reports Server (NTRS)

In a dogfight scenario, the task was to follow the target's roll angle while suppressing gust disturbances. All subjects adopted the same behavioral strategies in following the target while suppressing the gusts, and the MFP-fitted math model response was generally within one data symbol width. The results include the following: (1) comparisons of full roll motion (both with and without the spurious gravity tilt cue) with the static case. These motion cues help suppress disturbances with little net effect on the visual performance. Tilt cues were clearly used by the pilots but gave only small improvement in tracking errors. (2) The optimum washout (in terms of performance close to real world, similar behavioral parameters, significant motion attenuation (60 percent), and acceptable motion fidelity) was the combined attenuation and first-order washout. (3) Various trends in parameters across the motion conditions were apparent, and are discussed with respect to a comprehensive model for predicting adaptation to various roll motion cues.

Jex, H. R.; Magdaleno, R. E.; Junker, A. M.

1978-01-01

68

Primer vector theory applied to the linear relative-motion equations. [for N-impulse space trajectory optimization  

NASA Technical Reports Server (NTRS)

Prime vector theory is used in analyzing a set of linear relative-motion equations - the Clohessy-Wiltshire (C/W) equations - to determine the criteria and necessary conditions for an optimal N-impulse trajectory. The analysis develops the analytical criteria for improving a solution by: (1) moving any dependent or independent variable in the initial and/or final orbit, and (2) adding intermediate impulses. If these criteria are violated, the theory establishes a sufficient number of analytical equations. The subsequent satisfaction of these equations will result in the optimal position vectors and times of an N-impulse trajectory. The solution is examined for the specific boundary conditions of: (1) fixed-end conditions, two impulse, and time-open transfer; (2) an orbit-to-orbit transfer; and (3) a generalized renezvous problem.

Jezewski, D.

1980-01-01

69

Clouds  

NSDL National Science Digital Library

In this scenario-based, problem-based learning (PBL) activity, students investigate cloud formation, cloud classification, and the role of clouds in heating and cooling the Earth; how to interpret TRMM (Tropical Rainfall Measuring Mission) images and data; and the role clouds play in the Earthâs radiant budget and climate. Students assume the role of weather interns in a state climatology office and assist a frustrated student in a homework assignment. Learning is supported by a cloud in a bottle and an ice-albedo demonstration, a three-day cloud monitoring outdoor activity, and student journal assignments. The hands-on activities require two 2-liter soda bottles, an infrared heat lamp, and two thermometers. The resource includes a teacher's guide, questions and answer key, assessment rubric, glossary, and an appendix with information supporting PBL in the classroom.

70

Clouds  

NSDL National Science Digital Library

Created by Carl Wozniak, Clouds attempts to make the study of clouds and the processes of cloud formation more accessible for elementary and early secondary classroom study. The site accomplishes this by breaking information down into five sections, complemented by both descriptive text and relevant pictures. Pictures and graphics are perhaps the most classroom-friendly section of the site, as they are intended for use in non-profit, educational settings. Another primary section of the site is the glossary, aimed at explaining cloud-related terminology at a very simplistic level, understandable by younger students.

1999-01-01

71

Elucidation of Intersection Distribution in Motion Vectors from Successive Echocardiograms and its Application for Heart Diseases  

NASA Astrophysics Data System (ADS)

The expertise and experience are required for an examiner to diagnose using echocardiogram. To evaluate the malfunction of motion in the heart, many research of image processing method have developed but they were useful only for expert examiners. To bring benefit of portability in echography to wider medical staff, we have developed software to recognize the synchronous motion of heart by calculating intersection points between the instantaneous velocities of ventricular wall flow from successive echocardiograms. In addition, we defined intersection index to evaluate synchronous motion of heart by dividing echogram into small regions to calculate distribution of intersection points. Finally we introduced gravity point of the distribution and calculated its trajectory through a heartbeat. As the result, fluctuation of the gravity point in heart disease patients was strongly observed where the trajectory of the gravity point was stable in normal subjects.

Masuda, Kohji; Takahashi, Rui; Uchibori, Shun; Matsuura, Hirotaka; Yoshinaga, Takashi

72

Morhphological Shape Representation of Segmented Images Based on Temporally Modeled Motion Vectors  

Microsoft Academic Search

Region based coding schemes are among the most promising compression techniques for very low bit-rates. They consist of image segmentation, contour and texture coding. In this paper, a new shape representation for segmented images based on the geodesic morphological skeleton is presented. It is used for the coding of contour prediction residues obtained after motion compensation based on temporally modeled

Patrick Brigger; Serge Ayer; Murat Kunt

1994-01-01

73

THIRD-EPOCH MAGELLANIC CLOUD PROPER MOTIONS. I. HUBBLE SPACE TELESCOPE/WFC3 DATA AND ORBIT IMPLICATIONS  

SciTech Connect

We present proper motions for the Large and Small Magellanic Clouds (LMC and SMC) based on three epochs of Hubble Space Telescope data, spanning a {approx}7 yr baseline, and centered on fields with background QSOs. The first two epochs, the subject of past analyses, were obtained with ACS/HRC, and have been reanalyzed here. The new third epoch with WFC3/UVIS increases the time baseline and provides better control of systematics. The three-epoch data yield proper-motion random errors of only 1%-2% per field. For the LMC this is sufficient to constrain the internal proper-motion dynamics, as will be discussed in a separate paper. Here we focus on the implied center-of-mass proper motions: {mu} {sub W,LMC} = -1.910 {+-} 0.020 mas yr{sup -1}, {mu} {sub N,LMC} = 0.229 {+-} 0.047 mas yr{sup -1}, and {mu} {sub W,SMC} = -0.772 {+-} 0.063 mas yr{sup -1}, {mu} {sub N,SMC} = -1.117 {+-} 0.061 mas yr{sup -1}. We combine the results with a revised understanding of the solar motion in the Milky Way to derive Galactocentric velocities: v {sub tot,LMC} = 321 {+-} 24 km s{sup -1} and v {sub tot,SMC} = 217 {+-} 26 km s{sup -1}. Our proper-motion uncertainties are now dominated by limitations in our understanding of the internal kinematics and geometry of the Clouds, and our velocity uncertainties are dominated by distance errors. Orbit calculations for the Clouds around the Milky Way allow a range of orbital periods, depending on the uncertain masses of the Milky Way and LMC. Periods {approx}< 4 Gyr are ruled out, which poses a challenge for traditional Magellanic Stream models. First-infall orbits are preferred (as supported by other arguments as well) if one imposes the requirement that the LMC and SMC must have been a bound pair for at least several Gyr.

Kallivayalil, Nitya [Yale Center for Astronomy and Astrophysics, 260 Whitney Ave, New Haven, CT 06511 (United States)] [Yale Center for Astronomy and Astrophysics, 260 Whitney Ave, New Haven, CT 06511 (United States); Van der Marel, Roeland P.; Anderson, Jay [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)] [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Besla, Gurtina [Columbia Astrophysics Laboratory, 1027 Pupin Hall, MC 5247, New York, NY 10027 (United States)] [Columbia Astrophysics Laboratory, 1027 Pupin Hall, MC 5247, New York, NY 10027 (United States); Alcock, Charles, E-mail: nitya.kallivayalil@yale.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)] [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2013-02-20

74

Constants of motion for the planar orbit of a charged particle in a static and uniform magnetic field: the magnetic Laplace–Runge–Lenz vector  

NASA Astrophysics Data System (ADS)

In this paper we introduce an alternative approach to studying the motion of a planar charged particle subject to a static uniform magnetic field. It is well known that an electric charge under a uniform magnetic field has a planar motion if its initial velocity is perpendicular to the magnetic field. Although some constants of motion (CsM), as the energy and the angular momentum, have been widely discussed for this system, others have been neglected. We find that the angular momentum, the generator of the magnetic translations and the magnetic Laplace–Runge–Lenz vector are CsM for this particular system. We show also that these three quantities form an orthogonal basis of vectors. The present work addresses many aspects of the motion of a charged particle in a magnetic field that should be useful for students and tutors of the classical mechanics courses at the senior undergraduate level.

Velasco-Martínez, D.; Ibarra-Sierra, V. G.; Sandoval-Santana, J. C.; Kunold, A.; Cardoso, J. L.

2014-09-01

75

Structure and Semi-Fluid Motion Analysis of Stereoscopic Satellite Images for Cloud Tracking  

Microsoft Academic Search

Time-varying multispectral observations of cloudsfrom meteorological satellites are used to estimatecloud-top heights (structure) and cloud winds (semifluidmotion). Stereo image pairs over several timesteps were acquired by two geostationary satellites withsynchronized scanning instruments. Cloud-top heightestimation from these image pairs is performed usingan improved automatic stereo analysis algorithm on amassively parallel Maspar computer with 16K processors.A new category of...

Kannappan Palaniappan; Chandra Kambhamettu; Frederick Hasler; Dmitry B. GoldgofS

1995-01-01

76

Vector constraints on western U.S. deformation from space geodesy, neotectonics, and plate motions  

NASA Technical Reports Server (NTRS)

The rate-of-slip vector on the San Andreas fault in central California estimated from geodetic and Holocene geological data is inconsistent with the prediction of rigid plate models such as RM2. This well-known 'San Andreas discrepancy' is diagnostic of plate deformation distributed both east of the fault in the Basin and Range and west of the fault along the California continental margin. Constraints on the integrated deformation rates across these two regions consistent with: (1) the kinematical boundary conditions imposed by the rigid plate model; (2) neotectonic and paleoseismic estimates of deformation rates; (3) ground-based geodetic measurements; and (4) rates of change observed by very long baseline interferometry along seven baselines to western U.S. sites are constructed. The space-geodetic data on Basin and Range extension taken over a 4-year interval are compatible with geological observations averaged over the Holocene; the best estimate of its integrated deformation rate, provided by the joint inversion of both data types, is 9.7 + or - 2.1 mm/yr, N 56 deg W + or - 10 deg, too small and in the wrong direction to account entirely for the San Andreas discrepancy. The integral of this deformation, estimated by subtracting the Basin and Range contribution from the discrepancy vector, requires significant right-lateral shear parallel to the San Andreas (13 + or - 5 mm/yr) and some compression perpendicular to it (9 + or - 3 mm/yr).

Minster, J. Bernard; Jordan, Thomas H.

1987-01-01

77

Fourier transform ion cyclotron resonance mass resolution and dynamic range limits calculated by computer modeling of ion cloud motion.  

PubMed

Particle-in-Cell (PIC) ion trajectory calculations provide the most realistic simulation of Fourier transform ion cyclotron resonance (FT-ICR) experiments by efficient and accurate calculation of the forces acting on each ion in an ensemble (cloud), including Coulomb interactions (space charge), the electric field of the ICR trap electrodes, image charges on the trap electrodes, the magnetic field, and collisions with neutral gas molecules. It has been shown recently that ion cloud collective behavior is required to generate an FT-ICR signal and that two main phenomena influence mass resolution and dynamic range. The first is formation of an ellipsoidal ion cloud (termed "condensation") at a critical ion number (density), which facilitates signal generation in an FT-ICR cell of arbitrary geometry because the condensed cloud behaves as a quasi-ion. The second phenomenon is peak coalescence. Ion resonances that are closely spaced in m/z coalesce into one resonance if the ion number (density) exceeds a threshold that depends on magnetic field strength, ion cyclotron radius, ion masses and mass difference, and ion initial spatial distribution. These two phenomena decrease dynamic range by rapid cloud dephasing at small ion density and by cloud coalescence at high ion density. Here, we use PIC simulations to quantitate the dependence of coalescence on each critical parameter. Transitions between independent and coalesced motion were observed in a series of the experiments that systematically varied ion number, magnetic field strength, ion radius, ion m/z, ion m/z difference, and ion initial spatial distribution (the present simulations begin from elliptically-shaped ion clouds with constant ion density distribution). Our simulations show that mass resolution is constant at a given magnetic field strength with increasing ion number until a critical value (N) is reached. N dependence on magnetic field strength, cyclotron radius, ion mass, and difference between ion masses was determined for two ion ensembles of different m/z, equal abundance, and equal cyclotron radius. We find that N and dynamic range depend quadratically on magnetic field strength in the range 1-21 Tesla. Dependences on cyclotron radius and ?m/z are linear. N depends on m/z as (m/z)(-2). Empirical expressions for mass resolution as a function of each of the experimental parameters are presented. Here, we provide the first exposition of the origin and extent of trade-off between FT-ICR MS dynamic range and mass resolution (defined not as line width, but as the separation between the most closely resolved masses). PMID:22033889

Vladimirov, Gleb; Hendrickson, Christopher L; Blakney, Greg T; Marshall, Alan G; Heeren, Ron M A; Nikolaev, Eugene N

2012-02-01

78

A study of stability indexes and vertical motion in relation to convective clouds over Texas  

E-print Network

for the degree of MASTER OF SCIENCE January 1970 Major Subject: Meteorology A STUDY OF STABILITY INDEXES AND VERTICAL NOTION IN RELATION TO CONVECTIVE CLOUDS OVER TEXAS A Thesi. s by DAVID NICNAEL BOOTH Approved as to style and content by: airman o... it ee ea of p men January 1970 ABSTRACT A Study of Stability Indexes and Vertical Notion in Relation to Convective Clouds Over Texas. (January 1970) David N. Booth, B. S, , T xas MN University Directed by: Dr, James R, Scoggins Nine stability...

Booth, David Michael

2012-06-07

79

Correlation of Damage of Steel Moment-Resisting Frames to a Vector-valued Ground Motion Parameter Set that includes Energy Demands: Collaborative Research of the  

E-print Network

organizations for post-earthquake emergency resource management. This study is empirical in nature. We considerCorrelation of Damage of Steel Moment-Resisting Frames to a Vector-valued Ground Motion Parameter accurate assessment of seismic performance of buildings is of paramount importance for designing new safer

Manuel, Lance

80

THE M31 VELOCITY VECTOR. I. HUBBLE SPACE TELESCOPE PROPER-MOTION MEASUREMENTS  

SciTech Connect

We present the first proper-motion (PM) measurements for the galaxy M31. We obtained new V-band imaging data with the Hubble Space Telescope ACS/WFC and the WFC3/UVIS instruments of three fields: a spheroid field near the minor axis, an outer disk field along the major axis, and a field on the Giant Southern Stream. The data provide five to seven year time baselines with respect to pre-existing deep first-epoch observations of the same fields. We measure the positions of thousands of M31 stars and hundreds of compact background galaxies in each field. High accuracy and robustness is achieved by building and fitting a unique template for each individual object. The average PM for each field is obtained from the average motion of the M31 stars between the epochs with respect to the background galaxies. For the three fields, the observed PMs ({mu}{sub W}, {mu}{sub N}) are, in units of mas yr{sup -1}, (- 0.0458, -0.0376) {+-} (0.0165, 0.0154), (- 0.0533, -0.0104) {+-} (0.0246, 0.0244), and (- 0.0179, -0.0357) {+-} (0.0278, 0.0272), respectively. The ability to average over large numbers of objects and over the three fields yields a final displacement accuracy of a few thousandths of a pixel, corresponding to only 12 {mu}as yr{sup -1}. This is comparable to what has been achieved for other Local Group galaxies using Very Long Baseline Array observations of water masers. Potential systematic errors are controlled by an analysis strategy that corrects for detector charge transfer inefficiency, spatially and time-dependent geometric distortion, and point-spread function variations. The robustness of the PM measurements and uncertainties are supported by the fact that data from different instruments, taken at different times and with different telescope orientations, as well as measurements of different fields, all yield statistically consistent results. Papers II and III of this series explore the implications of the new measurements for our understanding of the history, future, and mass of the Local Group.

Sohn, Sangmo Tony; Anderson, Jay; Van der Marel, Roeland P., E-mail: tsohn@stsci.edu [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

2012-07-01

81

Jupiter cloud composition, stratification, convection, and wave motion: a view from new horizons.  

PubMed

Several observations of Jupiter's atmosphere made by instruments on the New Horizons spacecraft have implications for the stability and dynamics of Jupiter's weather layer. Mesoscale waves, first seen by Voyager, have been observed at a spatial resolution of 11 to 45 kilometers. These waves have a 300-kilometer wavelength and phase velocities greater than the local zonal flow by 100 meters per second, much higher than predicted by models. Additionally, infrared spectral measurements over five successive Jupiter rotations at spatial resolutions of 200 to 140 kilometers have shown the development of transient ammonia ice clouds (lifetimes of 40 hours or less) in regions of strong atmospheric upwelling. Both of these phenomena serve as probes of atmospheric dynamics below the visible cloud tops. PMID:17932284

Reuter, D C; Simon-Miller, A A; Lunsford, A; Baines, K H; Cheng, A F; Jennings, D E; Olkin, C B; Spencer, J R; Stern, S A; Weaver, H A; Young, L A

2007-10-12

82

Voyager 2 observations of Saturn's northern mid-latitude cloud features - Morphology, motions, and evolution  

NASA Technical Reports Server (NTRS)

Voyager 2 images provide a basis for detailed study of the morphology and circulation of Saturn's northern midlatitudes. Both Saturn's large-scale cloud bands and the distribution of its local cloud features have a characteristic zonal organization. The region between 30 N and 45 N contains two oppositely directed jets in close proximity, with many bright, active features in the westward jet, and an unusual ribbonlike wave feature encircling the planet in the eastward jet. Several of the smaller features within the westward jet do not remain at fixed latitudes and interact with each other. One group of v-shaped features is found to have periods of high activity correlated with the passage of a cyclonic bright spot. The ribbon wave was Fourier analyzed to determine its spectral composition. The greatest power is near wave number 9, with significant additional peaks appearing at planetary wave numbers 19, 25-27, 35-38, and 47-51. The phase velocity increases with wave number but is not well described by a Rossby-Haurwitz dispersion relation. The curvature of the mean wind profile obtained from cloud tracking indicates that the westward jet exceeds the standard barotropic instability condition, while the eastward jet marginally exceeds the deep-circulation instability condition of Ingersoll and Pollard (1982). The rms eddy velocities on Saturn are less than half as large as those observed on Jupiter.

Sromovsky, L. A.; Revercomb, H. E.; Krauss, R. J.; Suomi, V. E.

1983-01-01

83

Motion.  

ERIC Educational Resources Information Center

This issue of Exploratorium Magazine focuses on the topic of motion. Contents include: (1) "First Word" (Zach Tobias); (2) "Cosmic Collisions" (Robert Irion); (3) "The Mobile Cell" (Karen E. Kalumuck); (4) "The Paths of Paths" (Steven Vogel); (5) "Fragments" (Pearl Tesler); (6) "Moving Pictures" (Amy Snyder); (7) "Plants on the Go" (Katharine…

Brand, Judith, Ed.

2002-01-01

84

ULTRAVIOLET INDUCED MOTION OF A FLUORESCENT DUST CLOUD IN AN ARGON DIRECT CURRENT GLOW DISCHARGE PLASMA  

SciTech Connect

Dusty plasmas consist of electrons, ions, neutrals and nm-?m sized particles commonly referred to as dust. In man-made plasmas this dust may represent impurities in a tokamak or plasma etching processing. In astrophysical plasmas this dust forms structures such as planetary rings and comet tails. To study dusty plasma dynamics an experiment was designed in which a 3:1 silica (<5 ?m diameter) and fl uorescent dust mixture was added to an argon DC glow discharge plasma and exposed to UV radiation. This fl uorescent lighting technique offers an advantage over laser scattering (which only allows two-dimensional slices of the cloud to be observed) and is simpler than scanning mirror techniques or particle image velocimetry. Under typical parameters (P=150 mTorr, V anode= 100 V, Vcathode= -400 V, Itotal < 2mA) when the cloud is exposed to the UV light (100W, ? = 365 nm) the mixture fl uoresces, moves ~2mm towards the light source and begins rotating in a clockwise manner (as seen from the cathode). By calibrating a UV lamp and adjusting the relative intensity of the UV with a variable transformer it was found that both translational and rotational velocities are a function of UV intensity. Additionally, it was determined that bulk cloud rotation is not seen when the dust tray is not grounded while bulk translation is. This ongoing experiment represents a novel way to control contamination in man-made plasmas and a path to a better understanding of UV-bathed plasma systems in space..

Hvasta, M.G.; and Zwicker, A.

2008-01-01

85

Nowcasting of cloud cover with MSG  

NASA Astrophysics Data System (ADS)

In this poster, an algorithm is shown to detect water and ice clouds seperately and forecast their developement for the next timesteps. It is based on Meteosat SEVIRI (Spinning Enhanced Visible and Infrared Imager) data from almost all channels with a timestep of 15 minutes. In order to derive cloud cover, optical depth and height of ice clouds the "Cirrus Optical properties derived from CALIOP and SEVIRI during day and night" (COCS) algorithm (Kox 2012) was used. For the determination of water clouds a cloud mask was developed. For a most accurate forecast the detected clouds are divided into two groups, convective and advective, and afterwards treated seperately. The forecast of advective clouds basically takes place with the pyramidal matcher ("optical flow" technique, Zinner et al. 2008) by determining a motion vector field from two consecutive images. The clouds are then classified as objects with similar properties (optical depth, temperature) and a forecast for each object separately is then performed. For the detection of convective clouds the tracking and nowcasting algorithm Cb-TRAM (CumulonimBus TRacking And Monitoring, Zinner et al. 2008) is used, which divides convection into three stages. The further development und thus the forecast of these clouds is dependent of the current stage. Appications to selected case studies will be shown.

Sirch, Tobias; Bugliaro, Luca

2014-05-01

86

Discrimination of waist motions based on surface EMG for waist power assist suit using support vector machine  

Microsoft Academic Search

This paper presents a signal processing for discrimination of waist motions including forward and backward bendings and right and left twists. The system is planed to implement to a waist power assist suit that physically helps a caregiver in personal care tasks. The motion discrimination is based on surface electromyogram (SEMG) of right and left erector spinae muscles that dominate

Kouta Kashiwagi; Takashi Nakakuki; Chiharu Ishii

2011-01-01

87

Realistic modeling of ion cloud motion in a Fourier transform ion cyclotron resonance cell by use of a particle-in-cell approach.  

PubMed

Using a 'Particle-In-Cell' approach taken from plasma physics we have developed a new three-dimensional (3D) parallel computer code that today yields the highest possible accuracy of ion trajectory calculations in electromagnetic fields. This approach incorporates coulombic ion-ion and ion-image charge interactions into the calculation. The accuracy is achieved through the implementation of an improved algorithm (the so-called Boris algorithm) that mathematically eliminates cyclotron motion in a magnetic field from digital equations for ion motion dynamics. It facilitates the calculation of the cyclotron motion without numerical errors. At every time-step in the simulation the electric potential inside the cell is calculated by direct solution of Poisson's equation. Calculations are performed on a computational grid with up to 128 x 128 x 128 nodes using a fast Fourier transform algorithm. The ion populations in these simulations ranged from 1000 up to 1,000,000 ions. A maximum of 3,000,000 time-steps were employed in the ion trajectory calculations. This corresponds to an experimental detection time-scale of seconds. In addition to the ion trajectories integral time-domain signals and mass spectra were calculated. The phenomena observed include phase locking of particular m/z ions (high-resolution regime) inside larger ion clouds. A focus was placed on behavior of a cloud of ions of a single m/z value to understand the nature of Fourier transform ion cyclotron resonance (FTICR) resolution and mass accuracy in selected ion mode detection. The behavior of two and three ion clouds of different but close m/z was investigated as well. Peak coalescence effects were observed in both cases. Very complicated ion cloud dynamics in the case of three ion clouds was demonstrated. It was found that magnetic field does not influence phase locking for a cloud of ions of a single m/z. The ion cloud evolution time-scale is inversely proportional to magnetic field. The number of ions needed for peak coalescence depends quadratically on the magnetic field. PMID:17944004

Nikolaev, Eugene N; Heeren, Ron M A; Popov, Alexander M; Pozdneev, Alexander V; Chingin, Konstantin S

2007-01-01

88

Automatic generation of time resolved motion vector fields of coronary arteries and 4D surface extraction using rotational x-ray angiography  

NASA Astrophysics Data System (ADS)

Rotational coronary angiography provides a multitude of x-ray projections of the contrast agent enhanced coronary arteries along a given trajectory with parallel ECG recording. These data can be used to derive motion information of the coronary arteries including vessel displacement and pulsation. In this paper, a fully automated algorithm to generate 4D motion vector fields for coronary arteries from multi-phase 3D centerline data is presented. The algorithm computes similarity measures of centerline segments at different cardiac phases and defines corresponding centerline segments as those with highest similarity. In order to achieve an excellent matching accuracy, an increasing number of bifurcations is included as reference points in an iterative manner. Based on the motion data, time-dependent vessel surface extraction is performed on the projections without the need of prior reconstruction. The algorithm accuracy is evaluated quantitatively on phantom data. The magnitude of longitudinal errors (parallel to the centerline) reaches approx. 0.50 mm and is thus more than twice as large as the transversal 3D extraction errors of the underlying multi-phase 3D centerline data. It is shown that the algorithm can extract asymmetric stenoses accurately. The feasibility on clinical data is demonstrated on five different cases. The ability of the algorithm to extract time-dependent surface data, e.g. for quantification of pulsating stenosis is demonstrated.

Jandt, Uwe; Schäfer, Dirk; Grass, Michael; Rasche, Volker

2009-01-01

89

Break-up of stratus cloud structure predicted from non-Brownian motion liquid water and brightness temperature fluctuations  

Microsoft Academic Search

The Detrended Fluctuation Analysis statistical method is applied to microwave radiometer and infrared thermometer radiance data in order to examine stratus cloud dynamics. The existence of long-range power law correlations in stratus cloud liquid water path and radiance (brightness temperature) fluctuations is demonstrated to occur over about a two-hour period. Moreover, using a finite-size (time) interval window, a change from

K. Ivanova; M. Ausloos; E. E. Clothiaux; T. P. Ackerman

2000-01-01

90

Implementation of a state of the art automated system for the production of cloud/water vapor motion winds from geostationary satellites  

NASA Technical Reports Server (NTRS)

The thrust of the proposed effort under this contract is aimed at improving techniques to track water vapor data in sequences of imagery from geostationary satellites. In regards to this task, significant testing, evaluation, and progress was accomplished during this period. Sets of winds derived from Meteosat data were routinely produced during Atlantic hurricane events in the 1993 season. These wind sets were delivered via Internet in real time to the Hurricane Research Division in Miami for their evaluation in a track forecast model. For eighteen cases in which 72-hour forecasts were produced, thirteen resulted in track forecast improvements (some quite significant). In addition, quality-controlled Meteosat water vapor winds produced by NESDIS were validated against rawinsondes, yielding an 8 m/s RMS. This figure is comparable to upper-level cloud drift wind accuracies. Given the complementary horizontal coverage in cloud-free areas, we believe that water vapor vectors can supplement cloud-drift wind information to provide good full-disk coverage of the upper tropospheric flow. The impact of these winds on numerical analysis and forecasts will be tested in the next reporting period.

Velden, Christopher S.

1994-01-01

91

Qualitative Vector Algebra  

Microsoft Academic Search

A significantaspect of reasoning about physicalsituationsinvolvesanalysisof the interactionof physical parameters that have both magnitude and direction. There have been some attempts to model motion and rotationin two dimensions, but none ofthese approaches have been extended togeneral vectoranalysis. Humans, however, are exceptionally good in reasoning about directionand motion . In thispaper, we definea framework calledQualitative Vector Algebra (QVA) forqualitativereasoning about vector

Uckun Serdar

92

Kinematic differential geometry of a rigid body in spatial motion using dual vector calculus: Part-II  

Microsoft Academic Search

In the present paper, partially based on Part I of this paper, the special points; inflection points, acceleration centers and the points with the zero tangential components, which we call Bresse complexes, of the dual spherical motion X^=A^xˆ are discussed and computer aided graphs of some of them shown in line space withA^=cos?ˆcos?ˆ-sin?ˆ-cos?ˆsin?ˆsin?ˆcos?ˆcos?ˆ-sin?ˆsin?ˆsin?ˆ0cos?ˆ,where ?ˆ(t)=?(t)+???(t),?ˆ(t)=?(t)+???(t) are the function of real parameter

Ö. Köse; C. C. Sarioglu; B. Karabey; I. Karakiliç

2006-01-01

93

Cloud Services Cloud Services  

E-print Network

Cloud Services Cloud Services In 2012 UCD IT Services launched an exciting new set of cloud solutions called CloudEdu, which includes cloud servers, cloud storage, cloud hosting and cloud network. The CloudEdu package includes a consultancy service in design, deployment, management and utilisation

94

LABORATORY IV CIRCULAR MOTION  

E-print Network

objects moving in uniform circular motion. This is the same motion that describes satellites in orbit's instantaneous and average velocity and acceleration from video images. · Analyze a vector in terms of its

Minnesota, University of

95

Physics Classroom: Motion Characteristics for Circular Motion  

NSDL National Science Digital Library

This resource guides the user through characteristics of circular motion. The same concepts and principles used to describe the motion of an object can also be used to describe and explain the motion of objects in circular pathways. This tutorial is broken into five sections addressing: the mechanics of circular motion, centripetal force, algebraic and trigonometric problems and solutions, and a full chapter that debunks the centrifugal "force" misconception. The interactive problems use diagrams and force vectors to help students visualize how vector components affect the way circular motion is characterized.

Henderson, Tom

2007-01-18

96

Robust vector sensor array processing and performance analysis .  

E-print Network

??Acoustic vector sensors, which measure scalar pressure along with particle motion (a vector quantity), feature many advantages over omnidirectional hydrophone sensors. A sizable literature exists… (more)

Poulsen, Andrew Joseph

2009-01-01

97

Closed Large Cell Clouds  

article title:  Closed Large Cell Clouds in the South Pacific     ... unperturbed by cyclonic or frontal activity. When the cell centers are cloudy and the main sinking motion is concentrated at cell ...

2013-04-19

98

Interstellar Clouds by Searchlight  

NASA Astrophysics Data System (ADS)

Interpretation of high-resolution observations of absorption by interstellar clouds of radiation from extragalactic sources should include the effect of the Earth's motion with respect to the source. High-resolution H I absorption profiles that are not heavily blended have been published for eight sources. New observations of these sources may show temporal variations that are at least in part due to the Earth's motion, and that can lead to estimates of the tiny-scale structure of the clouds.

Dieter-Conklin, Nan

2009-04-01

99

Vertical Velocity Measurements in Warm Stratiform Clouds  

NASA Astrophysics Data System (ADS)

Measurements of vertical air motion in warm boundary layer clouds are key for quantitatively describing cloud-scale turbulence and for improving our understanding of cloud and drizzle microphysical processes. Recently, a new technique that produces seamless measurements of vertical air velocity in the cloud and sub-cloud layers for both drizzling and non-drizzling stratocumulus clouds has been developed. The technique combines radar Doppler spectra-based retrievals of vertical air motion in cloud and light drizzle conditions with a novel neural network analysis during heavily drizzling periods. Observations from Doppler lidars are used to characterize sub-cloud velocities and to evaluate the performance of the technique near the cloud base. The technique is applied to several cases of stratiform clouds observed by the ARM Mobile Facility during the Two-Column Aerosol Project (TCAP) campaign in Cape Cod. The observations clearly illustrate coupling of the sub-cloud and cloud layer turbulent structures.

Luke, E. P.; Kollias, P.

2013-12-01

100

Mesoscale circulation at the upper cloud level at middle latitudes from the imaging by Venus Monitoring Camera onboard Venus Express  

NASA Astrophysics Data System (ADS)

The Venus Monitoring Camera onboard ESA Venus Express spacecraft acquired a great number of UV images (365 nm) allowing us to track the motion of cloud features at the upper cloud layer of Venus. A digital method developed to analyze correlation functions between two UV images provided wind vector fields on the Venus day side (9-16 hours local time) from the equator to high latitudes. Sizes and regions for the correlation were chosen empirically, as a trade-off of sensitivity against noise immunity and vary from 10(°) x7.5(°) to 20(°) x10(°) depending on the grid step, making this method suitable to investigate the mesoscale circulation. Previously, the digital method was used for investigation of the circulation at low latitudes and provided good agreement with manual tracking of the motion of cloud patterns. Here we present first results obtained by this method for middle latitudes (25(°) S-75(°) S) on the basis of 270 orbits. Comparing obtained vector fields with images for certain orbits, we found a relationship between morphological patterns of the cloud cover at middle latitudes and parameters of the circulation. Elongated cloud features, so-called streaks, are typical for middle latitudes, and their orientation varies over wide range. The behavior of the vector field of velocities depends on the angle between the streak and latitude circles. In the middle latitudes the average angle of the flow deviation from the zonal direction is equal to -5.6(°) ± 1(°) (the sign “-“ means the poleward flow, the standard error is given). For certain orbits, this angle varies from -15.6(°) ± 1(°) to 1.4(°) ± 1(°) . In some regions at latitudes above 60(°) S the meridional wind is equatorward in the morning. The relationship between the cloud cover morphology and circulation peculiarity can be attributed to the motion of the Y-feature in the upper cloud layer due to the super-rotation of the atmosphere.

Patsaeva, Marina; Ignatiev, Nikolay; Markiewicz, Wojciech; Khatuntsev, Igor; Titov, Dmitrij; Patsaev, Dmitry

101

Mesoscale cloud phenomena observed by LANDSAT  

NASA Technical Reports Server (NTRS)

Examples of certain mesoscale cloud features - jet cirrus, eddies/vortices, cloud banding, and wave clouds - were collected from LANDSAT imagery and placed into Mason's four groups of causes of cloud formation based on the mechanism of vertical motion which produces condensation. These groups are as follows: (1) layer clouds formed by widespread regular ascent; (2) layer clouds caused by irregular stirring motions; (3) convective clouds; and (4) clouds formed by orographic disturbances. These mechanisms explain general cloud formation. Once formed, other forces may play a role in the deformation of a cloud or cloud mass into unusual and unique meso- and microscale patterns. Each example presented is followed by a brief discussion describing the synoptic situation, and some inference into the formation and occurrence of the more salient features. No major attempt was made to discuss in detail the meteorological and topographic interplay producing these mesoscale features.

Ormsby, J. P.

1977-01-01

102

Low complexity motion estimation algorithm by multiresolution search for long-term memory motion compensation  

Microsoft Academic Search

We propose a new low complexity motion estimation (ME) algo- rithm using multiresolution motion search for long term memory motion compensation (LTMC, (1)). While multiresolution motion search has been used for standard single-frame motion compensa- tion, here we introduce several novel techniques to exploit it effi- ciently in the context of LTMC. The proposed algorithm computes a coarse motion vector

Hyukjune Chung; Antonio Ortega; Yutaka Horiguchi

2002-01-01

103

Physclips: Circular Motion  

NSDL National Science Digital Library

This web page provides a multimedia introduction to circular motion. It includes topics such as acceleration, velocity, vectors, the Earth's rotation, and nonuniform circular motion. Short video clips and diagrams are integrated with text to promote understanding of important concepts. This tutorial is part of the PhysClip collection of web-based resources on introductory mechanics, electricity, and magnetism.

Wolfe, Joe

2009-10-14

104

Weyl's spaces with shear-free and expansion-free conformal Killing vectors and the motion of a free spinless test particle  

E-print Network

Conditions for the existence of shear-free and expansion-free non-null vector fields in spaces with affine connections and metrics are found. On their basis Weyl's spaces with shear-free and expansion-free conformal Killing vectors are considered. The necessary and sufficient conditions are found under which a free spinless test particle could move in spaces with affine connections and metrics on a curve described by means of an auto-parallel equation. In Weyl's spaces with Weyl's covector, constructed by the use of a dilaton field, the dilaton field appears as a scaling factor for the rest mass density of the test particle. PACS numbers: 02.40.Ky, 04.20.Cv, 04.50.+h, 04.90.+e

S. Manoff; B. Dimitrov

2000-11-13

105

Vector reconstruction from firing rates  

Microsoft Academic Search

In a number of systems including wind detection in the cricket, visual motion perception and coding of arm movement direction in the monkey and place cell response to position in the rat hippocampus, firing rates in a population of tuned neurons are correlated with a vector quantity. We examine and compare several methods that allow the coded vector to be

Emilio Salinas; L. F. Abbott

1994-01-01

106

A vector-dyadic development of the equations of motion for N-coupled flexible bodies and point masses. [spacecraft trajectories  

NASA Technical Reports Server (NTRS)

The equations of motion for a system of coupled flexible bodies, rigid bodies, point masses, and symmetric wheels were derived. The equations were cast into a partitioned matrix form in which certain partitions became nontrivial when the effects of flexibility were treated. The equations are shown to contract to the coupled rigid body equations or expand to the coupled flexible body equations all within the same basic framework. Furthermore, the coefficient matrix always has the computationally desirable property of symmetry. Making use of the derived equations, a comparison was made between the equations which described a flexible body model and those which described a rigid body model of the same elastic appendage attached to an arbitrary coupled body system. From the comparison, equivalence relations were developed which defined how the two modeling approaches described identical dynamic effects.

Frisch, H. P.

1975-01-01

107

Vector Voyage!  

NSDL National Science Digital Library

In this activity, students will use vector analysis to understand the concept of dead reckoning. Students will use vectors to plot their course based on a time and speed. They will then correct the positions with vectors representing winds and currents.

Integrated Teaching And Learning Program

108

Project Physics Reader 1, Concepts of Motion.  

ERIC Educational Resources Information Center

As a supplement to Project Physics Unit 1, 21 articles are presented in this reader. Concepts of motion are discussed under headings: motion, motion in words, representation of movement, introducing vectors, Galileo's discussion of projectile motion, Newton's laws of dynamics, the dynamics of a golf club, report on Tait's lecture on force, and bad…

Harvard Univ., Cambridge, MA. Harvard Project Physics.

109

Cloud Spirals and Outflow in Tropical Storm Katrina  

NASA Technical Reports Server (NTRS)

On Tuesday, August 30, 2005, NASA's Multi-angle Imaging SpectroRadiometer retrieved cloud-top heights and cloud-tracked wind velocities for Tropical Storm Katrina, as the center of the storm was situated over the Tennessee valley. At this time Katrina was weakening and no longer classified as a hurricane, and would soon become an extratropical depression. Measurements such as these can help atmospheric scientists compare results of computer-generated hurricane simulations with observed conditions, ultimately allowing them to better represent and understand physical processes occurring in hurricanes.

Because air currents are influenced by the Coriolis force (caused by the rotation of the Earth), Northern Hemisphere hurricanes are characterized by an inward counterclockwise (cyclonic) rotation towards the center. It is less widely known that, at high altitudes, outward-spreading bands of cloud rotate in a clockwise (anticyclonic) direction. The image on the left shows the retrieved cloud-tracked winds as red arrows superimposed across the natural color view from MISR's nadir (vertical-viewing) camera. Both the counter-clockwise motion for the lower-level storm clouds and the clockwise motion for the upper clouds are apparent in these images. The speeds for the clockwise upper level winds have typical values between 40 and 45 m/s (144-162 km/hr). The low level counterclockwise winds have typical values between 7 and 24 m/s (25-86 km/hr), weakening with distance from the storm center. The image on the right displays the cloud-top height retrievals. Areas where cloud heights could not be retrieved are shown in dark gray. Both the wind velocity vectors and the cloud-top height field were produced by automated computer recognition of displacements in spatial features within successive MISR images acquired at different view angles and at slightly different times.

The Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously, viewing the entire globe between 82o north and 82o south latitude every nine days. This image covers an area of about 380 kilometers by 1970 kilometers. These data products were generated from a portion of the imagery acquired during Terra orbit 30324 and utilize data from blocks 55-68 within World Reference System-2 path 22.

MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Science Mission Directorate, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is managed for NASA by the California Institute of Technology.

2005-01-01

110

Cloud Fun  

NSDL National Science Digital Library

Learners complete a series of hands-on and investigative activities to explore cumulus clouds. Learners observe cumulus clouds outside, read a book about how cumulus clouds differ from other clouds, and create a list of words that describe cumulus clouds. Then, learners create their own cumulus cloud out of white paper and complete the Cloud Fun Student Activity sheet that includes a description of the cloud and what the weather was like on the day the cloud was observed. Learners will use their five senses to describe their clouds. Clouds can be displayed in the classroom or assembled into a class book. This lesson guide includes brief background information about cumulus clouds, adaptations for younger and older learners, and extension ideas.

Program, The G.

2006-01-01

111

Robust vector sensor array processing and performance analysis  

E-print Network

Acoustic vector sensors, which measure scalar pressure along with particle motion (a vector quantity), feature many advantages over omnidirectional hydrophone sensors. A sizable literature exists on the theory of processing ...

Poulsen, Andrew Joseph

2009-01-01

112

Graph Matching Motion Model  

NSDL National Science Digital Library

The Graph Matching Motion Model shows the graph of position as a function of time, and the motion diagram, for a particular object that experiences one-dimensional motion with constant acceleration. Using the sliders, try to match the motion of the red object to that of the blue object - this should also get the two position versus time graphs to match. Then, predict what the velocity and acceleration graphs look like, by sliding the end points of the red lines up or down to give correct straight-line graphs. The Graph Matching Motion model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_bu_vector_graph_matching.jar file will run the program if Java is installed.

Duffy, Andrew

2010-05-02

113

Motion graphs  

Microsoft Academic Search

In this paper we present a novel method for creating realistic, controllable motion. Given a corpus of motion capture data, we automatically construct a directed graph called a motion graph that encapsulates connections among the database. The motion graph consists both of pieces of original motion and automatically generated transitions. Motion can be generated simply by building walks on the

Lucas Kovar; Michael Gleicher; Frederic H. Pighin

2002-01-01

114

Cloud Protocols  

NSDL National Science Digital Library

The purpose of this activity is to observe the type and cover of clouds including contrails. Students observe which of ten types of clouds and how many of three types of contrails are visible and how much of the sky is covered by clouds (other than contrails) and how much is covered by contrails. Intended outcomes are that students learn how to make estimates from observations and how to categorize specific clouds following general descriptions for the categories. They will learn the meteorological concepts of cloud heights, types, and cloud cover and learn the ten basic cloud types. Supporting background materials for both student and teacher are included.

The GLOBE Program, UCAR (University Corporation for Atmospheric Research)

2003-08-01

115

Force and Motion: Position and Motion  

NSDL National Science Digital Library

This Science Object is the first of four Science Objects in the Force and Motion SciPack. It provides an understanding of how changes in position and motion can affect the way objects move, focusing on constant motion (where the direction and speed remain the same) and acceleration (a change in motion due to a change in an object's direction or speed). The position of an object must be described relative to some other object while the motion of an object can be described by its direction and speed. Velocity is a measure of both an object's speed and its direction (and can be described by vectors). Learning Outcomes:� Identify the position of one object relative to the position of another object by providing the approximate distance and angles between the objects, the angles being measured from some reference line.� Define the concepts of speed and velocity.� Determine the average speed of an object given necessary information.� Describe, draw, or otherwise detail the velocity of an object given magnitude and direction.� Define acceleration.� Recognize examples of acceleration and provide examples of acceleration.� Distinguish between constant and changing motion.� Distinguish increasing speed from increasing acceleration.� Recognize that the state of rest is a state of zero speed (rather than as something fundamentally different than motion).

National Science Teachers Association (NSTA)

2006-11-01

116

1D Uniformly Accelerated Motion  

NSDL National Science Digital Library

The representation depicts an object moving along a "track" marked in .5 meter intervals. As the object moves, displacement-time, velocity-time, and acceleration-time graphs record the motion in real time. The user may select various types of motion to be depicted, as well as edit a velocity-time graph and have the resulting motion depicted. As the object moves, color coded vectors display its displacement, velocity and acceleration.

117

Vector Fields  

NSDL National Science Digital Library

Vector fields are vectors which change from point to point. A standard example is the velocity of moving air, in other words, wind. For instance, the current wind pattern in the San Francisco area can be found at . This site has a 2-dimensional representation; careful reading of the webpage will tell you at what elevation the wind is shown. How would you represent a vector field in 3 dimensions? What features are important? Some simple examples are shown. Each can be rotated by clicking and dragging with the mouse. Explore!

Ay, Tevian

2006-01-01

118

A Hybrid Adaptive Search Algorithm for Fast Block Motion Estimation  

Microsoft Academic Search

This paper proposes a hybrid adaptive search algorithm (HASA) for block-based motion estimation. The proposed algorithm exploits the correlation between the block distortion measure (BDM) of the search origin (0,O) and its displacement from the motion vector to predict the range of motion. Based on the predicted motion type and the center-biased statistical distribution of motion vectors in low bit

Chok-Kwan Cheung; Lai-Man Po

1996-01-01

119

The Physics Classroom: Vectors - Fundamentals and Operations  

NSDL National Science Digital Library

This interactive tutorial provides comprehensive help and practice in understanding vector quantities. It is organized into six sections: vector direction, vector addition, resultants, components, vector resolution, and component addition. It closes with relative velocity and riverboat problems, plus a discussion of the interdependence of perpendicular components of motion. Each section explains a topic and provides exercises for learner self-assessment. Images, animations, and graphs are placed throughout to illustrate the concepts. Editor's Note: Fluency in vector operations requires practice, and this tutorial provides it. Additional guidance is offered by clicking "Student Extras" at the top of the tutorial page.

Henderson, Tom

120

On the Relationship between Thermodynamic Structure and Cloud Top, and Its Climate Significance in the Arctic  

E-print Network

On the Relationship between Thermodynamic Structure and Cloud Top, and Its Climate Significance as an important process controlling thermodynamic structure and efficiency of cloud-generated motions. The portion of CII clouds above the inversion contains cloud radar signatures consistent with cloud droplets

Shupe, Matthew

121

Cloud patterns lee of Hawaii Island: A synthesis of satellite observations and numerical simulation  

E-print Network

Cloud patterns lee of Hawaii Island: A synthesis of satellite observations and numerical simulation on lee cloud formation during summer. Over the island, the cloud distribution is consistent cloud production in the upward motion. Such an offshore cloud band is not found off the northwest coast

Xie, Shang-Ping

122

Equivalent Vectors  

ERIC Educational Resources Information Center

The cross-product is a mathematical operation that is performed between two 3-dimensional vectors. The result is a vector that is orthogonal or perpendicular to both of them. Learning about this for the first time while taking Calculus-III, the class was taught that if AxB = AxC, it does not necessarily follow that B = C. This seemed baffling. The…

Levine, Robert

2004-01-01

123

Vector quantization  

NASA Technical Reports Server (NTRS)

During the past ten years Vector Quantization (VQ) has developed from a theoretical possibility promised by Shannon's source coding theorems into a powerful and competitive technique for speech and image coding and compression at medium to low bit rates. In this survey, the basic ideas behind the design of vector quantizers are sketched and some comments made on the state-of-the-art and current research efforts.

Gray, Robert M.

1989-01-01

124

Position, Velocity, and Acceleration in Uniform Circular Motion  

NSDL National Science Digital Library

This applet displays the position, velocity, and acceleration vectors for an object moving in uniform circular motion. The vectors are shown on different graphs. The graphs can be set to display constant motion or they can be paused and moved through the motion step by step.

Sternin, Edward

2006-04-14

125

Optical Structure and Proper-Motion Age of the Oxygen-rich Supernova Remnant 1E 0102-7219 in the Small Magellanic Cloud  

E-print Network

We present new optical emission-line images of the young SNR 1E 0102-7219 (E0102) in the SMC obtained with the HST Advanced Camera for Surveys (ACS). E0102 is a member of the oxygen-rich class of SNRs showing strong oxygen, neon , and other metal-line emissions in its optical and X-ray spectra, and an absence of H and He. The progenitor of E0102 may have been a Wolf-Rayet star that underwent considerable mass loss prior to exploding as a Type Ib/c or IIL/b SN. The ejecta in this SNR are fast-moving (V > 1000 km/s) and emit as they are compressed and heated in the reverse shock. In 2003, we obtained optical [O III], H-alpha, and continuum images with the ACS Wide Field Camera. The [O III] image captures the full velocity range of the ejecta, and shows considerable high-velocity emission projected in the middle of the SNR that was Doppler-shifted out of the narrow F502N bandpass of a previous Wide Field and Planetary Camera 2 image from 1995. Using these two epochs separated by ~8.5 years, we measure the transverse expansion of the ejecta around the outer rim in this SNR for the first time at visible wavelengths. From proper-motion measurements of 12 ejecta filaments, we estimate a mean expansion velocity for the bright ejecta of ~2000 km/s and an inferred kinematic age for the SNR of \\~2050 +/- 600 years. The age we derive from HST data is about twice that inferred by Hughes et al.(2000) from X-ray data, though our 1-sigma error bars overlap. Our proper-motion age is consistent with an independent optical kinematic age derived by Eriksen et al.(2003) using spatially resolved [O III] radial-velocity data. We derive an expansion center that lies very close to X-ray and radio hotspots, which could indicate the presence of a compact remnant (neutron star or black hole).

Steven L. Finkelstein; Jon A. Morse; James C. Green; Jeffrey L. Linsky; J. Michael Shull; Theodore P. Snow; John T. Stocke; Kenneth R. Brownsberger; Dennis C. Ebbets; Erik Wilkinson; Sara R. Heap; Claus Leitherer; Blair D. Savage; Oswald H. Siegmund; Alan Stern

2006-01-24

126

A fast and adaptive motion tracking scheme  

Microsoft Academic Search

The unacceptable computational cost of motion tracking (MT) using full search (FS) led to explosive research in MT. A fast and adaptive MT scheme is presented in this paper. The correlation of spatial and temporal neighboring blocks is used firstly to predict an initial motion vector (MV) for the current block. By the region motion intensity, various search patterns are

Xuedong Liu; Yihua Tan; Jian Liu

2008-01-01

127

Synoptic and Mesoscale Cloud Tracking  

NASA Technical Reports Server (NTRS)

The papers in this section include: 1)'Wind Derivation from Geostationary Satellites'; 2) 'The Operational Processing of Wind Estimates from Cloud Motions: Past, Present, and Future'; 3) 'Intercomparision of SMS Wind Sets: A Study Using Rapid Scan Imagery'; 4) 'Mesoscale Wind Fields for a Severe Storm Situation Determined from SMS Cloud Observations'; 5) 'Moisture Convergence Using Satellite-Derived Wind Fields: A Severe Local Storm Case Study'

Wilson, G.

1982-01-01

128

Cloud Computing  

SciTech Connect

Chicago Matters: Beyond Burnham (WTTW). Chicago has become a world center of "cloud computing." Argonne experts Pete Beckman and Ian Foster explain what "cloud computing" is and how you probably already use it on a daily basis.

Pete Beckman and Ian Foster

2009-12-04

129

A Catalog of HI Clouds in the Large Magellanic Cloud  

E-print Network

A 21 cm neutral hydrogen interferometric survey of the Large Magellanic Cloud (LMC) combined with the Parkes multi-beam HI single-dish survey clearly shows that the HI gas is distributed in the form of clumps or clouds. The HI clouds and clumps have been identified using a thresholding method with three separate brightness temperature thresholds ($T_b$). Each catalog of HI cloud candidates shows a power law relationship between the sizes and the velocity dispersions of the clouds roughly following the Larson Law scaling $\\sigma_v \\propto R^{0.5}$, with steeper indices associated with dynamically hot regions. The clouds in each catalog have roughly constant virial parameters as a function mass suggesting that that the clouds are all in roughly the same dynamical state, but the values of the virial parameter are significantly larger than unity showing that turbulent motions dominate gravity in these clouds. The mass distribution of the clouds is a power law with differential indices between -1.6 and -2.0 for the three catalogs. In contrast, the distribution of mean surface densities is a log-normal distribution.

S. Kim; E. Rosolowsky; Y. Lee; Y. Kim; Y. C. Jung; M. A. Dopita; B. G. Elmegreen; K. C. Freeman; R. J. Sault; M. J. Kesteven; D. McConnell; Y. -H. Chu

2007-06-11

130

Cloud Watch  

NSDL National Science Digital Library

The purpose of this activity is to explore the connections between cloud type, cloud cover, and weather and stimulate student interest in taking cloud type observations. Students observe cloud type and coverage and weather conditions over a five-day period and correlate these observations. Students make and test predictions using these observations. The intended outcome is that students learn to draw inferences from observations and use them to make and test predictions.

The GLOBE Program, UCAR (University Corporation for Atmospheric Research)

2003-08-01

131

Cloud Types  

NSDL National Science Digital Library

This tutorial explains common cloud classifications and the Latin root words that have been adapted to create the various names of clouds. The classification is subdivided into high-, low-, and mid-level types, clouds with vertical development, and other, less common types. Each description is accompanied by an example photograph.

2005-03-10

132

Enhanced Cloud Disruption by Magnetic Field Interaction  

NASA Astrophysics Data System (ADS)

We present results from the first three-dimensional numerical simulations of moderately supersonic cloud motion through a tenuous, magnetized medium. We show that the interaction of the cloud with a magnetic field perpendicular to its motion has a great dynamical impact on the development of instabilities at the cloud surface. Even for initially spherical clouds, magnetic field lines become trapped in surface deformations and undergo stretching. The consequent field amplification that occurs there and, in particular, its variation across the cloud face then dramatically enhance the growth rate of Rayleigh-Taylor unstable modes, hastening the cloud disruption. Animations and color images from this work have been posted at http://www.msi.umn.edu/Projects/twj/mhd3d/.

Gregori, G.; Miniati, Francesco; Ryu, Dongsu; Jones, T. W.

1999-12-01

133

Motion Commotion  

NSDL National Science Digital Library

Students learn why and how motion occurs and what governs changes in motion, as described by Newton's three laws of motion. They gain hands-on experience with the concepts of forces, changes in motion, and action and reaction. In an associated literacy activity, students design a behavioral survey and learn basic protocol for primary research, survey design and report writing.

Integrated Teaching And Learning Program

134

Beyond pixels : exploring new representations and applications for motion analysis  

E-print Network

The focus of motion analysis has been on estimating a flow vector for every pixel by matching intensities. In my thesis, I will explore motion representations beyond the pixel level and new applications to which these ...

Liu, Ce, Ph. D. Massachusetts Institute of Technology

2009-01-01

135

Efficient Cost Measures for Motion Compensation at Low Bit Rates  

E-print Network

We present and compare methods for choosing motion vectors for block-based motion-compensated video coding. The primary focus is on videophone and video- conferencing applications, where low bit rates are neces- sary, ...

Hoang, Dzung T.; Long, Philip M.; Vitter, Jeffrey Scott

1996-01-01

136

Fast full search motion estimation algorithm using various matching scans in video coding  

Microsoft Academic Search

To reduce the amount of computation in a full search (FS) algorithm for fast motion estimation, we propose a novel and fast FS motion estimation algorithm. The computational reduction without any degradation in the predicted image comes from fast elimination of impossible motion vectors. We obtain faster elimination of inappropriate motion vectors using efficient matching units from localization of the

Jong-Nam Kim; Sung-Cheal Byun; Byung-Ha Ahn

2001-01-01

137

Evaluation of Techniques for Modeling of Layered Motion Structure  

Microsoft Academic Search

Motion information scalability is important for scalable bit- stream adaptation on low bit-rates, when motion rate occu- pies a significant portion of the total bit-rate. This type of scalability can be achieved by layered representation of mo- tion block partitioning and predictive coding of associated motion vectors across these layers. So far, several ap- proaches for creating layered motion structure

Marta Mrak; Nikola Sprljan; Ebroul Izquierdo

2006-01-01

138

Selective Vectorization for Short-Vector Instructions  

E-print Network

Multimedia extensions are nearly ubiquitous in today's general-purpose processors. These extensions consist primarily of a set of short-vector instructions that apply the same opcode to a vector of operands. Vector ...

Amarasinghe, Saman

2009-12-18

139

Cloud Types  

NSDL National Science Digital Library

This table provides a quick reference to cloud types. Clouds are divided into groups mainly based on the height of the cloud's base above the Earth's surface. The table further divides the types according to group, atmospheric layer, and base height. Links to additional information are embedded in the text, and users can select beginner, intermediate, or advanced levels of difficulty. A Spanish translation is available.

140

ARM Data for Cloud Parameterization  

SciTech Connect

The PI's ARM investigation (DE-IA02-02ER633 18) developed a physically-based subgrid-scale saturation representation that fully considers the direct interactions of the parameterized subgrid-scale motions with subgrid-scale cloud microphysical and radiative processes. Major accomplishments under the support of that interagency agreement are summarized in this paper.

Xu, Kuan-Man

2006-10-02

141

Operational implications of a cloud model simulation of space shuttle exhaust clouds in different atmospheric conditions  

NASA Technical Reports Server (NTRS)

A three-dimensional cloud model was used to characterize the dominant influence of the environment on the Space Shuttle exhaust cloud. The model was modified to accept the actual heat and moisture from rocket exhausts and deluge water as initial conditions. An upper-air sounding determined the ambient atmosphere in which the cloud would grow. The model was validated by comparing simulated clouds with observed clouds from four actual Shuttle launches. Results are discussed with operational weather forecasters in mind. The model successfully produced clouds with dimensions, rise, decay, liquid water contents, and vertical motion fields very similar to observed clouds whose dimensions were calculated from 16 mm film frames. Once validated, the model was used in a number of different atmospheric conditions ranging from very unstable to very stable. Wind shear strongly affected the appearance of both the ground cloud and vertical column cloud. The ambient low-level atmospheric moisture governed the amount of cloud water in model clouds. Some dry atmospheres produced little or no cloud water. An empirical forecast technique for Shuttle cloud rise is presented and differences between natural atmospheric convection and exhaust clouds are discussed.

Zak, J. A.

1989-01-01

142

The velocity dispersion of the giant molecule clouds: A viscous origin  

Microsoft Academic Search

The observations of interstellar cloud motion show that the cloud velocity dispersion is nearly constant, to within a factor of 2, for clouds covering at least three orders of magnitude in mass. For example, the Giant Molecular Cloud (GMC) with typical masses of approx 5 x 10 to the 5th power solar masses have a one-dimensional planar, cloud-cloud, random velocity

C. J. Jog; J. P. Ostriker

1986-01-01

143

Shapes of Bubbles and Drops in Motion.  

ERIC Educational Resources Information Center

Explains the shape distortions that take place in fluid packets (bubbles or drops) with steady flow motion by using the laws of Archimedes, Pascal, and Bernoulli rather than advanced vector calculus. (WRM)

O'Connell, James

2000-01-01

144

A cloud model simulation of space shuttle exhaust clouds in different atmospheric conditions  

NASA Technical Reports Server (NTRS)

A three-dimensional cloud model was used to characterize the dominant influence of the environment on the Space Shuttle exhaust cloud. The model was modified to accept the actual heat and moisture from rocket exhausts and deluge water as initial conditions. An upper-air sounding determined the ambient atmosphere in which the cloud could grow. The model was validated by comparing simulated clouds with observed clouds from four actual Shuttle launches. The model successfully produced clouds with dimensions, rise, decay, liquid water contents and vertical motion fields very similar to observed clouds whose dimensions were calculated from 16 mm film frames. Once validated, the model was used in a number of different atmospheric conditions ranging from very unstable to very stable. In moist, unstable atmospheres simulated clouds rose to about 3.5 km in the first 4 to 8 minutes then decayed. Liquid water contents ranged from 0.3 to 1.0 g kg-1 mixing ratios and vertical motions were from 2 to 10 ms-1. An inversion served both to reduce entrainment (and erosion) at the top and to prevent continued cloud rise. Even in the most unstable atmospheres, the ground cloud did not rise beyond 4 km and in stable atmospheres with strong low level inversions the cloud could be trapped below 500 m. Wind shear strongly affected the appearance of both the ground cloud and vertical column cloud. The ambient low-level atmospheric moisture governed the amount of cloud water in model clouds. Some dry atmospheres produced little or no cloud water. One case of a simulated TITAN rocket explosion is also discussed.

Chen, C.; Zak, J. A.

1989-01-01

145

Performance Comparison of Auxiliary Vector and RAKE-MF Receiver for Transport of H.264/AVC  

E-print Network

motion estimation, multi-frame motion prediction, quarter pixel motion accuracy, different intra encodingPerformance Comparison of Auxiliary Vector and RAKE-MF Receiver for Transport of H.264/AVC Video-CDMA wireless channels using Auxiliary Vector (AV) and RAKE-MF receivers and confirm the superiority of the AV

Kondis, Lisimachos Paul

146

Motion Sickness  

MedlinePLUS

... Motion sickness, whether on boats or in planes, cars or amusement rides, can strike anyone. 290229 InteliHealth ... Motion sickness, whether on boats or in planes, cars or amusement rides, can strike anyone. Those who ...

147

Rate determination from vector observations  

NASA Technical Reports Server (NTRS)

Vector observations are a common class of attitude data provided by a wide variety of attitude sensors. Attitude determination from vector observations is a well-understood process and numerous algorithms such as the TRIAD algorithm exist. These algorithms require measurement of the line of site (LOS) vector to reference objects and knowledge of the LOS directions in some predetermined reference frame. Once attitude is determined, it is a simple matter to synthesize vehicle rate using some form of lead-lag filter, and then, use it for vehicle stabilization. Many situations arise, however, in which rate knowledge is required but knowledge of the nominal LOS directions are not available. This paper presents two methods for determining spacecraft angular rates from vector observations without a priori knowledge of the vector directions. The first approach uses an extended Kalman filter with a spacecraft dynamic model and a kinematic model representing the motion of the observed LOS vectors. The second approach uses a 'differential' TRIAD algorithm to compute the incremental direction cosine matrix, from which vehicle rate is then derived.

Weiss, Jerold L.

1993-01-01

148

Cloud Services  

Microsoft Academic Search

Summary form only given. Cloud Computing has been identified as one of the major IT trends for the upcoming decades, long before it grew in interest as a result of the current economic crisis. Cloud Computing will shift the economic landscape of information and communication technologies to the same magnitude as did the first wave of the Internet. It will

J. Schaper

2010-01-01

149

Complex Clouds  

... the north of Enderbyland, East Antarctica. The image at left was created by overlying a natural-color view from MISR's ... causes the cloud-tops to be brightly outlined by the sun behind them, and enhances the shadows cast by clouds with significant vertical ...

2013-04-16

150

Uranus - Discrete Cloud  

NASA Technical Reports Server (NTRS)

This false-color Voyager picture of Uranus shows a discrete cloud seen as a bright streak near the planet's limb. The picture is a highly processed composite of three images obtained Jan. 14, 1986, when the spacecraft was 12.9 million kilometers (8.0 million miles) from the planet. The cloud visible here is the most prominent feature seen in a series of Voyager images designed to track atmospheric motions. (The occasional donut-shaped features, including one at the bottom, are shadows cast by dust in the camera optics; the processing necessary to bring out the faint features on the planet also brings out these camera blemishes.) Three separate images were shuttered through violet, blue and orange filters. Each color image showed the cloud to a different degree; because they were not exposed at exactly the same time, the images were processed to provide a correction for a good spatial match. In a true-color image, the cloud would be barely discernible; the false color helps bring out additional details. The different colors imply variations in vertical structure, but as yet is not possible to be specific about such differences. One possibility is that the Uranian atmosphere contains smog-like constituents, in which case some color differences may represent differences in how these molecules are distributed. The Voyager project is managed for NASA by the Jet Propulsion Laboratory.

1986-01-01

151

Cloud Computing For Bioinformatics  

E-print Network

Cloud Computing For Bioinformatics #12;Cloud Computing: what is it? · Cloud Computing Computing abstracts infrastructure from application. · Cloud Computing should save you time the way software & deploy your application Cloud Computing #12;Advantages: ­ Reliability: Decoupling applications from

Ferrara, Katherine W.

152

Ionization and expansion of barium clouds in the ionosphere  

NASA Technical Reports Server (NTRS)

A recently envelope 3D model is used here to study the motion of the barium clouds released in the ionosphere, including the ionization stage. The ionization and the expansion of the barium clouds and the interaction between the clouds and the background ions are investigated using three simulations: a cloud without a directional velocity, a cloud with an initial velocity of 5 km/s across the B field, and a cloud with initial velocity components of 2 km/s both along and across the B field.

Ma, T.-Z.; Schunk, R. W.

1993-01-01

153

Arctic mixed-phase summer clouds: Lessons from ASCOS  

NASA Astrophysics Data System (ADS)

As part of the 2007-2009 International Polar Year, the 2008 Arctic Summer Cloud and Ocean Study (ASCOS) experiment gathered detailed observations of the autumn central Arctic troposphere, boundary layer and surface energy budget, with an emphasis on how mixed-phase clouds impact the system. This presentation provides an overview of results from ASCOS examining the interactions between thermodynamics, boundary layer structure and dynamic motions generated within mixed-phase clouds. Over the Arctic Ocean, mixed-phase clouds in the lower troposphere occur frequently. These clouds exert the largest, most critical component on the surface energy budget via interactions with radiative fluxes. The surface cloud-radiative effect has the potential to control the sign and magnitude of the surface energy residual (positive - melting, or negative - freezing) and the boundary layer stability. Despite a common near-neutrally stratified boundary layer up to below ~ 500 m, mixed-phase clouds were most frequently found to be decoupled from the surface. Cloud-generated vertical motions produced via radiative divergence near cloud top produce mixing across the cloud layer and into the sub-cloud layer. The extent at which these motions couple with the surface mixed-layer correlates positively with liquid water path, cloud base height and cloud thickness; all of these factors affect the strength of vertical motions produced by the cloud layer. Persistence of the cloud is attributed to moisture inversions co-located with temperature inversions, often characterizing the upper third of the cloud layers. In-cloud vertical velocity characteristics derived from cloud radar shows a unique vertical structure that corresponds with the thermodynamic structure within the cloud. Despite cloud penetration within the stable, yet moist, temperature inversion, we show that peak cloud-generated vertical velocity overturning time scales are surprisingly similar and coherent across three levels within cloud; additionally velocity overturning time scales are similar regardless of coupling between the cloud-surface system. These findings help to better understand the resilience of Arctic mixed-phase clouds.

Tjernström, Michael; Sedlar, Joseph; Brooks, Ian; Persson, Ola; Shupe, Matthew

2014-05-01

154

MOTION ESTIMATION FOR H.264/AVC USING PROGRAMMABLE GRAPHICS HARDWARE  

E-print Network

.264/AVC depends on the motion vector (MV) predictor which is the median MV of three neighboring coded, Single Instruction Multiple Data (SIMD) extensions have been de- veloped for central processing unit (CPU- ference at frame-level using GPU. In H.264/AVC, the motion vector (MV) predictor, which is the median MV

Chan, Shueng-Han Gary

155

Magnetohydrodynamic stability of broad line region clouds  

NASA Astrophysics Data System (ADS)

Hydrodynamic stability has been a longstanding issue for the cloud model of the broad line region in active galactic nuclei. We argue that the clouds may be gravitationally bound to the supermassive black hole. If true, stabilization by thermal pressure alone becomes even more difficult. We further argue that if magnetic fields are present in such clouds at a level that could affect the stability properties, they need to be strong enough to compete with the radiation pressure on the cloud. This would imply magnetic field values of a few gauss for a sample of active galactic nuclei we draw from the literature. We then investigate the effect of several magnetic configurations on cloud stability in axisymmetric magnetohydrodynamic simulations. For a purely azimuthal magnetic field which provides the dominant pressure support, the cloud first gets compressed by the opposing radiative and gravitational forces. The pressure inside the cloud then increases, and it expands vertically. Kelvin-Helmholtz and column density instabilities lead to a filamentary fragmentation of the cloud. This radiative dispersion continues until the cloud is shredded down to the resolution level. For a helical magnetic field configuration, a much more stable cloud core survives with a stationary density histogram which takes the form of a power law. Our simulated clouds develop sub-Alfvénic internal motions on the level of a few hundred km s-1.

Krause, Martin; Schartmann, Marc; Burkert, Andreas

2012-10-01

156

Characteristic nature of vertical motions observed in Arctic mixed-phase stratocumulus  

NASA Astrophysics Data System (ADS)

Over the Arctic Ocean, little is known on cloud-generated buoyant overturning vertical motions within mixed-phase stratocumulus clouds. Characteristics of such motions are important for understanding the diabatic processes associated with the vertical motions, the lifetime of the cloud layer and its micro- and macrophysical characteristics. In this study, we exploit a suite of surface-based remote sensors over the high-Arctic sea ice during a weeklong period of persistent stratocumulus in August 2008 to derive the in-cloud vertical motion characteristics. In-cloud vertical velocity skewness and variance profiles are found to be strikingly different from observations within lower-latitude stratocumulus, suggesting these Arctic mixed-phase clouds interact differently with the atmospheric thermodynamics (cloud tops extending above a stable temperature inversion base) and with a different coupling state between surface and cloud. We find evidence of cloud-generated vertical mixing below cloud base, regardless of surface-cloud coupling state, although a decoupled surface-cloud state occurred most frequently. Detailed case studies are examined, focusing on three levels within the cloud layer, where wavelet and power spectral analyses are applied to characterize the dominant temporal and horizontal scales associated with cloud-generated vertical motions. In general, we find a positively correlated vertical motion signal amongst vertical levels within the cloud and across the full cloud layer depth. The coherency is dependent upon other non-cloud controlled factors, such as larger, mesoscale weather passages and radiative shielding of low-level stratocumulus by one or more cloud layers above. Despite the coherency in vertical velocity across the cloud, the velocity variances were always weaker near cloud top, relative to cloud middle and base. Taken in combination with the skewness, variance and thermodynamic profile characteristics, we observe vertical motions near cloud top that behave differently than those from lower within the cloud layer. Spectral analysis indicates peak cloud-generated w variance timescales slowed only modestly during decoupled cases relative to coupled; horizontal wavelengths only slightly increased when transitioning from coupling to decoupling. The similarities in scales suggests that perhaps the dominant forcing for all cases is generated from the cloud layer, and it is not the surface forcing that characterizes the time- and space scales of in-cloud vertical velocity variance. This points toward the resilient nature of Arctic mixed-phase clouds to persist when characterized by thermodynamic regimes unique to the Arctic.

Sedlar, J.; Shupe, M. D.

2014-04-01

157

Walter Fendt Physics Applets: Projectile Motion  

NSDL National Science Digital Library

This Java applet demonstrates projectile motion. Set the initial speed, height, and mass of the projectile, the initial angle of the velocity, and the gravitational constant -- and view the resulting motion. Display options available include force vectors and potential/kinetic energies. This resource is part of a large collection of physics applets available in a wide range of languages.

Fendt, Walter

2007-02-05

158

Intermediate Mechanics Tutorials: Simple Harmonic Motion  

NSDL National Science Digital Library

This set of tutorial materials covers the topic of simple harmonic motion. Students examine qualitatively and quantitatively the motion of a simple harmonic oscillator, as exemplified by a mass attached to an ideal spring. There are two tutorials, one using motion graphs and one using vectors, to describe the motion. Students analyze and solve the differential equations of motion to develop an understanding of the physical parameters in the problem. This material also includes a pretest, example homework, and test questions. This is part of a large collection of similar tutorial materials in intermediate classical mechanics.

Wittmann, Michael C.; Ambrose, Bradley S.

2009-03-31

159

A comparative assessment of Kalpana-1 and MISR cloud tracked winds over the Indian Ocean region  

NASA Astrophysics Data System (ADS)

In this study, an attempt has been made to advance the error characteristic of atmospheric motion vectors (AMVs) derived from the infrared and water vapour channels of Kalpana-1 very high resolution radiometer by comparing against stereo motion vectors (SMVs) retrieved by tracking clouds from the multi-angle imaging spectro-radiometer (MISR) for a period of 9 months. Two different versions of the MISR SMVs with horizontal resolutions 70.4 and 17.6 km, respectively, are used for the inter-comparison. It is found that the Kalpana-1 AMV has stronger westerlies and southerlies than the MISR SMV at all latitudes and levels in majority of times. The performances of Kalpana-1 AMVs against MISR SMVs are assessed by doing a similar analysis where Meteosat-7 AMVs (infrared and water vapour AMVs) are also evaluated against the MISR SMVs for the same region. It is found that results of both AMVs (Kalpana-1 and Meteosat-7) with both sets of MISR SMVs are comparable with few exceptions. The zonal wind components of the MISR SMVs showed smaller mean wind difference and root mean square difference (RMSD) compared to the meridional wind components. The SMVs are typically assigned to higher altitudes than AMVs. Analysis related to the height discrepancies between MISR SMVs and AMVs shows that in the multi-layer cloud AMVs are tracked in upper level cloud targets, while SMVs are skewed more towards lower level. The accuracy is better for the low level where collocations are highly dense and gradually decreases towards the higher levels. Because of improvement in the MISR SMV retrieval algorithm, the errors in the meridional component of SMVs have improved in the recently released version with horizontal resolution of 17.6 km.

Deb, S. K.; Kaur, Inderpreet; Kishtawal, C. M.; Pal, P. K.

2014-08-01

160

Cloud Formation  

NASA Astrophysics Data System (ADS)

Cloud formation is crucial to the heritage of modern physics, and there is a rich literature on this important topic. In 1927, Charles T.R. Wilson was awarded the Nobel Prize in physics for applications of the cloud chamber.2 Wilson was inspired to study cloud formation after working at a meteorological observatory on top of the highest mountain in Scotland, Ben Nevis, and testified near the end of his life, "The whole of my scientific work undoubtedly developed from the experiments I was led to make by what I saw during my fortnight on Ben Nevis in September 1894."3 To form clouds, Wilson used the sudden expansion of humid air.4 Any structure the cloud may have is spoiled by turbulence in the sudden expansion, but in 1912 Wilson got ion tracks to show up by using strobe photography of the chamber immediately upon expansion.5 In the interim, Millikan's study in 1909 of the formation of cloud droplets around individual ions was the first in which the electron charge was isolated. This study led to his famous oil drop experiment.6 To Millikan, as to Wilson, meteorology and physics were professionally indistinct. With his meteorological physics expertise, in WWI Millikan commanded perhaps the first meteorological observation and forecasting team essential to military operation in history.7 But even during peacetime meteorology is so much of a concern to everyone that a regular news segment is dedicated to it. Weather is the universal conversation topic, and life on land could not exist as we know it without clouds. One wonders then, why cloud formation is never covered in physics texts.

Graham, Mark Talmage

2004-05-01

161

Two block-based motion compensation methods for video coding  

Microsoft Academic Search

Two new motion compensation methods for video coding are presented. The first method named motion-partitioned adaptive block matching algorithm (MPA-BMA) uses motion boundary information as the sub-dividing or merging criteria to form variable-size matching blocks. The second method named predictive block matching algorithm (PBMA) eliminates the need of sending motion data by predicting motion vectors from previously transmitted pixels. The

Yan Huang; Xinhua Zhuang; Changsheng Yang

1996-01-01

162

Dynamics of magnetic clouds in interplanetary space  

NASA Technical Reports Server (NTRS)

Magnetic clouds observed in interplanetary space may be regarded as extraneous bodies immersed in the magnetized medium of the solar wind. The interface between a magnetic cloud and its surrounding medium separates the internal and external magnetic fields. Polarization currents are induced in the peripheral layer to make the ambient magnetic field tangential. The motion of a magnetic cloud through the interplanetary medium may be partitioned into a translational motion of the magnetic cloud as a whole and an expansive motion of the volume relative to the axis of the magnetic cloud. The translational motion is determined by two kinds of forces, i.e., the gravitational force exerted by the Sun, and the hydromagnetic buoyancy force exerted by the surrounding medium. On the other hand, the expansive motion is determined by the pressure gradient sustaining the gross difference between the internal and external pressures and by the self-induced magnetic force that results from the interaction among the internal currents. The force resulting from the internal and external currents is a part of the hydromagnetic buoyancy force, manifested by a thermal stress caused by the inhomogeneity of the ambient magnetic pressure.

Yeh, Tyan

1987-01-01

163

Animating Motion  

NSDL National Science Digital Library

This lesson challenges students to apply their knowledge of object motion by animating sequences of hand-rendered pictures that model a set of physical conditions. The challenges include animating the orbital motion of planets and satellites, the effects of gravity on a falling body, and motions of objects in inertial (moving) frames of reference. The lesson was created by a high school physics teacher to help learners build quantitative reasoning skills in preparation for understanding kinematics.

Latham, Ted

2004-07-16

164

Magical Motion  

NSDL National Science Digital Library

Students watch video clips from the October Sky and Harry Potter and the Sorcerer's Stone movies to see examples of projectile motion. Then they explore the relationships between displacement, velocity and acceleration, and calculate simple projectile motion. The objective of this activity is to articulate concepts related to force and motion through direct immersive interaction based on "The Science Behind Harry Potter" theme. Students' interest is piqued by the use of popular culture in the classroom.

National Science Foundation GK-12 and Research Experience for Teachers (RET) Programs,

165

A Model of Cloud Fragmentation  

E-print Network

We present a model in which the supersonic motions observed in molecular clouds are driven by gravitational energy released as large structures fragment into smaller ones. The fragmentation process begins in large molecular clouds, and continues down to fragments of a critical mass, at which gravitational confinement may be replaced by pressure confinement. The power laws that describe the scaling of density and mass, and number spectra and mass spectra of the fragments are given in terms of that of the observed velocity dispersion of the fragments. The results agree reasonably well with observations over the range from several to about a third of a million solar masses.

George B. Field; Eric G. Blackman; Eric Keto

2006-01-25

166

Interaction of a neutral cloud moving through a magnetized plasma  

NASA Technical Reports Server (NTRS)

Current collection by outgassing probes in motion relative to a magnetized plasma may be significantly affected by plasma processes that cause electron heating and cross field transport. Simulations of a neutral gas cloud moving across a static magnetic field are discussed. The authors treat a low-Beta plasma and use a 2-1/2 D electrostatic code linked with the authors' Plasma and Neutral Interaction Code (PANIC). This study emphasizes the understanding of the interface between the neutral gas cloud and the surrounding plasma where electrons are heated and can diffuse across field lines. When ionization or charge exchange collisions occur a sheath-like structure is formed at the surface of the neutral gas. In that region the crossfield component of the electric field causes the electron to E times B drift with a velocity of the order of the neutral gas velocity times the square root of the ion to electron mass ratio. In addition a diamagnetic drift of the electron occurs due to the number density and temperature inhomogeneity in the front. These drift currents excite the lower-hybrid waves with the wave k-vectors almost perpendicular to the neutral flow and magnetic field again resulting in electron heating. The thermal electron current is significantly enhanced due to this heating.

Goertz, C. K.; Lu, G.

1990-01-01

167

Joint depth-motion dense estimation for multiview video coding  

Microsoft Academic Search

The multiview video coding (MVC) extension of H.264\\/MPEG-4 AVC [1] is one of the most promising visual encoders for three-dimensional television and free viewpoint video applications. In this paper, we propose a joint dense motion\\/disparity estimation algorithm, designed to replace the classical temporal\\/inter-view unit within MVC, which uses a block-based motion\\/disparity estimation. The motion vector fields and the disparity vector

Ismaël Daribo; Wided Miled; Béatrice Pesquet-Popescu

2010-01-01

168

CLOUD CONDENSATION NUCLEI MEASUREMENTS WITHIN CLOUDS  

EPA Science Inventory

Measurements of the spectra of cloud condensation nuclei (CCN) within and near the boundaries of clouds are presented. Some of the in-cloud measurements excluded the nuclei within cloud droplets (interstitial CCN) while others included all nuclei inside the cloud (total CCN). The...

169

Tectonic Plate Motion  

NSDL National Science Digital Library

The representation shows the direction of motion of the Earth's major plates as measured through NASA's satellite laser ranging (SLR) technology. A series of world maps, accompanying text, and the subsequent links explain this technology in great detail. One can click on the Index Map for Satellite Laser Ranging site Velocity and see the vectors (arrows) that indicate the direction and rate of movement of Earth's plates in much more detail. Accompanying text gives a more detailed explanation of what each sub map is showing.

170

Lidar cloud studies for FIRE and ECLIPS  

NASA Technical Reports Server (NTRS)

Optical remote sensing measurements of cirrus cloud properties were collected by one airborne and four ground-based lidar systems over a 32 h period during this case study from the First ISCCP (International Satellite Cloud Climatology Program) Regional Experiment (FIRE) Intensive Field Observation (IFO) program. The lidar systems were variously equipped to collect linear depolarization, intrinsically calibrated backscatter, and Doppler velocity information. Data presented describe the temporal evolution and spatial distribution of cirrus clouds over an area encompassing southern and central Wisconsin. The cirrus cloud types include: dissipating subvisual and thin fibrous cirrus cloud bands, an isolated mesoscale uncinus complex (MUC), a large-scale deep cloud that developed into an organized cirrus structure within the lidar array, and a series of intensifying mesoscale cirrus cloud masses. Although the cirrus frequently developed in the vertical from particle fall-streaks emanating from generating regions at or near cloud tops, glaciating supercooled (-30 to -35 C) altocumulus clouds contributed to the production of ice mass at the base of the deep cirrus cloud, apparently even through riming, and other mechanisms involving evaporation, wave motions, and radiative effects are indicated. The generating regions ranged in scale from approximately 1.0 km cirrus uncinus cells, to organized MUC structures up to approximately 120 km across.

Sassen, Kenneth; Grund, Christian J.; Spinhirne, James D.; Hardesty, Michael; Alvarez, James

1990-01-01

171

Kepler Motion  

NSDL National Science Digital Library

This website, from the National Taiwan Normal University, provides a demonstration of Kepler's laws of planetary motion. The site offers a description of all three laws and a brief history of Johann Kepler and his discoveries. The applet can be adjusted to display several different variables of planetary motion to simulate each law effectively.

Hwang, Fu-Kwun

2008-10-28

172

Vector Addition Calculator  

NSDL National Science Digital Library

The Vector Addition Calculator lets students add vectors graphically in 2 dimensions by dragging the tips of the vectors. The results of a component method of addition for the same problem are also displayed.

Joiner, David; The Shodor Education Foundation, Inc.

173

Star Formation in Transient Molecular Clouds  

E-print Network

We present the results of a numerical simulation in which star formation proceeds from an initially unbound molecular cloud core. The turbulent motions, which dominate the dynamics, dissipate in shocks leaving a quiescent region which becomes gravitationally bound and collapses to form a small multiple system. Meanwhile, the bulk of the cloud escapes due to its initial supersonic velocities. In this simulation, the process naturally results in a star formation efficiency of 50%. The mass involved in star formation depends on the gas fraction that dissipates sufficient kinetic energy in shocks. Thus, clouds with larger turbulent motions will result in lower star formation efficiencies. This implies that globally unbound, and therefore transient giant molecular clouds (GMCs), can account for the low efficiency of star formation observed in our Galaxy without recourse to magnetic fields or feedback processes. Observations of the dynamic stability in molecular regions suggest that GMCs may not be self-gravitating, supporting the ideas presented in this letter.

Paul C. Clark; Ian A. Bonnell

2003-11-12

174

The use of the Q-vector in operational meteorology  

E-print Network

. Sco (Head of Department) May 19BB ABSTRACT The Use of the Q-vector in Operational Kfeteorology. (ofay 1988) Charles Arthur LeMay, B. S. , Baptist College Chair of Advisory Committee: Dr. Dusan Djuric Evaluation of atmospheric vertical motion... is now possible on widely available and inexpensive micro ? computers. Using the Q-vector l'orm of the omega equation, formulated by Hoskins et al. (1978) allows a meteorologist to evaluate vertical motion throughout the atmosphere. Case studies...

LeMay, Charles Arthur

2012-06-07

175

Are Bred Vectors The Same As Lyapunov Vectors?  

NASA Astrophysics Data System (ADS)

Regional loss of predictability is an indication of the instability of the underlying flow, where small errors in the initial conditions (or imperfections in the model) grow to large amplitudes in finite times. The stability properties of evolving flows have been studied using Lyapunov vectors (e.g., Alligood et al, 1996, Ott, 1993, Kalnay, 2002), singular vectors (e.g., Lorenz, 1965, Farrell, 1988, Molteni and Palmer, 1993), and, more recently, with bred vectors (e.g., Szunyogh et al, 1997, Cai et al, 2001). Bred vectors (BVs) are, by construction, closely related to Lyapunov vectors (LVs). In fact, after an infinitely long breeding time, and with the use of infinitesimal ampli- tudes, bred vectors are identical to leading Lyapunov vectors. In practical applications, however, bred vectors are different from Lyapunov vectors in two important ways: a) bred vectors are never globally orthogonalized and are intrinsically local in space and time, and b) they are finite-amplitude, finite-time vectors. These two differences are very significant in a dynamical system whose size is very large. For example, the at- mosphere is large enough to have "room" for several synoptic scale instabilities (e.g., storms) to develop independently in different regions (say, North America and Aus- tralia), and it is complex enough to have several different possible types of instabilities (such as barotropic, baroclinic, convective, and even Brownian motion). Bred vectors share some of their properties with leading LVs (Corazza et al, 2001a, 2001b, Toth and Kalnay, 1993, 1997, Cai et al, 2001). For example, 1) Bred vectors are independent of the norm used to define the size of the perturba- tion. Corazza et al. (2001) showed that bred vectors obtained using a potential enstro- phy norm were indistinguishable from bred vectors obtained using a streamfunction squared norm, in contrast with singular vectors. 2) Bred vectors are independent of the length of the rescaling period as long as the perturbations remain approximately linear (for example, for atmospheric models the interval for rescaling could be varied between a single time step and 1 day without affecting qualitatively the characteristics of the bred vectors. However, the finite-amplitude, finite-time, and lack of orthogonalization of the BVs introduces important differences with LVs: 1) In regions that undergo strong instabilities, the bred vectors tend to be locally domi- 1 nated by simple, low-dimensional structures. Patil et al (2001) showed that the BV-dim (appendix) gives a good estimate of the number of dominant directions (shapes) of the local k bred vectors. For example, if half of them are aligned in one direction, and half in a different direction, the BV-dim is about two. If the majority of the bred vectors are aligned predominantly in one direction and only a few are aligned in a second direction, then the BV-dim is between 1 and 2. Patil et al., (2001) showed that the regions with low dimensionality cover about 20% of the atmosphere. They also found that these low-dimensionality regions have a very well defined vertical structure, and a typical lifetime of 3-7 days. The low dimensionality identifies regions where the in- stability of the basic flow has manifested itself in a low number of preferred directions of perturbation growth. 2) Using a Quasi-Geostrophic simulation system of data assimilation developed by Morss (1999), Corazza et al (2001a, b) found that bred vectors have structures that closely resemble the background (short forecasts used as first guess) errors, which in turn dominate the local analysis errors. This is especially true in regions of low dimensionality, which is not surprising if these are unstable regions where errors grow in preferred shapes. 3) The number of bred vectors needed to represent the unstable subspace in the QG system is small (about 6-10). This was shown by computing the local BV-dim as a function of the number of independent bred vectors. Convergence in the local dimen- sion starts to occur at about 6 BVs, and is essentially

Kalnay, E.; Corazza, M.; Cai, M.

176

Curious About Clouds  

NSDL National Science Digital Library

What are the characteristics of the 3 main types of clouds, and what weather does each of these clouds produce? 3 Main Types of Clouds Use this website to start learn about the 3 main types of clouds: Cumulus, Stratus, and Cirrus Use your cloud graphic organizer and fill in the three main types of clouds along with information describing them. Clouds Weather Video Watch this video to learn how clouds are formed and what happens ...

Stewart, Ms.

2010-03-24

177

Cloud Formation  

NSDL National Science Digital Library

This Classroom Connectors lesson plan teaches students how clouds are formed through the condensation of water vapor. This includes learning about climate types and how they change, the greenhouse effect, how clouds affect weather and climate, and condensation. The site provides goals, objectives, an outline, time required, materials, activities, and closure ideas for the lesson. The Classroom Connectors address content with an activity approach while incorporating themes necessary to raise the activity to a higher cognition level. The major motivation is to employ instructional strategies that bring the students physically and mentally into touch with the science they are studying.

178

Cloud Thickness from Diffusion of Lidar Pulses in Clouds  

NASA Technical Reports Server (NTRS)

Measurements of the distribution of reflected light from a laser beam incident on an aqueous suspension of particles or "cloud" with known thickness and particle size distribution are reported. The distribution is referred to as the "cloud radiative Green's function", G. In the diffusion domain, G is sensitive to cloud thickness, allowing that important quantity to be retrieved. The goal of the laboratory simulation is to provide preliminary estimates of sensitivity of G to cloud thickness,for use in the optimal design of an offbeam Lidar instrument for remote sensing of cloud thickness (THOR, Thickness from Offbeam Returns). These clouds of polystyrene microspheres suspended in water are analogous to real clouds of water droplets suspended in air. The microsphere size distribution is roughly lognormal, from 0.5 microns to 25 microns, similar to real clouds. Density of suspended spheres is adjusted so mean-free-path of visible photons is about 10 cm, approximately 1000 times smaller than in real clouds. The light source is a ND:YAG laser at 530 nm. Detectors are flux and photon-counting Photomultiplier Tube (PMTS), with a glass probe for precise positioning. A Labview 5 VI controls positioning, and data acquisition, via an NI Motion Control board connected to a stepper motor driving an Edmund linear slider, and a 16-channel 16-bit NI-DAQ board. The stepper motor is accurate to 10 microns, and step size is selectable from the VI software. Far from the incident beam, the rate of exponential increase as the direction of the incident beam is approached scales as expected from diffusion theory, linearly with the cloud thickness, and inversely as the square root of the reduced optical thickness, and is independent of particle size. Near the beam the signal begins to increase faster than exponential, due to single and low-order scattering near the backward direction, and here the distribution depends on particle size. Results are being used to verify 3D Monte Carlo radiative transfer simulations, used to estimate signal-to-noise ratios for remotely sensed off beam returns, for both homogeneous and inhomogeneous clouds. Signal-to-noise estimates show that unfiltered observations are straight forward at night, while narrow band pass filters are being studied for day.

Cahalan, Robert F.; Davis, A.; McGill, Matthew

1999-01-01

179

Six Myths on the Virial Theorem for Interstellar Clouds  

E-print Network

It has been paid little or no attention to the implications that turbulent fragmentation has on the validity of at least six common assumptions on the Virial Theorem (VT), which are: (i) the only role of turbulent motions within a cloud is to provide support against collapse, (ii) the surface terms are negligible compared to the volumetric ones, (iii) the gravitational term is a binding source for the clouds, (iv) the sign of the second-time derivative of the moment of inertia determines whether the cloud is contracting or expanding, (v) interstellar clouds are in Virial Equilibrium (VE), and (vi) Larson's (1981) relations are the observational proof that clouds are in VE. Interstellar clouds cannot fulfill these assumptions, however, because turbulent fragmentation will induce flux of mass, moment and energy between the clouds and their environment, and will favor local collapse while may disrupt the clouds within a dynamical timescale. It is argued that, although the observational and numerical evidence sug...

Ballesteros-Paredes, J

2006-01-01

180

Vectors in Use in a 3D Juggling Game Simulation  

ERIC Educational Resources Information Center

The new representations enabled by the educational computer game the "Juggler" can place vectors in a central role both for controlling and measuring the behaviours of objects in a virtual environment simulating motion in three-dimensional spaces. The mathematical meanings constructed by 13 year-old students in relation to vectors as objects, as a…

Kynigos, Chronis; Latsi, Maria

2006-01-01

181

Fault Motion  

NSDL National Science Digital Library

This collection of animations provides elementary examples of fault motion intended for simple demonstrations. Examples include dip-slip faults (normal and reverse), strike-slip faults, and oblique-slip faults.

182

Wave Motion  

NSDL National Science Digital Library

This site from Carl Nave at Georgia State University presents a discussion of wave motion. The site explains the velocity of idealized ocean waves and details the measurement of large waves aboard the USS Ramapo.

Carl R. (Rod) Nave; University, Georgia S.

183

Projectile Motion  

NSDL National Science Digital Library

This page asks you to consider a projectile thrown at some angle as having the motion of two similar projectiles, one that travels upward with a constant downward acceleration and one that travels horizontally at constant velocity.

Christian, Wolfgang; Belloni, Mario

2008-02-19

184

A multistage approach to vector quantization  

E-print Network

is achieved by coding vectors instead of scalars. This fact is true for mem- Journal model is IEEE Transactions on Automatic Controk oryless dais, sonrc& s as w& II as I'or so?r?s with memory. Cloud design tech?iques I'or v&'ctor co&I&'rs &v&sne v& ly... is achieved by coding vectors instead of scalars. This fact is true for mem- Journal model is IEEE Transactions on Automatic Controk oryless dais, sonrc& s as w& II as I'or so?r?s with memory. Cloud design tech?iques I'or v&'ctor co&I&'rs &v&sne v& ly...

Bellubbi, Rajeev V.

2012-06-07

185

Cloud classification using whole-sky imager data  

SciTech Connect

Clouds are one of the most important moderators of the earth radiation budget and one of the least understood. The effect that clouds have on the reflection and absorption of solar and terrestrial radiation is strongly influenced by their shape, size, and composition. Physically accurate parameterization of clouds is necessary for any general circulation model (GCM) to yield meaningful results. The work presented here is part of a larger project that is aimed at producing realistic three-dimensional (3D) volume renderings of cloud scenes, thereby providing the important shape information for parameterizing GCMs. The specific goal of the current study is to develop an algorithm that automatically classifies (by cloud type) the clouds observed in the scene. This information will assist the volume rendering program in determining the shape of the cloud. Much work has been done on cloud classification using multispectral satellite images. Most of these references use some kind of texture measure to distinguish the different cloud types and some also use topological features (such as cloud/sky connectivity or total number of clouds). A wide variety of classification methods has been used, including neural networks, various types of clustering, and thresholding. The work presented here utilizes binary decision trees to distinguish the different cloud types based on cloud feature vectors.

Buch, K.A. Jr.; Sun, Chen-Hui

1995-02-01

186

Cloud Arcs  

... active than the other clouds, causing much of the air near the centers of the arcs to rise. This air spreads out horizontally in ... inside the arcs are kept clear. At the arcs, the horizontal flow of sinking air is now quite weak and on meeting the undisturbed air it can ...

2013-04-19

187

Rotations with Rodrigues' Vector  

ERIC Educational Resources Information Center

The rotational dynamics was studied from the point of view of Rodrigues' vector. This vector is defined here by its connection with other forms of parametrization of the rotation matrix. The rotation matrix was expressed in terms of this vector. The angular velocity was computed using the components of Rodrigues' vector as coordinates. It appears…

Pina, E.

2011-01-01

188

Particle Cloud Flames in Acoustic Fields  

NASA Technical Reports Server (NTRS)

Results are presented on a study of flames supported by clouds of particles suspended in air, at pressures about 100 times lower than normal. In the experiment, an acoustic driver (4-in speaker) placed at one end of a closed tube, 0.75-m long and 0.05 m in diameter, disperses a cloud of lycopodium particles during a 0.5-sec powerful acoustic burst. Properties of the particle cloud and the flame were recorded by high-speed motion pictures and optical transmission detectors. Novel flame structures were observed, which owe their features to partial confinement, which encourages flame-acoustic interactions, segregation of particle clouds into laminae, and penetration of the flame's radiative flux density into the unburned particle-cloud regimes. Results of these experiments imply that, for particles in confined spaces, uncontrolled fire and explosion may be a threat even if the Phi(0) values are below some apparent lean limit.

Berlad, A. L.; Tangirala, V.; Ross, H.; Facca, L.

1990-01-01

189

Topographic Structure from Motion  

NASA Astrophysics Data System (ADS)

The production of high-resolution topographic datasets is of increasing concern and application throughout the geomorphic sciences, and river science is no exception. Consequently, a wide range of topographic measurement methods have evolved. Despite the range of available methods, the production of high resolution, high quality digital elevation models (DEMs) generally requires a significant investment in personnel time, hardware and/or software. However, image-based methods such as digital photogrammetry have steadily been decreasing in costs. Initially developed for the purpose of rapid, inexpensive and easy three dimensional surveys of buildings or small objects, the "structure from motion" photogrammetric approach (SfM) is a purely image based method which could deliver a step-change if transferred to river remote sensing, and requires very little training and is extremely inexpensive. Using the online SfM program Microsoft Photosynth, we have created high-resolution digital elevation models (DEM) of rivers from ordinary photographs produced from a multi-step workflow that takes advantage of free and open source software. This process reconstructs real world scenes from SfM algorithms based on the derived positions of the photographs in three-dimensional space. One of the products of the SfM process is a three-dimensional point cloud of features present in the input photographs. This point cloud can be georeferenced from a small number of ground control points collected via GPS in the field. The georeferenced point cloud can then be used to create a variety of digital elevation model products. Among several study sites, we examine the applicability of SfM in the Pedernales River in Texas (USA), where several hundred images taken from a hand-held helikite are used to produce DEMs of the fluvial topographic environment. This test shows that SfM and low-altitude platforms can produce point clouds with point densities considerably better than airborne LiDAR, with horizontal and vertical precision in the centimeter range, and with very low capital and labor costs and low expertise levels. Advanced structure from motion software (such as Bundler and OpenSynther) are currently under development and should increase the density of topographic points rivaling those of terrestrial laser scanning when using images shot from low altitude platforms such as helikites, poles, remote-controlled aircraft and rotocraft, and low-flying manned aircraft. Clearly, the development of this set of inexpensive and low-required-expertise tools has the potential to fundamentally shift the production of digital fluvial topography from a capital-intensive enterprise of a low number of researchers to a low-cost exercise of many river researchers.

Fonstad, M. A.; Dietrich, J. T.; Courville, B. C.; Jensen, J.; Carbonneau, P.

2011-12-01

190

Vector Acoustics, Vector Sensors, and 3D Underwater Imaging  

NASA Astrophysics Data System (ADS)

Vector acoustic data has two more dimensions of information than pressure data and may allow for 3D underwater imaging with much less data than with hydrophone data. The vector acoustic sensors measures the particle motions due to passing sound waves and, in conjunction with a collocated hydrophone, the direction of travel of the sound waves. When using a controlled source with known source and sensor locations, the reflection points of the sound field can be determined with a simple trigonometric calculation. I demonstrate this concept with an experiment that used an accelerometer based vector acoustic sensor in a water tank with a short-pulse source and passive scattering targets. The sensor consists of a three-axis accelerometer and a matched hydrophone. The sound source was a standard transducer driven by a short 7 kHz pulse. The sensor was suspended in a fixed location and the hydrophone was moved about the tank by a robotic arm to insonify the tank from many locations. Several floats were placed in the tank as acoustic targets at diagonal ranges of approximately one meter. The accelerometer data show the direct source wave as well as the target scattered waves and reflections from the nearby water surface, tank bottom and sides. Without resorting to the usual methods of seismic imaging, which in this case is only two dimensional and relied entirely on the use of a synthetic source aperture, the two targets, the tank walls, the tank bottom, and the water surface were imaged. A directional ambiguity inherent to vector sensors is removed by using collocated hydrophone data. Although this experiment was in a very simple environment, it suggests that 3-D seismic surveys may be achieved with vector sensors using the same logistics as a 2-D survey that uses conventional hydrophones. This work was supported by the Office of Naval Research, program element 61153N.

Lindwall, D.

2007-12-01

191

Giant Molecular Clouds in the Magellanic Clouds  

NASA Astrophysics Data System (ADS)

We review the present knowledge of Giant molecular clouds in the Large and Small Magellanic Cloud. In particular we discuss the molecular cloud properties and its relation to massive star formation. Additionally we present recent results of the 1.2mm continuum observations with SIMBA towards molecular cloud and star forming regions and its implications on dust properties on these low metallicity galaxies.

Rubio, M.

2004-12-01

192

Cloud Controlling Factors --Low Clouds BJORN STEVENS,  

E-print Network

Cloud Controlling Factors -- Low Clouds BJORN STEVENS, Department of Atmospheric and Oceanic) clouds is reviewed, with an emphasis on factors that may be expected to change in a changing climate of low-cloud control- ling processes are offered: these include renewing our focus on theory, model

Stevens, Bjorn

193

Cloud Tracking in Cloud-Resolving Models  

E-print Network

Cloud Tracking in Cloud-Resolving Models RMetS Conference 4th September 2007 Bob Plant Department of Meteorology, University of Reading, UK #12;Introduction Obtain life cycle statistics for clouds in CRM simulations What is the distribution of cloud lifetimes? What factors determine the lifetime of an individual

Plant, Robert

194

Cloud Controlling Factors --Low Clouds BJORN STEVENS,  

E-print Network

Cloud Controlling Factors -- Low Clouds BJORN STEVENS, Department of Atmospheric and Oceanic conspire to determine the statistics and cli- matology of layers of shallow (boundary layer) clouds of low-cloud control- ling processes are offered: these include renewing our focus on theory, model

Stevens, Bjorn

195

Neutral cold gas (H atoms): HI clouds, 50% MISM  

E-print Network

Neutral cold gas (H atoms): HI clouds, 50% MISM Tk = 100 K, n = 102 cm-3 observation: hyperfine transition of the fundamental level, F = 1-0 = 21 cm, = 1 420 405 751.786 Hz Interstellar Medium: HI clouds & Hindman (Sidney) Prediction and discovery of the HI 21 cm line #12;Radiative processes: thermal motion

Estalella, Robert

196

Characterization of free breathing patterns with 5D lung motion model  

SciTech Connect

Purpose: To determine the quiet respiration breathing motion model parameters for lung cancer and nonlung cancer patients. Methods: 49 free breathing patient 4DCT image datasets (25 scans, cine mode) were collected with simultaneous quantitative spirometry. A cross-correlation registration technique was employed to track the lung tissue motion between scans. The registration results were applied to a lung motion model: X-vector=X-vector{sub 0}+{alpha}-vector{beta}-vector f, where X-vector is the position of a piece of tissue located at reference position X-vector{sub 0} during a reference breathing phase (zero tidal volume v, zero airflow f). {alpha}-vector is a parameter that characterizes the motion due to air filling (motion as a function of tidal volume v) and {beta}-vector is the parameter that accounts for the motion due to the imbalance of dynamical stress distributions during inspiration and exhalation that causes lung motion hysteresis (motion as a function of airflow f). The parameters {alpha}-vector and {beta}-vector together provide a quantitative characterization of breathing motion that inherently includes the complex hysteresis interplay. The {alpha}-vector and {beta}-vector distributions were examined for each patient to determine overall general patterns and interpatient pattern variations. Results: For 44 patients, the greatest values of |{alpha}-vector| were observed in the inferior and posterior lungs. For the rest of the patients, |{alpha}-vector| reached its maximum in the anterior lung in three patients and the lateral lung in two patients. The hysteresis motion {beta}-vector had greater variability, but for the majority of patients, |{beta}-vector| was largest in the lateral lungs. Conclusions: This is the first report of the three-dimensional breathing motion model parameters for a large cohort of patients. The model has the potential for noninvasively predicting lung motion. The majority of patients exhibited similar |{alpha}-vector| maps and the |{beta}-vector| maps showed greater interpatient variability. The motion parameter interpatient variability will inform our need for custom radiation therapy motion models. The utility of this model depends on the parameter stability over time, which is still under investigation.

Zhao Tianyu; Lu Wei; Yang Deshan; Mutic, Sasa; Noel, Camille E.; Parikh, Parag J.; Bradley, Jeffrey D.; Low, Daniel A. [Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri 63110 (United States)

2009-11-15

197

Present-day plate motions  

NASA Technical Reports Server (NTRS)

A data set comprising 110 spreading rates, 78 transform fault azimuths and 142 earthquake slip vectors was inverted to yield a new instantaneous plate motion model, designated RM2. The mean averaging interval for the relative motion data was reduced to less than 3 My. A detailed comparison of RM2 with angular velocity vectors which best fit the data along individual plate boundaries indicates that RM2 performs close to optimally in most regions, with several notable exceptions. On the other hand, a previous estimate (RM1) failed to satisfy an extensive set of new data collected in the South Atlantic Ocean. It is shown that RM1 incorrectly predicts the plate kinematics in the South Atlantic because the presently available data are inconsistent with the plate geometry assumed in deriving RM1. It is demonstrated that this inconsistency can be remedied by postulating the existence of internal deformation with the Indian plate, although alternate explanations are possible.

Minster, J. B.; Jordan, T. H.

1977-01-01

198

Chapter 1 Brownian motion c # Brownian motion  

E-print Network

Chapter 1 Brownian motion c �á# Brownian motion and stochastic calculus #12;Chapter 1 Brownian Brownian motion c �á# Chapter 1. Brownian motion #12;Chapter 1 Brownian motion c �á# 1.1 Basic concepts, xt = x(t), t 0. #12;Chapter 1 Brownian motion c �á# 1.1 Basic concepts on stochastic processes

Zhang, Li-Xin

199

Imaging vector fields using Line Integral Convolution  

SciTech Connect

Imaging vector fields has applications in science, art, image processing and special effects. An effective new approach is to use linear and curvilinear filtering techniques to locally blur textures along a vector field. This approach builds on several previous texture generation and filtering techniques. It is, however, unique because it is local, one-dimensional and independent of any predefined geometry or texture. The technique is general and capable of imaging arbitrary two- and three-dimensional vector fields. The local one-dimensional nature of the algorithm lends itself to highly parallel and efficient implementations. Furthermore, the curvilinear filter is capable of rendering detail on very intricate vector fields. Combining this technique with other rendering and image processing techniques -- like periodic motion filtering -- results in richly informative and striking images. The technique can also produce novel special effects.

Cabral, B.; Leedom, L.C.

1993-03-01

200

Earth Exploration Toolbook Chapter: Analyzing Plate Motion Using EarthScope GPS Data  

NSDL National Science Digital Library

DATA: EarthScope GPS Data. TOOLS: Spreadsheet, Google Maps. SUMMARY: Learn how GPS monuments make precise measurements of Earth's surface. Graph motion data and map velocity vectors to explore tectonic motion and surface deformation in the Pacific Northwest.

201

Cloud Security by Max Garvey  

E-print Network

Cloud Security Survey by Max Garvey #12;Cloudy Cloud is Cloudy What is the cloud? On Demand Service Network access Resource pooling Elasticity of Resources Measured Service #12;Cloud Types/Variants Iaa Cloud Public Cloud Hybrid Cloud combination. Private cloud with overflow going to public cloud. #12

Tolmach, Andrew

202

Diagnosing Pressure in Molecular Clouds through Observations and Simulations  

NASA Astrophysics Data System (ADS)

Pressure plays a key role in the dynamics of molecular clouds, the birthplaces of stars. Internally, pressure acts against gravity, resisting global collapse and helping explain the overall low star formation efficiencies observed. Externally, the pressure of the ambient lower-density interstellar medium (ISM), in which molecular clouds form, may help to promote cloud stability over timescales long enough for star formation to occur. This basic picture is complicated by several factors. For one, the internal structure of molecular clouds is extremely complex. Turbulent motions, which are supersonic on all but the smallest scales within clouds, promote support globally, but can also create shocks, leading to intricate substructure in a cloud’s density and velocity fields. Furthermore, the boundary of a cloud (on which external pressure presumably acts) is difficult to concretely define, as there is in reality a relatively smooth transition from the more diffuse, warm, atomic ISM to the dense, cold, molecule-dominated cloud itself. Observational diagnostics of pressure are scarce, as they require simultaneous measurement of both gas motions and density. Moreover, assessing the role of pressure in detail within clouds is contingent on knowledge of the cloud’s internal hierarchy. We present a new diagnostic probe of pressure as a function of scale within molecular clouds. We employ 13CO molecular line data from the COMPLETE survey to decompose a molecular cloud into its hierarchical substructure through the use of dendrogram analysis. We take the “kinetic pressure” in the gas to be P=??v2, where ? is the volume density derived from molecular line intensity and simple geometric assumptions, and ?v is the velocity dispersion computed from spectral linewidths. Specifically, we calculate the kinetic pressure within and at the interface between each nested structure in the dendrogram. We compare observational results on the Perseus molecular cloud with analysis of radiative transfer-processed turbulent simulations to assess the ability of our diagnostic to measure the true pressure within star-forming gas.

Faesi, Christopher; Offner, S.; Goodman, A. A.; Bisbas, T.

2014-01-01

203

Clouds and Dust Storms  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Released 2 July 2004 The atmosphere of Mars is a dynamic system. Water-ice clouds, fog, and hazes can make imaging the surface from space difficult. Dust storms can grow from local disturbances to global sizes, through which imaging is impossible. Seasonal temperature changes are the usual drivers in cloud and dust storm development and growth.

Eons of atmospheric dust storm activity has left its mark on the surface of Mars. Dust carried aloft by the wind has settled out on every available surface; sand dunes have been created and moved by centuries of wind; and the effect of continual sand-blasting has modified many regions of Mars, creating yardangs and other unusual surface forms.

This image was acquired during mid-spring near the North Pole. The linear water-ice clouds are now regional in extent and often interact with neighboring cloud system, as seen in this image. The bottom of the image shows how the interaction can destroy the linear nature. While the surface is still visible through most of the clouds, there is evidence that dust is also starting to enter the atmosphere.

Image information: VIS instrument. Latitude 68.4, Longitude 180 East (180 West). 38 meter/pixel resolution.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

2004-01-01

204

Reduced Vector Preisach Model  

NASA Technical Reports Server (NTRS)

A new vector Preisach model, called the Reduced Vector Preisach model (RVPM), was developed for fast computations. This model, derived from the Simplified Vector Preisach model (SVPM), has individual components that like the SVPM are calculated independently using coupled selection rules for the state vector computation. However, the RVPM does not require the rotational correction. Therefore, it provides a practical alternative for computing the magnetic susceptibility using a differential approach. A vector version, using the framework of the DOK model, is implemented. Simulation results for the reduced vector Preisach model are also presented.

Patel, Umesh D.; Torre, Edward Della; Day, John H. (Technical Monitor)

2002-01-01

205

Modular Approach to Physics: Centripetal Motion Simulator  

NSDL National Science Digital Library

In this simulation, the path of an object in centripetal motion can be followed. The user can add an angular acceleration, and graph the particle's position, velocity, and forces acting on it. The vectors menu offers eight choices plus force components to display a variety of velocity and acceleration vectors. This item is part of a larger collection of physics simulations sponsored by the MAP project (Modular Approach to Physics).

Austin, David; Martin, Brian

2008-08-03

206

Geoacoustic inversion using the vector field  

NASA Astrophysics Data System (ADS)

The main goal of this project was to study the use of the acoustic vector field, separately or in combination with the scalar field, to estimate the depth dependent geoacoustic properties of the seafloor via non-linear inversion. The study was performed in the context of the Sediment Acoustics Experiment 2004 (SAX04) conducted in the Northern Gulf of Mexico (GOM) where a small number of acoustic vector sensors were deployed in close proximity to the seafloor. A variety of acoustic waveforms were transmitted into the seafloor at normal incidence. The acoustic vector sensors were located both above and beneath the seafloor interface where they measured the acoustic pressure and the acoustic particle acceleration. Motion data provided by the buried vector sensors were affected by a suspension response that was sensitive to the mass properties of the sensor, the sediment density and sediment elasticity (e.g., shear wave speed). The suspension response for the buried vector sensors included a resonance within the analysis band of 0.4 to 2.0 kHz. The suspension resonance represented an unknown complex transfer function between the acoustic vector field in the seabed and data representing that field. Therefore, inverse methods developed for this study were required to 1) estimate dynamic properties of the sensor suspension resonance and 2) account for the associated corruption of vector field data. A method to account for the vector sensor suspense response function was integrated directly into the inversion methods such that vector channel data corruption was reduced and an estimate of the shear wave speed in the sediment was returned. Inversions of real and synthetic data sets indicated that information about sediment shear wave speed was carried by the suspension response of the buried sensors, as opposed to being contained inherently within the acoustic vector field.

Crocker, Steven E.

207

Estimating Cloud Cover  

ERIC Educational Resources Information Center

The purpose of this activity was to help students understand the percentage of cloud cover and make more accurate cloud cover observations. Students estimated the percentage of cloud cover represented by simulated clouds and assigned a cloud cover classification to those simulations. (Contains 2 notes and 3 tables.)

Moseley, Christine

2007-01-01

208

Cloud Computing Adam Barker  

E-print Network

Cloud Computing 1 Adam Barker #12;Overview · Introduction to Cloud computing · Enabling / Constraints 2 #12;Cloud Computing · Cloud computing provides resizable computing capacity that enables users to build and host applications in a data centre · Cloud computing characteristics · Computing as a utility

St Andrews, University of

209

Co/ Observations of the Lupus Dark Clouds  

NASA Astrophysics Data System (ADS)

An extensive mapping of CO (J = 1-0) emission from the Lupus 2 dark clouds has been made. Complementary observations in CO (J = 2-1) and 13CO (J = 1-0) over the central main cloud were obtained. The molecular gas motions are small over the entire cloud complex but asymmetric line profiles exist possibly due to the presence of two velocity components separated by about 1km s `in the main cloud. The relative intensity of these components changes gradually over the main cloud. We have found no evidence for any molecular outflows in the region. In particular the molecular gas is quiescent over the extremely active T Tauri star RU Lupi with its associated imbedded infrared sources and the Herbig-Haro object HH 55 in the main cloud. From this certain constraints can be put on the mass loss from the star. We derive a mass of about 10 Msun for the main cloud and estimate that a similar mass resides in two filaments northeast and west of this core in addition to two isolated cloudlets. We also report on a few CO observations made in the Lupus 3 dark clouds where a complex velocity pattern was found at one location.

Gahm, G. F.; Johansson, L. E. B.; Liseau, R.

1993-07-01

210

The Structure of the Local Interstellar Medium IV: Dynamics, Morphology, Physical Properties, and Implications of Cloud-Cloud Interactions  

E-print Network

We present an empirical dynamical model of the local interstellar medium based on 270 radial-velocity measurements for 157 sight lines toward nearby stars. Physical-parameter measurements (i.e., temperature, turbulent velocity, depletions) are available for 90 components, or one-third of the sample, enabling initial characterizations of the physical properties of LISM clouds. The model includes 15 warm clouds located within 15 pc of the Sun, each with a different velocity vector. We derive projected morphologies of all clouds and estimate the volume filling factor of warm partially ionized material in the LISM to be between ~5.5% and 19%. Relative velocities of potentially interacting clouds are often supersonic, consistent with heating, turbulent, and metal-depletion properties. Cloud-cloud collisions may be responsible for the filamentary morphologies found in ~1/3 of LISM clouds, the distribution of clouds along the boundaries of the two nearest clouds (LIC and G), the detailed shape and heating of the Mic Cloud, the location of nearby radio scintillation screens, and the location of a LISM cold cloud. Contrary to previous claims, the Sun appears to be located in the transition zone between the LIC and G Clouds.

Seth Redfield; Jeffrey L. Linsky

2007-09-27

211

Projectile Motion  

NSDL National Science Digital Library

In this interactive simulation adapted from University of Colorado’s Physics Education Technology project, learn about projectile motion by firing various objects from a virtual cannon into the air. Experiment with the settings and try to hit a target.

Foundation, Wgbh E.

2007-04-19

212

Quantum Motion  

NSDL National Science Digital Library

This resource illustrates the motion of a Gaussian wavepacket in one dimension scattering off of a barrier. The shape and size of the barrier can be changed, including creating a double barrier. The width, initial position, and total energy of the wavefunction can all be changed as well. Dimensionless units are used.

Group, Kansas S.; Zollman, Dean A.

2004-04-04

213

Spring Motion  

NSDL National Science Digital Library

Created by Lang Moore and David Smith for the Connected Curriculum Project, the purposes of this module are to investigate a mathematical model for spring motion and to study the effect of increased damping. This is one within a much larger set of learning modules hosted by Duke University.

Moore, Lang; Smith, David

2010-06-09

214

Brownian Motion.  

ERIC Educational Resources Information Center

Explains the phenomenon of Brownian motion, which serves as a mathematical model for random processes. Topics addressed include kinetic theory, Einstein's theory, particle displacement, and others. Points out that observations of the random course of a particle suspended in fluid led to the first accurate measurement of atomic mass. (DH)

Lavenda, Bernard H.

1985-01-01

215

Brownian Motion  

NSDL National Science Digital Library

This simulation shows Brownian motion, the random movement of particles in a fluid or gas due to molecular bombardment. The simulation records the path of a suspended particle and also shows how gas molecules collide with the particle and the container walls. The user can adjust the number of particles and the relative masses.

Hwang, Fu-Kwun

2008-04-14

216

Adding Two Vectors  

NSDL National Science Digital Library

This website from David M. Harrison of the University of Toronto's physics department provides an animation of the addition of two vectors. Instructors may use this animation in explaining the concept of adding vectors and demonstrating the steps involved.

Harrison, David M.

2010-08-13

217

Teaching Universal Gravitation with Vector Games  

NASA Astrophysics Data System (ADS)

Like many high school and college physics teachers, I have found playing vector games to be a useful way of illustrating the concepts of inertia, velocity, and acceleration. Like many, I have also had difficulty in trying to get students to understand Newton's law of universal gravitation, specifically the inverse-square law and its application to motion. In this paper, I'll outline a way to address this problem through use of a vector game. The inspiration for this idea came from a January 1998 article in The Physics Teacher by Michael Vinson entitled "Space Race: A Game of Physics Adventure."

Lowry, Matthew

2008-12-01

218

Cloud Computing og availability  

E-print Network

Cloud Computing og availability Projekt i pålidelighed Henrik Lavdal - 20010210 Søren Bardino Kaa - 20011654 Gruppe 8 19-03-2010 #12;Cloud Computing og availability Side 2 af 28 Indholdsfortegnelse ...........................................................................................5 Cloud computing

Christensen, Henrik Bærbak

219

Support vector domain description  

Microsoft Academic Search

This paper shows the use of a data domain description method, inspired by the support vector machine by Vapnik, called the support vector domain description (SVDD). This data description can be used for novelty or outlier de- tection. A spherically shaped decision boundary around a set of objects is constructed by a set of support vectors describing the sphere boundary.

David M. J. Tax; Robert P. W. Duin

1999-01-01

220

Rhotrix Vector Spaces  

ERIC Educational Resources Information Center

By rhotrix we understand an object that lies in some way between (n x n)-dimensional matrices and (2n - 1) x (2n - 1)-dimensional matrices. Representation of vectors in rhotrices is different from the representation of vectors in matrices. A number of vector spaces in matrices and their properties are known. On the other hand, little seems to be…

Aminu, Abdulhadi

2010-01-01

221

Dust cloud manipulation in microgravity experiments  

NASA Astrophysics Data System (ADS)

The European Space Agency’s scientific program Interactions in Cosmic and Atmospheric Particle Systems (ICAPS) [1] attributed for the International Space Station is aimed at increasing our knowledge about dust agglomeration in astrophysical processes mostly related to proto-planetary matter formation. These processes are simulated experimentally in clouds initially composed of about micrometre-sized solid particles. Relatively low gas pressure provides intensive enough particle Brownian motion but considerably reduces the experimentation time at normal gravity. Microgravity removes this problem but long duration experiments result in cloud depletion due to grain diffusion to the chamber walls and particle number density decrease due to agglomeration. The main problem comes from the fact that residual forces quickly sweep away the cloud from the observation volume thus drastically reducing the experiment duration. We developed different cloud manipulation systems that solve these problems and provide additional research opportunities in investigation of dust clouds. Particularly, they counterbalance external perturbations and solve the most challenging task of the increase of particle number concentration (cloud squeezing). There are several driving forces that may be used separately or in combination. Thermophoresis and gas flows induced by thermal creep are most favourable for cloud manipulation because they are nearly independent from particle properties. Electrostatic force allows detect charged particles, while photophoresis is sensitive to particle dimensions. The system provides two main regimes - 1) cloud positioning or displacement and 2) dynamic trapping. In absence of repulsive forces between particles the latter regime leads to cloud squeezing and intensive forced particle agglomeration. The cloud manipulation system additionally provides temperature stabilization or, on the contrary, high temperature variation in the observation volume; formation of controlled temperature gradients, intensive three-dimensional periodic shear flow or three-dimensional gas density pulsations of the contraction-expansion type. In short duration microgravity conditions of the Bremen drop tower we observed controlled cloud displacement, trapping, rapid growth of extended agglomerates, formation of complex three-dimensional cloud patterns, and motion of charged particles. The results may be applied in other projects dealing with dust clouds in microgravity. ESA PRODEX program and the Belgian Federal Science Policy Office are greatly acknowledged. [1] Blum, J. et al. (2008). Europhysicsnews, 39/3, 27-29.

Vedernikov, Andrei; Blum, Jurgen; Ingo Von Borstel, Olaf; Schraepler, Rainer; Balapanov, Daniyar; Cecere, Anselmo

222

Bad Clouds  

NSDL National Science Digital Library

This information is designed to belie the misconception that the capacity of air to hold water vapor is temperature dependent and that air can become saturated with water vapor. The temperature of a cloud droplet or ice crystal will be nearly the same as that of the air, so people imagine that somehow the air was to blame. But, if the other gases of the air were removed, leaving everything else the same, condensation and evaporation would proceed as before and the air was irrelevant to the behavior of the water molecules. It is therefore not correct to assign the behavior of water to an invented holding capacity of the air.

Fraser, Alistair

223

Types of Clouds  

NSDL National Science Digital Library

This is a basic lesson on clouds. Very nice photos of cumulus and cumulonimbus clouds are presented on the page as well as a description of all major cloud types and their associated weather. Two activities are presented. One invites the learner to create a cloud, while the other involves creating a collage of cloud images along with information about the weather associated with each cloud type.

Friend, Duane

224

Multivariate respiratory motion prediction.  

PubMed

In extracranial robotic radiotherapy, tumour motion is compensated by tracking external and internal surrogates. To compensate system specific time delays, time series prediction of the external optical surrogates is used. We investigate whether the prediction accuracy can be increased by expanding the current clinical setup by an accelerometer, a strain belt and a flow sensor. Four previously published prediction algorithms are adapted to multivariate inputs-normalized least mean squares (nLMS), wavelet-based least mean squares (wLMS), support vector regression (SVR) and relevance vector machines (RVM)-and evaluated for three different prediction horizons. The measurement involves 18 subjects and consists of two phases, focusing on long term trends (M1) and breathing artefacts (M2). To select the most relevant and least redundant sensors, a sequential forward selection (SFS) method is proposed. Using a multivariate setting, the results show that the clinically used nLMS algorithm is susceptible to large outliers. In the case of irregular breathing (M2), the mean root mean square error (RMSE) of a univariate nLMS algorithm is 0.66 mm and can be decreased to 0.46 mm by a multivariate RVM model (best algorithm on average). To investigate the full potential of this approach, the optimal sensor combination was also estimated on the complete test set. The results indicate that a further decrease in RMSE is possible for RVM (to 0.42 mm). This motivates further research about sensor selection methods. Besides the optical surrogates, the sensors most frequently selected by the algorithms are the accelerometer and the strain belt. These sensors could be easily integrated in the current clinical setup and would allow a more precise motion compensation. PMID:25254327

Dürichen, R; Wissel, T; Ernst, F; Schlaefer, A; Schweikard, A

2014-10-21

225

Multivariate respiratory motion prediction  

NASA Astrophysics Data System (ADS)

In extracranial robotic radiotherapy, tumour motion is compensated by tracking external and internal surrogates. To compensate system specific time delays, time series prediction of the external optical surrogates is used. We investigate whether the prediction accuracy can be increased by expanding the current clinical setup by an accelerometer, a strain belt and a flow sensor. Four previously published prediction algorithms are adapted to multivariate inputs—normalized least mean squares (nLMS), wavelet-based least mean squares (wLMS), support vector regression (SVR) and relevance vector machines (RVM)—and evaluated for three different prediction horizons. The measurement involves 18 subjects and consists of two phases, focusing on long term trends (M1) and breathing artefacts (M2). To select the most relevant and least redundant sensors, a sequential forward selection (SFS) method is proposed. Using a multivariate setting, the results show that the clinically used nLMS algorithm is susceptible to large outliers. In the case of irregular breathing (M2), the mean root mean square error (RMSE) of a univariate nLMS algorithm is 0.66 mm and can be decreased to 0.46 mm by a multivariate RVM model (best algorithm on average). To investigate the full potential of this approach, the optimal sensor combination was also estimated on the complete test set. The results indicate that a further decrease in RMSE is possible for RVM (to 0.42 mm). This motivates further research about sensor selection methods. Besides the optical surrogates, the sensors most frequently selected by the algorithms are the accelerometer and the strain belt. These sensors could be easily integrated in the current clinical setup and would allow a more precise motion compensation.

Dürichen, R.; Wissel, T.; Ernst, F.; Schlaefer, A.; Schweikard, A.

2014-10-01

226

Kepler Motion  

NSDL National Science Digital Library

This java applet displays Kepler's three laws of planetary motion in action. Users can select which of the three laws they wish to be animated and alter the initial conditions, observing how orbital paths and velocities change. Kepler derived his three laws after years of study on data that he inherited from his mentor, Tycho Brahe. Instructions on how to use the animation are provided, and a list of links to other related sites is included.

Hwang, Fu-Kwun

2004-10-27

227

Motion Simulator  

NASA Technical Reports Server (NTRS)

The development of the electric space actuator represents an unusual case of space technology transfer wherein the product was commercialized before it was used for the intended space purpose. MOOG, which supplies the thrust vector control hydraulic actuators for the Space Shuttle and brake actuators for the Space Orbiter, initiated development of electric actuators for aerospace and industrial use in the early 1980s. NASA used the technology to develop an electric replacement for the Space Shuttle main engine TVC actuator. An electric actuator is used to take passengers on a realistic flight to Jupiter at the US Space and Rocket Center, Huntsville, Alabama.

1993-01-01

228

ContentsContents2828vector 1. Background to Vector Calculus  

E-print Network

ContentsContents2828vector calculus 1 1. Background to Vector Calculus 2. Differential Vector;Background to Vector Calculus 28.1 Introduction Vector Calculus is the study of the various derivatives (VERSION 1: April 14, 2004): Workbook Level 1 28.1: Background to Vector Calculus #12;Solution In the first

Vickers, James

229

On the Hydrodynamic Interaction of Shock Waves with Interstellar Clouds. II. The Effect of Smooth Cloud Boundaries on Cloud Destruction and Cloud Turbulence  

NASA Astrophysics Data System (ADS)

The effect of smooth cloud boundaries on the interaction of steady planar shock waves with interstellar clouds is studied using a local adaptive mesh refinement technique with an axisymmetric Godunov hydrodynamic scheme. A three-dimensional calculation is also done to confirm the two-dimensional results. We find that smooth cloud boundaries significantly affect cloud morphology and retard cloud destruction. After shock passage, a sharp density jump forms due to velocity gradients generated in the smooth cloud boundary. We refer to this density jump as a ``slip surface'' because the velocity is sheared parallel to its surface. The formation of a slip surface leads to complete cloud destruction because of the Kelvin-Helmholtz and Rayleigh-Taylor instabilities. We construct analytic models of cloud drag and vorticity generation that compare well with the numerical results. Small shreds formed by the instabilities have significant velocity dispersions of 10%-20% of the ambient shock velocity. They could be related to the small cold H I clouds recently observed by Stanimirovi? & Heiles. The dependence of the velocity dispersion on region size, the so-called line width-size relation, is found to be time-dependent. In the early stages, the line width-size relation is more or less flat because of the significant small-scale fluctuations generated by the Kelvin-Helmholtz instability. In the later stages, the small-scale fluctuations tend to damp, leading to a line width that increases with size. The possibility of gravitational instability triggered by shock compression is discussed. We show that gravitational collapse can be induced in an initially uniform cloud by a radiative shock (?<4/3) only if it is not too strong and nonthermal motions are weak.

Nakamura, Fumitaka; McKee, Christopher F.; Klein, Richard I.; Fisher, Robert T.

2006-06-01

230

Object flow: A descriptor for classifying traffic motion  

Microsoft Academic Search

We present and evaluate a novel scene descriptor for classifying urban traffic by object motion. Atomic 3D flow vectors are extracted and compensated for the vehicle's egomotion, using stereo video sequences. Votes cast by each flow vector are accumulated in a bird's eye view histogram grid. Since we are directly using low-level object flow, no prior object detection or tracking

Andreas Geiger; Bernd Kitt

2010-01-01

231

Triboelectrification Based Motion Sensor for Human-Machine Interfacing  

E-print Network

vector sensor,20 tactile sensor,21 tracking sensor,22 and acoustic sensor.23 It is known that human skin nanosensors,14,15 biosensor,16 displacement vector sensor,17 acceleration sensor,18 pressure sensor,19 windTriboelectrification Based Motion Sensor for Human-Machine Interfacing Weiqing Yang,,, Jun Chen

Wang, Zhong L.

232

Particle Motion On A Curve Model  

NSDL National Science Digital Library

The Particle Motion On A Curve model simulates the dynamics of a particle sliding on a curve y=f(x) with friction. The model displays normal, friction, and gravitational force vectors and the local radius of curvature. Units are chosen such that mass m=1 and acceleration of gravity g=1. The Particle Motion On A Curve model was developed using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_mech_newton_ParticleMotionOnCurve.jar file will run the program if Java is installed.

Christian, Wolfgang

2011-06-08

233

Estimating Conical Motion From Magnetometer Measurements  

NASA Technical Reports Server (NTRS)

Method of digital processing of outputs of magnetometer mounted on scientific instrument or other assembly provides estimates of parameters of slow oscillatory motion of assembly at constant or nearly constant frequency, in which motion one axis of assembly describes elliptical cone about nominal fixed or nearly fixed axis. Conceived for use in estimating rotational-and-vibrational motion of small instrumented satellite and 20-km-long tether anchored at lower end to Space Shuttle. Applicable to almost any situation in which assembly moves conically about known axis while measuring known vector.

Polites, M. E.

1993-01-01

234

Ice Clouds in Martian Arctic (Accelerated Movie)  

NASA Technical Reports Server (NTRS)

Clouds scoot across the Martian sky in a movie clip consisting of 10 frames taken by the Surface Stereo Imager on NASA's Phoenix Mars Lander.

This clip accelerates the motion. The camera took these 10 frames over a 10-minute period from 2:52 p.m. to 3:02 p.m. local solar time at the Phoenix site during Sol 94 (Aug. 29), the 94th Martian day since landing.

Particles of water-ice make up these clouds, like ice-crystal cirrus clouds on Earth. Ice hazes have been common at the Phoenix site in recent days.

The camera took these images as part of a campaign by the Phoenix team to see clouds and track winds. The view is toward slightly west of due south, so the clouds are moving westward or west-northwestward.

The clouds are a dramatic visualization of the Martian water cycle. The water vapor comes off the north pole during the peak of summer. The northern-Mars summer has just passed its peak water-vapor abundance at the Phoenix site. The atmospheric water is available to form into clouds, fog and frost, such as the lander has been observing recently.

The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

2008-01-01

235

Tracking motion objects in infrared videos  

Microsoft Academic Search

We propose motion detection and object tracking method that is particularly suitable for infrared videos. Detection of moving objects in infrared videos is based on changing texture in parts of the view field. We estimate the speed of texture change by measuring the spread of texture vectors in the texture space. This method allows us to robustly detect very fast

Longin Jan Latecki; Roland Miezianko; Dragoljub Pokrajac

2005-01-01

236

Motion Control  

NSDL National Science Digital Library

While this site is considered a news source, it is perhaps best used as an educational reference for mechanical engineering topics. A very interesting section called Brushing Up is periodically updated with a new article describing one of the "core principles governing physics and the laws of motion." Fun with Fundamentals is another feature geared mainly for high school students. Here, a challenging problem is proposed, and the user must solve it. The solution to the problem is given in the following issue. Lastly, Design Basics discusses several concepts, such as motors, fluid power, and gears.

1993-01-01

237

Rotating Motion  

NSDL National Science Digital Library

In these problems, two people ride on a merry-go-round (radius fixed at 10 m..it's big!). One rider tosses a ball toward the other. The period of motion can be varied as can the initial velocity of the ball, relative to rider. One of the problems is to select the initial velocity of the ball so that it passes through center of the merry-go-round. Another is for the rider who throws the ball to catch it him/herself after exactly half a rotation.

Christian, Wolfgang; Belloni, Mario

2008-02-19

238

Investigation of water vapor motion winds from geostationary satellites  

NASA Technical Reports Server (NTRS)

Water vapor imagery from geostationary satellites has been available for over a decade. These data are used extensively by operational analysts and forecasters, mainly in a qualitative mode (Weldon and Holmes 1991). In addition to qualitative applications, motions deduced in animated water vapor imagery can be used to infer wind fields in cloudless regimes, thereby augmenting the information provided by cloud-drift wind vectors. Early attempts at quantifying the data by tracking features in water vapor imagery met with modest success (Stewart et al. 1985; Hayden and Stewart 1987). More recently, automated techniques have been developed and refined, and have resulted in upper-level wind observations comparable in quality to current operational cloud-tracked winds (Laurent 1993). In a recent study by Velden et al. (1993) it was demonstrated that wind sets derived from Meteosat-3 (M-3) water vapor imagery can provide important environmental wind information in data void areas surrounding tropical cyclones, and can positively impact objective track forecasts. M-3 was repositioned to 75W by the European Space Agency in 1992 in order to provide complete coverage of the Atlantic Ocean. Data from this satellite are being transmitted to the U.S. for operational use. Compared with the current GOES-7 (G-7) satellite (positioned near 112W), the M-3 water vapor channel contains a superior horizontal resolution (5 km vs. 16 km ). In this paper, we examine wind sets derived using automated procedures from both GOES-7 and Meteosat-3 full disk water vapor imagery in order to assess this data as a potentially important source of large-scale wind information. As part of a product demonstration wind sets were produced twice a day at CIMSS during a six-week period in March and April (1994). These data sets are assessed in terms of geographic coverage, statistical accuracy, and meteorological impact through preliminary results of numerical model forecast studies.

Velden, Christopher S.; Nieman, Steven J.; Wanzong, Steven

1994-01-01

239

Visual simulation of clouds  

Microsoft Academic Search

Clouds present serious problems to standard computer image generation techniques because clouds do not have well-defined surfaces and boundaries. In addition, clouds contain varying degrees of translucence, and their amorphous structure can change with time. Although several approaches to cloud simulation have produced impressive results, they have relied on complex mathematical models which produce high computation costs for a single

Geoffrey Y. Gardner

1985-01-01

240

Cloud Spectrum Measurements  

E-print Network

Cloud Seed Techniques (Mali, Saudi Arabia) Basic Cloud Parameter (MPACE) Icing Studies (WISP04` Cloud Spectrum Measurements By David Delene #12;Forward Scattering Spectrometer Probe (FSSP The ¶amount of liquid water for a given volume of air may be determined through mass integration of the cloud

Delene, David J.

241

Planning cloud seeding research  

Microsoft Academic Search

It is suggested that a theory of cloud seeding needs to be developed before seeding experiments can be properly planned and assessed. This theory will arise from improved knowledge of cloud processes gained by the study of natural clouds. Some techniques used in observing shower clouds in Sweden are described, and some preliminary results mentioned.

F. H. Ludlam

1955-01-01

242

Cloud Liquid Water Measurements  

E-print Network

Liquid Water Content? Determines the Potential of Enhancing Precipitation using Cloud Seed TechniquesCloud Liquid Water Measurements By David Delene University of North Dakota #12;Why Measure Cloud (Mali, Saudi Arabia) Basic Cloud Parameter (MPACE) Icing Studies (WISP04, Sikorsky) Comparison

Delene, David J.

243

Cloud Computing For Bioinformatics  

E-print Network

Cloud Computing For Bioinformatics EC2 and AMIs #12;Quick-starting an EC2 instance (let's get our feet wet!) Cloud Computing #12;Cloud Computing: EC2 instance Quick Start · On EC2 console, we can click on Launch Instance · This will let us get up and going quickly #12;Cloud Computing: EC2 instance

Ferrara, Katherine W.

244

Low-complexity motion estimation for VLBR video coders  

Microsoft Academic Search

A significant improvement of block-based motion estimation strategies is presented, which supports fast computation and VLBR coding. For each block, a spatio-temporal context is defined based on nearest neighbors in the current and previous frames, and a prediction list is built. Then, the best matching vector within the list is chosen as an estimation of the block motion. An additional

Francesco G. B. De Natale; Fabrizio Granelli; Gianni Vernazza

2002-01-01

245

A novel VLSI architecture of motion compensation for multiple standards  

Microsoft Academic Search

Motion compensation (MC) is one of the most important technologies capable of removing the temporal redundancy and widely adopted by the main video standards. From the older MPEG-2 to the latest H.264 and the Chinese AVS, many efficient coding tools have been introduced into MC, such as new motion vector prediction, bi-directional matching, quarter precision interpolation, etc. However, these new

Junhao Zheng; Wen Gao; David Wu; Don Xie

2008-01-01

246

Affine schemes in mesh-based video motion compensation  

Microsoft Academic Search

We evaluate the performances of different implementations of affine transform in a motion compensation architecture based on a hierarchical adaptive structured mesh. The architecture predicts the next video frame using the reference frame, mesh code and mesh node motion vectors. It achieves significant reduction in describing the mesh topology by coding the splitting in recursive triangulation of the initial coarse

Anant Utgikar; Wael Badawy; Guna Seetharaman; Magdy Bayoumi

2003-01-01

247

Efficient Hierarchical Motion Estimation Algorithm and Its VLSI Architecture  

Microsoft Academic Search

This paper addresses the development and hardware implementation of an efficient hierarchical motion estimation algorithm, HMEA, using multiresolution frames to reduce the computational complexity. Excellent estimation performance is ensured using an averaging filter to downsample the original image. At the smallest resolution, the least two motion vector candidates are selected using a full-search block matching algorithm. At the middle level,

Bing-fei Wu; Hsin-yuan Peng; Tung-lung Yu

2008-01-01

248

Dissipative force on an external quark in heavy quark cloud  

E-print Network

Within the finite temperature N = 4 strongly coupled super Yang- Mills, we compute the dissipative force on an external quark in the presence of evenly distributed heavy quark cloud. This is computed holographically by constructing the corresponding gravity dual. We study the behaviour of this force as a function of the cloud density. Along the way we also analyze the stability of the gravity dual for vector and tensor perturbations.

Shankhadeep Chakrabortty

2011-07-31

249

Symbolic computer vector analysis  

NASA Technical Reports Server (NTRS)

A MACSYMA program is described which performs symbolic vector algebra and vector calculus. The program can combine and simplify symbolic expressions including dot products and cross products, together with the gradient, divergence, curl, and Laplacian operators. The distribution of these operators over sums or products is under user control, as are various other expansions, including expansion into components in any specific orthogonal coordinate system. There is also a capability for deriving the scalar or vector potential of a vector field. Examples include derivation of the partial differential equations describing fluid flow and magnetohydrodynamics, for 12 different classic orthogonal curvilinear coordinate systems.

Stoutemyer, D. R.

1977-01-01

250

MAC3: Vectors  

NSDL National Science Digital Library

This resource is a set of instructional materials developed to help beginning physics students build a solid understanding of vector algebra. It contains two lecture presentations in PDF format and a companion assessment. It gives an overview of terminology, vector notation, and a variety of methods for solving problems relating to vectors. One of the authors' goals is to help students differentiate between the uses of vectors in mathematics vs. physics. This resource is part of a collection developed by the NSF-funded Mathematics Across the Community College Curriculum (MAC 3).

Friesen, Larry; Gillis, Anne

2008-12-22

251

Society for Vector Ecology  

NSDL National Science Digital Library

Formed in 1968, the Society for Vector Ecology (SOVE) is dedicated to studying "all aspects of the biology, ecology, and control of arthropod vectors and the interrelationships between the vectors and the disease agents they transmit." Comprised of researchers and operational and extension personnel around the globe, SOVE tracks and studies the biological organisms that transmit diseases. The SOVE Website contains information related to the Society (e.g., mission, history), its publications (journal, newsletter -- both .pdf format), and professional opportunities (conferences, employment). Several dozen links to additional vector ecology resources are provided.

2008-09-12

252

Ocular tracking responses to background motion gated by feature-based attention.  

PubMed

Involuntary ocular tracking responses to background motion offer a window on the dynamics of motion computations. In contrast to spatial attention, we know little about the role of feature-based attention in determining this ocular response. To probe feature-based effects of background motion on involuntary eye movements, we presented human observers with a balanced background perturbation. Two clouds of dots moved in opposite vertical directions while observers tracked a target moving in horizontal direction. Additionally, they had to discriminate a change in the direction of motion (±10° from vertical) of one of the clouds. A vertical ocular following response occurred in response to the motion of the attended cloud. When motion selection was based on motion direction and color of the dots, the peak velocity of the tracking response was 30% of the tracking response elicited in a single task with only one direction of background motion. In two other experiments, we tested the effect of the perturbation when motion selection was based on color, by having motion direction vary unpredictably, or on motion direction alone. Although the gain of pursuit in the horizontal direction was significantly reduced in all experiments, indicating a trade-off between perceptual and oculomotor tasks, ocular responses to perturbations were only observed when selection was based on both motion direction and color. It appears that selection by motion direction can only be effective for driving ocular tracking when the relevant elements can be segregated before motion onset. PMID:24920026

Souto, David; Kerzel, Dirk

2014-09-01

253

SinoCor: motion correction in SPECT  

NASA Astrophysics Data System (ADS)

Motion is a serious artifact in Cardiac nuclear imaging because the scanning operation takes a long time. Since reconstruction algorithms assume consistent or stationary data the quality of resulting image is affected by motion, sometimes significantly. Even after adoption of the gold standard MoCo(R) algorithm from Cedars-Sinai by most vendors, heart motion remains a significant challenge. Also, any serious study in quantitative analysis necessitates correction for motion artifacts. It is generally recognized that human eye is a very sensitive tool for detecting motion. However, two reasons prevent such manual correction: (1) it is costly in terms of specialist's time, and (2) no such tool for manual correction is available currently. Previously, at SPIE-MIC'11, we presented a simple tool (SinoCor) that allows sinograms to be corrected manually or automatically. SinoCor performs correction of sinograms containing inter-frame patient or respiratory motions using rigid-body dynamics. The software is capable of detecting the patient motion and estimating the body-motion vector using scanning geometry parameters. SinoCor applies appropriate geometrical correction to all the frames subsequent to the frame when the movement has occurred in a manual or automated mode. For respiratory motion, it is capable of automatically smoothing small oscillatory (frame-wise local) movements. Lower order image moments are used to represent a frame and the required rigid body movement compensation is computed accordingly. Our current focus is on enhancement of SinoCor with the capability to automatically detect and compensate for intra-frame motion that causes motion blur on the respective frame. Intra-frame movements are expected in both patient and respiratory motions. For a controlled study we also have developed a motion simulator. A stable version of SinoCor is available under license from Lawrence Berkeley National Laboratory.

Mitra, Debasis; Eiland, Daniel; Abdallah, Mahmoud; Bouthcko, Rostyslav; Gullberg, Grant T.; Schechtmann, Norberto

2012-02-01

254

Diffuse Reflection of Laser Light From Clouds  

NASA Technical Reports Server (NTRS)

Laser light reflected from an aqueous suspension of particles or "cloud" with known thickness and particle size distribution defines the "cloud radiative Green's function", G. G is sensitive to cloud thickness, allowing retrieval of that important quantity. We describe a laboratory simulation of G, useful in design of an offbeam Lidar instrument for remote sensing of cloud thickness. Clouds of polystyrene microspheres suspended in water are analogous to real clouds of water droplets suspended in air. The size distribution extends from 0.5 microns to 25 microns, roughly lognormal, similar to real clouds. Density of suspended spheres is adjusted so photon mean-free-path is about 10 cm, 1000 times smaller than in real clouds. The light source is a Nd:YAG laser at 530 nm. Detectors are flux and photon-counting PMTs, with a glass probe for precise positioning. A Labview 5 VI controls position and data acquisition, via an NI Motion Control board connected to a stepper motor driving an Edmund linear slider,and a 16-channel 16-bit NI-DAQ board. The stepper motor is accurate to 10 microns. Step size is selectable. Far from the beam, the rate of exponential increase in the beam direction scales as expected from diffusion theory, linearly with cloud thickness, and inversely as the square root of the reduced optical thickness, independent of particle size. Nearer the beam the signal increases faster than exponential and depends on particle size. Results verify 3D Monte Carlo simulations that demonstrate detectability of remotely sensed offbeam returns, without filters at night, with narrow bandpass filter in day.

Cahalan, R. F.; Davis, A.; McGill, M.

1999-01-01

255

Morphology and ionization of the interstellar cloud surrounding the solar system.  

PubMed

The first encounter between the sun and the surrounding interstellar cloud appears to have occurred 2000 to 8000 years ago. The sun and cloud space motions are nearly perpendicular, an indication that the sun is skimming the cloud surface. The electron density derived for the surrounding cloud from the carbon component of the anomalous cosmic ray population in the solar system and from the interstellar ratio of Mg(+) to Mg degrees toward Sirius support an equilibrium model for cloud ionization (an electron density of 0.22 to 0.44 per cubic centimeter). The upwind magnetic field direction is nearly parallel to the cloud surface. The relative sun-cloud motion indicates that the solar system has a bow shock. PMID:17833816

Frisch, P C

1994-09-01

256

Long-term memory motion-compensated prediction  

Microsoft Academic Search

Long-term memory motion-compensated prediction extends the spatial displacement vector utilized in block-based hybrid video coding by a variable time delay permitting the use of more frames than the previously decoded one for motion compensated prediction. The long-term memory covers several seconds of decoded frames at the encoder and decoder. The use of multiple frames for motion compensation in most cases

Thomas Wiegand; Xiaozheng Zhang; Bernd Girod

1999-01-01

257

Motion Information Inferring Scheme for Multi-View Video Coding  

NASA Astrophysics Data System (ADS)

This letter proposes a motion information inferring scheme for multi-view video coding motivated by the idea that the aspect of motion vector between the corresponding positions in the neighboring view pair is quite similar. The proposed method infers the motion information from the corresponding macroblock in the neighboring view after RD optimization with the existing prediction modes. This letter presents evaluation showing that the method significantly enhances the efficiency especially at high bit rates.

Koo, Han-Suh; Jeon, Yong-Joon; Jeon, Byeong-Moon

258

Plate Motions  

NSDL National Science Digital Library

To prepare for this exercise students read the Chapter on plate tectonics in their text book. In class, they are given a color isochron map of the sea floor. They are given 4 tasks: Answer basic questions about the timing and rate of opening of the N. and S. Atlantic; Determine what has happened to the oceanic crust that is created on the eastern side of the East Pacific Rise; Determine what type of plate boundary existed on the western edge of the N. America plate before the San Andreas Fault and when this transition occurred; and Reconstruct the motion of the plates over the last 40 Ma assuming that the surface area of the Earth has not changed.

Nunn, Jeffrey

259

Motion Simulator  

NASA Technical Reports Server (NTRS)

MOOG, Inc. supplies hydraulic actuators for the Space Shuttle. When MOOG learned NASA was interested in electric actuators for possible future use, the company designed them with assistance from Marshall Space Flight Center. They also decided to pursue the system's commercial potential. This led to partnership with InterActive Simulation, Inc. for production of cabin flight simulators for museums, expositions, etc. The resulting products, the Magic Motion Simulator 30 Series, are the first electric powered simulators. Movements are computer-guided, including free fall to heighten the sense of moving through space. A projection system provides visual effects, and the 11 speakers of a digital laser based sound system add to the realism. The electric actuators are easier to install, have lower operating costs, noise, heat and staff requirements. The U.S. Space & Rocket Center and several other organizations have purchased the simulators.

1993-01-01

260

Olympic Motion  

NSDL National Science Digital Library

The following resource is fromLessonopoly, which has created student activities and lesson plans to support the video series, Science of the Olympic Winter Games, created by NBC Learn and the National Science Foundation. Featuring exclusive footage from NBC Sports and contributions from Olympic athletes and NSF scientists, the series will help teach your students valuable scientific concepts. In this particular lesson, students will learn about motion and their body at two different levels: cellular and muscular. Students will examine human blood to identify its basic components and will conduct a test to determine their reflex reaction time. Students will also create a flow chart to show the role of cells in muscle contraction.

2010-01-01

261

SURFACE CLOUD RADIATIVE FORCING, CLOUD FRACTION AND CLOUD ALBEDO: THEIR RELATIONSHIP AND MULTISCALE VARIATION  

E-print Network

SURFACE CLOUD RADIATIVE FORCING, CLOUD FRACTION AND CLOUD ALBEDO: THEIR RELATIONSHIP AND MULTISCALE/Atmospheric Sciences Division Brookhaven National Laboratory P.O. Box, Upton, NY www.bnl.gov ABSTRACT Cloud-induced climate change. Cloud-radiative forcing, cloud fraction, and cloud albedo are three key quantities

262

PhET Teacher Activities: Vectors Simulations Lab  

NSDL National Science Digital Library

This virtual lab was developed by a high school teacher specifically for use with the PhET simulation "Motion in 2D". It provides explicit direction for using the simulation to explore vector quantities, vector addition, and calculating resultants. In the last half of the activity, students demonstrate understanding by performing specific calculations, then using the simulation to check their work. The lesson includes printable student data tables. The associated simulation (which must be running to complete this activity) is available from PhET at: Motion in 2D.

Bires, Chris

2013-02-05

263

Role of Gravity Waves in Determining Cirrus Cloud Properties  

NASA Technical Reports Server (NTRS)

Cirrus clouds are important in the Earth's radiation budget. They typically exhibit variable physical properties within a given cloud system and from system to system. Ambient vertical motion is a key factor in determining the cloud properties in most cases. The obvious exception is convectively generated cirrus (anvils), but even in this case, the subsequent cloud evolution is strongly influenced by the ambient vertical motion field. It is well know that gravity waves are ubiquitous in the atmosphere and occur over a wide range of scales and amplitudes. Moreover, researchers have found that inclusion of statistical account of gravity wave effects can markedly improve the realism of simulations of persisting large-scale cirrus cloud features. Here, we use a 1 -dimensional (z) cirrus cloud model, to systematically examine the effects of gravity waves on cirrus cloud properties. The model includes a detailed representation of cloud microphysical processes (bin microphysics and aerosols) and is run at relatively fine vertical resolution so as to adequately resolve nucleation events, and over an extended time span so as to incorporate the passage of multiple gravity waves. The prescribed gravity waves "propagate" at 15 m s (sup -1), with wavelengths from 5 to 100 km, amplitudes range up to 1 m s (sup -1)'. Despite the fact that the net gravity wave vertical motion forcing is zero, it will be shown that the bulk cloud properties, e.g., vertically-integrated ice water path, can differ quite significantly from simulations without gravity waves and that the effects do depend on the wave characteristics. We conclude that account of gravity wave effects is important if large-scale models are to generate realistic cirrus cloud property climatology (statistics).

OCStarr, David; Singleton, Tamara; Lin, Ruei-Fong

2008-01-01

264

Six Myths on the Virial Theorem Applied to Interstellar Clouds  

NASA Astrophysics Data System (ADS)

The interstellar medium is highly dynamic and turbulent. However, little or no attention has been paid in the literature to the implications that this fact has on the validity of at least six common assumptions on the Virial Theorem (VT), which are: (i) the only role of turbulent motions within a cloud is to provide support against collapse, (ii) the surface terms are negligible compared to the volumetric ones, (iii) the gravitational term is a binding source for the clouds since it can be approximated by the gravitational energy, (iv) the sign of the second-time derivative of the moment of inertia determines whether the cloud is contracting (ddot{I} < 0) or expanding (ddot{I} > 0), (v) interstellar clouds are in Virial Equilibrium (VE), and (vi) Larson's (1981) relations (mean density-size and velocity dispersion-size) are the observational proof that clouds are in VE. Turbulent, supersonic interstellar clouds cannot fulfill these assumptions, however, because turbulent fragmentation will induce flux of mass, moment and energy between the clouds and their environment, and will favor local collapse while may disrupt the clouds within a dynamical timescale. It is argued that, although the observational and numerical evidence suggests that interstellar clouds are not in VE, the so-called ``Virial Mass'' estimations, which actually should be called ``energy-equipartition mass'' estimations, are good order-of magnitude estimations of the actual mass of the clouds just because observational surveys will tend to detect interstellar clouds appearing to be close to energy equipartition. Similarly, order of magnitude estimations of the energy content of the clouds are reasonable. However, since clouds are actually out of VE, as suggested by asymmetrical line profiles, they should be transient entities. These results are compatible with observationally-based estimations for rapid star formation, and call into question the models for the star formation efficiency based on clouds being in VE.

Ballesteros-Paredes, J.

2009-05-01

265

Vector Calculus Spring 1997  

E-print Network

Vector Calculus Math 241 Spring 1997 Instructor Information: Professor: Bob Sharpley Office: 313D­ tor calculus including vector fields, line integrals, and Green's theorem in the plane. Exams in Math 142 or an equivalent course. Text: Calculus with Analytic Geometry, by D. Varberg and E.J. Purcell

Sharpley, Robert

266

Retroviruses as vectors.  

PubMed

Recombinant retroviruses have long been used to deliver heterologous genes to mammalian cells. Convenient packaging cell lines and vector plasmids have been distributed widely and 'home-made' retroviral vectors have now become a useful research tool in many laboratories. Compared to more traditional methods of gene transfer, retroviral vectors are extraordinarily efficient gene delivery vehicles which cause no detectable harm as they enter their target cells. In the nucleus the retroviral necleic acid becomes integrated into chromosomal DNA, ensuring its long-term persistence and stable transmission to all future progeny of the transduced cell. Up to 8 kilobases of foreign gene sequence can be packaged in a retroviral vector and this is more than enough for most gene therapy applications. Retroviral vectors can also be manufactured in large quantities to meet very stringent safety specifications. They have therefore been selected as the vectors of choice in 80% of the clinical gene therapy trials that have been approved to date. So far there have been no reported short- or long-term toxicity problems associated with their use in human gene therapy trials, now dating back to 1989. However, despite this impressive record, there is still great scope (and need) for the development of new, improved retroviral vectors and packaging systems to fuel further advances in the field of human gene therapy. In the following discussion, existing retroviral vectors are reviewed and current areas of technological development are emphasised. PMID:7767638

Vile, R G; Russell, S J

1995-01-01

267

Hunting the Vector Hybrid  

E-print Network

The current state of analysis of e+e- annihilation below 2.0 GeV and of the vector component of tau decay is reviewed. The evidence for and against the presence of hybrid vectors is discussed. It is concluded that the data strongly favour their inclusion, and the consequences of this are outlined.

A Donnachie; Yu S Kalashnikova

1999-01-18

268

Support Vector Data Description  

Microsoft Academic Search

Data domain description concerns the characterization of a data set. A good description covers all target data but includes no superfluous space. The boundary of a dataset can be used to detect novel data or outliers. We will present the Support Vector Data Description (SVDD) which is inspired by the Support Vector Classifier. It obtains a spherically shaped boundary around

David M. J. Tax; Robert P. W. Duin

2004-01-01

269

Stability of Horndeski vector-tensor interactions  

NASA Astrophysics Data System (ADS)

We study the Horndeski vector-tensor theory that leads to second order equations of motion and contains a non-minimally coupled abelian gauge vector field. This theory is remarkably simple and consists of only 2 terms for the vector field, namely: the standard Maxwell kinetic term and a coupling to the dual Riemann tensor. Furthermore, the vector sector respects the U(1) gauge symmetry and the theory contains only one free parameter, M2, that controls the strength of the non-minimal coupling. We explore the theory in a de Sitter spacetime and study the presence of instabilities and show that it corresponds to an attractor solution in the presence of the vector field. We also investigate the cosmological evolution and stability of perturbations in a general FLRW spacetime. We find that a sufficient condition for the absence of ghosts is M2 > 0. Moreover, we study further constraints coming from imposing the absence of Laplacian instabilities. Finally, we study the stability of the theory in static and spherically symmetric backgrounds (in particular, Schwarzschild and Reissner-Nordström-de Sitter). We find that the theory, quite generally, do have ghosts or Laplacian instabilities in regions of spacetime where the non-minimal interaction dominates over the Maxwell term. We also calculate the propagation speed in these spacetimes and show that superluminality is a quite generic phenomenon in this theory.

Beltrán Jiménez, Jose; Durrer, Ruth; Heisenberg, Lavinia; Thorsrud, Mikjel

2013-10-01

270

Vector theories in cosmology  

SciTech Connect

This article provides a general study of the Hamiltonian stability and the hyperbolicity of vector field models involving both a general function of the Faraday tensor and its dual, f(F{sup 2},FF-tilde), as well as a Proca potential for the vector field, V(A{sup 2}). In particular it is demonstrated that theories involving only f(F{sup 2}) do not satisfy the hyperbolicity conditions. It is then shown that in this class of models, the cosmological dynamics always dilutes the vector field. In the case of a nonminimal coupling to gravity, it is established that theories involving Rf(A{sup 2}) or Rf(F{sup 2}) are generically pathologic. To finish, we exhibit a model where the vector field is not diluted during the cosmological evolution, because of a nonminimal vector field-curvature coupling which maintains second-order field equations. The relevance of such models for cosmology is discussed.

Esposito-Farese, Gilles; Pitrou, Cyril; Uzan, Jean-Philippe [GRECO, Institut d'Astrophysique de Paris, UMR 7095-CNRS, Universite Pierre et Marie Curie-Paris 6, 98bis boulevard Arago, F-75014 Paris (France); Institute of Cosmology and Gravitation, Dennis Sciama Building, Burnaby Road, Portsmouth, PO1 3FX (United Kingdom); GRECO, Institut d'Astrophysique de Paris, UMR 7095-CNRS, Universite Pierre et Marie Curie-Paris 6, 98bis boulevard Arago, F-75014 Paris (France) and Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701, Cape Town (South Africa)

2010-03-15

271

Vector generator scan converter  

DOEpatents

High printing speeds for graphics data are achieved with a laser printer by transmitting compressed graphics data from a main processor over an I/O (input/output) channel to a vector generator scan converter which reconstructs a full graphics image for input to the laser printer through a raster data input port. The vector generator scan converter includes a microprocessor with associated microcode memory containing a microcode instruction set, a working memory for storing compressed data, vector generator hardward for drawing a full graphic image from vector parameters calculated by the microprocessor, image buffer memory for storing the reconstructed graphics image and an output scanner for reading the graphics image data and inputting the data to the printer. The vector generator scan converter eliminates the bottleneck created by the I/O channel for transmitting graphics data from the main processor to the laser printer, and increases printer speed up to thirty fold.

Moore, James M. (Livermore, CA); Leighton, James F. (Livermore, CA)

1990-01-01

272

Vector generator scan converter  

DOEpatents

High printing speeds for graphics data are achieved with a laser printer by transmitting compressed graphics data from a main processor over an I/O channel to a vector generator scan converter which reconstructs a full graphics image for input to the laser printer through a raster data input port. The vector generator scan converter includes a microprocessor with associated microcode memory containing a microcode instruction set, a working memory for storing compressed data, vector generator hardware for drawing a full graphic image from vector parameters calculated by the microprocessor, image buffer memory for storing the reconstructed graphics image and an output scanner for reading the graphics image data and inputting the data to the printer. The vector generator scan converter eliminates the bottleneck created by the I/O channel for transmitting graphics data from the main processor to the laser printer, and increases printer speed up to thirty fold. 7 figs.

Moore, J.M.; Leighton, J.F.

1988-02-05

273

Limits to Cloud Susceptibility  

NASA Technical Reports Server (NTRS)

1-kilometer AVHRR observations of ship tracks in low-level clouds off the west coast of the U S. were used to determine limits for the degree to which clouds might be altered by increases in anthropogenic aerosols. Hundreds of tracks were analyzed to determine whether the changes in droplet radii, visible optical depths, and cloud top altitudes that result from the influx of particles from underlying ships were consistent with expectations based on simple models for the indirect effect of aerosols. The models predict substantial increases in sunlight reflected by polluted clouds due to the increases in droplet numbers and cloud liquid water that result from the elevated particle concentrations. Contrary to the model predictions, the analysis of ship tracks revealed a 15-20% reduction in liquid water for the polluted clouds. Studies performed with a large-eddy cloud simulation model suggested that the shortfall in cloud liquid water found in the satellite observations might be attributed to the restriction that the 1-kilometer pixels be completely covered by either polluted or unpolluted cloud. The simulation model revealed that a substantial fraction of the indirect effect is caused by a horizontal redistribution of cloud water in the polluted clouds. Cloud-free gaps in polluted clouds fill in with cloud water while the cloud-free gaps in the surrounding unpolluted clouds remain cloud-free. By limiting the analysis to only overcast pixels, the current study failed to account for the gap-filling predicted by the simulation model. This finding and an analysis of the spatial variability of marine stratus suggest new ways to analyze ship tracks to determine the limit to which particle pollution will alter the amount of sunlight reflected by clouds.

Coakley, James A., Jr.

2002-01-01

274

Lecture outline Support vector machines  

E-print Network

Lecture outline · Support vector machines #12;Support Vector Machines · Find a linear hyperplane (decision boundary) that will separate the data #12;Support Vector Machines · One Possible Solution #12;Support Vector Machines · Another possible solution #12;Support Vector Machines · Other possible solutions

Terzi, Evimaria

275

Lecture outline Support vector machines  

E-print Network

Lecture outline · Support vector machines #12;Support Vector Machines · Find a linear hyperplane (decision boundary) that will separate the data #12;Support Vector Machines · One Possible Solution B1 #12;Support Vector Machines · Another possible solution B2 #12;Support Vector Machines · Other possible

Terzi, Evimaria

276

Complex Vector Formalism of Harmonic Oscillator in Geometric Algebra: Particle Mass, Spin and Dynamics in Complex Vector Space  

NASA Astrophysics Data System (ADS)

Elementary particles are considered as local oscillators under the influence of zeropoint fields. Such oscillatory behavior of the particles leads to the deviations in their path of motion. The oscillations of the particle in general may be considered as complex rotations in complex vector space. The local particle harmonic oscillator is analyzed in the complex vector formalism considering the algebra of complex vectors. The particle spin is viewed as zeropoint angular momentum represented by a bivector. It has been shown that the particle spin plays an important role in the kinematical intrinsic or local motion of the particle. From the complex vector formalism of harmonic oscillator, for the first time, a relation between mass and bivector spin has been derived in the form . Where, is the angular velocity bivector of complex rotations, is the velocity of light. The unit vector acts as an operator on the idempotents and to give the eigen values The constant represents two fold nature of the equation corresponding to particle and antiparticle states. Further the above relation shows that the mass of the particle may be interpreted as a local spatial complex rotation in the rest frame. This gives an insight into the nature of fundamental particles. When a particle is observed from an arbitrary frame of reference, it has been shown that the spatial complex rotation dictates the relativistic particle motion. The mathematical structure of complex vectors in space and spacetime is developed.

Muralidhar, K.

2014-03-01

277

On the stability and causality of scalar-vector theories  

NASA Astrophysics Data System (ADS)

Various extensions of standard inflationary models have been proposed recently by adding vector fields. Because they are generally motivated by large-scale anomalies, and the possibility of statistical anisotropy of primordial fluctuations, such models require to introduce non-standard couplings between vector fields on the one hand, and either gravity or scalar fields on the other hand. In this article, we study models involving a vector field coupled to a scalar field. We derive restrictive necessary conditions for these models to be both stable (Hamiltonian bounded by below) and causal (hyperbolic equations of motion).

Fleury, Pierre; Beltrán Almeida, Juan P.; Pitrou, Cyril; Uzan, Jean-Philippe

2014-11-01

278

Collective motion  

NASA Astrophysics Data System (ADS)

We review the observations and the basic laws describing the essential aspects of collective motion - being one of the most common and spectacular manifestation of coordinated behavior. Our aim is to provide a balanced discussion of the various facets of this highly multidisciplinary field, including experiments, mathematical methods and models for simulations, so that readers with a variety of background could get both the basics and a broader, more detailed picture of the field. The observations we report on include systems consisting of units ranging from macromolecules through metallic rods and robots to groups of animals and people. Some emphasis is put on models that are simple and realistic enough to reproduce the numerous related observations and are useful for developing concepts for a better understanding of the complexity of systems consisting of many simultaneously moving entities. As such, these models allow the establishing of a few fundamental principles of flocking. In particular, it is demonstrated, that in spite of considerable differences, a number of deep analogies exist between equilibrium statistical physics systems and those made of self-propelled (in most cases living) units. In both cases only a few well defined macroscopic/collective states occur and the transitions between these states follow a similar scenario, involving discontinuity and algebraic divergences.

Vicsek, Tamás; Zafeiris, Anna

2012-08-01

279

Tvashtar in Motion  

NASA Technical Reports Server (NTRS)

This five-frame sequence of New Horizons images captures the giant plume from Io's Tvashtar volcano. Snapped by the probe's Long Range Reconnaissance Imager (LORRI) as the spacecraft flew past Jupiter earlier this year, this first-ever 'movie' of an Io plume clearly shows motion in the cloud of volcanic debris, which extends 330 kilometers (200 miles) above the moon's surface. Only the upper part of the plume is visible from this vantage point -- the plume's source is 130 kilometers (80 miles) below the edge of Io's disk, on the far side of the moon.

The appearance and motion of the plume is remarkably similar to an ornamental fountain on Earth, replicated on a gigantic scale. The knots and filaments that allow us to track the plume's motion are still mysterious, but this movie is likely to help scientists understand their origin, as well as provide unique information on the plume dynamics.

Io's hyperactive nature is emphasized by the fact that two other volcanic plumes are also visible off the edge of Io's disk: Masubi at the 7 o'clock position, and a very faint plume, possibly from the volcano Zal, at the 10 o'clock position. Jupiter illuminates the night side of Io, and the most prominent feature visible on the disk is the dark horseshoe shape of the volcano Loki, likely an enormous lava lake. Boosaule Mons, which at 18 kilometers (11 miles) is the highest mountain on Io and one of the highest mountains in the solar system, pokes above the edge of the disk on the right side.

The five images were obtained over an 8-minute span, with two minutes between frames, from 23:50 to 23:58 Universal Time on March 1, 2007. Io was 3.8 million kilometers (2.4 million miles) from New Horizons; the image is centered at Io coordinates 0 degrees north, 342 degrees west.

The pictures were part of a sequence designed to look at Jupiter's rings, but planners included Io in the sequence because the moon was passing behind Jupiter's rings at the time.

2007-01-01

280

The Response of Area MT and VI Neurons to Transparent Motion  

Microsoft Academic Search

An important use of motion information is to segment a com- plex visual scene into surfaces and objects. Transparent motions present a particularly difficult problem for segmen- tation because more than one velocity vector occurs at each local region in the image, and current machine vision sys- tems fail in these circumstances. The fact that motion trans- parency is prevalent

Robert J. Snowden; Stefan Treue; Roger G. Erickson; Richard A. Andersen

1991-01-01

281

Joint global motion estimation and coding for scalable H.264\\/SVC high-definition video streams  

Microsoft Academic Search

This paper presents a joint indexing-coding approach applied to global camera motion detection in the scalable H.264\\/SVC compressed domain. Our goal is to facilitate and to improve indexing in the MPEG compressed domain, if necessary by modifying the original coded stream, without losing compatibility with the standard. In frames with very noisy motion vector fields, we use the global motion

Christian Käs; Henri Nicolas

2008-01-01

282

Motion Compensated Error Concealment for HEVC Based on Block-Merging and Residual Energy  

E-print Network

by defining three types of variable size unit: Coding Unit (CU), Prediction Unit (PU) and Transform Unit (TU PUs. PUs are the basic unit for motion prediction. After PU segmentation, a proper size of TU software HM. The motion vector from the co-located block will be refined for motion compensation. Based

Cosman, Pamela C.

283

A novel hexagon-based search algorithm for fast block motion estimation  

Microsoft Academic Search

In block motion estimation, search patterns with different shape or size have a very important impact on search speed and distortion performance. In this paper, we propose a novel algorithm using a hexagon-based search (HEXBS) pattern for fast block motion estimation. The proposed HEXBS algorithm may find any motion vector with fewer search points than the diamond search (DS) algorithm.

Ce Zhu; Xiao Lin; Lap-Pui Chau; Keng-Pang Lim; Hock-Ann Ang; Choo-Yin Ong

2001-01-01

284

The interstellar cloud surrounding the Sun: a new perspective  

NASA Astrophysics Data System (ADS)

Aims: We offer a new, simpler picture of the local interstellar medium, made of a single continuous cloud enveloping the Sun. This new outlook enables the description of a diffuse cloud from within and brings to light some unexpected properties. Methods: We re-examine the kinematics and abundances of the local interstellar gas, as revealed by the published results for the ultraviolet absorption lines of Mg II, Fe II, and H I. Results: In contrast to previous representations, our new picture of the local interstellar medium consists of a single, monolithic cloud that surrounds the Sun in all directions and accounts for most of the matter present in the first 50 parsecs around the Sun. The cloud fills the space around us out to about 9 pc in most directions, although its boundary is very irregular with possibly a few extensions up to 20 pc. The cloud does not behave like a rigid body: gas within the cloud is being differentially decelerated in the direction of motion, and the cloud is expanding in directions perpendicular to this flow, much like a squashed balloon. Average H I volume densities inside the cloud vary between 0.03 and 0.1 cm-3 over different directions. Metals appear to be significantly depleted onto grains, and there is a steady increase in depletion from the rear of the cloud to the apex of motion. There is no evidence that changes in the ionizing radiation influence the apparent abundances. Secondary absorption components are detected in 60% of the sight lines. Almost all of them appear to be interior to the volume occupied by the main cloud. Half of the sight lines exhibit a secondary component moving at about -7.2 km s-1 with respect to the main component, which may be the signature of a shock propagating toward the cloud's interior.

Gry, Cécile; Jenkins, Edward B.

2014-07-01

285

Streaming instabilities in multicomponent interstellar clouds  

SciTech Connect

Streaming instabilities in interstellar clouds have been investigated. It is pointed out that the motion of a lighter dust species relative to a plasma containing a heavier dust species can give rise to low frequency electrostatic fluctuations. The dust ion acoustic and dust acoustic waves can become unstable in such plasmas. The instability regions are influenced by the presence of background dust. Since interstellar clouds have relative motions in many cases and contain dust species, therefore the present results indicate the presence of an electrostatic dust ion acoustic wave and dust acoustic wave in such systems. The results have been applied to interstellar medium using particular data and comparisons have been made with previous works.

Shan, S. Ali; Sajid, M. [Theoretical Plasma Physics Division, PINSTECH, P. O. Nilore, Islamabad (Pakistan); Saleem, H. [Theoretical Plasma Physics Division, PINSTECH, P. O. Nilore, Islamabad (Pakistan); National Centre for Physics (NCP), Quaid-i-Azam University, Islamabad (Pakistan)

2008-07-15

286

Polarization evolution characteristics of focused hybridly polarized vector fields  

NASA Astrophysics Data System (ADS)

We investigate the focusing property and the polarization evolution characteristics of hybridly polarized vector fields in the focal region. Three types of hybridly polarized vector fields, namely azimuthal-variant hybridly polarized vector field, radial-variant hybridly polarized vector field, and spatial-variant hybridly polarized vector field, are experimentally generated. The intensity distributions and the polarization evolution of these hybridly polarized vector fields focused under low numerical aperture (NA) are experimentally studied and good agreements with the numerical simulations are obtained. The three-dimensional (3D) state of polarization and the field distribution within the focal volume of these hybridly polarized vector fields under high-NA focusing are studied numerically. The optical curl force on Rayleigh particles induced by tightly focused hybridly polarized vector fields, which results in the orbital motion of trapped particles, is analyzed. Simulation results demonstrate that polarization-only modulation provided by the hybridly polarized vector field allows one to control both the intensity distribution and 3D elliptical polarization in the focal region, which may find interesting applications in particle trapping, manipulation, and orientation analysis.

Gu, Bing; Pan, Yang; Rui, Guanghao; Xu, Danfeng; Zhan, Qiwen; Cui, Yiping

2014-08-01

287

Venus winds are zonal and retrograde below the clouds  

NASA Technical Reports Server (NTRS)

Winds in the lower atmosphere of Venus, inferred from three-dimensional radio interferometric tracking of the descents of the Pioneer day and north probes, are predominantly easterly with speeds of about 1 M/sec near the surface, 50 at the bottom of the clouds, and more than 200 within the densest, middle cloud layer. Between about 25 and 55 km altitude the average flow was slanted equatorward, with superimposed wavelike motions and alternating layers of high and low shear

Counselman, C. C., III; Gourevitch, S. A.; King, R. W.; Loriot, G. B.; Prinn, R. G.

1979-01-01

288

Polycistronic viral vectors.  

PubMed

Traditionally, vectors for gene transfer/therapy experiments were mono- or bicistronic. In the latter case, vectors express the gene of interest coupled with a marker gene. An increasing demand for more complex polycistronic vectors has arisen in recent years to obtain complex gene transfer/therapy effects. In particular, this demand is stimulated by the hope of a more powerful effect from combined gene therapy than from single gene therapy in a process whose parallels lie in the multi-drug combined therapies for cancer or AIDS. In the 1980's we had only splicing signals and internal promoters to construct such vectors: now a new set of biotechnological tools enables us to design new and more reliable bicistronic and polycistronic vectors. This article focuses on the description and comparison of the strategies for co-expression of two genes in bicistronic vectors, from the oldest to the more recently described: internal promoters, splicing, reinitiation, IRES, self-processing peptides (e.g. foot-and-mouth disease virus 2A), proteolytic cleavable sites (e.g. fusagen) and fusion of genes. I propose a classification of these strategies based upon either the use of multiple transcripts (with transcriptional mechanisms), or single transcripts (using translational/post-translational mechanisms). I also examine the different attempts to utilize these strategies in the construction of polycistronic vectors and the main problems encountered. Several potential uses of these polycistronic vectors, both in basic research and in therapy-focused applications, are discussed. The importance of the study of viral gene expression strategies and the need to transfer this knowledge to vector design is highlighted. PMID:12189721

de Felipe, P

2002-09-01

289

Motion vector concealment in temporal scalability for scalable video coding  

Microsoft Academic Search

In scalable video coding, temporal scalability adopts the inter layer prediction coding structure to increase the coding efficiency. However, any lost single bit in base layer or lower enhancement layer may result in the loss one or more frames and serious visual quality degradation in the decoded image at the receiver. To preserve good image quality, the error concealment algorithm

Kuei-Ting Kuo; Pei-Jun Lee; Guo-Long Huang; Wen-June Wang

2010-01-01

290

Motion vector prediction in interactive 3D rendered video stream  

Microsoft Academic Search

In this research we describe a scheme for distributed 3 D interactive rendering system, which allows high performance rendering at a remote location and the interactive visualization of the resulting rendered images at a general purpose workstation terminal connected through h ighspeed network. The key to this approach is a video compression scheme of this s ystem which h as

Javed I. Khan

1996-01-01

291

Particles in Motion; Kepler's Laws 14.1. Vector Functions  

E-print Network

and has magnitude R 2. Example 14.2 A missile is fired on the surface of the earth at an angle of the trajectory of the missile. We know that the acceleration is that due to gravity, pointing downward determine when the missile hits the ground again, and how far it has travelled. For X¡ t¢ is horizontal when

McKay, Benjamin

292

Inline motion in flapping foils for improved force vectoring performance  

E-print Network

In this thesis, I study the effect of adding in-line oscillation to heaving and pitching foils using a power downstroke. I show that far from being a limitation imposed by the muscular structure of certain animals, in-line ...

Izraelevitz, Jacob (Jacob Samuel)

2013-01-01

293

Dual-FOV Raman and Doppler lidar studies of aerosol-cloud interactions: Simultaneous profiling of aerosols, warm-cloud properties, and vertical wind  

NASA Astrophysics Data System (ADS)

For the first time, colocated dual-field of view (dual-FOV) Raman lidar and Doppler lidar observations (case studies) of aerosol and cloud optical and microphysical properties below and within thin layered liquid water clouds are presented together with an updraft and downdraft characterization at cloud base. The goal of this work is to investigate the relationship between aerosol load close to cloud base and cloud characteristics of warm (purely liquid) clouds and the study of the influence of vertical motions and turbulent mixing on this relationship. We further use this opportunity to illustrate the applicability of the novel dual-FOV Raman lidar in this field of research. The dual-FOV lidar combines the well-established multiwavelength Raman lidar technique for aerosol retrievals and the multiple-scattering Raman lidar technique for profiling of the single-scattering extinction coefficient, effective radius, number concentration of the cloud droplets, and liquid water content. Key findings of our 3 year observations are presented in several case studies of optically thin altocumulus layers occurring in the lower free troposphere between 2.5 and 4 km height over Leipzig, Germany, during clean and polluted situations. For the clouds that we observed, the most direct link between aerosol proxy (particle extinction coefficient) and cloud proxy (cloud droplet number concentration) was found at cloud base during updraft periods. Above cloud base, additional processes resulting from turbulent mixing and entrainment of dry air make it difficult to determine the direct impact of aerosols on cloud processes.

Schmidt, Jörg; Ansmann, Albert; Bühl, Johannes; Baars, Holger; Wandinger, Ulla; Müller, Detlef; Malinka, Aleksey V.

2014-05-01

294

PSC Meteorology Program Cloud Boutique  

NSDL National Science Digital Library

Plymouth State College (PSC) provides the PSC Meteorology Program Cloud Boutique Website to "provide explanations of and access to detailed pictures of some basic cloud forms." Spectacular images and brief descriptions of high clouds (cirrus, cirrocumulus, and cirrostratus), middle clouds (altocumulus and altostratus), low clouds (cumulus, stratocumulus, stratus, and fog), multi-layer clouds (nimbostratus and cumulonimbus), and orographic clouds (lenticular and cap), among others are included. The site is an excellent general cloud reference.

295

MAC^3: Vectors Worksheet  

NSDL National Science Digital Library

This page contains a worksheet on the topic of vectors for beginning physics students. It was developed as a companion to the lecture presentations by the same authors (see Related Items on this page for a link.) A primary goal of the full instructional unit is to help physics and calculus students differentiate the uses of vectors for physics vs. mathematics, a difficulty known as the "vector calculus gap". This resource is part of a collection developed by the NSF-funded Mathematics Across the Community College Curriculum (MAC 3).

Friesen, Larry; Gillis, Anne

2008-12-22

296

Clouds and global warming  

Microsoft Academic Search

Real clouds may moderate global warming by negative feedback, or may work the other way. Comparison between observations and predictions suggests that clouds are cooling influences outside the tropics.

John Maddox

1990-01-01

297

"Electrostructural Phase Changes" In Charged Particulate Clouds: Planetary and Astrophysical Implications  

NASA Astrophysics Data System (ADS)

There is empirical evidence that freely-suspended triboelectrostatically charged particulate clouds of dielectric materials undergo rapid conversion from (nominally) monodispersed "aerosols" to a system of well-defined grain aggregates after grain motion or fluid turbulence ceases within the cloud. In United States Microgravity Laboratory Space Shuttle experiments USML-1 and USML-2, it was found that ballistically-energized grain dispersions would rapidly convert into populations of filamentary aggregates after natural fluid (air) damping of grain motion. Unless continuously disrupted mechanically, it was impossible to maintain a non-aggregated state for the grain clouds of sand-size materials. Similarly, ground- based experiments with very fine dust-size material produced the same results: rapid, impulsive "collapse" of the dispersed grains into well-defined filamentary structures. In both ground-based and microgravity experiments, the chains or filaments were created by long-range dipole electrostatic forces and dipole-induced dielectric interactions, not by monopole interactions. Maintenance of the structures was assisted by short-range static boundary adhesion forces and van der Waals interactions. When the aggregate containers in the USML experiments were disturbed after aggregate formation, the quiescently disposed filaments would rearrange themselves into fractal bundles and tighter clusters as a result of enforced encounters with one another. The long-range dipole interactions that bring the grains together into aggregates are a product of randomly-distributed monopole charges on the grain surfaces. In computer simulations, it has been shown that when the force vectors of all the random charges (of both sign) on a grain are resolved mathematically by assuming Coulombic interaction between them, the net result is a dipole moment on individual grains, even though the grains are electrically neutral insofar as there is no predominance, on their surface, of one charge sign over another. The random charges of both sign derive from natural grain-to-grain interactions that produce triboelectrification via charge exchange every time grain surfaces make contact with one another. The conversion from a random distribution of grains (upon which there are randomly distributed charges) into an organization of electrostatically-ordered aggregates, can be regarded (within the framework of granular-material science) as an "electrical or Coulombic phase change" of the particulate cloud. It is not totally dissimilar from the more normal phase-change concept in which, for example, a gas with long free-path-molecules suddenly becomes a solid as a result of structural ordering of the molecules (notably, also the result of electronic forces, albeit at a different scale). In both the gas-to-solid case, and the aerosol-to-aggregate case, the same materials and charges are present before and after the phase change, but their arrangement now has a higher degree of order and a lower-energy configuration. An input of energy into the system is required to reverse the situation. The aggregates in the USML experiments were observed to undergo at least two phase changes as noted above. The point about phase changes, and by implication, the "electrostructural" reorganizations in particulate clouds, is the following: (a) they can occur very rapidly, almost spontaneously, above a critical cloud density, (b) in going from a higher energy state to a lower energy state, they convert to a denser system, (c) energy must be required to reverse the situation, implying that energy is released during the high-to-low energy phase change. In applying this information to natural particulate clouds, some inferences can be made (it is stressed that reference is still to dielectric materials attracted by dipole forces). There are several natural settings to which the USML observations apply, and to which the phase-change implications likewise apply. Dense clouds of triboelectrically-charged, kinetically-energized grains are

Marshall, J. R.

1999-09-01

298

"Electrostructural Phase Changes" In Charged Particulate Clouds: Planetary and Astrophysical Implications  

NASA Technical Reports Server (NTRS)

There is empirical evidence that freely-suspended triboelectrostatically charged particulate clouds of dielectric materials undergo rapid conversion from (nominally) monodispersed "aerosols" to a system of well-defined grain aggregates after grain motion or fluid turbulence ceases within the cloud. In United States Microgravity Laboratory Space Shuttle experiments USML-1 and USML-2, it was found that ballistically-energized grain dispersions would rapidly convert into populations of filamentary aggregates after natural fluid (air) damping of grain motion. Unless continuously disrupted mechanically, it was impossible to maintain a non-aggregated state for the grain clouds of sand-size materials. Similarly, ground- based experiments with very fine dust-size material produced the same results: rapid, impulsive "collapse" of the dispersed grains into well-defined filamentary structures. In both ground-based and microgravity experiments, the chains or filaments were created by long-range dipole electrostatic forces and dipole-induced dielectric interactions, not by monopole interactions. Maintenance of the structures was assisted by short-range static boundary adhesion forces and van der Waals interactions. When the aggregate containers in the USML experiments were disturbed after aggregate formation, the quiescently disposed filaments would rearrange themselves into fractal bundles and tighter clusters as a result of enforced encounters with one another. The long-range dipole interactions that bring the grains together into aggregates are a product of randomly-distributed monopole charges on the grain surfaces. In computer simulations, it has been shown that when the force vectors of all the random charges (of both sign) on a grain are resolved mathematically by assuming Coulombic interaction between them, the net result is a dipole moment on individual grains, even though the grains are electrically neutral insofar as there is no predominance, on their surface, of one charge sign over another. The random charges of both sign derive from natural grain-to-grain interactions that produce triboelectrification via charge exchange every time grain surfaces make contact with one another. The conversion from a random distribution of grains (upon which there are randomly distributed charges) into an organization of electrostatically-ordered aggregates, can be regarded (within the framework of granular-material science) as an "electrical or Coulombic phase change" of the particulate cloud. It is not totally dissimilar from the more normal phase-change concept in which, for example, a gas with long free-path-molecules suddenly becomes a solid as a result of structural ordering of the molecules (notably, also the result of electronic forces, albeit at a different scale). In both the gas-to-solid case, and the aerosol-to-aggregate case, the same materials and charges are present before and after the phase change, but their arrangement now has a higher degree of order and a lower-energy configuration. An input of energy into the system is required to reverse the situation. The aggregates in the USML experiments were observed to undergo at least two phase changes as noted above. The point about phase changes, and by implication, the "electrostructural" reorganizations in particulate clouds, is the following: (a) they can occur very rapidly, almost spontaneously, above a critical cloud density, (b) in going from a higher energy state to a lower energy state, they convert to a denser system, (c) energy must be required to reverse the situation, implying that energy is released during the high-to-low energy phase change. In applying this information to natural particulate clouds, some inferences can be made (it is stressed that reference is still to dielectric materials attracted by dipole forces). There are several natural settings to which the USML observations apply, and to which the phase-change implications likewise apply. Dense clouds of triboelectrically-charged, kinetically-energized grains are

Marshall, J. R.

1999-01-01

299

Transport, Collective Motion, and Brownian Motion  

Microsoft Academic Search

A theory of many-particle systems is developed to formulate transport, collective motion, and Brownian motion from a unified, statistical-mechanical point of view. This is done by, first, rewriting the equation of motion in a generalized form of the Langevin equation in the stochastic theory of Brownian motion and then, either studying the average evolution of a non-equilibrium system or calculating

Hazime Mori

1965-01-01

300

Six Myths on the Virial Theorem for Interstellar Clouds  

E-print Network

It has been paid little or no attention to the implications that turbulent fragmentation has on the validity of at least six common assumptions on the Virial Theorem (VT), which are: (i) the only role of turbulent motions within a cloud is to provide support against collapse, (ii) the surface terms are negligible compared to the volumetric ones, (iii) the gravitational term is a binding source for the clouds, (iv) the sign of the second-time derivative of the moment of inertia determines whether the cloud is contracting or expanding, (v) interstellar clouds are in Virial Equilibrium (VE), and (vi) Larson's (1981) relations are the observational proof that clouds are in VE. Interstellar clouds cannot fulfill these assumptions, however, because turbulent fragmentation will induce flux of mass, moment and energy between the clouds and their environment, and will favor local collapse while may disrupt the clouds within a dynamical timescale. It is argued that, although the observational and numerical evidence suggests that interstellar clouds are not in VE, the so-called ``Virial Mass'' estimations, which actually should be called ``energy-equipartition mass'' estimations, are good order-of magnitude estimations of the actual mass of the clouds just because observational surveys will tend to detect interstellar clouds appearing to be close to energy equipartition. However, since clouds are actually out of VE, as suggested by asymmetrical line profiles, they should be transient entities. These results are compatible with observationally-based estimations for rapid star formation. , and call into question the models for the star formation efficiency based on clouds being in VE.

Javier Ballesteros-Paredes

2006-06-05

301

CloudTransport: Using Cloud Storage for  

E-print Network

destinations even if the provider is compromised. 1 Introduction Internet censorship is typically practicedCloudTransport: Using Cloud Storage for Censorship-Resistant Networking Chad Brubaker1,2 , Amir Houmansadr2 , and Vitaly Shmatikov2 1 Google 2 The University of Texas at Austin Abstract. Censorship

Shmatikov, Vitaly

302

LCD motion blur reduction: a signal processing approach.  

PubMed

Liquid crystal displays (LCDs) have shown great promise in the consumer market for their use as both computer and television displays. Despite their many advantages, the inherent sample-and-hold nature of LCD image formation results in a phenomenon known as motion blur. In this work, we develop a method for motion blur reduction using the Richardson-Lucy deconvolution algorithm in concert with motion vector information from the scene. We further refine our approach by introducing a perceptual significance metric that allows us to weight the amount of processing performed on different regions in the image. In addition, we analyze the role of motion vector errors in the quality of our resulting image. Perceptual tests indicate that our algorithm reduces the amount of perceivable motion blur in LCDs. PMID:18270104

Har-Noy, Shay; Nguyen, Truong Q

2008-02-01

303

Computer animation of clouds  

SciTech Connect

Computer animation of outdoor scenes is enhanced by realistic clouds. I will discuss several different modeling and rendering schemes for clouds, and show how they evolved in my animation work. These include transparency-textured clouds on a 2-D plane, smooth shaded or textured 3-D clouds surfaces, and 3-D volume rendering. For the volume rendering, I will present various illumination schemes, including the density emitter, single scattering, and multiple scattering models.

Max, N.

1994-01-28

304

Motion Compensation Research Based on Motion Sensors  

Microsoft Academic Search

To attain high quality images, it is essential that very accurate motion compensation be applied to the radar returns to reduce image degradation, caused by spurious antenna center motion, to acceptable levels. A kind of high precision SINS\\/GPS integrated system for airborne SAR motion compensation is presented. This system, integrated the long-term stability of GPS (global positioning system) and the

Tan Gewei

2010-01-01

305

Self Motion Perception and Motion Sickness  

NASA Technical Reports Server (NTRS)

The studies conducted in this research project examined several aspects of motion sickness in animal models. A principle objective of these studies was to investigate the neuroanatomy that is important in motion sickness with the objectives of examining both the utility of putative models and defining neural mechanisms that are important in motion sickness.

Fox, Robert A. (Principal Investigator)

1991-01-01

306

Variations of zonal wind speed at Venus cloud tops from Venus Monitoring Camera UV images  

NASA Astrophysics Data System (ADS)

7 years of continuous monitoring of Venus by ESA's Venus Express provided an opportunity to study dynamics of the atmosphere of Venus. Venus Monitoring Camera (VMC) [1] delivered the longest and the most complete so far set of UV images to study the cloud level circulation by tracking motion of the cloud features. We analyzed 130 orbits with manual cloud tracking and 600 orbits with digital correlation method. Here we present the latest update of our results. Total number of wind vectors derived in this work is approximately a half million. During Venus Express observations the mean zonal speed was in the range of 85-110 m/s. VMC observations indicated a long term trend for the zonal wind speed at low latitudes to increase. The origin of low frequency trend with a period about 3000 days is unclear. Fourier analysis [2-3] of revealed quasi-periodicities in the zonal circulation at low latitudes. Two groups of the periods were found. The first group is close to the period of superrotation at low latitudes (4.83±0.1 days) with the period 4.1-5.1 days and the amplitude ranging from ±4.2 to ±17.4 m/s. The amplitude and phase of oscillations demonstrates dependence from the latitude and also time variability with preserving stable parameters of oscillation during at least 70 days. Short term oscillations may be caused by wave processes in the mesosphere of Venus at the cloud top level. Wave number of the observed oscillations is 1. The second group is a long term periods caused by orbital motion of Venus (116 days, 224 days) and is related to the periodicity in VMC observations. Also VMC UV observations showed a clear diurnal pattern of the mean circulation. The zonal wind demonstrated semi-diurnal variations with minimum speed close to noon (11-14 h) and maxima in the morning (8-9 h) and in the evening (16-17 h). The meridional component clearly peaks in the early afternoon (13-15h) at latitudes near 50S. The minimum of the meridional wind is located at low latitudes in the morning (8-11h). References [1] Markiewicz W. J. et al.: Venus Monitoring Camera for Venus Express // Planet. Space Sci.. V.55(12). pp1701-1711. doi:10.1016/j.pss.2007.01.004, 2007. [2] Deeming T.J.: Fourier analysis with unequally-spaced data. Astroph. and Sp. Sci. V.36, pp137-158, 1975. [3] Terebizh, V.Yu. Time series analysis in astrophysics. Moscow: "Nauka," Glav. red. fiziko-matematicheskoi lit-ry, 1992. In Russian

Khatuntsev, Igor; Patsaeva, Marina; Ignatiev, Nikolai; Titov, Dmitri; Markiewicz, Wojciech J.

2013-04-01

307

Jovian Lightning and Moonlit Clouds  

NASA Technical Reports Server (NTRS)

Jovian lightning and moonlit clouds. These two images, taken 75 minutes apart, show lightning storms on the night side of Jupiter along with clouds dimly lit by moonlight from Io, Jupiter's closest moon. The images were taken in visible light and are displayed in shades of red. The images used an exposure time of about one minute, and were taken when the spacecraft was on the opposite side of Jupiter from the Earth and Sun. Bright storms are present at two latitudes in the left image, and at three latitudes in the right image. Each storm was made visible by multiple lightning strikes during the exposure. Other Galileo images were deliberately scanned from east to west in order to separate individual flashes. The images show that Jovian and terrestrial lightning storms have similar flash rates, but that Jovian lightning strikes are a few orders of magnitude brighter in visible light.

The moonlight from Io allows the lightning storms to be correlated with visible cloud features. The latitude bands where the storms are seen seem to coincide with the 'disturbed regions' in daylight images, where short-lived chaotic motions push clouds to high altitudes, much like thunderstorms on Earth. The storms in these images are roughly one to two thousand kilometers across, while individual flashes appear hundreds of kilometer across. The lightning probably originates from the deep water cloud layer and illuminates a large region of the visible ammonia cloud layer from 100 kilometers below it.

There are several small light and dark patches that are artifacts of data compression. North is at the top of the picture. The images span approximately 50 degrees in latitude and longitude. The lower edges of the images are aligned with the equator. The images were taken on October 5th and 6th, 1997 at a range of 6.6 million kilometers by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov.

1997-01-01

308

Conference on Cloud Physics, Tucson, Ariz., October 21-24, 1974, Proceedings  

NASA Technical Reports Server (NTRS)

Condensation and ice nucleation processes are considered, taking into account measurements of cloud nuclei and aerosol size spectra in the semiarid Southwest, the formation of sulfates and the enhancement of cloud condensation nuclei in clouds, biogenic sources of atmospheric ice nuclei, and the experimental determination of the deposition coefficient of water vapor onto ice. Other topics discussed are related to precipitation growth processes, the role of ice in cloud systems, cloud modeling, measurements in Colorado hailstorms during the national hail research experiment, cloud measurements, and measurement techniques. Attention is also given to cloud electrification, zero-gravity experiments, and the control of cloud development by larger scale motions. Individual items are announced in this issue.

1975-01-01

309

Clouds in Planetary Atmospheres  

NASA Technical Reports Server (NTRS)

In the terrestrial atmosphere clouds are familiar as vast collections of small water drops or ice cyrstals suspended in the air. The study of clouds touches on many facets of armospheric science. The chemistry of clouds is tied to the chemistry of the surrounding atmosphere.

West, R.

1999-01-01

310

XSEDE Cloud Survey Report  

E-print Network

XSEDE Cloud Survey Report David Lifka, Cornell Center for Advanced Computing Ian Foster, ANL, ANL and The University of Chicago A National Science Foundation-sponsored cloud user survey was conducted from September 2012 to April 2013 by the XSEDE Cloud Integration Investigation Team to better

Walter, M.Todd

311

Bad Meteorology: Bad Clouds  

NSDL National Science Digital Library

This site provides an explanation for cloud formation and seeks to correct myths or misconceptions about how clouds form. Water vapor, condensation, and evaporation are discussed in the context of dew-point temperature and saturation. Educators and anyone explaining cloud formation will find hints on how to present the correct information and avoid misinforming their audiences.

Fraser, Alistair

312

CONTRIBUTED Green Cloud Computing  

E-print Network

CONTRIBUTED P A P E R Green Cloud Computing: Balancing Energy in Processing, Storage, and Transport to energy consumption and cloud computing seems to be an alternative to office-based computing. By Jayant computing is rapidly expanding as an alternative to conventional office-based computing. As cloud computing

Tucker, Rod

313

Cloud Scaling Properties and Cloud Parameterization  

NASA Technical Reports Server (NTRS)

Cloud liquid and cloud traction variability is studied as a function of horizontal scale in the ECMWF forecast model during several 10-day runs at the highest available model resolution, recently refined from approximately 60 km (T213) down to approximately 20 km (T639). At higher resolutions, model plane-parallel albedo biases are reduced, so that models may be tuned to have larger, more realistic, cloud liquid water amounts, However, the distribution of cloud liquid assumed -within- each gridbox, for radiative and thermodynamic computations, depends on ad hoc assumptions that are not necessarily consistent with observed scaling properties, or with scaling properties produced by the model at larger scales. To study the larger-scale cloud properties, ten locations on the Earth are chosen to coincide with locations having considerable surface data available for validation, and representing a variety of climatic regimes, scaling exponents are determined from a range or scales down to model resolution, and are re-computed every three hours, separately for low, medium and high clouds, as well as column-integrated cloudiness. Cloud variability fluctuates in time, due to diurnal, synoptic and other' processes, but scaling exponents are found to be relatively stable. various approaches are considered for applying computed cloud scaling to subgrid cloud distributions used for radiation, beyond simple random or maximal overlap now in common use. Considerably more work is needed to compare model cloud scaling with observations. This will be aided by increased availability of high-resolution surface, aircraft and satellite data, and by the increasing resolution of global models,

Cahalan, R. F.; Morcrette, J. J.

1998-01-01

314

Understanding Vector Fields.  

ERIC Educational Resources Information Center

Presented are activities that help students understand the idea of a vector field. Included are definitions, flow lines, tangential and normal components along curves, flux and work, field conservation, and differential equations. (KR)

Curjel, C. R.

1990-01-01

315

Poynting-vector filter  

DOEpatents

A determination is made of frequency components associated with a particular bearing or location resulting from sources emitting electromagnetic-wave energy for which a Poynting-Vector can be defined. The broadband frequency components associated with a specific direction or location of interest are isolated from other components in the power spectrum that are not associated with the direction or location of interest. The collection of pointing vectors can be used to characterize the source.

Carrigan, Charles R. (Tracy, CA)

2011-08-02

316

Vector sampling expansion  

Microsoft Academic Search

The vector sampling expansion (VSE) is an extension of Papoulis' (1977) generalized sampling expansion (GSE) to the vector case. In VSE, N bandlimited signals, all with the same bandwidth B, are passed through a multi-input-multi-output (MIMO) linear time invariant system that generates M (M⩾N) output signals. The goal is to reconstruct the input signals from the samples of the output

D. Seidner; M. Feder

2000-01-01

317

Impact of Microwaves on the Electron Cloud and Incoherent Effects  

SciTech Connect

We consider the use of microwaves for manipulating the electron cloud, describing an exploratory experiment at PEP-II as well as computer simulations of the electron cloud build up in the presence of a microwave for an LHC dipole. We then show that the incoherent effects of the electron cloud--energy loss and transverse emittance growth due to scattering off the electrons--are negligible. This suggests that the disturbance of the coherent electron motion may be another possible application of microwaves, which could prevent beam emittance growth and beam loss.

Decker, Franz-Josef

2002-08-09

318

Cloud Arcs in the Western Pacific  

NASA Technical Reports Server (NTRS)

Small cumulus clouds in this natural-color view from the Multi-angle Imaging SpectroRadiometer have formed a distinctive series of quasi-circular arcs. Clues regarding the formation of these arcs can be found by noting that larger clouds exist in the interior of each arc.

The interior clouds are thicker and likely to be more convectively active than the other clouds, causing much of the air near the centers of the arcs to rise. This air spreads out horizontally in all directions as it rises and continues to spread out as it begins to sink back to the surface. This pushes any existing small cumulus clouds away from the central region of convection.

As the air sinks, it also warms, preventing other small clouds from forming, so that the regions just inside the arcs are kept clear. At the arcs, the horizontal flow of sinking air is now quite weak and on meeting the undisturbed air it can rise again slightly -- possibly assisting in the formation of new small cumulus clouds. Although examples of the continuity of air, in which every rising air motion must be compensated by a sinking motion elsewhere, are very common, the degree of organization exhibited here is relatively rare, as the wind field at different altitudes usually disrupts such patterns. The degree of self organization of this cloud image, whereby three or four such circular events form a quasi-periodic pattern, probably also requires a relatively uncommon combination of wind, temperature and humidity conditions for it to occur.

The image was acquired by MISR's nadir camera on March 11, 2002, and is centered west of the Marshall Islands. Enewetak Atoll is discernible through thin cloud as the turquoise band near the right-hand edge of the image.

The Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously from pole to pole, and views almost the entire globe every 9 days. This image is a portion of the data acquired during Terra orbit 11863, and covers an area of about 380 kilometers x 345 kilometers. It utilizes data from blocks 80 to 82 within World Reference System-2 path 90.

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

2002-01-01

319

Self-Motion Perception and Motion Sickness  

NASA Technical Reports Server (NTRS)

Motion sickness typically is considered a bothersome artifact of exposure to passive motion in vehicles of conveyance. This condition seldom has significant impact on the health of individuals because it is of brief duration, it usually can be prevented by simply avoiding the eliciting condition and, when the conditions that produce it are unavoidable, sickness dissipates with continued exposure. The studies conducted examined several aspects of motion sickness in animal models. A principle objective of these studies was to investigate the neuroanatomy that is important in motion sickness with the objectives of examining both the utility of putative models and defining neural mechanisms that are important in motion sickness.

Fox, Robert A.

1991-01-01

320

Particle Cloud Detection Using Coherent Laser Radar Systems Step One  

NASA Astrophysics Data System (ADS)

Biological and chemical agents are spread out in the atmosphere in the form of particle clouds. Hence, a method to detect and localize such clouds remotely is desired. The authors report some initial experiments performed with a recently developed coherent laser radar (CLR) system wherein the results direct their future work. The CLR was used to detect particles in motion at a distance of about 25 m in a laboratory environment. These initial tests have revealed that particles are detectable by the use of a CLR and that their velocity distribution can be measured. In coming studies the authors are going to use particles with known size distribution and measure the concentration of the generated clouds/particle streams. The detection capability of the CLR system will then be determined as a function of distance and particle cloud characteristics. The goal will be to describe the conditions under which the CLR can perform as a detector of various types of clouds.

Kullander, F.; Carlsson, T.; Letalick, D.; Lindgren, M.

2001-11-01

321

Computing and Partitioning Cloud Feedbacks Using Cloud Property Histograms. Part I: Cloud Radiative Kernels  

E-print Network

Computing and Partitioning Cloud Feedbacks Using Cloud Property Histograms. Part I: Cloud Radiative 2011) ABSTRACT This study proposes a novel technique for computing cloud feedbacks using histograms integrated cloud feedbacks computed in this manner agree remarkably well with the adjusted change in cloud

Hartmann, Dennis

322

Mixed-phase cloud phase partitioning using millimeter wavelength cloud radar Doppler velocity spectra  

NASA Astrophysics Data System (ADS)

and quantifying cloud liquid drop contributions to radar returns from mixed-phase clouds remains a challenge because the radar signal is frequently dominated by the returns from the ice particles within the radar sample volume. We present a technique that extracts the weak cloud liquid drop contributions from the total radar returns in profiling cloud radar Doppler velocity spectra. Individual spectra are first decomposed using a continuous wavelet transform, the resulting coefficients of which are used to identify the region in the spectra where cloud liquid drops contribute. By assuming that the liquid contribution to each Doppler spectrum is Gaussian shaped and centered on an appropriate peak in the wavelet coefficients, the cloud liquid drop contribution may be estimated by fitting a Gaussian distribution centered on the velocity of this peak to the original Doppler spectrum. The cloud liquid drop contribution to reflectivity, the volume mean vertical air motion, subvolume vertical velocity variance, and ice particle mean fall speed can be estimated based on the separation of the liquid contribution to the radar Doppler spectrum. The algorithm is evaluated using synthetic spectra produced from output of a state-of-the-art large eddy simulation model study of an Arctic mixed-phase cloud. The retrievals of cloud liquid drop mode reflectivities were generally consistent with the original model values with errors less than a factor of 2. The retrieved volume mean vertical air velocities reproduced the updraft and downdraft structures, but with an overall bias of approximately -0.06 m s-1. Retrievals based on Ka-band Atmospheric Radiation Measurement Program Zenith Radar observations from Barrow, Alaska, during October 2011 are also presented.

Yu, G.; Verlinde, J.; Clothiaux, E. E.; Chen, Y.-S.

2014-06-01

323

Double production of vector quarkonia in exclusive Higgs boson decays  

SciTech Connect

Partial widths with respect to the exclusive decays of Standard Model Higgs bosons to pairs of vector quarkonia, H {sup {yields}}J/{psi}J/{psi}, H {sup {yields}}YY, H {sup {yields}}J/{psi}{phi}, and H {sup {yields}}J/{psi}Y, were calculated with allowance for relativistic corrections associated with the internal motion of quarks in qarkonia.

Kartvelishvili, V. G., E-mail: V.Kartvelishvili@lancaster.ac.u [University of Lancaster (United Kingdom); Luchinsky, A. V., E-mail: Alexey.Luchinsky@ihep.ru; Novoselov, A. A., E-mail: Alexey.Novoselov@cern.c [Institute for High Energy Physics (Russian Federation)

2010-06-15

324

Intergalactic HI Clouds  

E-print Network

Neutral intergalactic clouds are so greatly out numbered by galaxies that their integral HI content is negligible in comparison to that contained in optically luminous galaxies. In fact, no HI cloud that is not associated with a galaxy or grouping of galaxies has yet been identified. This points to a causal relationship that relies on gravitational potentials that bind galaxies also being responsible for confining HI clouds to sufficient density that they can become self-shielding to the ionizing background radiation. Unconfined clouds of low density become ionized, but confined clouds find themselves vulnerable to instability and collapse, leading to star formation.

F. H. Briggs

2005-02-16

325

Introduction to Clouds  

NSDL National Science Digital Library

This site provides the user an opportunity to explore storm clouds and climate change through the use of NASA climate research data obtained through satellite imaging. The user is challenged to investigate actual scientific research data on clouds and storms, and make observations and interpretations available to NASA research scientists for review. Topics addressed by these investigations include the role of clouds in relation to the changing climate of Earth, the role of clouds in warming or cooling the planet, and the major types of clouds produced by storms.

Tselioudis, George; Petersen, Christopher

1997-01-01

326

The supersymmetric configurations of N = 2 , d = 4 supergravity coupled to vector supermultiplets  

Microsoft Academic Search

We classify all supersymmetric configurations of ungauged N=2,d=4 supergravity coupled to n vector multiplets and determine under which conditions they are also classical solutions of the equations of motion. The supersymmetric configurations fall into two classes, depending on the timelike or null nature of the Killing vector constructed from Killing spinor bilinears. The timelike class configurations are essentially the ones

Patrick Meessen; Tomás Ortín

2006-01-01

327

Time correlations and 1\\/f behavior in backscattering radar reflectivity measurements from cirrus cloud ice fluctuations  

Microsoft Academic Search

The state of the atmosphere is governed by the classical laws of fluid motion and exhibits correlations in various spatial and temporal scales. These correlations are crucial to understand the short- and long-term trends in climate. Cirrus clouds are important ingredients of the atmospheric boundary layer. To improve future parameterization of cirrus clouds in climate models, it is important to

K. Ivanova; T. P. Ackerman; E. E. Clothiaux; P. Ch. Ivanov; H. E. Stanley; M. Ausloos

2003-01-01

328

Movie of High Clouds on Jupiter  

NASA Technical Reports Server (NTRS)

Jupiter's high-altitude clouds are seen in this brief movie made from seven frames taken by the narrow-angle camera of NASA's Cassini spacecraft. This is the first time a movie sequence of Jupiter has been made that illustrates the motions of the high-altitude clouds on a global scale.

The images were taken at a wavelength that is absorbed by methane, one chemical in Jupiter's lower clouds. So, dark areas are relatively free of high clouds, and the camera sees through to the methane in a lower level. Bright areas are places with high, thick clouds that shield the methane below.

Jupiter's equator and Great Red Spot are covered with high-altitude, hazy clouds.

The movie covers the time period between Oct. 1 and Oct. 5, 2000, latitudes from 50 degrees north to 50 degrees south, and a 100-degree sweep of longitude. Those factors were the same for a Cassini movie of cloud motions previously released (PIA02829), but that movie used frames taken through a blue filter, which showed deeper cloud levels and sharper detail. Features in this methane-filter movie appear more diffuse.

Among the nearly stationary features are the Red Spot and some bright ovals at mid-latitudes in both hemispheres. These are anticyclonic (counter-clockwise rotating) storms. They are bright in the methane band because of their high clouds associated with rising gas. They behave differently from terrestrial cyclones, which swirl in the opposite direction. The mechanism making the Red Spot and similar spots stable apparently has no similarity to the mechanism which feeds terrestrial cyclones.

Some small-scale features are fascinating because of their brightness fluctuations. Such fluctuations observed in the methane band are probably caused by strong vertical motions, which form clouds rapidly, as in Earth's thunderstorms. Near the upper left corner in this movie, a number of smaller clouds appear to circulate counterclockwise around a dark spot, and these clouds fluctuate in brightness, so they may be candidates for lightning storms.

A pattern of lighter areas between darker patches can be seen in the darkest band a little north of the bright equatorial region. This may be tied to a wave-like temperature variation across the planet. If confirmed, this would be the first time such large-scale stratospheric temperature waves have been visibly linked to variations in haze thickness.

Cassini is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini mission for NASA's Office of Space Science, Washington, D.C.

2000-01-01

329

New techniques in 3D scalar and vector field visualization  

SciTech Connect

At Lawrence Livermore National Laboratory (LLNL) we have recently developed several techniques for volume visualization of scalar and vector fields, all of which use back-to-front compositing. The first renders volume density clouds by compositing polyhedral volume cells or their faces. The second is a ``splatting`` scheme which composites textures used to reconstruct the scalar or vector fields. One version calculates the necessary texture values in software, and another takes advantage of hardware texture mapping. The next technique renders contour surface polygons using semi-transparent textures, which adjust appropriately when the surfaces deform in a flow, or change topology. The final one renders the ``flow volume`` of smoke or dye tracer swept out by a fluid flowing through a small generating polygon. All of these techniques are applied to a climate model data set, to visualize cloud density and wind velocity.

Max, N.; Crawfis, R.; Becker, B.

1993-05-05

330

EVA: an explicit vector language  

Microsoft Academic Search

Fortran is the main language used on supercomputer today. Indeed, all supercomputers compilers have extensions, providing language features for explicit vector handling, to Fortran 77. These extensions are different on each machine and their functions are limited. Even with the next standard Fortran 8x, vector syntax is incomplete. EVA is an explicit vector language with powerful vector handling tools. Taking

Jean-Luc Dekeyser; Philippe Marquet; Philippe Preux; Philippe Marquet

1990-01-01

331

Bit vector encoding via decomposition  

Microsoft Academic Search

The decomposition encoding of an n-bit vector V is an approach to the problem of how best to encode a bit vector under the constraints that this vector be encoded into blocks of t bits, and that access time for each bit of the original vector be constant, i.e. \\

Ralph D. Jeffords

1982-01-01

332

BROWNIAN MOTION MAXWELL STOLARSKI  

E-print Network

BROWNIAN MOTION MAXWELL STOLARSKI Abstract. This paper introduces Brownian motion and covers several in- variances of Brownian motion, some of which follow from the definition and another which follows from the strong Markov property of Brownian motion. We go on to show the nondifferentiability

May, J. Peter

333

Working inside the Cloud: Developing a Cloud Computing Infrastructure  

E-print Network

UROP 2012 Working inside the Cloud: Developing a Cloud Computing Infrastructure Cloud computing and live-migration of running VM. USI participates to the development of the first European Cloud computing for a motivated student that will have a chance to improve his/her knowledge on Cloud computing, Java and/or Ruby

Krause, Rolf

334

Chemical cloud tracking systems  

NASA Astrophysics Data System (ADS)

This paper describes the Chemical Cloud Tracking System (CCTS) which has been installed at Dugway Proving Ground. The CCTS allows mapping of chemical clouds in real time from a safe standoff distance. The instruments used are passive standoff chemical agent detectors (FTIRs). Each instrument individually can only measure the total of all the chemical in its line-of-site; the distance to the cloud is unknown. By merging data from multiple vantage points (either one instrument moving past the cloud or two or more instruments spaced so as to view the cloud from different directions) a map of the cloud locations can be generated using tomography. To improve the sensitivity and accuracy of the cloud map, chemical point sensors can be added to the sensor array being used. The equipment required for the CCTS is commercially available. Also, the data fusion techniques (tomography) have been demonstrated previously in the medical field. The Chemical Cloud Tracking System can monitor the movement of many chemical clouds of either military or industrial origin. Since the technique is standoff, the personnel are not exposed to toxic hazards while they follow the cloud. Also, the equipment works on-the-move which allows rapid response to emergency situations (plant explosions, tanker car accidents, chemical terrorism, etc.).

Grim, Larry B.; Gruber, Thomas C., Jr.; Marshall, Martin; Rowland, Brad

2002-02-01

335

Bunyavirus-Vector Interactions  

PubMed Central

The Bunyaviridae family is comprised of more than 350 viruses, of which many within the Hantavirus, Orthobunyavirus, Nairovirus, Tospovirus, and Phlebovirus genera are significant human or agricultural pathogens. The viruses within the Orthobunyavirus, Nairovirus, and Phlebovirus genera are transmitted by hematophagous arthropods, such as mosquitoes, midges, flies, and ticks, and their associated arthropods not only serve as vectors but also as virus reservoirs in many cases. This review presents an overview of several important emerging or re-emerging bunyaviruses and describes what is known about bunyavirus-vector interactions based on epidemiological, ultrastructural, and genetic studies of members of this virus family. PMID:25402172

Horne, Kate McElroy; Vanlandingham, Dana L.

2014-01-01

336

What is a Cloud?  

NASA Astrophysics Data System (ADS)

There are multiple factors that cause disagreements between differing methods using differing instruments to infer cloud amounts. But along with these issues is a fundamental concern that has permeated all comparisons and supersedes such questions as what are the uncertainty estimates of a given retrieval. To wit: what is a cloud? How can uncertainty of a cloud amount measurement be determined when there is no absolute 'truth' on what defines a cloud, as opposed to cloud-free? Recent research comparing a decade of surface- and satellite-based retrievals of cloud amount for the ARM Southern Great Plains site shows significant disagreements. While Total Sky Imager 100-degree FOV, Shortwave (SW) Radiative Flux Analysis, GOES satellite and PATMOS-x satellite amounts agree relatively well, ISCCP satellite and ARSCL time-series cloud amounts are significantly greater, 15% (ISCCP) and 8% (ARSCL) larger in average diurnal variations. In both cases, it appears that optically thin high ice is counted as 'cloud' in ARSCL and ISCCP that is not categorized as cloud by all the others. Additionally, cloud amounts from three methods (ISCCP, ARSCL, and GOES) show an overall increase of 8%-10% in the annually averaged cloud fractions from 1998 to 2009, while those from the other three (TSI, SWFA, PATMOS-x) show little trend for this period. So one wonders: are cloud amounts increasing or not over this period? The SW Flux Analysis used sky imager retrievals as 'truth' in development of the methodology (Long et al, 2006a), where sky imagery itself used human observations as the model (Long et al., 2006b). Min et al. (2008) then used SW Flux Analysis retrievals as 'truth' to develop an MFRSR-based spectral SW retrieval method. Dupont et al. (2008) show that the SW-based retrievals allow up to a visible optical depth of 0.15 (95% of occurrences) under the 'clear-sky' category which primarily consists of sub-visual cirrus, which by ancestry applies to spectral SW, sky imager and human observations as well. This defines what we label the 'traditional' definition of 'what is a cloud' that has produced the long records based on human observations. But we submit that declaring 'cloud amount' by some methodology is not sufficient to be scientifically useful, but also a physical value of the cloud/clear delimiting factor used to detect what is a cloud must also be given. Perhaps visible optical depth might serve as a common variable to denote various retrievals clear/cloud limit, but some common variable needs to be agreed upon else discussions of quantifying 'uncertainty' is putting the cart before the horse. We will present examples and discussion of all the above.

Long, C. N.; Wu, W.

2013-12-01

337

An Autonomous Reliabilit Cloud Comput  

E-print Network

An Autonomous Reliabilit Ami Cloud Comput Department of Computing and Informa Abstract--Cloud computing paradigm allo based access to computing and storages s Internet. Since with advances of Cloud. Keywords- Cloud computing; SLA negotiat I. INTRODUCTION Cloud computing has transferred the services

Buyya, Rajkumar

338

Vector cross product in n-dimensional vector space  

E-print Network

The definition of vector cross product (VCP) introduced by Eckmann only exists in thethree- and the seven- dimensional vector space. In this paper, according to the orthogonal completeness, magnitude of basis vector cross product and all kinds of combinations of basis vector $\\hat{e}_i$, the generalized definition of VCP in the odd n-dimensional vector space is given by introducing a cross term $X_{AB}$. In addition, the definition is validated by reducing the generalization definition to the fundamental three- and seven-dimensional vector space.

Xiu-Lao Tian; Chao Yang; Yang Hu; Chao Tian

2013-10-19

339

Modular Approach to Physics: Projectile Motion: One Ball  

NSDL National Science Digital Library

This web page contains a simulation-based module on projectile motion with or without air resistance. By controlling the initial velocity, strength of gravity, and drag coefficient of air, the applet promotes understanding of the projectile motion. The Vectors panel allows display of drag force, gravitational force, velocity, and acceleration vectors. The simulation's Help provides detailed lessons with related problems/solutions, learning outcomes, and instructions for use. This item is part of a larger collection of simulation-based physics modules sponsored by the MAP project (Modular Approach to Physics).

2008-05-30

340

Modular Approach to Physics: Work and Energy in Projectile Motion  

NSDL National Science Digital Library

This web page contains a simulation-based module on projectile motion without air resistance. Users can alter the initial trajectory of the ball, the force of gravity, and the mass of the ball. The path of the ball can be traced, showing parabolic motion. Through the vectors menu, the velocity, force of acceleration, and force of gravity vectors can be plotted. The help section provides full instructions for use plus supplementary student activities. This item is part of a larger collection of simulation-based physics modules sponsored by the MAP project (Modular Approach to Physics).

2008-08-15

341

Flat Bottom Clouds  

NSDL National Science Digital Library

In this activity, students investigate how pressure affects the temperature of air and how this relates to the formation of clouds in the troposphere. They will form a cloud in a bottle, find the dew point and relative humidity of air at different places in the school and use a chart to estimate how high that air would have to rise to form a cloud.

Robison, David

342

Three Clouds Activity  

NSDL National Science Digital Library

The University of Michigan's educational site called Windows to the Universe (last mentioned in the January 6, 1999 Scout Report for Science and Engineering) has added many new lessons to their content. Highlights of these include two activities centered around cloud formation. The Three Clouds uses items such as a jugs and jars, a plastic bag, an aquarium thermometer, and an overhead projector to explore how clouds form and the relationship between the hydrosphere and human activity.

1995-01-01

343

Incoherent effect of space charge and electron cloud  

Microsoft Academic Search

Trapping by resonances or scattering off resonances induced by space charge (SC) or electron cloud (EC) in conjunction with synchrotron motion can explain observations of slow beam loss and emittance growth, which are often accompanied by changes in the longitudinal beam profile. In this paper we review the recent progress in understanding and modeling of the underlying mechanisms, highlight the

G. Franchetti; W. Fischer; I. Hofmann; F. Zimmermann

2009-01-01

344

Geoengineering marine stratocumulus clouds.  

E-print Network

??Marine cloud brightening (MCB) geoengineering has been proposed as a means of ameliorating anthropogenic climate change. High concentrations of nanometre-sized aerosols would be emitted from… (more)

Jenkins, Annabel Ka Lai

2014-01-01

345

Grid und Cloud Computing.  

E-print Network

??In dieser Arbeit werden die theoretischen Konzepte und mögliche praktische Anwendungsmöglichkeiten von Grid- und Cloud-Computing dargestellt. Als erster Teil der Arbeit wird zuerst auf Grids… (more)

Shahi Barogh, Bahareh

2010-01-01

346

Microbiologists search the clouds  

NASA Astrophysics Data System (ADS)

On 22 May, a team of microbiologists used a prototype cloud-catcher mounted on a research plane to collect samples from low-lying cumulus clouds near Oxford, England. The researchers, from the University of East London (UEL), are investigating whether an active and self-sustaining ecosystem exists in clouds, and whether airborne microbes may play an active role in forming clouds and causing rainfall.While scientists have known that microorganisms, including bacteria, fungal spores, and algae, can survive and possibly reproduce in the atmosphere, the challenge, according to the UEL researchers, is to accurately detect, identify, and analyze microbial communities.

Showstack, Randy

347

Redundancy, Self-Motion, and Motor Control  

PubMed Central

Outside the laboratory, human movement typically involves redundant effector systems. How the nervous system selects among the task-equivalent solutions may provide insights into how movement is controlled. We propose a process model of movement generation that accounts for the kinematics of goal-directed pointing movements performed with a redundant arm. The key element is a neuronal dynamics that generates a virtual joint trajectory. This dynamics receives input from a neuronal timer that paces end-effector motion along its path. Within this dynamics, virtual joint velocity vectors that move the end effector are dynamically decoupled from velocity vectors that do not. Moreover, the sensed real joint configuration is coupled back into this neuronal dynamics, updating the virtual trajectory so that it yields to task-equivalent deviations from the dynamic movement plan. Experimental data from participants who perform in the same task setting as the model are compared in detail to the model predictions. We discover that joint velocities contain a substantial amount of self-motion that does not move the end effector. This is caused by the low impedance of muscle joint systems and by coupling among muscle joint systems due to multiarticulatory muscles. Back-coupling amplifies the induced control errors. We establish a link between the amount of self-motion and how curved the end-effector path is. We show that models in which an inverse dynamics cancels interaction torques predict too little self-motion and too straight end-effector paths. PMID:19718817

Martin, V.; Scholz, J. P.; Schoner, G.

2011-01-01

348

Enhanced motion aftereffect for complex motions  

Microsoft Academic Search

We measured the magnitude of the motion aftereffect (MAE) elicited by gratings viewed through four spatial apertures symmetrically positioned around fixation. The gratings were identical except for their orientations, which were varied to form patterns of global motion corresponding to radiation, rotation or translation. MAE magnitude was estimated by three methods: the duration of the MAE; the contrast required to

Peter J. Bex; Andrew B. Metha; Walter Makous

1999-01-01

349

Extraction of Motion Activity from Scalable-Coded Video Sequences  

Microsoft Academic Search

This work presents an efficient approach for the calculation of the MPEG-7 descriptor for motion activity from scalable-coded\\u000a video sequences, which include scalable motion vectors and variable block sizes. We first describe the adaptation of the constant\\u000a block-size assumption of the MPEG-7 descriptor to this new coding domain. Then we compare the results obtained with those\\u000a for MPEG-1 videos in

Luis Herranz; Fabricio Tiburzi; Jesús Bescós

2006-01-01

350

A boundary property of semimartingale reflecting Brownian motions  

Microsoft Academic Search

Summary We consider a class of reflecting Brownian motions on the non-negative orthant inRK. In the interior of the orthant, such a process behaves like Brownian motion with a constant covariance matrix and drift vector. At each of the (K-1)-dimensional faces that form the boundary of the orthant, the process reflects instantaneously in a direction that is constant over the

M. I. Reiman; R. J. Williams

1988-01-01

351

Computing secular motion under slowly rotating quadratic perturbation  

E-print Network

We consider secular perturbations of nearly Keplerian two-body motion under a perturbing potential that can be approximated to sufficient accuracy by expanding it to second order in the coordinates. After averaging over time to obtain the secular Hamiltonian, we use angular momentum and eccentricity vectors as elements. The method of variation of constants then leads to a set of equations of motion that are simple and regular, thus allowing efficient numerical integration. Some possible applications are briefly described.

S. Mikkola; P. Nurmi

2006-06-09

352

Cloud Boundaries During FIRE 2.  

National Technical Information Service (NTIS)

To our knowledge, previous observations of cloud boundaries have been limited to studies of cloud bases with ceilometers, cloud tops with satellites, and intermittent reports by aircraft pilots. Comprehensive studies that simultaneously record information...

T. Uttal, S. M. Shaver, E. E. Clothiaux, T. P. Ackerman

1993-01-01

353

Perceptual asynchrony for motion  

PubMed Central

Psychophysical experiments show that two different visual attributes, color and motion, processed in different areas of the visual brain, are perceived at different times relative to each other (Moutoussis and Zeki, 1997a). Here we demonstrate psychophysically that two variants of the same attribute, motion, which have the same temporal structure and are processed in the same visual areas, are also processed asynchronously. When subjects were asked to pair up–down motion of dots in one half of their hemifield with up-right motion in the other, they perceived the two directions of motion asynchronously, with the advantage in favor of up-right motion; when they were asked to pair the motion of white dots moving against a black background with that of red dots moving against an equiluminant green background, they perceived the luminant motion first, thus demonstrating a perceptual advantage of luminant over equiluminant motion. These results were not affected by motion speed or perceived motion “streaks.” We thus interpret these results to reflect the different processing times produced by luminant and equiluminant motion stimuli or by different degrees of motion direction change, thus adding to the evidence that processing time within the visual system is a major determinant of perceptual time. PMID:24624071

Lo, Yu Tung; Zeki, Semir

2014-01-01

354

Branching Brownian motion with selection  

E-print Network

In this thesis, branching Brownian motion (BBM) is a random particle system where the particles diffuse on the real line according to Brownian motions and branch at constant rate into a random number of particles with expectation greater than 1. We study two models of BBM with selection: BBM with absorption at a space-time line and the N-BBM, where, as soon as the number of particles exceeds a given number N, only the N right-most particles are kept, the others being removed from the system. For the first model, we study the law of the number of absorbed particles in the case where the process gets extinct almost surely, using a relation between the Fisher-Kolmogorov-Petrovskii-Piskounov (FKPP) and the Briot-Bouquet equations. For the second model, the study of which represents the biggest part of the thesis, we give a precise asymptotic on the position of the cloud of particles when N is large. More precisely, we show that it converges at the timescale log^3 N to a L\\'evy process plus a linear drift, both of them explicit, which confirms a prediction by Brunet, Derrida, Mueller and Munier. This study contributes to the understanding of travelling waves of FKPP type under the influence of noise. Finally, in a third part we point at the relation between the BBM and stable point processes.

Pascal Maillard

2012-10-12

355

Turbulence in high latitude molecular clouds  

NASA Astrophysics Data System (ADS)

We summarize a continuing investigation of turbulence in high-latitude translucent molecular clouds. These low mass (~ 50 M(solar), nearby (~ 100 pc), non-star forming clouds appear to be condensing out of the atomic cirrus and must be forced by external dynamical processes, since they lack internal sources, for which we can distinguish the injection scale for the turbulence. We have now mapped three clouds -- MBM 3, MBM 16, and MBM 40 -- with high spatial (0.03 pc) and velocity resolution (<0.08 km/s) in 12CO(1-0) 13CO(1-0) (NRAO 12m and FCRAO). All three clouds show evidence for large-shear flows and we propose that the turbulent motions are powered by shear-flow instability. The densest gas is structured into filaments but the velocity profiles do not change in going across a filament indicating that shocks are not compressing the gas. The density field is more likely the result of thermal instability. The velocity-size relationship, a commonly used diagnostic of ISM turbulence, does not hold in these clouds: the linewidth does not increase with region size. The centroid velocity probability distribution function (PDF) is a more precise measure of turbulence. In these clouds the PDFs exhibit broad wings, consistent with a Lorentzian distribution and showing evidence non-Gaussian correlated processes. This is a clear signature of intermittency. We have also begun a mapping survey of CS (1-0), CS (2-1), H2CO, and HCO+ at Arecibo and OSO and willdiscuss results for the Polaris flare and L1512. We will also discusssome implications of these studies for the turbulent dissipation in these systems.

Shore, S. N.; Larosa, T. N.; Magnani, L.; Chastain, R. J.; Costagliola, F.

356

Observing, Describing, and Identifying Clouds  

NSDL National Science Digital Library

In this activity students observe and sketch clouds, describing their forms. They initially generate descriptions of a personal nature and then move toward building a more scientific vocabulary. They then correlate their descriptions with the standard classifications using the ten cloud types identified for GLOBE. Each student develops a personal cloud booklet to be used in conjunction with the GLOBE Cloud Chart. . The intended outcome is that students will be able to identify cloud types using standard cloud classification names.

The GLOBE Program, UCAR (University Corporation for Atmospheric Research)

2003-08-01

357

Effects on non-linearities on aircraft poststall motion  

SciTech Connect

The poststall maneuverability controlled by thrust vectoring has become one of the important aspects of new fighter development projects. In simplified case, the motion of aircraft can be described by 6DOF nonlinear system. The lecture deals with the longitudinal motion of poststall maneuverable aircraft. The investigation made about the effects of non-linearities in aerodynamic coefficients having considerable non-linearities and hysteresisis an the poststall motions. There were used some different models of aerodynamic coefficients. The results of investigation have shown that the poststall domain of vectored aircraft can be divided into five different pHs in field of thrust - pitch vector angle, and the chaotic motions of aircraft can be found at the different frequencies of thrust deflection. There were defined an unstable right domain with an unstable oscillation and a field of overpulling at poststall motion. The certain frequency chaotic attractors were got at frequencies of Oxitation between the 0.15 and 0.65 rad/sec. The pitching moment derivatives had the big influence on the chaotic motions, while the lift coefficient derivatives bad the reasonable effects, only.

Rohacs, J. [Technical Univ. of Budapest (Hungary); Thomasson, P. [Crainfield Univ. (United Kingdom); Mosehilde, E. [Technical Univ. of Denmark (Denmark)] [and others

1994-12-31

358

Fractal vector measures and vector calculus on planar fractal domains  

Microsoft Academic Search

We define an abstract framework for self-similar vector-valued Borel measures on a compact space X based upon a formulation of Iterated Function Systems (IFS) on such measures. This IFS method permits the construction of tangent and normal vector measures to planar fractal curves. Line integrals of smooth vector fields over planar fractal curves may then be defined. These line integrals

F. Mendivil; E. R. Vrscay

2002-01-01

359

The 27-28 October 1986 FIRE cirrus case study - Meteorology and clouds. [First International Satellite Cloud Climatology Project Regional Experiment  

NASA Technical Reports Server (NTRS)

A detailed case study is conducted of cirrus clouds that were observed intensely over a 36-h period from 1200 UTC October 27 to 0000 UTC October 29, 1986. The clouds varied in density and structure as synoptic and mesoscale features passed through the region. The study seeks to provide a meteorological overview including a synoptic and regional perspective; to document the rawinsonde-resolved atmospheric structure and large-scale forcing associated with the observed cloud systems; and to provide understanding of the relationship between atmospheric structure and the character of the corresponding cloud fields. Regional analyses of the static stability structure and vertical motion are presented and interpreted with respect to the characteristics of the corresponding cloud fields as deduced from satellite and lidar observations. It is suggested that mesoscale organization must be taken into account in parametric treatments of cirrus for large-scale atmospheric models. It is shown that cloud generation typically occurred at multiple levels.

Starr, David O'C.; Wylie, Donald P.

1990-01-01

360

Motion Toward and Away  

NSDL National Science Digital Library

Learn to differentiate between graphs of forward and backward motion. Predict what graphs look like before using a motion sensor, and then compare your predictions with real data. Respond to questions about several other position-time graphs and also explore position-time graphs that do not start at the origin (0,0). Motion Toward and Away is the second of five SmartGraphs activities designed for a typical physical science unit of study on the motion of objects.

Consortium, The C.

2012-02-07

361

Force and Motion  

NSDL National Science Digital Library

Explore interactive sites and sites with information about putting objects into motion with different forces. 1. Read the top two sections about Motion and Force and then answer questions #1 and #2 on your worksheet. Force and Motion Information 2. Scroll down and read the section about inertia. Force and Motion Information Then click the box that says "law of inertia" and learn more about inertia on this page. Newton s Laws Now answer #3 ...

Benson, Carrie

2013-01-31

362

Yugoslav strong motion network  

Microsoft Academic Search

Data concerning ground motion and the response of structures during strong earthquakes are necessary for seismic hazard evaluation and the definition of design criteria for structures to be constructed in seismically active zones. The only way to obtain such data is the installation of a strong-motion instrument network. The Yugoslav strong-motion programme was created in 1972 to recover strong-motion response

Vladimir Mihailov

1985-01-01

363

Relationship between cloud radiative forcing, cloud fraction and cloud albedo, and new surface-based approach for determining cloud albedo  

SciTech Connect

This paper focuses on three interconnected topics: (1) quantitative relationship between surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo; (2) surface-based approach for measuring cloud albedo; (3) multiscale (diurnal, annual and inter-annual) variations and covariations of surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo. An analytical expression is first derived to quantify the relationship between cloud radiative forcing, cloud fraction, and cloud albedo. The analytical expression is then used to deduce a new approach for inferring cloud albedo from concurrent surface-based measurements of downwelling surface shortwave radiation and cloud fraction. High-resolution decade-long data on cloud albedos are obtained by use of this surface-based approach over the US Department of Energy's Atmospheric Radiaton Measurement (ARM) Program at the Great Southern Plains (SGP) site. The surface-based cloud albedos are further compared against those derived from the coincident GOES satellite measurements. The three long-term (1997-2009) sets of hourly data on shortwave cloud radiative forcing, cloud fraction and cloud albedo collected over the SGP site are analyzed to explore the multiscale (diurnal, annual and inter-annual) variations and covariations. The analytical formulation is useful for diagnosing deficiencies of cloud-radiation parameterizations in climate models.

Liu, Y.; Wu, W.; Jensen, M. P.; Toto, T.

2011-07-21

364

Viral vectors for veterinary vaccines.  

PubMed

Whatever strategy is adopted for the development of viral vectors for delivery of veterinary vaccines there are several key points to consider: (1) Will the vectored vaccine give a delivery advantage compared to what's already available? (2) Will the vectored vaccine give a manufacturing advantage compared to what's already available? (3) Will the vectored vaccine provide improved safety compared to what's already available? (5) Will the vectored vaccine increase the duration of immunity compared to what's already available? (6) Will the vectored vaccine be more convenient to store compared to what's already available? (7) Is the vectored vaccine compatible with other vaccines? If there is no other alternative available then the answer to these questions is easy. However, if there are alternative vaccines available then the answers to these questions become very important because the answers will determine whether a vectored vaccine is merely a good laboratory idea or a successful vaccine. PMID:9890015

Sheppard, M

1999-01-01

365

New Form of Cloud  

Microsoft Academic Search

THE kind of cloud described by M. André Poëy (NATURE, Oct. 19, 1871, p. 489) is by no means new or rare if I can judge correctly from the figure and explanation. It may often be seen on the lower part of the flank of a great rain or thunder cloud, and appears to arise from the dropping or subsidence

1871-01-01

366

Canopy In The Clouds  

NSDL National Science Digital Library

Canopy In The Clouds is a free educational research focused on providing innovative and immersive earth and life science educational media from the perspective of a tropical montane clouds forest. All information on the website is peer-reviewed for accuracy and continually updated.

367

Counting the clouds  

Microsoft Academic Search

Cloud processes are very important for the global circulation of the atmosphere. It is now possible, though very expensive, to simulate the global circulation of the atmosphere using a model with resolution fine enough to explicitly represent the larger individual clouds. An impressive preliminary calculation of this type has already been performed by Japanese scientists, using the Earth Simulator. Within

David A Randall

2005-01-01

368

Clues About Clouds  

NSDL National Science Digital Library

In this weather activity which requires adult supervision, learners will get a chance to make a cloud right here on Earth! They learn about the different ingredients a cloud needs in order to form, and then duplicate the process that usually takes place thousands of feet above their heads.

Cosi

2009-01-01

369

FIRE Arctic Clouds Experiment  

Microsoft Academic Search

An overview is given of the First ISCCP Regional Experiment Arctic Clouds Experiment that was conducted dur- ing April-July 1998. The principal goal of the field experiment was to gather the data needed to examine the impact of arctic clouds on the radiation exchange between the surface, atmosphere, and space, and to study how the surface influ- ences the evolution

J. A. Curry; P. V. Hobbs; M. D. King; D. A. Randall; P. Minnis; G. A. Isaac; J. O. Pinto; T. Uttal; A. Bucholtz; D. G. Cripe; H. Gerber; C. W. Fairall; T. J. Garrett; J. Hudson; J. M. Intrieri; C. Jakob; T. Jensen; P. Lawson; D. Marcotte; L. Nguyen; P. Pilewskie; A. Rangno; D. C. Rogers; K. B. Strawbridge; F. P. J. Valero; A. G. Williams; D. Wylie

2000-01-01

370

Cloud Physics: The Basics  

NSDL National Science Digital Library

This website from the Oklahoma Weather Modification Program encourages students to initiate a debate on the controversy surrounding the issue of inducing or enhancing precipitation. The exercise describes the two basic tenets of cloud seeding: the Static Phase Hypothesis and the Dynamic Phase Hypothesis. Also provided are links to a weather and climate glossary and further information about clouds and precipitation.

Klatt, Michael L.

2008-01-14

371

On the initial motion of artificial comets in the AMPTE releases  

NASA Technical Reports Server (NTRS)

A model describing the initial Ba(+) cloud noted in the AMPTE program is presented which stresses the diamagnetic aspects of the interaction. Based on the observed magnetic field profile, it is suggested that the Ba(+) gyroradius becomes shorter than the cloud radius, and that the Ba(+) ions are magnetized. Momentum coupling force between the Ba(+) cloud and the solar wind in their relative streaming direction will produce an acceleration drift in the direction identical to the observed motion of the cloud, and the observed acceleration force is used to compute the magnitude of the coupling force and to compare it with other models.

Papadopoulos, K.; Lui, A. T. Y.

1986-01-01

372

Segmentation and Recognition using Structure from Motion Point Clouds  

E-print Network

with object category. We introduce features that project the 3D cues back to the 2D image plane while modeling spatial layout and context. A randomized decision forest combines many such features to achieve a coherent appearance-based descriptors or dense depth estimates obtained using e.g., dense stereo or laser range

Martin, Ralph R.

373

Intraseasonal Behavior of Clouds, Temperature, and Motion in the Tropics  

Microsoft Academic Search

The spectral character of tropical convection is investigated in an 11-yr record of outgoing longwave radiation from the Advanced Very High Resolution Radiometer to identify interaction with the tropical circulation. Along the equator in the eastern hemisphere, the space-time spectrum of convection possesses a broad peak at wave-numbers 1-3 and eastward periods of 35-95 days. Significantly broader than the dynamical

Murry L. Salby; Harry H. Hendon

1994-01-01

374

Objects in Motion  

ERIC Educational Resources Information Center

One thing scientists study is how objects move. A famous scientist named Sir Isaac Newton (1642-1727) spent a lot of time observing objects in motion and came up with three laws that describe how things move. This explanation only deals with the first of his three laws of motion. Newton's First Law of Motion says that moving objects will continue…

Damonte, Kathleen

2004-01-01

375

Making Sense of Motion  

NSDL National Science Digital Library

This activity is designed to introduce motion concepts to students through active, hands-on investigation, and to help activate their prior knowledge about motion. It can be developed into a culminating assessment for a unit on force and motion that uses higher-order thinking skills to make sense of the experience.

King, Kenneth

2005-02-01

376

Hyperbolic Dynamics Brownian Motion  

E-print Network

Hyperbolic Dynamics and Brownian Motion an introduction Jacques FRANCHI and Yves LE JAN January page 167 VI.1) Discrete martingales and stochastic integrals page 168 VI.2) Brownian Motion page 172 VI Stochastic Differential Equations page 205 VII.3) Approximation of left Brownian motions by exponentials page

Franchi, Jacques

377

BROWNIAN MOTION JUSTIN HARTMANN  

E-print Network

BROWNIAN MOTION JUSTIN HARTMANN Abstract. This paper begins to explore a rigorous introduction explanation of terms and ideas and then move onto an attempt at explaining Brownian motion. Contents 1 Motion 6 Acknowledgments 9 References 9 This paper attempts to explain the phenomenon known as Brownian

May, J. Peter

378

A numerical model of electrodynamics of plasma within the contaminant gas cloud of the Space Shuttle Orbiter at low earth orbit  

NASA Technical Reports Server (NTRS)

A two-dimensional cloud was used to study the plasma dynamics within the outgas cloud associated with the Orbiter. It is shown that the polarization field is not symmetric about the direction of motion of the outgas cloud. It rotates in a way that can be predicted in simple cases by the ratio of the Hall and Pederson currents within the outgas cloud. The polarization field magnitude produced in the model was not large.

Eccles, J. Vincent; Raitt, W. John; Banks, Peter M.

1989-01-01

379

On the origin of the Orion and Monoceros molecular cloud complexes  

NASA Technical Reports Server (NTRS)

A detailed model for the origin of the Orion and Monoceros cloud complexes is presented, showing that a single high-velocity H I cloud-galaxy collision can explain their main observed features. The collision generates massive shocked layers, and self-gravity can then provide the conditions for the transformation of these layers into molecular clouds. The clouds formed by the collision maintain the motion of their parental shocked gas and reach positions located far away from the plane. According to this model, both the Orion and Monoceros complexes were formed some 60 million yr ago, when the original shocked layer was fragmented by Galactic tidal forces.

Franco, J.; Tenorio-Tagle, G.; Bodenheimer, P.; Rozyczka, M.; Mirabel, I. F.

1988-01-01

380

Can Protostellar Jets Drive Supersonic Turbulence in Molecular Clouds?  

E-print Network

Jets and outflows from young stellar objects are proposed candidates to drive supersonic turbulence in molecular clouds. Here, we present the results from multi-dimensional jet simulations where we investigate in detail the energy and momentum deposition from jets into their surrounding environment and quantify the character of the excited turbulence with velocity probability density functions. Our study include jet--clump interaction, transient jets, and magnetised jets. We find that collimated supersonic jets do not excite supersonic motions far from the vicinity of the jet. Supersonic fluctuations are damped quickly and do not spread into the parent cloud. Instead subsonic, non-compressional modes occupy most of the excited volume. This is a generic feature which can not be fully circumvented by overdense jets or magnetic fields. Nevertheless, jets are able to leave strong imprints in their cloud structure and can disrupt dense clumps. Our results question the ability of collimated jets to sustain supersonic turbulence in molecular clouds.

Robi Banerjee; Ralf S. Klessen; Christian Fendt

2007-06-25

381

Formation and spread of aircraft-induced holes in clouds.  

PubMed

Hole-punch and canal clouds have been observed for more than 50 years, but the mechanisms of formation, development, duration, and thus the extent of their effect have largely been ignored. The holes have been associated with inadvertent seeding of clouds with ice particles generated by aircraft, produced through spontaneous freezing of cloud droplets in air cooled as it flows around aircraft propeller tips or over jet aircraft wings. Model simulations indicate that the growth of the ice particles can induce vertical motions with a duration of 1 hour or more, a process that expands the holes and canals in clouds. Global effects are minimal, but regionally near major airports, additional precipitation can be induced. PMID:21719676

Heymsfield, Andrew J; Thompson, Gregory; Morrison, Hugh; Bansemer, Aaron; Rasmussen, Roy M; Minnis, Patrick; Wang, Zhien; Zhang, Damao

2011-07-01

382

Vectors from A to B  

NSDL National Science Digital Library

This is an activity about vectors and velocity. It outlines the addition and subtraction of vectors, and introduces the application of trigonometry to describing vectors. The resource is designed to support student analysis of THEMIS (Time History of Events and Macroscale Interactions during Substorms) Magnetometer line-plot data. Learners will complete worksheets consisting of problem sets that allow them to work with vector data in magnetic fields. This is activity 15 from Exploring Magnetism: Earth's Magnetic Personality.

383

Prebiotic chemistry in clouds  

NASA Technical Reports Server (NTRS)

The chemical evolution hypothesis of Woese (1979), according to which prebiotic reactions occurred rapidly in droplets in giant atmospheric reflux columns was criticized by Scherer (1985). This paper proposes a mechanism for prebiotic chemistry in clouds that answers Scherer's concerns and supports Woese's hypothesis. According to this mechanism, rapid prebiotic chemical evolution was facilitated on the primordial earth by cycles of condensation and evaporation of cloud drops containing clay condensation nuclei and nonvolatile monomers. For example, amino acids supplied by, or synthesized during entry of meteorites, comets, and interplanetary dust, would have been scavenged by cloud drops containing clay condensation nuclei and would be polymerized within cloud systems during cycles of condensation, freezing, melting, and evaporation of cloud drops.

Oberbeck, Verne R.; Marshall, John; Shen, Thomas

1991-01-01

384

Fluidic thrust vector control  

NASA Astrophysics Data System (ADS)

The design and testing of a fluidic control nozzle for tactical missile thrust vector control (TVC) are discussed. Attention is given to a nozzle with a circular cross section up to the point of flow separation, two control ports that alternately open and close, and a nozzle extension downstream of the control ports being a two-dimensional rectangular slot. Design of the TVC system involved characterizing the flow and the sensitivity parameters, the dynamic response, and the performance of hot-gas firings. The test firings verified the feasibility of a nozzle that could withstand 5000 F, the use of thrust vector angles of over 20 deg. A dynamic model test demonstrated a repeatable performance with pressures up to 2000 psia, driving frequencies up to 50 Hz, and a response of 10-15 msec. Adjustment of the chamber pressures permitted equivalent performance using with different heat ratios during cold dynamic tests with CH4.

Haloulakos, V. E.

385

Preloadable vector sensitive latch  

NASA Technical Reports Server (NTRS)

A preloadable vector-sensitive latch which automatically releases when the force vector from a latch memebr reaches a specified release angle is presented. In addition, it contains means to remove clearance between the latched members and to preload the latch to prevent separation at angles less than the specified release angle. The latch comprises a triangular main link, a free link connected between a first corner of the main link and a yoke member, a housing, and an actuator connected between the yoke member and the housing. A return spring bias means connects the main link to a portion of the housing. A second corner of the main link is slidably and pivotally connected to the housing via a slot in a web portion of the housing. The latch housing has a rigid docking ring alignable with a mating locking ring which is engageable by a locking roller journalled on the third corner of the triangular main link.

Acres, William R. (inventor)

1987-01-01

386

Kinematics of vector fields  

E-print Network

Different (not only by sign) affine connections are introduced for contravariant and covariant tensor fields over a differentiable manifold by means of a non-canonical contraction operator, defining the notion dual bases and commuting with the covariant and with the Lie-differential operator. Classification of the linear transports on the basis of the connections between the connections is given. Notion of relative velocity and relative acceleration for vector fields are determined. By means of these kinematic characteristics several other types of notions as shear velocity, shear acceleration, rotation velocity, rotation acceleration, expansion velocity and expansion acceleration are introduced and on their basis auto-parallel and non-isotropic (non-null) vector fields are classified.

S. Manoff

2000-03-02

387

Interannual Variations of Arctic Cloud Types  

E-print Network

a sub-dataset over only the Arctic ocean Cloud trends over the Arctic ocean Correlations of cloud-ice retreat - Less September ice More autumn cloud cover #12;Arctic Ocean Cloud Study Results Cloud changes

Hochberg, Michael

388

Vector Magnetograph Design  

NASA Technical Reports Server (NTRS)

This report covers work performed during the period of November 1994 through March 1996 on the design of a Space-borne Solar Vector Magnetograph. This work has been performed as part of a design team under the supervision of Dr. Mona Hagyard and Dr. Alan Gary of the Space Science Laboratory. Many tasks were performed and this report documents the results from some of those tasks, each contained in the corresponding appendix. Appendices are organized in chronological order.

Chipman, Russell A.

1996-01-01

389

Fractional Vector Calculus  

Microsoft Academic Search

\\u000a The calculus of derivatives and integrals of non-integer order go back to Leibniz, Liouville, Grünwald, Letnikov and Riemann.\\u000a The fractional calculus has a long history from 1695, when the derivative of order ? = 0.5 was described by Leibniz (Oldham and Spanier, 1974; Samko et al., 1993; Ross, 1975). The history of fractional vector\\u000a calculus (FVC) is not so long.

Vasily E. Tarasov

390

Vector Difference Calculus  

Microsoft Academic Search

Space is filled with triangulating graph \\\\calG to serve as a quadrature grid. A discrete analog of the theory of differential forms is constructed using the associated simplical complex. The role of a basis for Lambda^p at a point is played by the set of (p+1) -simplices containing a given vertex. Vector difference operations analogous to div, grad and curl,

W. A. Schwalm; M. K. Schwalm; M. Giona

1998-01-01

391

Applications of Vector Calculus  

Microsoft Academic Search

\\u000a This chapter provides a brief introduction to some of the many applications of vector calculus to physics. Each of these is\\u000a a vast topic in itself and is the subject of numerous books and a great deal of current research, so it is not possible to\\u000a go into any detail in this book. However, a number of important governing equations

Paul C. Matthews

392

Elusive vector glueball  

SciTech Connect

If the vector glueball {Omicron} exists in the mass range that theory suggests, its resonant production cross section can be detected in e{sup +}e{sup -} annihilation only if the decay width is very narrow ({le} a few MeV). Otherwise {Omicron} will be observed only indirectly through its mixing with {psi}{prime}. We propose a few tests of the {Omicron}-{psi}{prime} mixing for future charm factories.

Suzuki, Mahiko

2002-05-01

393

A vector product in R  

Microsoft Academic Search

In nearly all undergraduate textbooks on applied analysis, the vector product is introduced only in R, giving many students the impression, that this is a special feature of this particular vector space. The author suggests avoiding this conclusion by introducing the complex numbers as an example of a vector product in R. The purpose of this paper is twofold: first,

A. R. Walter

1996-01-01

394

Scientific processor vector file organization  

SciTech Connect

This patent describes in a scientific vector processor having multiple independent instruction execution pipelines, a vector file memory system. It comprises: a first vector file means for addressable storing a plurality of vector files made up of vector elements in a predetermined storage configuration and a second equal vector file means for addressably storing a second plurality of vector files made up of vector elements in the predetermined storage configuration. Each of the first and second vector file means including an identical plurality of N memory blocks, wherein each of the memory blocks comprises a random access memory means having storage locations for storing vector elements, addressing means for providing address signals for addressing the storage locations, and a separate writing means for writing vector elements in addressed ones of the storage locations. Each of the random access memory means including a plurality of successive addressable storage locations wherein each such successive location stores contiguous information successively separated by N locations, where N equals the number of the N memory blocks; N address registers; and a time slot management mechanism coupled to each of the vector file means to allocate and maintain memory access.

Lahti, A.E.

1989-10-17

395

Symmetries of vector exterior differential systems and the inverse problem in second-order Ostrohrads'kyj mechanics  

E-print Network

Symmetries of variational problems are considered as symmetries of vector bundle valued exterior differential systems. This approach is then applied to third order ordinary variational equations of motion of the semi-classical spinning particle.

R. Ya. Matsyuk

2014-06-23

396

Precipitation growth in convective clouds. [hail  

NASA Technical Reports Server (NTRS)

Analytical solutions to the equations of both the growth and motion of hailstones in updrafts and of cloud water contents which vary linearly with height were used to investigate hail growth in a model cloud. A strong correlation was found between the hail embyro starting position and its trajectory and final size. A simple model of the evolution of particle size distribution by coalescence and spontaneous and binary disintegrations was formulated. Solutions for the mean mass of the distribution and the equilibrium size distribution were obtained for the case of constant collection kernel and disintegration parameters. Azimuthal scans of Doppler velocity at a number of elevation angles were used to calculate high resolution vertical profiles of particle speed and horizontal divergence (the vertical air velocity) in a region of widespread precipitation trailing a mid-latitude squall line.

Srivastava, R. C.

1981-01-01

397

Search for Remnant Clouds Associated with the TW Hya Association  

NASA Astrophysics Data System (ADS)

We report on a search for the parental molecular clouds of the TW Hya association (TWA), using CO emission and NaI absorption lines. TWA is the nearest young (˜50pc; ˜10Myr) stellar association; yet in spite of its youth there has been no detection of any associated natal molecular gas, as is the case with other typical young clusters. Using infrared maps as a guide, we conducted a CO cloud survey toward a region with a dust extinction of E(B - V) > 0.2mag, or AV > 0.6mag. CO emission was detected in the direction of three IR dust clouds, and we rejected one cloud out of the TWA, because no interstellar Na absorption was detected in the nearby Hipparcos stars, implying that it is too distant to relate to the TWA. The two other clouds exhibit only faint and small-scale CO emission. Interstellar NaI absorptions of Hipparcos targets (HIP 57809, HIP 64837, and HIP 64925, at distances of 133, 81, and 101pc, respectively) by these clouds were also detected. We conclude that only a small fraction of the interstellar matter (ISM) toward the infrared (IR) dust cloud is located at a distance less than 100pc, which may be all that is left out of the remnant clouds of TWA; the remaining remnant cloud dissipated within the last ˜1Myr. Such a short-dissipation timescale may be due to an external perturbation or kinematic segregation that has a large stellar proper motion relative to the natal cloud.

Tachihara, Kengo; Neuhäuser, Ralph; Fukui, Yasuo

2009-06-01

398

Dual motion valve with single motion input  

NASA Technical Reports Server (NTRS)

A dual motion valve includes two dual motion valve assemblies with a rotary input which allows the benefits of applying both rotary and axial motion to a rotary sealing element with a plurality of ports. The motion of the rotary sealing element during actuation provides axial engagement of the rotary sealing element with a stationary valve plate which also has ports. Fluid passages are created through the valve when the ports of the rotary sealing element are aligned with the ports of the stationary valve plate. Alignment is achieved through rotation of the rotary sealing element with respect to the stationary valve plate. The fluid passages provide direct paths which minimize fluid turbulence created in the fluid as it passes through the valve.

Belew, Robert (inventor)

1987-01-01

399

July 2012July 2012 Cloud Computing and Virtualization:Cloud Computing and Virtualization  

E-print Network

July 2012July 2012 Cloud Computing and Virtualization:Cloud Computing and Virtualization/26/2633 Recent: CloudRecent: Cloud The fast growth of cloud computing Cloud file storage/synchronization services Google entries about cloud computing: 184,000,000 #12;July 2012July 2012 44/26/2644 Our CloudOur Cloud 7

Liu, Jiangchuan (JC)

400

Motion-compensated subband coding with scene adaptivity  

NASA Astrophysics Data System (ADS)

This paper presents a new motion compensated subband video coding algorithm with scene adaptive motion interpolation. The work builds on temporal segmentation for determining the reference frame positions, and multi-resolution motion estimation in the subband domain. In the proposed approach, the reference frames for motion estimation are adaptively selected using the temporal segmentation of the lowest spatial subband. Motion compensation is used after subband filtering because it produces better performance than subband filtering after motion compensation. The proposed scene adaptive scheme, temporally adaptive motion interpolation (TAMI), determines the number and the positions of the reference frames for motion estimation using two types of temporal segmentation algorithms. The input video is split into the 7 spatial subbands by using a pair of low-pass and high-pass biorthogonal filters, and the TAMI algorithm is applied on the lowest of the subbands. Motion vectors for each subband are generated by a hierarchical motion estimation approach. Block-wise DPCM and a uniform quantizer are used only for the lowest subband of an intra frame, and all the other subbands are coded by PCM with a dead-zone quantizer. Simulation results show that the scene adaptive scheme compares favorably with the fixed interpolation structure.

Lee, Jungwoo; Dickinson, Bradley W.

1994-05-01

401

Quasar Proper Motions and Low-Frequency Gravitational Waves  

E-print Network

We report observational upper limits on the mass-energy of the cosmological gravitational-wave background, from limits on proper motions of quasars. Gravitational waves with periods longer than the time span of observations produce a simple pattern of apparent proper motions over the sky, composed primarily of second-order transverse vector spherical harmonics. A fit of such harmonics to measured motions yields a 95%-confidence limit on the mass-energy of gravitational waves with frequencies <2e-9 Hz, of <0.11/h*h times the closure density of the universe.

Carl R. Gwinn; T. Marshall Eubanks; Ted Pyne; Mark Birkinshaw; Demetrios N. Matsakis

1996-10-12

402

Reconstructing tethered satellite skiprope motion by bandpass filtering magnetometer measurements  

NASA Technical Reports Server (NTRS)

This paper presents a unique scheme for reconstructing tethered satellite skiprope motion by ground processing satellite magnetometer measurements. The measurements are modified based on ground knowledge of the earth's magnetic field and passed through bandpass filters tuned to the skiprope frequency. Skiprope motion is then deduced from the steady-state outputs of the filters. Simulation results are presented which verify the scheme and show it to be robust. The concept is not just limited to tethered satellites. Indeed, it can be applied whenever there is a need to reconstruct the coning motion of a body about a known axis, given measurements of a known vector in body-fixed axes.

Polites, M. E.

1992-01-01

403

Hydrogen Atom in Relativistic Motion  

E-print Network

The Lorentz contraction of bound states in field theory is often appealed to in qualitative descriptions of high energy particle collisions. Surprisingly, the contraction has not been demonstrated explicitly even in simple cases such as the hydrogen atom. It requires a calculation of wave functions evaluated at equal (ordinary) time for bound states in motion. Such wave functions are not obtained by kinematic boosts from the rest frame. Starting from the exact Bethe-Salpeter equation we derive the equal-time wave function of a fermion-antifermion bound state in QED, i.e., positronium or the hydrogen atom, in any frame to leading order in alpha. We show explicitly that the bound state energy transforms as the fourth component of a vector and that the wave function of the fermion-antifermion Fock state contracts as expected. Transverse photon exchange contributes at leading order to the binding energy of the bound state in motion. We study the general features of the corresponding fermion-antifermion-photon Fock states, and show that they do not transform by simply contracting. We verify that the wave function reduces to the light-front one in the infinite momentum frame.

M. Jarvinen

2004-11-16

404

Research for current cloud computing and cloud security technology  

Microsoft Academic Search

This paper introduces the concept, development, key features, applications of cloud computing. The difference to grid computing is discussed. Eight kinds of typical open source cloud computing projects are described, the security reference models of cloud services are given. Cloud computing security challenges and countermeasures are discussed in this paper.

Chen Hongsong; Fu Zhongchuan

2010-01-01

405

Cloud Condensation Nuclei Retrievals at Cloud Base in North Dakota  

E-print Network

accuracy #12;POLCAST4 Polarimetric Cloud Analysis and Seeding Test 4 Field campaign held in the summerCloud Condensation Nuclei Retrievals at Cloud Base in North Dakota · Mariusz Starzec #12;Motivation Compare University of Wyoming (UWyo) and Droplet Measurement Technologies (DMT) cloud condensation nuclei

Delene, David J.

406

Vector representation of tourmaline compositions  

NASA Technical Reports Server (NTRS)

The vector method for representing mineral compositions of amphibole and mica groups is applied to the tourmaline group. Consideration is given to the methods for drawing the relevant vector diagrams, relating the exchange vectors to one another, and contouring the diagrams for constant values of Na, Ca, Li, Fe, Mg, Al, Si, and OH. The method is used to depict a wide range of possible tourmaline end-member compositions and solid solutions, starting from a single point. In addition to vector depictions of multicomponent natural tourmalines, vectors are presented for simpler systems such as (Na,Al)-tourmalines, alkali-free tourmalines, and elbaites.

Burt, Donald M.

1989-01-01

407

A New Approach to using a Cloud-Resolving Model to Study the Interactions between Clouds, Precipitation and Aerosols  

NASA Technical Reports Server (NTRS)

Numerical cloud models, which are based the non-hydrostatic equations of motion, have been extensively applied to cloud-scale and mesoscale processes during the past four decades. Because cloud-scale dynamics are treated explicitly, uncertainties stemming from convection that have to be parameterized in (hydrostatic) large-scale models are obviated, or at least mitigated, in cloud models. Global models will use the non-hydrostatic framework when their horizontal resolution becomes about 10 km, the theoretical limit for the hydrostatic approximation. This juncture will be reached one to two decades from now. Over the past generation, voluminous datasets on atmospheric convection have been accumulated from radar, instrumented aircraft, satellites, and rawinsonde measurements in field campaigns, enabling the detailed evaluation of models. Improved numerical methods have resulted in more accurate and efficient dynamical cores in models. Improvements have been made in the parameterizations of microphysical processes, radiation, boundary-layer effects, and turbulence; however, microphysical parameterizations remain a major source of uncertainty in all classes of atmospheric models. In recent years, exponentially increasing computer power has extended cloud-resolving-model integrations from hours to months, the number of computational grid points from less than a thousand to close to ten million. Three-dimensional models are now more prevalent. Much attention is devoted to precipitating cloud systems where the crucial 1-km scales are resolved in horizontal domains as large as 10,000 km in two-dimensions, and 1,000 x 1,000 square kilometers in three-dimensions. Cloud models now provide statistical information useful for developing more realistic physically-based parameterizations for climate models and numerical weather prediction models. A review of developments and applications of cloud models in the past, present and future will be presented in this talk. In particular, a new approach to using cloud-resolving models to study the interactions between clouds, precipitation and aerosols will be presented.

Tao, Wei-Kuo

2005-01-01

408

A New Approach to Using a Cloud-resolving Model to Study the Interactions Between Clouds, Precipitation and Aerosols  

NASA Technical Reports Server (NTRS)

Numerical cloud models, which are based the non-hydrostatic equations of motion, have been extensively applied to cloud-scale and mesoscale processes during the past four decades. Because cloud-scale dynamics are treated explicitly, uncertainties stemming from convection that have to be parameterized in (hydrostatic) large-scale models are obviated, or at least mitigated, in cloud models. Global models will use the non-hydrostatic framework when their horizontal resolution becomes about 10 km, the theoretical limit for the hydrostatic approximation. This juncture will be reached one to two decades from now. Over the past generation, voluminous datasets on atmospheric convection have been accumulated from radar, instrumented aircraft, satellites, and rawinsonde measurements in field campaigns, enabling the detailed evaluation of models. Improved numerical methods have resulted in more accurate and efficient dynamical cores in models. Improvements have been made in the parameterizations of microphysical processes, radiation, boundary-layer effects, and turbulence; however, microphysical parameterizations remain a major source of uncertainty in all classes of atmospheric models. In recent years, exponentially increasing computer power has extended cloud-resolving-model integrations from hours to months, the number of computational grid points from less than a thousand to close to ten million. Three-dimensional models are now more prevalent. Much attention is devoted to precipitating cloud systems where the crucial 1-km scales are resolved in horizontal domains as large as l0,OOO km in two-dimensions, and 1,OOO x 1,OOO km2 in three-dimensions. Cloud models now provide statistical information useful for developing more realistic physically-based parameterizations for climate models and numerical weather prediction models. A review of developments and applications of cloud models in the past, present and future will be presented in this talk. In particular, a new approach to using cloud-resolving models to study the interactions between clouds, precipitation and aerosols will be presented.

Tao, Wei-Kuo

2005-01-01

409

A New Approach to using a Cloud-Resolving Model to Study the Interactions between Clouds, Precipitation and Aerosols  

NASA Technical Reports Server (NTRS)

Numerical cloud models, which are based the non-hydrostatic equations of motion, have been extensively applied to cloud-scale and mesoscale processes during the past four decades. Because cloud-scale dynamics are treated explicitly, uncertainties stemming from convection that have to be parameterized in (hydrostatic) large-scale models are obviated, or at least mitigated, in cloud models. Global models will use the non-hydrostatic framework when their horizontal resolution becomes about 10 kilometers, the theoretical limit for the hydrostatic approximation. This juncture will be reached one to two decades from now. Over the past generation, voluminous datasets on atmospheric convection have been accumulated from radar, instrumented aircraft, satellites, and rawinsonde measurements in field campaigns, enabling the detailed evaluation of models. Improved numerical methods have resulted in more accurate and efficient dynamical cores in models. Improvements have been made in the parameterizations of microphysical processes, radiation, boundary-layer effects, and turbulence; however, microphysical parameterizations remain a major source of uncertainty in all classes of atmospheric models. In recent years, exponentially increasing computer power has extended cloud-resolving-model integrations from hours to months, the number of computational grid points from less than a thousand to close to ten million. Three-dimensional models are now more prevalent. Much attention is devoted to precipitating cloud systems where the crucial 1-kilometer scales are resolved in horizontal domains as large as 10,000 kilometers in two dimensions, and 1,000 x 1,000 square kilometers in three-dimensions. Cloud models now provide statistical information useful for developing more realistic physically-based parameterizations for climate models and numerical weather prediction models. A review of developments and applications of cloud models in the past, present and future will be presented in this talk. In particular, a new approach to using cloud-resolving models to study the interactions between clouds, precipitation and aerosols will be presented.

Tao, Wei-Kuo

2005-01-01

410

Diagnosing AIRS Sampling with CloudSat Cloud Classes  

NASA Technical Reports Server (NTRS)

AIRS yield and sampling vary with cloud state. Careful utilization of collocated multiple satellite sensors is necessary. Profile differences between AIRS and ECMWF model analyses indicate that AIRS has high sampling and excellent accuracy for certain meteorological conditions. Cloud-dependent sampling biases may have large impact on AIRS L2 and L3 data in climate research. MBL clouds / lower tropospheric stability relationship is one example. AIRS and CloudSat reveal a reasonable climatology in the MBL cloud regime despite limited sampling in stratocumulus. Thermodynamic parameters such as EIS derived from AIRS data map these cloud conditions successfully. We are working on characterizing AIRS scenes with mixed cloud types.

Fetzer, Eric; Yue, Qing; Guillaume, Alexandre; Kahn, Brian

2011-01-01

411

Image-based motion blur for stop motion animation  

Microsoft Academic Search

Stop motion animation is a well-established technique where still pictures of static scenes are taken and then played at film speeds to show motion. A major limitation of this method appears when fast motions are desired; most motion appears to have sharp edges and there is no visible motion blur. Appearance of motion blur is a strong perceptual cue, which

Gabriel J. Brostow; Irfan A. Essa

2001-01-01

412

Community Cloud Computing  

NASA Astrophysics Data System (ADS)

Cloud Computing is rising fast, with its data centres growing at an unprecedented rate. However, this has come with concerns over privacy, efficiency at the expense of resilience, and environmental sustainability, because of the dependence on Cloud vendors such as Google, Amazon and Microsoft. Our response is an alternative model for the Cloud conceptualisation, providing a paradigm for Clouds in the community, utilising networked personal computers for liberation from the centralised vendor model. Community Cloud Computing (C3) offers an alternative architecture, created by combing the Cloud with paradigms from Grid Computing, principles from Digital Ecosystems, and sustainability from Green Computing, while remaining true to the original vision of the Internet. It is more technically challenging than Cloud Computing, having to deal with distributed computing issues, including heterogeneous nodes, varying quality of service, and additional security constraints. However, these are not insurmountable challenges, and with the need to retain control over our digital lives and the potential environmental consequences, it is a challenge we must pursue.

Marinos, Alexandros; Briscoe, Gerard

413

Rigid Body Motion in Stereo 3D Simulation  

ERIC Educational Resources Information Center

This paper addresses the difficulties experienced by first-grade students studying rigid body motion at Sofia University. Most quantities describing the rigid body are in relations that the students find hard to visualize and understand. They also lose the notion of cause-result relations between vector quantities, such as the relation between…

Zabunov, Svetoslav

2010-01-01

414

PhET Simulation: Motion in 2D  

NSDL National Science Digital Library

This is an interactive simulation created to help beginners differentiate velocity and acceleration vectors. The user can move a ball with the mouse or let the simulation move the ball in four modes of motion (two types of linear, simple harmonic, and circular). Two vectors are displayed -- one green and one blue. As the motion of the ball changes, the vectors also change. Which color represents velocity and which acceleration? Editor's Note: This simulation was designed with improvements based on research of student interaction with the PhET resource "Ladybug Revolution". The authors added two new features for the beginning learner: linear acceleration and harmonic motion. To supplement the simulation, we recommend the Physics Classroom tutorial "Vectors and Direction" and the teacher-created lesson, "Vectors Phet Lab" -- see links in Related Materials. This item is part of a larger and growing collection of resources developed by the Physics Education Technology project (PhET), each designed to implement principles of physics education research.

415

Extended field observations of cirrus clouds using a ground-based cloud observing system  

NASA Technical Reports Server (NTRS)

The evolution of synoptic-scale dynamics associated with a middle and upper tropospheric cloud event that occurred on 26 November 1991 is examined. The case under consideration occurred during the FIRE CIRRUS-II Intensive Field Observing Period held in Coffeyville, KS during Nov. and Dec., 1991. Using data from the wind profiler demonstration network and a temporally and spatially augmented radiosonde array, emphasis is given to explaining the evolution of the kinematically-derived ageostrophic vertical circulations and correlating the circulation with the forcing of an extensively sampled cloud field. This is facilitated by decomposing the horizontal divergence into its component parts through a natural coordinate representation of the flow. Ageostrophic vertical circulations are inferred and compared to the circulation forcing arising from geostrophic confluence and shearing deformation derived from the Sawyer-Eliassen Equation. It is found that a thermodynamically indirect vertical circulation existed in association with a jet streak exit region. The circulation was displaced to the cyclonic side of the jet axis due to the orientation of the jet exit between a deepening diffluent trough and building ridge. The cloud line formed in the ascending branch of the vertical circulation with the most concentrated cloud development occurring in conjunction with the maximum large-scale vertical motion. The relationship between the large scale dynamics and the parameterization of middle and upper tropospheric clouds in large-scale models is discussed and an example of ice water contents derived from a parameterization forced by the diagnosed vertical motions and observed water vapor contents is presented.

Ackerman, Thomas P.

1994-01-01

416

Nighttime Clouds in Martian Arctic (Accelerated Movie)  

NASA Technical Reports Server (NTRS)

An angry looking sky is captured in a movie clip consisting of 10 frames taken by the Surface Stereo Imager on NASA's Phoenix Mars Lander.

The clip accelerates the motion. The images were take around 3 a.m. local solar time at the Phoenix site during Sol 95 (Aug. 30), the 95th Martian day since landing.

The swirling clouds may be moving generally in a westward direction over the lander.

The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

2008-01-01

417

Cloud Study Final Art Project  

NSDL National Science Digital Library

This activity is an art project completed at the end of a study of weather and clouds. Using home-made puffy paint, the students paint clouds on a piece of construction paper and write 2-3 facts about each cloud type on a note card that is glued on construction paper next to the appropriate cloud.

Toops, Kim

418

Convective Cloud Lifecycles Lunchtime seminar  

E-print Network

Convective Cloud Lifecycles Lunchtime seminar 19th May 2009 Bob Plant Department of Meteorology, University of Reading, UK #12;Introduction Obtain life cycle statistics for clouds in CRM simulations Why Conclusions Convective Cloud Lifecycles ­ p.1/3 #12;Why bother? Convective Cloud Lifecycles ­ p.2/3 #12;Some

Plant, Robert

419

Cloud Seeding By: Julie Walter  

E-print Network

Cloud Seeding By: Julie Walter Air Chem and Pollution #12;History · In Kurt Vonnegut's 1963 novel nuclei catalyst. #12;Cloud Seeding is... · a process that uses a product such as Silver Iodide or dry ice the freezing process of the ice nuclei in clouds. static seeding- involves cumulus clouds traveling west

Toohey, Darin W.

420

An infrared proper motion study of the Orion bullets  

E-print Network

We report the first IR proper motion measurements of the Herbig-Haro objects in the Orion Molecular Cloud--One using a four-year time baseline. The [Fe II] emitting bullets are moving of order 0.08 arcsec per year, or at about 170 \\kms. The direction of motion is similar to that inferred from their morphology. The proper motions of \\h2 emitting wakes behind the [Fe II] bullets, and of newly found \\h2 bullets, are also measured. \\h2 bullets have smaller proper motion than [Fe II] bullets, while \\h2 wakes with leading [Fe II] bullets appear to move at similar speeds to their associated bullets. A few instances of variability in the emission can be attributed to dense, stationary clumps in the ambient cloud being overrun, setting up a reverse--oriented bullet. Differential motion between [Fe II] bullets and their trailing \\h2 wakes is not observed, suggesting that these are not separating, and also that they have reached a steady--state configuration over at least 100 years. The most distant bullets have, on average, larger proper motions, but are not consistent with free expansion. Nevertheless an impulsive, or short--lived ($\\ll$ 1,000 years) duration for their origin seems likely.

J. -K. Lee; M. G. Burton

1999-08-04

421

Molecular Clouds toward the Super Star Cluster NGC 3603 Possible Evidence for a Cloud-Cloud Collision in Triggering the Cluster Formation  

NASA Astrophysics Data System (ADS)

We present new large field observations of molecular clouds with NANTEN2 toward the super star cluster NGC 3603 in the transitions 12CO(J = 2-1, J = 1-0) and 13CO(J = 2-1, J = 1-0). We suggest that two molecular clouds at 13 km s-1 and 28 km s-1 are associated with NGC 3603 as evidenced by higher temperatures toward the H II region, as well as morphological correspondence. The mass of the clouds is too small to gravitationally bind them, given their relative motion of ~20 km s-1. We suggest that the two clouds collided with each other 1 Myr ago to trigger the formation of the super star cluster. This scenario is able to explain the origin of the highest mass stellar population in the cluster, which is as young as 1 Myr and is segregated within the central sub-pc of the cluster. This is the second super star cluster along with Westerlund 2 where formation may have been triggered by a cloud-cloud collision.

Fukui, Y.; Ohama, A.; Hanaoka, N.; Furukawa, N.; Torii, K.; Dawson, J. R.; Mizuno, N.; Hasegawa, K.; Fukuda, T.; Soga, S.; Moribe, N.; Kuroda, Y.; Hayakawa, T.; Kawamura, A.; Kuwahara, T.; Yamamoto, H.; Okuda, T.; Onishi, T.; Maezawa, H.; Mizuno, A.

2014-01-01

422

Breathing motion compensated reconstruction for C-arm cone beam CT imaging: initial experience based on animal data  

NASA Astrophysics Data System (ADS)

C-arm based tomographic 3D imaging is applied in an increasing number of minimal invasive procedures. Due to the limited acquisition speed for a complete projection data set required for tomographic reconstruction, breathing motion is a potential source of artifacts. This is the case for patients who cannot comply breathing commands (e.g. due to anesthesia). Intra-scan motion estimation and compensation is required. Here, a scheme for projection based local breathing motion estimation is combined with an anatomy adapted interpolation strategy and subsequent motion compensated filtered back projection. The breathing motion vector is measured as a displacement vector on the projections of a tomographic short scan acquisition using the diaphragm as a landmark. Scaling of the displacement to the acquisition iso-center and anatomy adapted volumetric motion vector field interpolation delivers a 3D motion vector per voxel. Motion compensated filtered back projection incorporates this motion vector field in the image reconstruction process. This approach is applied in animal experiments on a flat panel C-arm system delivering improved image quality (lower artifact levels, improved tumor delineation) in 3D liver tumor imaging.

Schäfer, D.; Lin, M.; Rao, P. P.; Loffroy, R.; Liapi, E.; Noordhoek, N.; Eshuis, P.; Radaelli, A.; Grass, M.; Geschwind, J.-F. H.

2012-03-01

423

Properties of the Acoustic Vector Field in Underwater Waveguides  

NASA Astrophysics Data System (ADS)

This thesis focuses on the description and measurement of the underwater acoustic field, based on vector properties of acoustic particle velocity. The specific goal is to interpret vector sensor measurements in underwater waveguides, in particular those measurements made in littoral (shallow) waters. To that end, theoretical models, which include the effects of reflections from the waveguide boundaries, are developed for the acoustic intensity, i.e. the product of acoustic pressure and acoustic particle velocity. Vector properties of acoustic intensity are shown to correspond to a non-dimensional vector property of acoustic particle velocity, its degree of circularity, which describes the trajectory of particle motion. Both experimental measurements and simulations of this non-dimensional vector property are used to analyze characteristics of sound propagation in underwater waveguides. Two measurement techniques are utilized in the experiments described in this thesis. In the first, particle velocity is obtained indirectly by time integration of the measured pressure gradient between two closely spaced (with respect to an acoustic wavelength) conventional pressure sensitive hydrophones. This method was used in ocean experiments conducted with vertical line arrays of hydrophones. In the second technique, particle velocity is measured directly by time integration of the signal generated by an accelerometer. An additional pressure measurement from a co-located hydrophone forms what is known as a "combined sensor" in the Russian literature, which allows for estimation of the vector acoustic intensity. This method was utilized mainly in laboratory experiments.

Dall'Osto, David R.

424

Low-Complexity Context-Based Motion Compensation For Vlbr Video Encoding  

Microsoft Academic Search

An algorithm is proposed for block-motion estimation and coding characterized by fast computation and very low bitrate. For each block, a spatio-temporal context is defined based on nearest neighbors in the current and previous frames, and a prediction list is built. Then, the best matching vector within the list is chosen as an estimation of the block motion. Since coder

Francesco G. B. De Natale; Fabrizio Granelli

2001-01-01

425

A Fast Inverse Motion Compensation Algorithm for DCT-Domain Video Transcoder  

Microsoft Academic Search

The existing methods to perform motion compensation (MC) in discrete cosine transform (DCT) treat each 8 times 8 block as a fundamental unit and, therefore, involve the high cost of reconstructing prediction frames, especially when the half-pixel motion vectors (MVs) are involved. The proposed method operates on a block of variable size 16 Ny times 16 Nx, where Nx and

Vasant Patil; Rajeev Kumar

2008-01-01

426

Nonrigid Motion Analysis Based on Dynamic Refinement of Finite Element Models  

Microsoft Academic Search

We propose new algorithms for accurate nonrigid motion tracking. Given an initial model representing general knowledge of the object, a set of sparse correspondences, and incomplete or missing information about geometry or material properties, we can recover dense motion vectors using finite element models. The method is based on the iterative analysis of the differences between the actual and predicted

Leonid V. Tsap; Dmitry B. Goldgof; Sudeep Sarkar

2000-01-01

427

Nonrigid Motion Analysis Based on Dynamic Refinement of Finite Element Models  

Microsoft Academic Search

In this paper, we propose new algorithms for accurate nonrigid motion tracking. Given an initial model representing general knowledge of the object, a set of sparse correspondences, and incomplete or missing information about geometry or material properties, we can recover dense motion vectors using finite element models. The method is based on the iterative analysis of the differences between the

Leonid V. Tsap; Dmitry B. Goldgof; Sudeep Sarkar

1998-01-01

428

A new lossless multiresolution motion estimation algorithm using PDE, adaptive matching scan, and spiral search  

Microsoft Academic Search

We propose a new and fast multi-resolution motion estimation (MRME) algorithm using optimal matching units and scans for video coding, to significantly reduce the amount of computation in motion estimation. Our proposed algorithm has no any degradation of prediction quality compared to the original MRME algorithm. The computational reduction of our algorithm comes from fast elimination of unlikely candidate vectors.

Jong-Nam Kim; Kyung-Won Kang; Kwang-Seok Moon

2005-01-01

429

Motion of Spin 1/2 Massive Particle in a Curved Spacetime  

E-print Network

Quasi-classical picture of motion of spin 1/2 massive particle in a curved spacetime is built on base of simple Lagrangian model. The one is constructed due to analogy with Lagrangian of massive vector particle. Equations of motion and spin propagation coincide with Papapetrou equations describing dynamic of classical spinning particle in a curved spacetime.

A. T. Muminov

2007-09-28

430

Dipole beam breakup electron cloud instability of a relativistic positron bunch with a smooth model linear density  

Microsoft Academic Search

We study the beam breakup instability of the dipole coherent oscillations of the relativistic positron bunch interacting with initially unperturbed electron cloud. We assume a special distribution of the linear density of positrons along the bunch which enables the calculations of analytic solutions of the linearized equations of motion of the cloud electrons. With these assumptions equations describing centroid beam

D. V. Pestrikov

2005-01-01

431

The Old and New Meanings of Cloud 'Belt' and 'Zone': A Study of Jovian and Saturnian Atmospheric Banding  

E-print Network

The brightness of cloud bands on Jupiter and Saturn as a function of latitude is reported. Bright Jovian bands near the equator are located in regions of anti-cyclonic circulation of the atmosphere. By contrast, bright equatorial bands on Saturn are associated with cyclonic motion. Modern definitions of the cloud band terms 'zone' and 'belt' are distinguished from their old meanings.

Mallama, Anthony

2014-01-01

432

Anisotropic responses to motion toward and away from the eye  

NASA Technical Reports Server (NTRS)

When a rigid object moves toward the eye, it is usually perceived as being rigid. However, in the case of motion away from the eye, the motion and structure of the object are perceived nonveridically, with the percept tending to reflect the nonrigid transformations that are present in the retinal image. This difference in response to motion to and from the observer was quantified in an experiment using wire-frame computer-generated boxes which moved toward and away from the eye. Two theoretical systems are developed by which uniform three-dimensional velocity can be recovered from an expansion pattern of nonuniform velocity vectors. It is proposed that the human visual system uses two similar systems for processing motion in depth. The mechanism used for motion away from the eye produces perceptual errors because it is not suited to objects with a depth component.

Perrone, John A.

1986-01-01

433

Entrainment, Drizzle, and Cloud Albedo  

NASA Technical Reports Server (NTRS)

Increased aerosol and hence droplet concentrations in polluted clouds are expected to inhibit precipitation and thereby increase cloud water, leading to more reflective clouds that partially offset global warming. Yet polluted clouds are not generally observed to hold more water. Much of the uncertainty regarding the indirect aerosol effect stems from inadequate understanding of such changes in cloud water. Detailed simulations show that the relative humidity of air overlying stratocumulus is a leading factor determining whether cloud water increases or decreases when precipitation is suppressed. When the overlying air is dry, cloud water can decrease as droplet concentrations increase.

Ackerman, A. S.; Kirkpatrick, J. P.; Stevens, D. E.; Toon, O. B.

2004-01-01

434

Vectoring: Steering a Plane  

NSDL National Science Digital Library

In this two part activity, learners work in pairs or individually to discover how vectoring the thrust from a jet engine affects movement of an airplane. In part one, learners construct an F-15 ACTIVE model with a balloon engine. In part two, learners conduct a series of experiments by changing the angle of the straw to control the direction of the thrust. This activity emphasizes the scientific method including prediction, observation, data collection, and analysis. This lesson plan includes background information, an extension and a sample worksheet.

Nasa

2011-08-20

435

Performance characterization of Watson Ahumada motion detector using random dot rotary motion stimuli.  

PubMed

The performance of Watson & Ahumada's model of human visual motion sensing is compared against human psychophysical performance. The stimulus consists of random dots undergoing rotary motion, displayed in a circular annulus. The model matches psychophysical observer performance with respect to most parameters. It is able to replicate some key psychophysical findings such as invariance of observer performance to dot density in the display, and decrease of observer performance with frame duration of the display.Associated with the concept of rotary motion is the notion of a center about which rotation occurs. One might think that for accurate estimation of rotary motion in the display, this center must be accurately known. A simple vector analysis reveals that this need not be the case. Numerical simulations confirm this result, and may explain the position invariance of MST(d) cells. Position invariance is the experimental finding that rotary motion sensitive cells are insensitive to where in their receptive field rotation occurs.When all the dots in the display are randomly drawn from a uniform distribution, illusory rotary motion is perceived. This case was investigated by Rose & Blake previously, who termed the illusory rotary motion the omega effect. Two important experimental findings are reported concerning this effect. First, although the display of random dots evokes perception of rotary motion, the direction of motion perceived does not depend on what dot pattern is shown. Second, the time interval between spontaneous flips in perceived direction is lognormally distributed (mode approximately 2 s). These findings suggest the omega effect fits in the category of a typical bistable illusion, and therefore the processes that give rise to this illusion may be the same processes that underlie much of other bistable phenomenon. PMID:19225571

Jain, Siddharth

2009-01-01

436

GPS constraints on Africa (Nubia) and Arabia plate motions  

NASA Astrophysics Data System (ADS)

We use continuously recording GPS (CGPS) and survey-mode GPS (SGPS) observations to determine Euler vectors for relative motion of the African (Nubian), Arabian and Eurasian plates. We present a well-constrained Eurasia-Nubia Euler vector derived from 23 IGS sites in Europe and four CGPS and three SGPS sites on the Nubian Plate (-0.95 +/- 4.8°N, -21.8 +/- 4.3°E, 0.06 +/- 0.005° Myr-1). We see no significant (>1 mm yr-1) internal deformation of the Nubian Plate. The GPS Nubian-Eurasian Euler vector differs significantly from NUVEL-1A (21.0 +/- 4.2°N, -20.6 +/- 0.6°E, 0.12 +/- 0.015° Myr-1), implying more westward motion of Africa relative to Eurasia and slower convergence in the eastern Mediterranean. The Arabia-Eurasia and Arabia-Nubia GPS Euler vectors are less well determined, based on only one CGPS and three SGPS sites on the Arabian Plate. The preliminary Arabia-Eurasia and Arabia-Nubia Euler vectors are 27.4 +/- 1.0°N, 18.4 +/- 2.5°E, 0.40 +/- 0.04° Myr-1, and 30.5 +/- 1.0°N, 25.7 +/- 2.3°E, 0.37 +/- 0.04° Myr-1, respectively. The GPS Arabia-Nubia Euler vector differs significantly from NUVEL-1A (24.1 +/- 1.7°N, 24.0 +/- 3.5°E, 0.40 +/- 0.05° Myr-1), but is statistically consistent at the 95 per cent confidence level with the revised Euler vector reported by Chu & Gordon based on a re-evaluation of magnetic anomalies in the Red Sea (31.5 +/- 1.2°N, 23.0 +/- 2.7°E, 0.40 +/- 0.05° Myr-1). The motion implied in the Gulf of Aqaba and on the Dead Sea fault (DSF) by the new GPS Nubia-Arabia Euler vector (i.e. ignoring possible Sinai block motion and possible internal plate deformation) grades from pure left lateral strike-slip in the Gulf and on the southern DSF with increasing compression on the central and northern DSF with relative motion increasing from 5.6 to 7.5 mm yr-1 (+/-1 mm yr-1) from south to north. Along the northern DSF (i.e. north of the Lebanon restraining bend) motion is partitioned between 6 +/- 1 mm yr-1 left-lateral motion parallel to the fault trace and 4 +/- 1 mm yr-1 fault-normal compression. Relative motions on other plate boundaries (including the Anatolian and Aegean microplates) derived from the GPS Euler vectors agree qualitatively with the sense of motion indicated by focal mechanisms for large crustal earthquakes (M > 6). Where data are available on fault-slip rates on plate bounding faults (North Anatolian fault, East Anatolian fault, Dead Sea fault, Red Sea rift), they are generally lower than, but not significantly different from, the full plate motion estimates suggesting that the majority of relative plate motion is accommodated on these structures.

McClusky, S.; Reilinger, R.; Mahmoud, S.; Ben Sari, D.; Tealeb, A.

2003-10-01

437

Cloud Structure Anomalies Over the Tropical Pacific During the 1997/98 El Nino  

NASA Technical Reports Server (NTRS)

Satellite measurements of both cloud vertical structure and cloud-radiative forcing have been used to show that during the strong 1997/98 El Nino there was a substantial change in cloud vertical structure over the tropical Pacific Ocean. Relative to normal years, cloud altitudes were lower in the western portion of the Pacific and higher in the eastern portion. The reason for these redistributions was a collapse of the Walker circulation and enhanced large-scale upward motion over the eastern Pacific, both caused by the lack of a zonal sea surface temperature gradient during El Nino. It is proposed that these cloud structure changes, which significantly impact satellite measurements of the tropical Pacific's radiation budget, would serve as one useful means of testing cloud-climate interactions in climate models.

Cess, Robert D.; Zhang, Minghua; Wang, Pi-Huan; Wielicki, Bruce A.

2001-01-01

438

A GALACTIC ORIGIN FOR HE 0437-5439, THE HYPERVELOCITY STAR NEAR THE LARGE MAGELLANIC CLOUD  

SciTech Connect

We use Hubble Space Telescope imaging to measure the absolute proper motion of the hypervelocity star (HVS) HE 0437-5439, a short-lived B star located in the direction of the Large Magellanic Cloud (LMC). We observe ({mu}{sub {alpha}} {mu}{sub {delta}}) = (+0.53 {+-} 0.25(stat) {+-} 0.33(sys), + 0.09 {+-} 0.21(stat) {+-} 0.48(sys)) mas yr{sup -1}. The velocity vector points directly away from the center of the Milky Way; an origin from the center of the LMC is ruled out at the 3{sigma} level. The flight time of the HVS from the Milky Way exceeds its main-sequence lifetime, thus its stellar nature requires it to be a blue straggler. The large space velocity rules out a Galactic-disk ejection. Combining the HVS's observed trajectory, stellar nature, and required initial velocity, we conclude that HE 0437-5439 was most likely a compact binary ejected by the Milky Way's central black hole.

Brown, Warren R.; Geller, Margaret J.; Kenyon, Scott J. [Smithsonian Astrophysical Observatory, 60 Garden St., Cambridge, MA 02138 (United States); Anderson, Jay; Bond, Howard E.; Livio, Mario [Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218 (United States); Gnedin, Oleg Y., E-mail: wbrown@cfa.harvard.ed, E-mail: mgeller@cfa.harvard.ed, E-mail: skenyon@cfa.harvard.ed, E-mail: jayander@stsci.ed, E-mail: bond@stsci.ed, E-mail: mlivio@stsci.ed, E-mail: ognedin@umich.ed [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States)

2010-08-10

439

The collective gyration of a heavy ion cloud in a magnetized plasma  

NASA Technical Reports Server (NTRS)

In both the ionospheric barium injection experiments CRIT 1 and CRIT 2, a long duration oscillation was seen with a frequency close to the gyro frequency of barium and a time duration of about one second. A model for the phenomena which was proposed for the CRIT 1 experiment is compared to the results from CRIT 2 which made a much more complete set of measurements. The model follows the motion of a low Beta ion cloud through a larger ambient plasma. The internal field of the model is close to antiparallel to the injection direction v sub i but slightly tilted towards the self polarization direction E sub p = -V sub i by B. As the ions move across the magnetic field, the space charge is continuously neutralized by magnetic field aligned electron currents from the ambient ionosphere, drawn by the divergence in the perpendicular electric field. These currents give a perturbation of the magnetic field related to the electric field perturbation by Delta E/Delta B approximately equal to V sub A. The model predictions agree quite well with the observed vector directions, field strengths, and decay times of the electric and magnetic fields in CRIT 2. The possibility to extend the model to the active region, where the ions are produces in this type of self-ionizing injection experiments, is discussed.

Brenning, N.; Swenson, C.; Kelley, M. C.; Providakes, J.; Torbert, R.

1990-01-01

440

Motion-compensated wavelet transform coding for color video compression  

NASA Astrophysics Data System (ADS)

A video compression scheme based on the wavelet representation and multi-resolution motion estimation (MRME) is presented in this paper. The multiresolution/multifrequency nature of the discrete wavelet transform lends itself as an ideal tool for representing images and video signals. Wavelet transform decomposes a video frame into a set of sub-frames with different resolutions corresponding to different frequency bands. These multiresolution frames also provide a representation of the global motion structure of the video signals at different scales. The motion activities for a particular sub-frame in different resolutions are hence highly correlated since they actually specify the same motion structure at different scales. In the MRMC described the Section 4, motion vectors in higher resolution are predicted by the motion vectors in the lower resolution, and are refined at each step. In particular, we propose a variable block-size MRMC scheme in which the size of a block is adapted to its level in the pyramid. This scheme not only considerably reduces the searching and matching time but also provides a meaningful characterization of the intrinsic motion structure. The variable-size MRMC approach also avoids the drawback of the constant-size MRMC in describing small object motion activities. After wavelet decomposition, each scaled wavelet tends to have different statistical properties. An adaptive truncation process similar to [CHEN 84] was implemented and a bit allocation scheme similar to that in the transform coding is examined by adapting to the local variance distribution in each scaled wavelet. Based on the wavelet representation, variable-size MRMC approach and a uniform quantization scheme, four variations of the proposed motion-compensated wavelet video compression system are presented in Section 6. It is shown that the motion-compensated wavelet transform coding approach out-performs the conventional transform coding scheme in terms of the signal-to- noise ratio as well as the subjective performance.

Zhang, Ya-Qin; Zafar, Sohail

1991-11-01

441

GEOS-5 Modeled Clouds  

NASA Video Gallery

This visualization shows clouds from a simulation using the Goddard Earth Observing System Model, Verison 5 (GEOS-5). The global atmospheric simulation covers a period from Feb 3, 2010 through Feb ...

442

NASA Cloud Albedo Animation  

NSDL National Science Digital Library

Clouds greatly affect the Earth's solar energy balance. This animation shows how they deflect a portion of solar energy influx from reaching our planet's surface and how they insulate to prevent a total loss of thermal radiance out into space.

Nasa

443

Cryptographic cloud storage framework  

E-print Network

The cloud prevents cheap and convenient ways to create shared remote repositories. One concern when creating systems that provide security is if the system will be able to remain secure when new attacks are developed. As ...

Falk, Matthew D

2013-01-01

444

Canonical active Brownian motion  

E-print Network

Active Brownian motion is the complex motion of active Brownian particles. They are active in the sense that they can transform their internal energy into energy of motion and thus create complex motion patterns. Theories of active Brownian motion so far imposed couplings between the internal energy and the kinetic energy of the system. We investigate how this idea can be naturally taken further to include also couplings to the potential energy, which finally leads to a general theory of canonical dissipative systems. Explicit analytical and numerical studies are done for the motion of one particle in harmonic external potentials. Apart from stationary solutions, we study non-equilibrium dynamics and show the existence of various bifurcation phenomena.

Alexander Gluck; Helmuth Huffel; Sasa Ilijic

2008-09-29

445

Studying Clouds and Climate  

NSDL National Science Digital Library

With three levels to choose from on each page - beginner, intermediate or advanced - this site provides information on the role of CMMAP in the exploration of clouds and climate.CMMAP stands for the Center for Multi-Scale Modeling of Atmospheric Processes. CMMAP scientists are working on a new way to model the climate that will help us to better understand the roles clouds play today and in the future as our climate changes.

2007-01-02

446

Marine Cloud Brightening  

SciTech Connect

The idea behind the marine cloud-brightening (MCB) geoengineering technique is that seeding marine stratocumulus clouds with copious quantities of roughly monodisperse sub-micrometre sea water particles might significantly enhance the cloud droplet number concentration, and thereby the cloud albedo and possibly longevity. This would produce a cooling, which general circulation model (GCM) computations suggest could - subject to satisfactory resolution of technical and scientific problems identified herein - have the capacity to balance global warming up to the carbon dioxide-doubling point. We describe herein an account of our recent research on a number of critical issues associated with MCB. This involves (i) GCM studies, which are our primary tools for evaluating globally the effectiveness of MCB, and assessing its climate impacts on rainfall amounts and distribution, and also polar sea-ice cover and thickness; (ii) high-resolution modelling of the effects of seeding on marine stratocumulus, which are required to understand the complex array of interacting processes involved in cloud brightening; (iii) microphysical modelling sensitivity studies, examining the influence of seeding amount, seedparticle salt-mass, air-mass characteristics, updraught speed and other parameters on cloud-albedo change; (iv) sea water spray-production techniques; (v) computational fluid dynamics studies of possible large-scale periodicities in Flettner rotors; and (vi) the planning of a three-stage limited-area field research experiment, with the primary objectives of technology testing and determining to what extent, if any, cloud albedo might be enhanced by seeding marine stratocumulus clouds on a spatial scale of around 100 km. We stress that there would be no justification for deployment of MCB unless it was clearly established that no significant adverse consequences would result. There would also need to be an international agreement firmly in favour of such action.

Latham, John; Bower, Keith; Choularton, Tom; Coe, H.; Connolly, P.; Cooper, Gary; Craft, Tim; Foster, Jack; Gadian, Alan; Galbraith, Lee; Iacovides, Hector; Johnston, David; Launder, Brian; Leslie, Brian; Meyer, John; Neukermans, Armand; Ormond, Bob; Parkes, Ben; Rasch, Philip J.; Rush, John; Salter, Stephen; Stevenson, Tom; Wang, Hailong; Wang, Qin; Wood, Robert

2012-09-07

447

Marine cloud brightening  

PubMed Central

The idea behind the marine cloud-brightening (MCB) geoengineering technique is that seeding marine stratocumulus clouds with copious quantities of roughly monodisperse sub-micrometre sea water particles might significantly enhance the cloud droplet number concentration, and thereby the cloud albedo and possibly longevity. This would produce a cooling, which general circulation model (GCM) computations suggest could—subject to satisfactory resolution of technical and scientific problems identified herein—have the capacity to balance global warming up to the carbon dioxide-doubling point. We describe herein an account of our recent research on a number of critical issues associated with MCB. This involves (i) GCM studies, which are our primary tools for evaluating globally the effectiveness of MCB, and assessing its climate impacts on rainfall amounts and distribution, and also polar sea-ice cover and thickness; (ii) high-resolution modelling of the effects of seeding on marine stratocumulus, which are required to understand the complex array of interacting processes involved in cloud brightening; (iii) microphysical modelling sensitivity studies, examining the influence of seeding amount, seed-particle salt-mass, air-mass characteristics, updraught speed and other parameters on cloud–albedo change; (iv) sea water spray-production techniques; (v) computational fluid dynamics studies of possible large-scale periodicities in Flettner rotors; and (vi) the planning of a three-stage limited-area field research experiment, with the primary objectives of technology testing and determining to what extent, if any, cloud albedo might be enhanced by seeding marine stratocumulus clouds on a spatial scale of around 100×100?km. We stress that there would be no justification for deployment of MCB unless it was clearly established that no significant adverse consequences would result. There would also need to be an international agreement firmly in favour of such action. PMID:22869798

Latham, John; Bower, Keith; Choularton, Tom; Coe, Hugh; Connolly, Paul; Cooper, Gary; Craft, Tim; Foster, Jack; Gadian, Alan; Galbraith, Lee; Iacovides, Hector; Johnston, David; Launder, Brian; Leslie, Brian; Meyer, John; Neukermans, Armand; Ormond, Bob; Parkes, Ben; Rasch, Phillip; Rush, John; Salter, Stephen; Stevenson, Tom; Wang, Hailong; Wang, Qin; Wood, Rob

2012-01-01

448

Marine cloud brightening.  

PubMed

The idea behind the marine cloud-brightening (MCB) geoengineering technique is that seeding marine stratocumulus clouds with copious quantities of roughly monodisperse sub-micrometre sea water particles might significantly enhance the cloud droplet number concentration, and thereby the cloud albedo and possibly longevity. This would produce a cooling, which general circulation model (GCM) computations suggest could-subject to satisfactory resolution of technical and scientific problems identified herein-have the capacity to balance global warming up to the carbon dioxide-doubling point. We describe herein an account of our recent research on a number of critical issues associated with MCB. This involves (i) GCM studies, which are our primary tools for evaluating globally the effectiveness of MCB, and assessing its climate impacts on rainfall amounts and distribution, and also polar sea-ice cover and thickness; (ii) high-resolution modelling of the effects of seeding on marine stratocumulus, which are required to understand the complex array of interacting processes involved in cloud brightening; (iii) microphysical modelling sensitivity studies, examining the influence of seeding amount, seed-particle salt-mass, air-mass characteristics, updraught speed and other parameters on cloud-albedo change; (iv) sea water spray-production techniques; (v) computational fluid dynamics studies of possible large-scale periodicities in Flettner rotors; and (vi) the planning of a three-stage limited-area field research experiment, with the primary objectives of technology testing and determining to what extent, if any, cloud albedo might be enhanced by seeding marine stratocumulus clouds on a spatial scale of around 100×100 km. We stress that there would be no justification for deployment of MCB unless it was clearly established that no signi