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1

Cloud Motion Vectors from MISR using Sub-pixel Enhancements  

NASA Technical Reports Server (NTRS)

The operational retrieval of height-resolved cloud motion vectors by the Multiangle Imaging SpectroRadiometer on the Terra satellite has been significantly improved by using sub-pixel approaches to co-registration and disparity assessment, and by imposing stronger quality control based on the agreement between independent forward and aft triplet retrievals. Analysis of the fore-aft differences indicates that CMVs pass the basic operational quality control 67% of the time, with rms differences - in speed of 2.4 m/s, in direction of 17 deg, and in height assignment of 290 m. The use of enhanced quality control thresholds reduces these rms values to 1.5 m/s, 17 deg and 165 m, respectively, at the cost of reduced coverage to 45%. Use of the enhanced thresholds also eliminates a tendency for the rms differences to increase with height. Comparison of CMVs from an earlier operational version that had slightly weaker quality control, with 6-hour forecast winds from the Global Modeling and Assimilation Office yielded very low bias values and an rms vector difference that ranged from 5 m/s for low clouds to 10 m/s for high clouds.

Davies, Roger; Horvath, Akos; Moroney, Catherine; Zhang, Banglin; Zhu, Yanqiu

2007-01-01

2

A novel approach for the extraction of cloud motion vectors using airglow imager measurements  

NASA Astrophysics Data System (ADS)

The paper explores the possibility of implementing an advanced photogrammetric technique, generally employed for satellite measurements, on airglow imager, a ground-based remote sensing instrument primarily used for upper atmospheric studies, measurements of clouds for the extraction of cloud motion vectors (CMVs). The major steps involved in the algorithm remain the same, including image processing for better visualization of target elements and noise removal, identification of target cloud, setting a proper search window for target cloud tracking, estimation of cloud height, and employing 2-D cross-correlation to estimate the CMVs. Nevertheless, the implementation strategy at each step differs from that of satellite, mainly to suit airglow imager measurements. For instance, climatology of horizontal winds at the measured site has been used to fix the search window for target cloud tracking. The cloud height is estimated very accurately, as required by the algorithm, using simultaneous collocated Lidar measurements. High-resolution, both in space and time (4 min), cloud imageries are employed to minimize the errors in retrieved CMVs. The derived winds are evaluated against MST radar-derived winds by considering it as a reference. A very good correspondence is seen between these two wind measurements, both showing similar wind variation. The agreement is also found to be good in the both zonal and meridional wind velocities with RMSEs < 2.4 m s-1. At the end, the strengths and limitations of the algorithm are discussed, with possible solutions, wherever required.

Satheesh Kumar, S.; Narayana Rao, T.; Taori, A.

2015-03-01

3

An improved algorithm for extracting atmospheric motion vectors in cloud-free region from FY-2E thermal infrared imagery  

NASA Astrophysics Data System (ADS)

Atmospheric motion vectors (AMV) in cloud-free region can not be obtained with current operational cloud-motion tracking and water-vapor channel algorithms. The motivation of this study is to introduce a supplementary algorithm in order to work out the low-level AMVs in the clear area with FY-2E long wave, window (10.3~11.5, 11.6~12.8 ?m) channel imagery. It has been shown that the weak signals indicating water vapor in "cloud-free region" can be extracted from FY-2E long wave infrared imagery and may be used as tracers for atmospheric motion vectors. The algorithm, named as Second Order difference method, has been raised in order to weaken the surface temperature interference to the weak signals of water vapor in "cloud-free region" by means of split window and temporal difference calculations. The results from theory analysis and cases study show that this method can make up for the wind data in regions lack of cloud but rich of water vapor and comparison between the wind vectors from this method and the NCEP reanalysis data shows a good consistency.

Wang, Zhenhui; Zhang, Qing; Tang, Min; Zhao, Hang; Yang, Lu; Zhan, Yizhe

2014-10-01

4

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

5

Bidirectional motion estimation via vector propagation  

Microsoft Academic Search

A low-complexity vector propagation (VP) algorithm is introduced for the estimation of bidirectional motion vector fields in image sequences. The proposed VP algorithm exploits the strong correlation between forward and backward motion vector fields in image sequences. The performance of the VP algorithm is compared to that of a bidirectional multiresolution block-matching (MRBM) motion estimation (ME) algorithm. Computer simulation results

Showbhik Kalra; Man-Nang Chong

1998-01-01

6

Compressed Domain Video Watermarking in Motion Vector  

Microsoft Academic Search

\\u000a In this paper, a novel watermarking scheme in the compressed domain is proposed for video copyright protection. The robust\\u000a watermark is embedded in motion vectors of the bitstream based on the relationships between one-pixel accuracy and half-pixel\\u000a accuracy motion vectors at the encoder. Watermark can be blindly extracted by parsing the properties of motion vectors at\\u000a the decoder. Simulation results

Hao-xian Wang; Yue-nan Li; Zhe-ming Lu; Sheng-he Sun

2005-01-01

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

Wind estimates from cloud motions - Results from Phases I, II and III of an in situ aircraft verification experiment  

NASA Technical Reports Server (NTRS)

An experiment is in progress to verify geostationary-satellite-derived cloud-motion wind estimates by in-situ aircraft wind-velocity measurements. One or more 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. To date the experiment has been conducted over tropical oceans and in the western Gulf of Mexico. A total of 60 h have been spent tracking some 40 tropical cumulus and five cirrus clouds. Results for tropical cumulus clouds indicate excellent agreement between the cloud motion and the wind at cloud base. The magnitude of the vector difference between the cloud motion and the cloud-base wind is less than 1.3 m/s for 67% of the cases with track lengths of 1 h or longer. Similarly, the vector differences between the cloud motion and the wind at sub-cloud (150 m), mid-cloud, and cloud-top levels are 1.5, 3.6 and 7.0 m/s, respectively. The cirrus cloud motions agreed best with the mean wind in the cloud layer with a vector difference of about 1.6 m/s.

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

1977-01-01

10

Wind estimates from cloud motions - Preliminary results from phases I, II and III of an in situ aircraft verification experiment  

NASA Technical Reports Server (NTRS)

The accuracy of wind estimates derived from cloud motion is under investigation. Aircraft measurements of the ambient wind field have been compared with simultaneous inertial navigation system descriptions of the extent and motion of 40 tropical cumulus and 5 cirrus clouds. Preliminary results indicate that cloud-motion wind estimates are sufficiently accurate to be used in sensitive divergence, vorticity, and vertical motion calculations. The magnitude of the vector difference between the cirrus cloud velocity and the mean wind of the cloud layer was found to be about 1.6 m/sec. The major source of error is thought to be in determination of the position of the cloud. In the case of cumulus clouds, the magnitude of the vector difference between the aircraft-measured cloud motion and the cloud-base wind is less than 1.3 m/sec.

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

1976-01-01

11

Generation method of normal vector from disordered point cloud  

Microsoft Academic Search

The normal vector generation from point cloud plays a vital role in 3D laser scanning data processing. An effective generation method of normal vector from disordered point cloud is proposed in the paper. In the proposed method, disordered point cloud is firstly projected on the 2D plane via cylindrical surface. After establishing the triangle grids, the unit normal vector of

Zheng De-hua; Xu Jia; Chen Ren-xi

2009-01-01

12

Retrieval algorithms for cloud motion from ground-based images  

NASA Astrophysics Data System (ADS)

We present the preliminary results of a project, focused on obtaining information about the velocity and direction of motion of air masses by means of ground-based measurements of visible cloud motion. This information can be used in short-term local weather forecast and is helpful in studies of the dynamics of the physical processes in clouds. We report the recent progress in the development of algorithms and tools for retrieving the three-dimensional field of vectors of velocity of cloud motion from time series of ground-based digital images. The visible motion of a cloud is the compound effect of the translational drift of the cloud as a whole with the velocity of the adjacent air masses, and of deformations due to the physical processes in the atmosphere. Because of the continuous changes of shape, extracting the translational component in the displacement of a cloud from a series of consecutive images is a highly non-trivial problem. Our approach consists in selecting a set of characteristic reference patterns of the cloud on the first image of the series, tracking them on the subsequent images, and evaluating this way the individual displacement of each reference pattern. Specific algorithms are being developed for the optimal choice of the reference patterns on the starting image and the recognition of these patterns on the subsequent images, depending on the type of the observed cloud. For clouds with low contrast or no edges, such as Stratus, Nimbostratus and Stratocumulus, implementations of the Optical Flow method are under development. For clouds with distinct contours, such as Cumulus and Altocumulus, the edges are decomposed into one-dimensional curvilinear patterns. To reduce the uncertainties, a multi-parametric model of the transformations of the cloud shape between images is defined next which, besides parallel transport, also involves dilatation, rotation, and possibly some local deformations. The parameters of the model are calculated from the individual displacements of the patterns by a least-square fit. What is obtained this way is a smooth approximation to the two-dimensional field of angular velocities of the cloud surface as seen from the observer's position. The three-dimensional vectors of velocity of the cloud are calculated by combining the results of multiple synchronous observations from distant sites. Prior to be put together, the data from different observers are corrected for optical distortion. We analyse the various sources of uncertainty of the calculated velocities of air masses, related to inaccuracy of the digital images, to identification errors in tracking the reference patterns on the series of images and to triangulation. We show that external telemetric information about the distance to the observed clouds may reduce the uncertainty of the results. We also discuss the optimal choice of the time interval between consecutive images as a compromise between the increasing requirements for computational power and the higher efficiency of the pattern recognition methods at shorter time intervals. The work is partially supported by the Bulgarian NFSR under contract NZ-1414/04.

Bakalova, Kalinka

13

Motion/imagery secure cloud enterprise architecture analysis  

NASA Astrophysics Data System (ADS)

Cloud computing with storage virtualization and new service-oriented architectures brings a new perspective to the aspect of a distributed motion imagery and persistent surveillance enterprise. Our existing research is focused mainly on content management, distributed analytics, WAN distributed cloud networking performance issues of cloud based technologies. The potential of leveraging cloud based technologies for hosting motion imagery, imagery and analytics workflows for DOD and security applications is relatively unexplored. This paper will examine technologies for managing, storing, processing and disseminating motion imagery and imagery within a distributed network environment. Finally, we propose areas for future research in the area of distributed cloud content management enterprises.

DeLay, John L.

2012-06-01

14

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

E-print Network

CHAPTER 14 Particles in Motion; Kepler's Laws 14.1. Vector Functions Vector notation is well-axis; that is X¡ 0¢£ RI. At 205 #12;Chapter 14 Particles in Motion; Kepler's Laws 206 time t the particle has

McKay, Benjamin

15

New adaptive pixel decimation for block motion vector estimation  

Microsoft Academic Search

A new adaptive technique based on pixel decimation for the estimation of motion vector is presented. In a traditional approach, a uniform pixel decimation is used. Since part of the pixels in each block do not enter into the matching criterion, this approach limits the accuracy of the motion vector. In this paper, we select the most representative pixels based

Yui-Lam Chan; Wan-Chi Siu

1996-01-01

16

Photogrammetry and photo interpretation applied to analyses of cloud cover, cloud type, and cloud motion  

NASA Technical Reports Server (NTRS)

A determination was made of the areal extent of terrain obscured by clouds and cloud shadows on a portion of an Apollo 9 photograph at the instant of exposure. This photogrammetrically determined area was then compared to the cloud coverage reported by surface weather observers at approximately the same time and location, as a check on result quality. Stereograms prepared from Apollo 9 vertical photographs, illustrating various percentages of cloud coverage, are presented to help provide a quantitative appreciation of the degradation of terrain photography by clouds and their attendant shadows. A scheme, developed for the U.S. Navy, utilizing pattern recognition techniques for determining cloud motion from sequences of satellite photographs, is summarized. Clouds, turbulence, haze, and solar altitude, four elements of our natural environment which affect aerial photographic missions, are each discussed in terms of their effects on imagery obtained by aerial photography. Data of a type useful to aerial photographic mission planners, expressing photographic ground coverage in terms of flying height above terrain and camera focal length, for a standard aerial photograph format, are provided. Two oblique orbital photographs taken during the Apollo 9 flight are shown, and photo-interpretations, discussing the cloud types imaged and certain visible geographical features, are provided.

Larsen, P. A.

1972-01-01

17

Winds of Neptune - Voyager observations of cloud motions  

NASA Technical Reports Server (NTRS)

Results are presented on measurements of cloud motions in the atmosphere of Neptune, using high temporal and spatial resolution images acquired from Voyager cameras. The results obtained on cloud motions reveal a wide range of atmospheric periods between 12 and 21 hours, consistent with previous observations. The new results expand the latitudinal coverage, improve the determination of streak motions (especially near 30 deg N), and add statistical weight to altitudes already covered by previous measurements.

Limaye, Sanjay S.; Sromovsky, Lawrence A.

1991-01-01

18

Traffic congestion classification using motion vector statistical features  

NASA Astrophysics Data System (ADS)

Due to the rapid increase in population, one of the major problems faced by the urban areas is traffic congestion. In this paper we propose a method for classifying highway traffic congestion using motion vector statistical properties. Motion vectors are estimated using pyramidal Kanada-Lucas-Tomasi (KLT) tracker algorithm. Then motion vector features are extracted and are used to classify the traffic patterns into three categories: light, medium and heavy. Classification using neural network, on publicly available dataset, shows an accuracy of 95.28%, with robustness to environmental conditions such as variable luminance. Our system provides a more accurate solution to the problem as compared to the systems previously proposed.

Riaz, Amina; Khan, Shoab A.

2013-12-01

19

Volcanic explosion clouds - Density, temperature, and particle content estimates from cloud motion  

NASA Technical Reports Server (NTRS)

Photographic records of 10 vulcanian eruption clouds produced during the 1978 eruption of Fuego Volcano in Guatemala have been analyzed to determine cloud velocity and acceleration at successive stages of expansion. Cloud motion is controlled by air drag (dominant during early, high-speed motion) and buoyancy (dominant during late motion when the cloud is convecting slowly). Cloud densities in the range 0.6 to 1.2 times that of the surrounding atmosphere were obtained by fitting equations of motion for two common cloud shapes (spheres and vertical cylinders) to the observed motions. Analysis of the heat budget of a cloud permits an estimate of cloud temperature and particle weight fraction to be made from the density. Model results suggest that clouds generally reached temperatures within 10 K of that of the surrounding air within 10 seconds of formation and that dense particle weight fractions were less than 2% by this time. The maximum sizes of dense particles supported by motion in the convecting clouds range from 140 to 1700 microns.

Wilson, L.; Self, S.

1980-01-01

20

Clouds on Neptune: Motions, Evolution, and Structure  

NASA Technical Reports Server (NTRS)

The aims of our original proposal were these: (1) improving measurements of Neptune's circulation, (2) understanding the spatial distribution of cloud features, (3) discovery of new cloud features and understanding their evolutionary process, (4) understanding the vertical structure of zonal cloud patterns, (5) defining the structure of discrete cloud features, and (6) defining the near IR albedo and light curve of Triton. Towards these aims we proposed analysis of existing 1996 groundbased NSFCAM/IRTF observations and nearly simultaneous WFPC2 observations from the Hubble Space Telescope. We also proposed to acquire new observations from both HST and the IRTF.

Sromovsky, Larry A.; Morgan, Thomas (Technical Monitor)

2001-01-01

21

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

E-print Network

COMPARISON OF ATMOSPHERIC MOTION VECTORS AND DENSE VECTOR FIELDS CALCULATED FROM MSG IMAGES Andr images [Corpetti et al., 2002]. This method has been applied on consecutive MSG images in the thermal at subsatellite point, 15 min standard time interval, 12 channels for MSG satellites). The progress on tracking

Szantai Andr

22

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

23

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

24

A study on the motion vector prediction schemes for AVS  

NASA Astrophysics Data System (ADS)

The motion vector prediction (MVP) is an important part of video coding. There have been numerous workings on the topic done by researchers before. In this paper, a continue study on MVP of video coding based on the workings of predecessors is made. The video sequences with various motion characteristics are further investigated. The characteristics of motion vectors of objects in video scenes are discussed briefly. Then, summarizing these characteristics, two MVP schemes for a new coding standard, Audio and Video Standard (AVS), are proposed. In these schemes, current block"s MV can be predicted based on statistical correlation of MVs of spatial contiguous neighbor blocks. A correlation criterion is employed to measure how correlated between two MVs. With the correlation criterion, the correlated MVs of neighbor blocks are determined. Then, the predicted MV of current block can be obtained with some simple algebraic operations on determined MVs. The two proposed schemes, as the alternative ones of median predictor, are suitable for different video sequences with different motion characteristics, respectively. The experimental results show that the bit rate savings are achieved with these schemes in most of typical video sequences, compared with the median predictor implemented in AVS.

Qi, Honggang; Gao, Wen; Ma, Siwei; Zhao, Debin

2005-07-01

25

Rapid ray motions in barium plasma clouds and auroras  

SciTech Connect

Barium plasma clouds released at high latitudes characteristically become striated with many field-aligned rays. The rays which often resemble auroral features usually drift as a whole with the E [times] B/B[sup 2] drift of the cloud and alter position only slowly (order or tens of seconds). On two evenings in 1968, in releases from Andoya, Norway, anomalous field-aligned brightenings or emission enhancements of up to 3X were observed to move rapidly (10-20 km/s) through three different Ba[sup +] clouds. Similar effects were observed in Ba[sup +] clouds released from rockets launched from Poker Flat, Alaska: On March 21, 1973, in two Ba thermite releases and on March 22, 1980, in the Ba-shaped charge experiment Miss Peggy.' On these occasions, auroras on or near the Ba[sup +] L shell, also exhibited active rapid ray motions. This leads to the assumption that the two phenomena are related and the expectation that an explanation of the rapid ray motions in the Ba[sup +] clouds would lead to a better understanding of the physics of auroral ray motions and the auroral ionosphere. Seven possible mechanisms to produce the observed moving emission enhancements are discussed. Direct motion of an isolated Ba[sup +] ray past the other rays by E [times] B/B[sup 2] motion seems very unlikely due to the observed variations in the enhancements and the large E field required (> 500 mV/m). Compressional waves do not seem to be of sufficient amplitude or velocity. Absorption or radiation of Doppler shifted Ba[sup +] emissions by ions gyrating or moving at a few kilometers per second seems to be the most promising mechanism for producing the enhancements. The observations provide compelling 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. The affected regions have dimensions of order a few kilometers across B and move eastward at 10-20 km/s. 36 refs., 10 figs., 1 tab.

Wescott, E.M.; Hallinan, T.J.; Stenbaek-Nielsen, H.C.; Swift, D.W.; Wallis, D.D. (Univ. of Alaska, Fairbanks (United States))

1993-03-01

26

Spatial Motion of The Magellanic Clouds: Tidal Models Ruled Out?  

NASA Astrophysics Data System (ADS)

Recently, Kallivayalil et al. derived new values of the proper motion for the Large and Small Magellanic Clouds (LMC and SMC, respectively). The spatial velocities of both Clouds are unexpectedly higher than their previous values resulting from agreement between the available theoretical models of the Magellanic System and the observations of neutral hydrogen (H I) associated with the LMC and the SMC. Such proper motion estimates are likely to be at odds with the scenarios for creation of the large-scale structures in the Magellanic System suggested so far. We investigated this hypothesis for the pure tidal models, as they were the first ones devised to explain the evolution of the Magellanic System, and the tidal stripping is intrinsically involved in every model assuming the gravitational interaction. The parameter space for the Milky Way (MW)-LMC-SMC interaction was analyzed by a robust search algorithm (genetic algorithm) combined with a fast, restricted N-body model of the interaction. Our method extended the known variety of evolutionary scenarios satisfying the observed kinematics and morphology of the Magellanic large-scale structures. Nevertheless, assuming the tidal interaction, no satisfactory reproduction of the H I data available for the Magellanic Clouds was achieved with the new proper motions. We conclude that for the proper motion data by Kallivayalil et al., within their 1? errors, the dynamical evolution of the Magellanic System with the currently accepted total mass of the MW cannot be explained in the framework of pure tidal models. The optimal value for the western component of the LMC proper motion was found to be ?W lmcgsim -1.3 mas yr-1 in case of tidal models. It corresponds to the reduction of the Kallivayalil et al. value for ?W lmc by ? 40% in its magnitude.

R?i?ka, Adam; Theis, Christian; Palou, Jan

2009-02-01

27

Predictive motion vector field adaptive search technique (PMVFAST): enhancing block-based motion estimation  

NASA Astrophysics Data System (ADS)

Motion Estimation (ME) is an important part of most video encoding systems, since it could significantly affect the output quality of an encoded sequence. Unfortunately this feature requires a significant part of the encoding time especially when using the straightforward Full Search (FS) algorithm. In this paper a new algorithm is presented named as the Predictive Motion Vector Field Adaptive Search Technique (PMVFAST), which significantly outperforms most if not all other previously proposed algorithms in terms of Speed Up performance. In addition, the output quality of the encoded sequence in terms of PSNR is similar to that of the Full Search algorithm. The proposed algorithm relies mainly upon very robust and reliable predictive techniques and early termination criteria, which make use of parameters adapted to the local characteristics of a frame. Our experiments verify the superiority of the proposed algorithm, not only versus several other well-known fast algorithms, but also in many cases versus even the Full Search algorithm.

Tourapis, Alexis M.; Au, Oscar C. L.; Liou, Ming L.

2000-12-01

28

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

29

Proper Motions of the Large Magellanic Cloud and Small Magellanic Cloud: Re-Analysis of Hubble Space Telescope Data  

Microsoft Academic Search

Kallivayalil et al. have used the Hubble Space Telescope to measure proper motions of the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) using images in 21 and five fields, respectively, all centered on known quasi-stellar objects (QSOs). These results are more precise than previous measurements, but have surprising and important physical implications: for example, the LMC and SMC

Slawomir Piatek; Carlton Pryor; Edward W. Olszewski

2008-01-01

30

Improvement of image deblurring for opto-electronic joint transform correlator under projective motion vector estimation  

NASA Astrophysics Data System (ADS)

In this paper we propose an efficient algorithm to improve the performance of image deblurring based on opto-electronic joint transform correlator (JTC) that is capable of detecting the motion vector of a space camera. Firstly, the motion vector obtained from JTC is divided into many sub-motion vectors according to the projective motion path, which represents the degraded image as an integration of the clear scene under a sequence of planar projective transforms. Secondly, these sub-motion vectors are incorporated into the projective motion Richardson-Lucy (RL) algorithm to improve deblurred results. The simulation results demonstrate the effectiveness of the algorithm and the influence of noise on the algorithm performance is also statically analyzed.

Xiao, Xiao; Zhao, Hui; Zhang, Yang

2014-06-01

31

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

2015-01-01

32

An adaptive mode-driven spatiotemporal motion vector prediction for wavelet video coding  

NASA Astrophysics Data System (ADS)

The three-dimensional subband/wavelet codecs use 5/3 filters rather than Haar filters for the motion compensation temporal filtering (MCTF) to improve the coding gain. In order to curb the increased motion vector rate, an adaptive motion mode driven spatiotemporal motion vector prediction (AMDST-MVP) scheme is proposed. First, by making use of the direction histograms of four motion vector fields resulting from the initial spatial motion vector prediction (SMVP), the motion mode of the current GOP is determined according to whether the fast or complex motion exists in the current GOP. Then the GOP-level MVP scheme is thereby determined by either the S-MVP or the AMDST-MVP, namely, AMDST-MVP is the combination of S-MVP and temporal-MVP (T-MVP). If the latter is adopted, the motion vector difference (MVD) between the neighboring MV fields and the S-MVP resulting MV of the current block is employed to decide whether or not the MV of co-located block in the previous frame is used for prediction the current block. Experimental results show that AMDST-MVP not only can improve the coding efficiency but also reduce the number of computation complexity.

Zhao, Fan; Liu, Guizhong; Qi, Yong

2010-07-01

33

Clouds  

NSDL National Science Digital Library

First, the Project Atmosphere Canada offers a module to educate primary and secondary students about cloud formation and characteristics (1). The website outlines key points and offers a more in-depth discussion of water vapor, cloud formation, convection, air motion, severe weather, and more. The second website, by Scholastic, supplies many pdf documents of activities and lesson plans for all types of weather phenomena including clouds (2). Students can learn about condensation, discover what makes up a cloud, and find a key identifying the cloud types. Next, USA Today offers an online tutorial of the differing characteristics of clouds (3). Users can learn about Mammatus clouds, contrails, cloud seeding, and other cloud-related topics. At the fourth website, visitors can view meteorologist Dan Satterfield's amazing cloud photographs (4). Educators may find useful materials to supplement their lectures. Next, NASA's Climate and Radiation Branch furnishes "information on the fantastic variety of cloud forms and structures, and their implications for climate" (5). While the website is still being constructed, users can find useful information about the Bounded Cascades Fractal Cloud model, animations, and definitions of inhomogeneous cloud terminology. The sixth website, created by the National Center for Atmospheric Research and the University Corporation for Atmospheric Research, addresses how clouds impact our lives, how they cause chaos, and how they form (6). The enlightening descriptions are packed with colorful images and short quizzes. Next, The Australian Government's Bureau of Meteorology describes the useful of clouds as an indicator of weather conditions (7). After learning how moist air can form clouds, individuals can view images of the ten most common cloud types. Lastly, Enchanted Learning offers a table of the cloud types with their abbreviation, appearance, composition, and altitude along with explanations of cloud formation and the atmosphere (8). Educators can find simple activities dealing with cloud types and the water cycle.

34

Landsat 7 Reveals Large-scale Fractal Motion of Clouds  

NASA Technical Reports Server (NTRS)

This Landsat 7 image of clouds off the Chilean coast near the Juan Fernandez Islands (also known as the Robinson Crusoe Islands) on September 15, 1999, shows a unique pattern called a 'von Karman vortex street.' This pattern has long been studied in the laboratory, where the vortices are created by oil flowing past a cylindrical obstacle, making a string of vortices only several tens of centimeters long. Study of this classic 'flow past a circular cylinder' has been very important in the understanding of laminar and turbulent fluid flow that controls a wide variety of phenomena, from the lift under an aircraft wing to Earth's weather. Here, the cylinder is replaced by Alejandro Selkirk Island (named after the true 'Robinson Crusoe,' who was stranded here for many months in the early 1700s). The island is about 1.5 km in diameter, and rises 1.6 km into a layer of marine stratocumulus clouds. This type of cloud is important for its strong cooling of the Earth's surface, partially counteracting the Greenhouse warming. An extended, steady equatorward wind creates vortices with clockwise flow off the eastern edge and counterclockwise flow off the western edge of the island. The vortices grow as they advect hundreds of kilometers downwind, making a street 10,000 times longer than those made in the laboratory. Observing the same phenomenon extended over such a wide range of sizes dramatizes the 'fractal' nature of atmospheric convection and clouds. Fractals are characteristic of fluid flow and other dynamic systems that exhibit 'chaotic' motions. Both clockwise and counter-clockwise vortices are generated by flow around the island. As the flow separates from the island's leeward (away from the source of the wind) side, the vortices 'swallow' some of the clear air over the island. (Much of the island air is cloudless due to a local 'land breeze' circulation set up by the larger heat capacity of the waters surrounding the island.) The 'swallowed' gulps of clear island air get carried along within the vortices, but these are soon mixed into the surrounding clouds. Landsat is unique in its ability to image both the small-scale eddies that mix clear and cloudy air, down to the 30 meter pixel size of Landsat, but also having a wide enough field-of-view, 180 km, to reveal the connection of the turbulence to large-scale flows such as the subtropical oceanic gyres. Landsat 7, with its new onboard digital recorder, has extended this capability away from the few Landsat ground stations to remote areas such as Alejandro Island, and thus is gradually providing a global dynamic picture of evolving human-scale phenomena. (For more details on von Karman vortices, refer to http://climate.gsfc.nasa.gov/cahalan) Image and caption courtesy Bob Cahalan, NASA GSFC

2002-01-01

35

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 (72.62E, 10.57N) 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

36

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

37

Polarization Catastrophe Contributing to Rotation and Tornadic Motion in Cumulo-Nimbus Clouds  

NASA Astrophysics Data System (ADS)

When the concentration of sub-micron ice particles in a cloud exceeds 2.5E21 per cubic cm, divided by the squared average number of water molecules per crystallite, the polarization catastrophe occurs. Then all ice crystallites nucleated on aerosol dust particles align their dipole moments in the same direction, and a large polarization vector field is generated in the cloud. Often this vector field has a radial component directed away from the vertical axis of the cloud. It is induced by the pre-existing electric field caused by the charged screening layers at the cloud surface, the screening shell of the cloud. The presence of a vertical component of the magnetic field of the earth creates a density of linear momentum G=DxB in the azimuthal direction, where D=eE+P is the electric displacement vector and e is the vacuum permittivity. This linear momentum density yields an angular momentum density vector directed upward in the nordic hemisphere, if the polarization vector points away from the vertical axis of the cloud. When the cloud becomes colloidally unstable, the crystallites grow beyond the size limit at which they still could carry a large ferroelectric saturation dipole moment, and the polarization vector quickly disappears. Then the cloud begins to rotate with an angular momentum that has the same direction. Due to the large average number of water molecules in a crystallite, the polarization catastrophe (PC) is present in practically all clouds, and is compensated by masking charges. In cumulo-nimbus (thunder-) clouds the collapse of the PC is rapid, and the masking charges lead to lightning, and in the upper atmosphere also to sprites, elves, and blue jets. In stratus clouds, however, the collapse is slow, and only leads to reverse polarity in dissipating clouds (minus on the bottom), as compared with growing clouds (plus on the bottom, because of the excess polarization charge). References: P.H. Handel: "Polarization Catastrophe Theory of Cloud Electricity", J. Geophysical Research 90, 5857-5863 (1985). P.H. Handel and P.B. James: "Polarization Catastrophe Model of Static Electrification and Spokes in the B-Ring of Saturn", Geophys. Res. Lett. 10, 1-4 (1983).

Handel, P. H.

2007-05-01

38

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

39

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.

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

Motion clouds: model-based stimulus synthesis of natural-like random textures for the study of motion perception.  

PubMed

Choosing an appropriate set of stimuli is essential to characterize the response of a sensory system to a particular functional dimension, such as the eye movement following the motion of a visual scene. Here, we describe a framework to generate random texture movies with controlled information content, i.e., Motion Clouds. These stimuli are defined using a generative model that is based on controlled experimental parametrization. We show that Motion Clouds correspond to dense mixing of localized moving gratings with random positions. Their global envelope is similar to natural-like stimulation with an approximate full-field translation corresponding to a retinal slip. We describe the construction of these stimuli mathematically and propose an open-source Python-based implementation. Examples of the use of this framework are shown. We also propose extensions to other modalities such as color vision, touch, and audition. PMID:22423003

Leon, Paula Sanz; Vanzetta, Ivo; Masson, Guillaume S; Perrinet, Laurent U

2012-06-01

42

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

43

PROPER-MOTION STUDY OF THE MAGELLANIC CLOUDS USING SPM MATERIAL  

SciTech Connect

Absolute proper motions are determined for stars and galaxies to V = 17.5 over a 450 deg{sup 2} area that encloses both Magellanic Clouds. The proper motions are based on photographic and CCD observations of the Yale/San Juan Southern Proper Motion program, which span a baseline of 40 years. Multiple, local relative proper-motion measures are 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 of 1.4 million objects is used to derive the mean absolute proper motions of the Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC); ({mu}{sub {alpha}}cos {delta}, {mu}{sub {delta}}){sub LMC} = (1.89, + 0.39) {+-} (0.27, 0.27) masyr{sup -1} and ({mu}{sub {alpha}}cos {delta}, {mu}{sub {delta}}){sub SMC} = (0.98, - 1.01) {+-} (0.30, 0.29) masyr{sup -1}. These mean motions are based on best-measured samples of 3822 LMC stars and 964 SMC stars. A dominant portion (0.25 mas yr{sup -1}) of the formal errors is due to the estimated uncertainty in the inertial system of the Hipparcos Catalog stars used to anchor the bright end of our proper motion measures. A more precise determination can be made for the proper motion of the SMC relative to the LMC; ({mu}{sub {alpha}cos {delta}}, {mu}{sub {delta}}){sub SMC-LMC} = (-0.91, - 1.49) {+-} (0.16, 0.15) masyr{sup -1}. This differential value is combined with measurements of the proper motion of the LMC taken from the literature to produce new absolute proper-motion determinations for the SMC, as well as an estimate of the total velocity difference of the two clouds to within {+-}54 km s{sup -1}. The absolute proper-motion results are consistent with the Clouds' orbits being marginally bound to the Milky Way, albeit on an elongated orbit. The inferred relative velocity between the Clouds places them near their binding energy limit and, thus, no definitive conclusion can be made as to whether or not the Clouds are bound to one another.

Vieira, Katherine; Girard, Terrence M.; Van Altena, William F.; Casetti-Dinescu, Dana I.; Korchagin, Vladimir I.; Herrera, David, E-mail: kvieira@cida.v, E-mail: terry.girard@yale.ed, E-mail: william.vanaltena@yale.ed [Astronomy Department, Yale University, P.O. Box 208101, New Haven, CT 06520 (United States)

2010-12-15

44

Cloud field classification based upon high spatial resolution textural features. 2. Simplified vector approaches  

NASA Astrophysics Data System (ADS)

The huge volume of data being collected in global climate studies makes it necessary to develop efficient automatic data analysis methods. While most cloud classification algorithms are based upon multispectral signatures, there is growing use of textural features. The results given in Part 1 of this study demonstrate that textural features computed from the Gray Level Cooccurrence Matrix (GLCM) approach produce high cloud classification accuracies. The present study compares classification results derived from two vector approaches, Sum and Difference Histogram (SADH) and Gray Level Difference Vector (GLDV), with those from the GLCM approach. It is found that the SADH approach produces accuracies equivalent to those obtained using GLCM, but with greater ability to resolve error clusters; also, there is a 30% savings in run time and a 50% savings in storage requirements. The GLDV approach suffers a slight degradation in classification accuracy but has a 40% savings in run time and an 87% savings in storage requirements. Textural features are not highly sensitive to moderate variations in cloud threshold selection. However, the whole cloud, rather than only the brightest portions of the cloud, produce the highest classification accuracies. A very important result is that spatial information content and classification accuracy are preserved even at lower radiometric resolutions with effective gray levels of 16. means that significantly low resolution digitized versions of satellite imagery retain essentially the full spatial information content of the original digital data. Substitution of digitized imagery can significantly reduce the expense of many remote sensing studies.

Chen, D. W.; Sengupta, S. K.; Welch, R. M.

1989-10-01

45

Interactions between spacecraft motions and the atmospheric cloud physics laboratory experiments  

NASA Technical Reports Server (NTRS)

In evaluating the effects of spacecraft motions on atmospheric cloud physics laboratory (ACPL) experimentation, the motions of concern are those which will result in the movement of the fluid or cloud particles within the experiment chambers. Of the various vehicle motions and residual forces which can and will occur, three types appear most likely to damage the experimental results: non-steady rotations through a large angle, long-duration accelerations in a constant direction, and vibrations. During the ACPL ice crystal growth experiments, the crystals are suspended near the end of a long fiber (20 cm long by 200 micron diameter) of glass or similar material. Small vibrations of the supported end of the fiber could cause extensive motions of the ice crystal, if care is not taken to avoid this problem.

Anderson, B. J.

1981-01-01

46

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 Andr

47

Wave Motions In Molecular Clouds: Results in Two Dimensions  

E-print Network

We study the linear evolution of small perturbations in self-gravitating fluid systems in two spatial dimensions; we consider both cylindrical and cartesian (i.e., slab) geometries. The treatment is general, but the application is to molecular clouds. We consider a class of equations of state which heuristically take into account the presence of turbulence; in particular, we consider equations of state which are {\\it softer} than isothermal. We take the unperturbed cloud configuration to be in hydrostatic equilibrium. We find a class of wave solutions which propagate along a pressure supported cylinder (or slab) and have finite (trapped) spatial distributions in the direction perpendicular to the direction of propagation. Our results indicate that the dispersion relations for these two dimensional waves have similar forms for the two geometries considered here. Both cases possess a regime of instability and a fastest growing mode. We also find the (perpendicular) form of the perturbations for a wide range of wavelengths. Finally, we discuss the implications of our results for star formation and molecular clouds. The mass scales set by instabilities in both molecular cloud filaments and sheets are generally much larger than the masses of stars. However, these instabilities can determine the length scales for the initial conditions for protostellar collapse.

Curtis S. Gehman; Fred C. Adams; Marco Fatuzzo; Richard Watkins

1995-08-09

48

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

49

Segmentation and Recognition using Structure from Motion Point Clouds  

E-print Network

Research Cambridge 3 University of Cambridge (now with MirriAd Ltd.) 4 University of Cambridge Abstract. We motivate five simple cues designed to model specific patterns of motion and 3D world structure that vary to find their position in world space and their relationship to the moving camera path. We suggest five

Martin, Ralph R.

50

Motion and texture rate-allocation for prediction-based scalable motion-vector coding  

Microsoft Academic Search

Modern video coding applications require data transmission over variable-bandwidth wired and wireless network channels to a variety of terminals, possibly having different screen resolutions and available computing power. Scalable video coding technology is needed to optimally support these applications. Recently proposed wavelet-based video codecs employing spatial-domain motion-compensated temporal filtering (SDMCTF) provide quality, resolution and frame-rate scalability while delivering compression performance

Joeri Barbarien; Adrian Munteanu; Fabio Verdicchio; Yiannis Andreopoulos; Jan Cornelis; Peter Schelkens

2005-01-01

51

Motion Vector Field Estimation Using Brightness Constancy Assumption and Epipolar Geometry Constraint  

NASA Astrophysics Data System (ADS)

In most Photogrammetry and computer vision tasks, finding the corresponding points among images is required. Among many, the Lucas-Kanade optical flow estimation has been employed for tracking interest points as well as motion vector field estimation. This paper uses the IMU measurements to reconstruct the epipolar geometry and it integrates the epipolar geometry constraint with the brightness constancy assumption in the Lucas-Kanade method. The proposed method has been tested using the KITTI dataset. The results show the improvement in motion vector field estimation in comparison to the Lucas-Kanade optical flow estimation. The same approach has been used in the KLT tracker and it has been shown that using epipolar geometry constraint can improve the KLT tracker. It is recommended that the epipolar geometry constraint is used in advanced variational optical flow estimation methods.

Hosseinyalamdary, S.; Yilmaz, A.

2014-11-01

52

The Systemic Proper Motions of the Magellanic Clouds and their Orbits around the Milky Way  

NASA Astrophysics Data System (ADS)

The interaction between the Large and Small Magellanic Clouds (LMC & SMC) and the Milky Way (MW) is thought to have played an important role in the dynamical evolution of the MW's outer parts. The Clouds probe the potential of the MW dark halo in places where other kinematic tracers are unavailable and thus the MW-MC system has been a major subject of study. In particular, the global dynamics of both Clouds need to be well prescribed before other evolutionary features of the system can be understood. The radial velocities of the clouds are more readily determined than the transverse velocities, which can only be estimated using proper motions. We undertook a project using two epochs of HST/ACS data to determine the systemic proper motions of the Clouds. The Magellanic Cloud fields are centered on background QSOs that were discovered from their optical variability in the MACHO database (Geha et al. 2003). The final sample consists of 21 QSOs behind the LMC and 5 behind the SMC, distributed homogeneously behind the central few degrees of both Clouds. With a 2 year baseline and the use of the High Resolution Camera, we have determined the proper motion of the LMC to better than 5 \\ ? N = 0.44 0.05 mas/yr (Kallivayalil et al. 2005). This is the most accurate proper motion measurement for any MW satellite thus far. We will present this measurement, as well as our results for the SMC, and the conclusions we can draw about the Clouds' orbits around the MW. Our study shows that ground-based work on finding QSOs can be combined with high resolution HST data to get good measurements in a relatively short amount of time. When combined with HI data from the Magellanic Stream our measurements should provide new constraints on both the mass distribution of the Galactic Halo and models of the Stream. Support for this work was provided by NASA through grant numbers GO-09462 and GO-10130 from STScI. KHC's work was performed under the auspices of the U.S. DOE, NNSA, by the Univ. of California, LLNL under contract No. W-7405-Eng-48.

Kallivayalil, N.; van der Marel, R. P.; Alcock, C.; Axelrod, T.; Cook, K. H.; Drake, A. J.; Geha, M.

2005-12-01

53

Cloud field classification based upon high spatial resolution textural features. II - Simplified vector approaches  

NASA Technical Reports Server (NTRS)

This paper compares the results of cloud-field classification derived from two simplified vector approaches, the Sum and Difference Histogram (SADH) and the Gray Level Difference Vector (GLDV), with the results produced by the Gray Level Cooccurrence Matrix (GLCM) approach described by Welch et al. (1988). It is shown that the SADH method produces accuracies equivalent to those obtained using the GLCM method, while the GLDV method fails to resolve error clusters. Compared to the GLCM method, the SADH method leads to a 31 percent saving in run time and a 50 percent saving in storage requirements, while the GLVD approach leads to a 40 percent saving in run time and an 87 percent saving in storage requirements.

Chen, D. W.; Sengupta, S. K.; Welch, R. M.

1989-01-01

54

Retrieving the Velocity of Motion of Air Masses from Digital Images of Clouds  

NASA Astrophysics Data System (ADS)

An interdisciplinary project, aimed at developing tools for the determination of physical characteristics of the atmosphere by means of ground-based digital imaging in the visible range is in progress. Determining the 3-dimensional field of velocities of motion of the air masses from digital images of clouds is among the central tasks. The approach consists in identifying patterns of the cloud structure with characteristic shape and measuring their angular displacement by tracking them in series of consecutive digital images, taken at optimal time intervals. The geometrical mapping of the cloud of an image onto the following image (including translation, rotation, dilatation and additional small irregular deformations) is parameterized, and the numerical values of the parameters are computed by minimizing the sum over pixels of the squared deviation of the brightness, weighed with factors accounting for the representativeness of the group of pixels, and with constrains on the parameters describing irregular deformations.

Bakalova, Kalinka; Bakalov, Dimitar

2007-04-01

55

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

56

Intraseasonal behavior of clouds, temperature, and motion in the tropics  

NASA Technical Reports Server (NTRS)

The spectral character of tropical convection is investigated in an 11-yr record of outgoing longwave radiation from the Advanced Very High Resolution Radiometer (AVHRR) 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 wavenumbers 1-3 and eastward periods of 35-95 days. Significantly broader than the dynamical signal of the Madden-Julian oscillation (MJO), this quasi-discrete convective signal is associatd with a large-scale anomaly that propagates across and modulates time mean or 'climatological convection' over the equatorial Indian Ocean and western Pacific. Outside that region the convective signal is small, even though, under amplified conditions, coherence can be found east of the date line and in the subtropics. Having a zonal scale of approximately wavenumber 2, anomalous convection propagates eastward at some 5 m/s and suppresses as well as reinforces climatological in the eastern hemisphere. The convective signal amplifies to a seasonal maximum near vernal equinox and, to a weaker degree, again near autumnal equinox, when climatological convection and warm sea surface temperature (SST) cross the equator. Contemporaneous records of motion from European Center for medium-Range Weather Forecasts (ECMWF) analyses and tropospheric-mean temperature from Microwave Sounding Unit reveal an anomalous component of the tropical circulation that coexists with the convective signal and embodies many of the established properties of the MJO. In the eastern hemisphere, subtropical Rossby gyres and zonal Kelvin structure along the equator flank the convective anomaly as it tracks eastward, giving the anomalous circulation to form of a 'forced response.' In the western hemisphere, the dynamical signal is composed chiefly of wavenumber-1 Kelvin structure, which as the form of a 'propagating response' that is excited in and radiates away from anomalous convection at some 10 m/s. Kelvin structure comprising the propagating response appears in 850-mb and 200-mb zonal winds even when the convective signal is absent, albeit with much smaller amplitude. In contrast, the signal in 1000-mb convergence appears only when accompanied by anomalous convection, which suggests that convergence in the boundary layer is instrumental in achieving strong interaction with the convective pattern.

Salby, Murry L.; Hendon, Harry H.

1994-01-01

57

Cloud Radio-Multistatic Radar: Joint Optimization of Code Vector and Backhaul Quantization  

NASA Astrophysics Data System (ADS)

A multistatic radar set-up is considered in which distributed receive antennas are connected to a Fusion Center (FC) via limited-capacity backhaul links. Similar to cloud radio access networks in communications, the receive antennas quantize the received baseband signal before transmitting it to the FC. The problem of maximizing the detection performance at the FC jointly over the code vector used by the transmitting antenna and over the statistics of the noise introduced by backhaul quantization is investigated. Specifically, adopting the information-theoretic criterion of the Bhattacharyya distance to evaluate the detection performance at the FC and information-theoretic measures of the quantization rate, the problem at hand is addressed via a Block Coordinate Descent (BCD) method coupled with Majorization-Minimization (MM). Numerical results demonstrate the advantages of the proposed joint optimization approach over more conventional solutions that perform separate optimization.

Khalili, Shahrouz; Simeone, Osvaldo; Haimovich, Alexander M.

2015-04-01

58

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

59

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

60

Cloud shadow 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 is presented that measures cloud shadow motion vectors to estimate power plant ramp rates and provide short-term solar irradiance forecasts. The cloud shadow speed sensor (CSS) is constructed using an array of luminance sensors and a high-speed data acquisition system 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 shadow 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 shadow directions and speeds 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.

2014-06-01

61

VizieR Online Data Catalog: Lupus clouds proper motion study with VO (Lopez Marti+, 2011)  

NASA Astrophysics Data System (ADS)

The Lupus dark cloud complex is a well-known, nearby low-mass star-forming region, probably associated with the Gould Belt. In recent years, the number of stellar and substellar Lupus candidate members has been remarkably increased thanks to the Cores to Disks (c2d) Spitzer Legacy Program and other studies. However, most of these newly discovered objects still lack confirmation that they belong to the dark clouds. By using available kinematical information, we test the membership of the new Lupus candidate members proposed by the c2d program and by a complementary optical survey. We also investigate the relationship between the proper motions and other properties of the objects, in order to get some clues about their formation and early evolution. We compiled a list of members and possible members of Lupus 1, 3, and 4, together with all available information on their spectral types, disks, and physical parameters. Using Virtual Observatory tools, we cross-matched this list with the available astrometric catalogues to get proper motions for our objects. Our final sample contains sources with magnitudes I<16mag and estimated masses >~0.1M?. (5 data files).

Lopez Marti, B.; Jimenez-Esteban, F.; Solano, E.

2011-08-01

62

A convective vorticity vector associated with tropical convection: A two-dimensional cloud-resolving modeling study  

NASA Astrophysics Data System (ADS)

Although dry/moist potential vorticity ((? ??e)/?) is a useful physical quantity for meteorological analysis, it cannot be applied to the analysis of two-dimensional (2-D) simulations. A new vorticity vector (? ??e)/? (convective vorticity vector (CVV)) is introduced in this study to analyze 2-D cloud-resolving simulation data associated with 2-D tropical convection. The cloud model is forced by the vertical velocity, zonal wind, horizontal advection, and sea surface temperature obtained from the Tropical Ocean-Global Atmosphere (TOGA) Coupled Ocean-Atmosphere Response Experiment (COARE) and is integrated for a selected 10-day period. The CVV has zonal and vertical components in the 2-D 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, Shouting; Ping, Fan; Li, Xiaofan; Tao, Wei-Kuo

2004-07-01

63

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

64

Motion of the angular momentum vector in body coordinates for torque-free dual-spin spacecraft  

NASA Technical Reports Server (NTRS)

The motion of the angular momentum vector in body coordinates for torque free, asymmetric dual spin spacecraft without and, for a special case, with energy dissipation on the main spacecraft is investigated. Without energy dissipation, two integrals can be obtained from the Euler equations of motion. Using the classical method of elimination of variable, the motion about the equilibrium points (six for the general case) are derived with these integrals. For small nutation angle, theta, the trajectories about the theta = 0 deg and theta = 180 deg points readily show the requirements for stable motion about these points. Also the conditions needed to eliminate stable motion about the theta = 180 deg point as well as the other undesireable equilibrium points follow directly from these equations. For the special case where the angular momentum vector moves about the principal axis which contains the momentum wheel, the notion of 'free variable' azimuth angle is used. Physically this angle must vary from 0 to 2 pi in a circular periodic fashion. Expressions are thus obtained for the nutation angle in terms of the free variable and other spacecraft parameters. Results show that in general there are two separate trajectory expressions that govern the motion of the angular momentum vector in body coordinates.

Fedor, J. V.

1981-01-01

65

Clouds  

NSDL National Science Digital Library

Clouds comprise a wonderful focus for classroom study. They're ubiquitous, ever-changing, scientifically interesting and, most importantly for teachers, they're cheap. The material presented here includes sections on cloud formation, cloud types, cloud pictures, other cloud-related phenomena, and a glossary.

Carl Wozniak

66

2-D high-frame-rate dynamic elastography using delay compensated and angularly compounded motion vectors: preliminary results.  

PubMed

This paper describes a new ultrasound-based system for high-frame-rate measurement of periodic motion in 2-D for tissue elasticity imaging. Similarly to conventional 2-D flow vector imaging, the system acquires the RF signals from the region of interest at multiple steering angles. A custom sector subdivision technique is used to increase the temporal resolution while keeping the total acquisition time within the range suitable for real-time applications. Within each sector, 1-D motion is estimated along the beam direction. The intra- and inter-sector delays are compensated using our recently introduced delay compensation algorithm. In-plane 2-D motion vectors are then reconstructed from these delay-compensated 1-D motions. We show that Young's modulus images can be reconstructed from these 2-D motion vectors using local inversion algorithms. The performance of the system is validated quantitatively using a commercial flow phantom and a commercial elasticity phantom. At the frame rate of 1667 Hz, the estimated flow velocities with the system are in agreement with the velocity measured with a pulsed-wave Doppler imaging mode of a commercial ultrasound machine with manual angle correction. At the frame rate of 1250 Hz, phantom Young's moduli of 29, 6, and 54 kPa for the background, the soft inclusion, and the hard inclusion, are estimated to be 30, 11, and 53 kPa, respectively. PMID:21041130

Zahiri Azar, Reza; Baghani, Ali; Salcudean, Septimiu E; Rohling, Robert

2010-11-01

67

Laser filamentation induced air-flow motion in a diffusion cloud chamber.  

PubMed

We numerically simulated the air-flow motion in a diffusion cloud chamber induced by femtosecond laser filaments for different chopping rates. A two dimensional model was employed, where the laser filaments were treated as a heat flux source. The simulated patterns of flow fields and maximum velocity of updraft compare well with the experimental results for the chopping rates of 1, 5, 15 and 150 Hz. A quantitative inconsistency appears between simulated and experimental maximum velocity of updraft for 1 kHz repetition rate although a similar pattern of flow field is obtained, and the possible reasons were analyzed. Based on the present simulated results, the experimental observation of more water condensation/snow at higher chopping rate can be explained. These results indicate that the specific way of laser filament heating plays a significant role in the laser-induced motion of air flow, and at the same time, our previous conclusion of air flow having an important effect on water condensation/snow is confirmed. PMID:23609636

Sun, Haiyi; Liu, Jiansheng; Wang, Cheng; Ju, Jingjing; Wang, Zhanxin; Wang, Wentao; Ge, Xiaochun; Li, Chuang; Chin, See Leang; Li, Ruxin; Xu, Zhizhan

2013-04-22

68

Parallel algorithm for determining motion vectors in ice floe images by matching edge features  

NASA Technical Reports Server (NTRS)

A parallel algorithm is described to determine motion vectors of ice floes using time sequences of images of the Arctic ocean obtained from the Synthetic Aperture Radar (SAR) instrument flown on-board the SEASAT spacecraft. Researchers describe a parallel algorithm which is implemented on the MPP for locating corresponding objects based on their translationally and rotationally invariant features. The algorithm first approximates the edges in the images by polygons or sets of connected straight-line segments. Each such edge structure is then reduced to a seed point. Associated with each seed point are the descriptions (lengths, orientations and sequence numbers) of the lines constituting the corresponding edge structure. A parallel matching algorithm is used to match packed arrays of such descriptions to identify corresponding seed points in the two images. The matching algorithm is designed such that fragmentation and merging of ice floes are taken into account by accepting partial matches. The technique has been demonstrated to work on synthetic test patterns and real image pairs from SEASAT in times ranging from .5 to 0.7 seconds for 128 x 128 images.

Manohar, M.; Ramapriyan, H. K.; Strong, J. P.

1988-01-01

69

Real-time prediction of respiratory motion using a cascade structure of an extended Kalman filter and support vector regression  

NASA Astrophysics Data System (ADS)

The motion of thoracic and abdominal tumours induced by respiratory motion often exceeds 20 mm, and can significantly compromise dose conformality. Motion-adaptive radiotherapy aims to deliver a conformal dose distribution to the tumour with minimal normal tissue exposure by compensating for the tumour motion. This adaptive radiotherapy, however, requires the prediction of the tumour movement that can occur over the system latency period. In general, motion prediction approaches can be classified into two groups: model-based and model-free. Model-based approaches utilize a motion model in predicting respiratory motion. These approaches are computationally efficient and responsive to irregular changes in respiratory motion. Model-free approaches do not assume an explicit model of motion dynamics, and predict future positions by learning from previous observations. Artificial neural networks (ANNs) and support vector regression (SVR) are examples of model-free approaches. In this article, we present a prediction algorithm that combines a model-based and a model-free approach in a cascade structure. The algorithm, which we call EKF-SVR, first employs a model-based algorithm (named LCM-EKF) to predict the respiratory motion, and then uses a model-free SVR algorithm to estimate and correct the error of the LCM-EKF prediction. Extensive numerical experiments based on a large database of 304 respiratory motion traces are performed. The experimental results demonstrate that the EKF-SVR algorithm successfully reduces the prediction error of the LCM-EKF, and outperforms the model-free ANN and SVR algorithms in terms of prediction accuracy across lookahead lengths of 192, 384, and 576 ms.

Hong, S.-M.; Bukhari, W.

2014-07-01

70

Vectors  

NSDL National Science Digital Library

This web page, authored and curated by David P. Stern, introduces vectors as an extension of numbers having both magnitude and direction. The initial motivation is to describe velocity but the material includes a general discussion of vector algebra and an application to forces for the inclined plane. The page contains links to a related lesson plan and further opportunities to explore vectors. This is part of the extensive web site "From Stargazers to Starships", that uses space exploration and space science to introduce topics in physics and astronomy. Translations in Spanish and French are available.

Stern, David P. (David Peter), 1931-

71

Cloud shadow Speed Sensor (CSS)  

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 shadow motion vectors to estimate power plant ramp rates and provide short-term forecasting is presented. The Cloud shadow Speed Sensor (CSS) is constructed using an array of luminance sensors and a high-speed data acquisition system 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 shadow 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 shadow directions and speeds 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, Victor

72

A half-pel precision MPEG2 motion-estimation processor with concurrent three-vector search  

Microsoft Academic Search

A half-pel precision MPEG2 motion estimation processor using a 0.5 ?m CMOS technology supports all prediction modes in MPEG2 including frame, field and dual-prime prediction, and estimates three vectors concurrently. The multiple processor configuration allows a search range expansion by 127.5, keeping bus traffic constant. It integrates 850 K transistors in a 13.85 mm13.55 mm silicon die. The observed maximum

K. Ishihara; S. Masuda; S. Hattori; H. Nishikawa; Y. Ajioka; T. Yamada; H. Amishiro; S. Uramoto; M. Yoshimoto; T. Sumi

1995-01-01

73

An improved self-alignment method for strapdown inertial navigation system based on gravitational apparent motion and dual-vector  

NASA Astrophysics Data System (ADS)

Analysis and simulation results indicate that two problems should be solved when the self-alignment method based on gravitational apparent motion and dual-vector can be used for Strapdown Inertial Navigation System. The first one is how to identify the apparent motion from accelerometer measurement containing random noise and the second is how to avoid the collinear problem between two vectors used in alignment solution. In this paper, a parameter identification and reconstruction algorithm is proposed to solve the first problem and simulation results indicate that proposed algorithm can identify apparent motion from accelerometer measurements effectively; and reconstruction algorithm based on current identified parameters for dual-vector is designed in detail to solve the second problem which can make full use of newest identification and avoid collinear problem completely. Simulation and turntable results show that the proposed alignment method can fulfill self-alignment in a swinging condition and the alignment accuracy can reach the theoretical values determined by the sensor precision.

Liu, Xixiang; Zhao, Yu; Liu, Xianjun; Yang, Yan; Song, Qing; Liu, Zhipeng

2014-12-01

74

Clouds  

NSDL National Science Digital Library

Students learn about the varieties of clouds, what they look like and how they can affect our lives. Introduction: Have you ever wondered what kind of cloud makes rain, or which one makes fog? Have you ever wondered if there are clouds that mean the weather if going to be good or not? Today, we're going to learn about three different clouds that may ...

Ms. Doxey

2010-03-26

75

Assessing geoaccuracy of structure from motion point clouds from long-range image collections  

NASA Astrophysics Data System (ADS)

Automatically extracted and accurate scene structure generated from airborne platforms is a goal of many applications in the photogrammetry, remote sensing, and computer vision fields. This structure has traditionally been extracted automatically through the structure-from-motion (SfM) workflows. Although this process is very powerful, the analysis of error in accuracy can prove difficult. Our work presents a method of analyzing the georegistration error from SfM derived point clouds that have been transformed to a fixed Earth-based coordinate system. The error analysis is performed using synthetic airborne imagery which provides absolute truth for the ray-surface intersection of every pixel in every image. Three methods of georegistration are assessed; (1) using global positioning system (GPS) camera centers, (2) using pose information directly from on-board navigational instrumentation, and (3) using a recently developed method that utilizes the forward projection function and SfM-derived camera pose estimates. It was found that the georegistration derived from GPS camera centers and the direct use of pose information from on-board navigational instruments is very sensitive to noise from both the SfM process and instrumentation. The georegistration transform computed using the forward projection function and the derived pose estimates prove to be far more robust to these errors.

Nilosek, David; Walvoord, Derek J.; Salvaggio, Carl

2014-11-01

76

FAST MOTIONS OF GALAXIES IN THE COMA I CLOUD: A CASE OF DARK ATTRACTOR?  

SciTech Connect

We note that nearby galaxies having high negative peculiar velocities are distributed over the sky very inhomogeneously. A part of this anisotropy is caused by the 'Local Velocity Anomaly', i.e., by the bulk motion of nearby galaxies away from the Local Void. However, half of the fast-flying objects reside within a small region known as the Coma I cloud. According to Makarov and Karachentsev, this complex contains 8 groups, 5 triplets, 10 pairs, and 83 single galaxies with a total mass of 4.7 Multiplication-Sign 10{sup 13} M{sub Sun }. We use 122 galaxies in the Coma I region with known distances and radial velocities V{sub LG} < 3000 km s{sup -1} to draw the Hubble relation for them. The Hubble diagram shows a Z-shaped effect of infall with an amplitude of +200 km s{sup -1} on the nearby side and -700 km s{sup -1} on the back side. This phenomenon can be understood as the galaxy infall toward a dark attractor with a mass of {approx}2 Multiplication-Sign 10{sup 14} M{sub Sun} situated at a distance of 15 Mpc from us. The existence of a large void between the Coma and Virgo clusters also probably affects the Hubble flow around the Coma I.

Karachentsev, Igor D.; Nasonova, Olga G. [Special Astrophysical Observatory of the Russian Academy of Sciences, Nizhniy Arkhyz, Karachei-Cherkessia 369167 (Russian Federation); Courtois, Helene M., E-mail: ikar@luna.sao.ru, E-mail: h.courtois@ipnl.in2p3.fr, E-mail: phiruzi@gmail.com [Universite de Lyon, Universite Lyon 1, CNRS/IN2P3, Institut de Physique Nucleaire de Lyon, Villeurbanne (France)

2011-12-20

77

A proper motion study of the Lupus clouds using VO tools  

E-print Network

Aims: By using kinematical information, we test the membership of the new Lupus candidate members proposed by the Cores to Disks (c2d) Spitzer Legacy Program program and by a complementary optical survey. We also investigate the relationship between the proper motions (pm) and other properties, in order to get some clues about their formation and early evolution. Methods: We compiled a list of members and possible members of Lupus 1, 3, and 4, together with all information on their spectral types, disks, and physical parameters. Using VO-tools, we cross-matched this list with the astrometric catalogues to get pm. Our final sample contains sources with magnitudes I~0.1Msun. Results: According to the kinematic information, our sources can be divided into two main groups. The first one contains sources with higher pm in agreement with other Gould Belt populations and with spatial distribution, optical and near-infrared colours, and disk composition consistent with these objects belonging to the Lupus clouds. In ...

Mart, Beln Lpez; Solano, Enrique

2011-01-01

78

Influence of broken cloud fields on reflectance retrievals  

NASA Astrophysics Data System (ADS)

Surface solar radiation forecasting permits to predict photovoltaic plant production for a massive and safe integration of solar energy into the electric network. For short-term forecasts (intra-day), methods using images from meteorological geostationary satellites are more suitable than numerical weather prediction models. Forecast schemes consist in assessing cloud motion vectors and in extrapolating cloud patterns from a given satellite image in order to predict cloud cover state above a PV plant. Atmospheric motion vectors retrieval techniques have been studied for several decades in order to improve weather forecasts. However, solar energy forecasting requires the extraction of cloud motion vectors on a finer spatial- and time-resolution than those provided for weather forecast applications. Even if motion vector retrieval is a wide research field in image processing related topics, only block-matching techniques are operationally used for solar energy forecasts via satellite images. In this paper, we propose two motion vectors extraction methods originating from video compression techniques (correlation phase and optical flow methods). We implemented them on a 6-day dataset of Meteosat-10 satellite diurnal images. We proceeded to cloud pattern extrapolation and compared predicted cloud maps against actual ones at different time horizons from 15 minutes to 4 hours ahead. Forecast scores were compared to the state-of-the-art (block matching) method. Correlation phase methods do not outperform block-matching but their computation time is about 25 times shorter. Optical flow based method outperforms all the methods with a satisfactory time computing.

Sundberg, Robert; Richtsmeier, Steven; Adler-Golden, Steven

2014-10-01

79

Simultaneous spectrophotometric determination of nitroaniline isomers after cloud point extraction by using least-squares support vector machines  

NASA Astrophysics Data System (ADS)

Cloud point extraction has been used for the preconcentration of m-nitroaniline, o-nitroaniline and p-nitroaniline and later simultaneous spectrophotometric determination using polyethylene glycol tert-octylphenyl ether (Triton X-100) as surfactant. The resolution of a ternary mixture of the nitroaniline isomers (after extraction by cloud point) by the application of least-squares support vector machines (LS-SVM) was performed. The chemical parameters affecting the separation phase and detection process were studied and optimized. Under the optimum experimental conditions (i.e. pH 7.0, Triton X-100 = 0.6%, equilibrium time 20 min and cloud point 75 C), calibration graphs were linear in the range of 0.2-20.0, 0.1-15.0 and 0.1-17.0 ?g ml -1 with detection limits of 0.08, 0.05 and 0.06 ?g ml -1 for m-nitroaniline, o-nitroaniline and p-nitroaniline, respectively. The experimental calibration matrix was designed with 21 mixtures of these chemicals. The concentrations were varied between calibration graphs concentrations of nitroaniline isomers. The root mean square error of prediction (RMSEP) for m-nitroaniline, o-nitroaniline and p-nitroaniline were 0.0146, 0.0308 and 0.0304, respectively. This procedure allows the simultaneous determination of nitroaniline isomers in synthetic and real matrix samples good reliability of the determination was proved.

Niazi, Ali; Ghasemi, Jahanbakhsh; Yazdanipour, Ateesa

2007-11-01

80

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 Earths 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.

2012-08-03

81

Neuro-fuzzy based Motion Control of a Robotic Exoskeleton: Considering End-effector Force Vectors  

Microsoft Academic Search

To assist physically disabled, injured, and\\/or elderly persons, we have been developing a 3DOF exoskeleton robot for assisting upper-limb motion, since upper-limb motion is involved in a lot of activities of everyday life. The exoskeleton robot is mainly is controlled by the skin surface electromyogram (EMG) signals, since EMG signals of muscles directly reflect how the user intends to move.

Kazuo Kiguchi; Mohammad Habibur Rahman; Makoto Sasaki

2006-01-01

82

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

83

Imaging the outward motions of clumpy dust clouds around the red supergiant Antares with VLT/VISIR  

NASA Astrophysics Data System (ADS)

Aims: We present a 0."5-resolution 17.7 ?m image of the red supergiant Antares. Our aim is to study the structure of the circumstellar envelope in detail. Methods: Antares was observed at 17.7 ?m with the VLT mid-infrared instrument VISIR. Taking advantage of the BURST mode, in which a large number of short exposure frames are taken, we obtained a diffraction-limited image with a spatial resolution of 0."5. Results: The VISIR image shows six clumpy dust clouds located at 0."8-1."8 (43-96 R? = 136-306 AU) away from the star. We also detected compact emission within a radius of 0."5 around the star. Comparison of our VISIR image taken in 2010 and the 20.8 ?m image taken in 1998 with the Keck Telescope reveals the outward motions of four dust clumps. The proper motions of these dust clumps (with respect to the central star) amount to 0."2-0."6 in 12 years. This translates into expansion velocities (projected onto the plane of the sky) of 13-40 km s-1 with an uncertainty of 7 km s-1. The inner compact emission seen in the 2010 VISIR image is presumably newly formed dust, because it is not detected in the image taken in 1998. If we assume that the dust is ejected in 1998, the expansion velocity is estimated to be 34 km s-1, in agreement with the velocity of the outward motions of the clumpy dust clouds. The mass of the dust clouds is estimated to be (3-6) 10-9 M?. These values are lower by a factor of 3-7 than the amount of dust ejected in one year estimated from the (gas+dust) mass-loss rate of 2 10-6 M? yr-1, suggesting that the continuous mass loss is superimposed on the clumpy dust cloud ejection. Conclusions: The clumpy dust envelope detected in the 17.7 ?m diffraction-limited image is similar to the clumpy or asymmetric circumstellar environment of other red supergiants. The velocities of the dust clumps cannot be explained by a simple accelerating outflow, implying the possible random nature of the dust cloud ejection mechanism. Based on VISIR observations made with the Very Large Telescope of the European Southern Observatory. Program ID: 385.D-0120(A), 286.D-5007(A).

Ohnaka, K.

2014-08-01

84

Large-scale Environmental Variables and Transition to Deep Convection in Cloud Resolving Model Simulations: A Vector Representation  

SciTech Connect

Cloud resolving model simulations and vector analysis are used to develop a quantitative method of assessing regional variations in the relationships between various large-scale environmental variables and the transition to deep convection. Results of the CRM simulations from three tropical regions are used to cluster environmental conditions under which transition to deep convection does and does not take place. Projections of the large-scale environmental variables on the difference between these two clusters are used to quantify the roles of these variables in the transition to deep convection. While the transition to deep convection is most sensitive to moisture and vertical velocity perturbations, the details of the profiles of the anomalies vary from region to region. In comparison, the transition to deep convection is found to be much less sensitive to temperature anomalies over all three regions. The vector formulation presented in this study represents a simple general framework for quantifying various aspects of how the transition to deep convection is sensitive to environmental conditions.

Hagos, Samson M.; Leung, Lai-Yung R.

2012-11-01

85

Motion of a Vector Particle in a Curved Space-time. IV. Asymptotical shape of caustic  

E-print Network

The studies of influence of spin on a photon motion in a Schwartzschild spacetime is continued. In the previous paper [2] the first order correction to the geodesic motion is reduced to a non-uniform linear ordinary differential equation and the equation obtained has been solved by the standard method of integration of the Green function. If each photon draws a world line specified by this solution then light rays from infinitely distant source form a caustic which does not appear without the spin-gravity interaction. The goal of the present work is to obtain explicit form of caustic.

A. T. Muminov; Z. Ya. Turakulov

2007-06-26

86

A motion planning algorithm for a nonholonomic vehicle using vector potential functions in triangular regions  

Microsoft Academic Search

A motion planning algorithm for a nonholonomic vehicle in triangular regions is investigated. The regions are the result of splitting a larger and complex workspace, and are classified into three classes, that are, empty regions, obstacle-inside regions, and goal regions. The vehicle has to achieve a goal configuration from any initial configuration in the workspace. A set of procedures to

Anugrah Kusumo Pamosoaji; Augie Widyotriatmo; Keum-Shik Hong

2010-01-01

87

Fourier Transform Ion Cyclotron Resonance Mass Resolution and Dynamic Range Limits Calculated by Computer Modeling of Ion Cloud Motion  

NASA Astrophysics Data System (ADS)

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).

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

2012-02-01

88

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

89

Flare activity, sunspot motions, and the evolution of vector magnetic fields in Hale region 17244  

NASA Technical Reports Server (NTRS)

The magnetic and dynamical circumstances leading to the 1B/M4 flare of November 5, 1980 are studied, and a strong association is found between the buildup of magnetic shear and the onset of flare activity within the active region. The development of shear, as observed directly in vector magnetograms, is consistent in detail with the dynamical history of the active region and identifies the precise location of the optical and hard-X-ray kernels of the flare emission.

Neidig, Donald F.; Hagyard, Mona J.; Machado, Marcos E.; Smith, Jesse B., Jr.

1986-01-01

90

Spatial heterodyne Stokes vector imaging of the motional Stark-Zeeman multiplet.  

PubMed

We present a general Stokes interferometer/polarimeter suitable for polarimetric imaging the elliptically polarized motional Stark-Zeeman multiplet. We also introduce a fully phase-heterodyne spatial multiplex variant of the system that has been used for imaging of Balmer alpha emission from the heating neutral beam in the KSTAR super-conducting tokamak in Korea. The polarimeter performance is illustrated using various polarization test targets. PMID:23126853

Howard, John; Chung, Jinil

2012-10-01

91

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

1970-01-01

92

Cloud pattern prediction from geostationary meteorological satellite images for solar energy forecasting  

NASA Astrophysics Data System (ADS)

Surface solar radiation forecasting permits to predict photovoltaic plant production for a massive and safe integration of solar energy into the electric network. For short-term forecasts (intra-day), methods using images from meteorological geostationary satellites are more suitable than numerical weather prediction models. Forecast schemes consist in assessing cloud motion vectors and in extrapolating cloud patterns from a given satellite image in order to predict cloud cover state above a PV plant. Atmospheric motion vectors retrieval techniques have been studied for several decades in order to improve weather forecasts. However, solar energy forecasting requires the extraction of cloud motion vectors on a finer spatial- and time-resolution than those provided for weather forecast applications. Even if motion vector retrieval is a wide research field in image processing related topics, only block-matching techniques are operationally used for solar energy forecasts via satellite images. In this paper, we propose two motion vectors extraction methods originating from video compression techniques (correlation phase and optical flow methods). We implemented them on a 6-day dataset of Meteosat-10 satellite diurnal images. We proceeded to cloud pattern extrapolation and compared predicted cloud maps against actual ones at different time horizons from 15 minutes to 4 hours ahead. Forecast scores were compared to the state-of-the-art (block matching) method. Correlation phase methods do not outperform block-matching but their computation time is about 25 times shorter. Optical flow based method outperforms all the methods with a satisfactory time computing.

Cros, S.; Sbastien, N.; Liandrat, O.; Schmutz, N.

2014-10-01

93

Third-epoch Magellanic Cloud Proper Motions. II. The Large Magellanic Cloud Rotation Field in Three Dimensions  

NASA Astrophysics Data System (ADS)

We present the first detailed assessment of the large-scale rotation of any galaxy based on full three-dimensional velocity measurements. We do this for the LMC by combining our Hubble Space Telescope average proper motion (PM) measurements for stars in 22 fields, with existing line-of-sight (LOS) velocity measurements for 6790 individual stars. We interpret these data with a model of circular rotation in a flat disk. The PM and LOS data paint a consistent picture of the LMC rotation, and their combination yields several new insights. The PM data imply a stellar dynamical center that coincides with the H I dynamical center, and a rotation curve amplitude consistent with that inferred from LOS velocity studies. The implied disk viewing angles agree with the range of values found in the literature, but continue to indicate variations with stellar population and/or radius. Young (red supergiant) stars rotate faster than old (red and asymptotic giant branch) stars due to asymmetric drift. Outside the central region, the circular velocity is approximately flat at V circ = 91.7 18.8 km s-1. This is consistent with the baryonic Tully-Fisher relation and implies an enclosed mass M(8.7 kpc) = (1.7 0.7) 1010 M ?. The virial mass is larger, depending on the full extent of the LMC's dark halo. The tidal radius is 22.3 5.2 kpc (24.0 5.6). Combination of the PM and LOS data yields kinematic distance estimates for the LMC, but these are not yet competitive with other methods.

van der Marel, Roeland P.; Kallivayalil, Nitya

2014-02-01

94

Kinematical relations among radar-observed water concentrations, vertical motions, and liquid-water drop-size spectra in convective clouds  

E-print Network

KINEMATICAL RELATIONS AMONG RADAR-OBSERVED WATER CONCENTRATIONSp VERTICAL MOTIONS, AND LIQUID- WATER DROP-SIZE SPECTRA IN CONVECTIVE CLOUDS A Thesis By ROBERT CLAYTON RUNNELS Submitted to the Graduate School of the Agricultural and Mechanical... College of Texas in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE August 1962 Major Subject: METEOROLOGY KINEMATICAL RELATIONS AMONG RADAR-OBSERVED WATER CONCENTRATIONS' VERTICAL MOTIONS p AND LIQUID WATER DROP" SIZE...

Runnels, Robert Clayton

1962-01-01

95

General Physics I Exam 1 -Chs. 1,2,3 -Units, Motion, Vectors Sep. 12, 2012 Name Rec. Instr. Rec. Time  

E-print Network

General Physics I Exam 1 - Chs. 1,2,3 - Units, Motion, Vectors Sep. 12, 2012 Name Rec. Instr. Rec the car travel during the 10.8 seconds? 11. (16) The baseball team is practicing throwing balls vertically to fly from MHK to KCI (about 160 km)? 15. (16) In physics class students launch a projectile

Wysin, Gary

96

General Physics I Exam 1 -Chs. 1,2,3 -Units, Motion, Vectors Sep. 15, 2010 Name Rec. Instr. Rec. Time  

E-print Network

General Physics I Exam 1 - Chs. 1,2,3 - Units, Motion, Vectors Sep. 15, 2010 Name Rec. Instr. Rec direction using points of the compass, like "25 south of east". 12. (16) A baseball is thrown straight up so of the compass and an angle. 14. (16) In physics lab students are to launch a projectile from a point 245 m

Wysin, Gary

97

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

98

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

99

A Benchmark for Cloud Tracking Wind Measurements  

NASA Astrophysics Data System (ADS)

Cloud tracking has been the primary method of measuring wind speeds in planetary atmospheres through Earth- and space- based remote sensing. Latest developments of automated feature tracking software are able to harvest thousands of wind vectors out of a sequence of high-resolution images acquired with an appropriate temporal separation. However, unlike satellite-based cloud-tracking measurements of Earth, these planetary measurements cannot easily be validated against in-situ data, which makes the interpretation difficult when different cloud-tracking schemes do not agree on their results. To address the issue of data validation, we run multiple automated cloud-tracking software independently developed at multiple institutions on synthetic wind data generated using a General Circulation Model. Our simulations calculate the advection of tracer distributions to represent cloud motions as done by Sayanagi and Showman (2007, Icarus 187, p520-539). The motions of tracers are measured using cloud-tracking software to derive wind vector fields, which will be compared against the model "truth." We test the performance of cloud-tracking software for different wind scenarios. Our first test wind field contains a simple zonal jet. The second test scenario is a large vortex like Jupiters Great Red Spot. The third test case has waves propagating alongside a zonal jet. We compare the results returned from different cloud-tracking schemes and discuss what approaches work better at measuring winds. In addition to verifying the wind vector field measurements, we also address the accuracy and validity of eddy momentum flux measurements by tracking clouds. The difficulties of such measurements are discussed by Salyk et al. (2006, Icarus 185, p430-442), and we re-examine the issue using our synthetic wind data. From our experiments, we aim to establish a standard benchmark of cloud tracking measurements for planetary mission applications.

Sayanagi, K. M.; Mitchell, J.; Ingersoll, A. P.; Ewald, S. P.; Marcus, P. S.; de Pater, I.; Wong, M. H.; Choi, D. S.; Sussman, M.; Ogohara, K.; Imamura, T.; Kouyama, T.; Takagi, M.; Satoh, N.; Del Genio, A. D.; Barbara, J.; Sanchez-Lavega, A.; Hueso, R.; Garca-Melendo, E.; Simon-Miller, A. A.

2010-12-01

100

Motion.  

ERIC Educational Resources Information Center

This monograph was written for the Conference on the New Instructional Materials in Physics held at the University of Washington in summer, 1965. It is intended for use in an introductory course in college physics. It consists of an extensive qualitative discussion of motion followed by a detailed development of the quantitative methods needed to

Gerhart, James B.; Nussbaum, Rudi H.

101

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

102

An improved boundary element formulation for the motion of spherical bubbles  

Microsoft Academic Search

The dynamics of motion of small bubbles at large Reynolds numbers in an approximately inviscid vortex-free flow (i.e., ? u =0 , whereu is the flow velocity vector) is of interest in the study of heat conduction in composite materials and in electrostatics as well as for modeling bubble clouds, cavities, and fluids with bubbles. The analysis of motion of

V. A. Dobrushkin; M. Maxey

2008-01-01

103

Venus in motion: An animated video catalog of Pioneer Venus Orbiter Cloud Photopolarimeter images  

NASA Technical Reports Server (NTRS)

Images of Venus acquired by the Pioneer Venus Orbiter Cloud Photopolarimeter (OCPP) during the 1982 opportunity have been utilized to create a short video summary of the data. The raw roll by roll images were first navigated using the spacecraft attitude and orbit information along with the CPP instrument pointing information. The limb darkening introduced by the variation of solar illumination geometry and the viewing angle was then modelled and removed. The images were then projected to simulate a view obtained from a fixed perspective with the observer at 10 Venus radii away and located above a Venus latitude of 30 degrees south and a longitude 60 degrees west. A total of 156 images from the 1982 opportunity have been animated at different dwell rates.

Limaye, Sanjay S.

1992-01-01

104

Cloud-tracked Winds for the First MGS Mapping Year  

Microsoft Academic Search

We have measured winds using cloud motion in consecutive Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle global map swaths taken during the first mapping year (Ls 135 -360 -111 ). We present a total of 11,200 wind vectors collected in the north polar region during Ls 135 -195 (late summer\\/early fall) and Ls 20 -55 (mid spring),

H. Wang; A. Ingersoll

2003-01-01

105

Last developments of the EUMETSAT Atmospheric Motion Vector product derived from MSG images for assimilation in NWP models  

NASA Astrophysics Data System (ADS)

Atmospheric Motion Vectors (AMVs) are one of the most important products derived from all geostationary satellites, because they constitute a very important part of the observation data provided to Numerical Weather Prediction models. The Height Assignment (HA) is currently the most difficult task in the AMV extraction scheme. Several sources of error can be introduced at the height assignment step, but one of the main difficulties is to clearly identify the pixels that lead the tracking process in the tracer box, in order to select them for the HA calculation. A good pixel selection process should ensure to keep a direct link between the feature really tracked and the calculation of the height. The most common method sorts the coldest pixels in the target box and uses them to calculate the AMV height. However, recent work showed that some of the coldest pixels can have very small and/or negative contribution to the cross correlation process. Following these findings, it is then proposed to use individual pixel contribution to the cross correlation coefficient information in the pixel selection process, in order to get a closer link between the tracked feature tracked and the HA. This method has been tested on a parallel chain at EUMETSAT for two separated periods of one month. This presentation summarizes the main results of these operational tests, which show some improvements of the new scheme on the AMV product for both the VIS0.8, HRV and IR10.8 channels, increasing the total amount of good AMVs (Quality Index QI>80) and also the amount of good AMV/radiosonde collocations. Speed biases and RMS against radiosonde observations are generally a bit larger, especially the known slow bias observed at high levels for IR10.8 AMVs, but are calculated on a bigger amount of data.

Borde, Regis; Bertil Gustafsson, Jrgen; de Smet, Arthur; Dew, Greg

2010-05-01

106

ARM - Midlatitude Continental Convective Clouds Experiment (MC3E): Multi-Frequency Profilers, Vertical Air Motion (williams-vertair)  

DOE Data Explorer

This data was collected by the NOAA 449-MHz and 2.8-GHz profilers in support of the Department of Energy (DOE) and NASA sponsored Mid-latitude Continental Convective Cloud Experiment (MC3E). The profiling radars were deployed in Northern Oklahoma at the DOE Atmospheric Radiation Mission (ARM) Southern Great Plans (SGP) Central Facility from 22 April through 6 June 2011. NOAA deployed three instruments: a Parsivel disdrometer, a 2.8-GHz profiler, and a 449-MHz profiler. The parasivel provided surface estimates of the raindrop size distribution and is the reference used to absolutely calibrate the 2.8 GHz profiler. The 2.8-GHz profiler provided unattenuated reflectivity profiles of the precipitation. The 449-MHz profiler provided estimates of the vertical air motion during precipitation from near the surface to just below the freezing level. By using the combination of 2.8-GHz and 449-MHz profiler observations, vertical profiles of raindrop size distributions can be retrieved. The profilers are often reference by their frequency band: the 2.8-GHz profiler operates in the S-band and the 449-MHz profiler operates in the UHF band. The raw observations are available as well as calibrated spectra and moments. This document describes how the instruments were deployed, how the data was collected, and the format of the archived data.

Williams, Christopher; Jensen, Mike

107

Influence of the cosmological constant on the motion of Magellanic Clouds in the gravitational field of Milky Way  

SciTech Connect

Using the pseudo-Newtonian (PN) potential reflecting properties of the Schwarz-schild-de Sitter spacetime, we estimate the influence of the repulsive cosmological constant ? ? 1.3 10{sup ?56}cm{sup ?2} implied by recent cosmological tests onto the motion of both Small and Large Magellanic Clouds (SMC and LMC) in the gravitational field of the Milky Way. Considering detailed modelling of the gravitational field of the Galaxy disc, bulge and cold dark matter halo, the trajectories of SMC and LMC constructed for the PN potential with the cosmological constant are confronted to those given for ? = 0. In the realistic model of the extended cold dark matter halo its edge and related total mass are taken at typical values reflecting recent diversity in the total Galaxy mass estimates. In all cases, strong influence of the cosmological constant, on 10% level or higher, has been found for motion of both SMC and LMC. Inside the halo, the Newtonian part of the PN potential is exact enough, while outside the halo the PN potential can give relevant relativistic corrections. The role of the cosmological constant is most conspicuous when binding mass is estimated for the satellite galaxies. We have found a strong influence of cosmic repulsion on the total binding mass for both galaxies. For SMC there is the binding mass M{sub SMC}{sup ?=0} = 7.07 10{sup 11}M{sub ?} and M{sub SMC}{sup ?>0} = 8.61 10{sup 11}M{sub ?}, while even much higher increase is found for LMC, where M{sub LMC}{sup ?=0} = 1.50 10{sup 12}M{sub ?} and M{sub LMC}{sup ?} {sup >0} = 2.21 10{sup 12}M{sub ?}, putting serious doubts on the possibility that the LMC is bounded by the Milky Way. However, the estimates of binding masses are strongly influenced by initial velocity of SMC and LMC; we took the values inferred for the IAU MW rotation velocity ? 220 km/s. Our results indicate very important role of the cosmic repulsion in the motion of interacting galaxies, clearly demonstrated in the case of the satellite SMC and LMC galaxies moving in the field of Milky Way. In some cases, the effect of the cosmic repulsion can be even comparable to the effects of the dynamical friction and the Andromeda Galaxy.

Stuchlk, Zden?k; Schee, Jan, E-mail: zdenek.stuchlik@fpf.slu.cz, E-mail: jan.schee@fpf.slu.cz [Institute of Physics, Faculty of Philosophy and Science, Silesian University in Opava, Bezrucovo nm. 13, Opava (Czech Republic)

2011-09-01

108

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

109

Motion of a vector particle in a curved space-time. III. Development of techniques of calculation  

E-print Network

The studies of influence of spin on a photon's motion in a Schwartzschild spacetime is continued. In the previous paper [13] the first order correction to the geodesic motion is found for the first half of the photon world line. The system of equations for the first order correction to the geodesic motion is reduced to a non-uniform linear ordinary differential equation. The equation obtained is solved by the standard method of integration of the Green function.

Z. Y. Turakulov; A. T. Muminov

2006-07-24

110

Developing a Standardized Testing Procedure for Cloud Tracking Wind Measurement Methods  

NASA Astrophysics Data System (ADS)

We present preliminary results of our effort to develop a standardized benchmark test for cloud tracking wind measurement methods. Various algorithms have been developed over the years to measure wind speeds in planetary atmospheres through Earth- and space- based remote sensing. However, unlike satellite-based cloud-tracking measurements of Earth, these planetary measurements cannot easily be validated against in-situ data, which makes the interpretation difficult when different cloud-tracking schemes do not agree on their results. To address the issue of data validation, we run multiple automated cloud-tracking algorithms independently developed at multiple institutions on synthetic wind data generated using a General Circulation Model. Our simulations calculate the advection of tracer distributions to represent cloud motions as done by Sayanagi and Showman (2007, Icarus 187, p520-539). The motions of tracers are measured using cloud-tracking software to derive wind vector fields, which will be compared against the model "truth." In our synthetic wind/cloud fields, the tempo-spatial scales of the winds and clouds are separately controlled so that the robustness of cloud tracking tools can be assessed against various conditions. Our setup enables measuring the performance of cloud-tracking software using two metrics. The first metric is the ratio between characteristic length scale of cloud morphology Lcloud and the size of smallest eddies successfully resolved by a cloud-tracking method LLeddy, ? = Lcloud/L_{Leddy}. The second performance metric is the ratio between the temporal interval between image acquisitions Timaging and the characteristic lifetime of clouds Tcloud, ? = Timaging/T_cloud. These metrics are designed to compare the abilities of tracking algorithms to resolve cloud motions against the absolute theoretical limit; note that both metrics have the maximum value of 1.0 as cloud tracking methods cannot resolve features that change in less than the temporal and spatial scales of the clouds. Our study is supported by a grant from the NSF Planetary Astronomy program.

Sayanagi, K. M.; Barbara, J. M.; Bourque, B.; Choi, D. S.; De Pater, I.; Del Genio, A. D.; Ewald, S.; Garcia-Melendo, E.; Heavens, N. G.; Hueso, R.; Imamura, T.; Ingersoll, A. P.; Kouyama, T.; Liu, T.; Marcus, P. S.; Mitchell, J.; Ogohara, K.; Read, P. L.; Sanchez-Lavega, A.; Simon-Miller, A. A.; Sussman, M.; Takagi, M.; Wong, M. H.; Young, R. M.

2012-12-01

111

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 research objectives in this proposal were part of a continuing program at UW-CIMSS to develop and refine an automated geostationary satellite winds processing system which can be utilized in both research and operational environments. The majority of the originally proposed tasks were successfully accomplished, and in some cases the progress exceeded the original goals. Much of the research and development supported by this grant resulted in upgrades and modifications to the existing automated satellite winds tracking algorithm. These modifications were put to the test through case study demonstrations and numerical model impact studies. After being successfully demonstrated, the modifications and upgrades were implemented into the NESDIS algorithms in Washington DC, and have become part of the operational support. A major focus of the research supported under this grant attended to the continued development of water vapor tracked winds from geostationary observations. The fully automated UW-CIMSS tracking algorithm has been tuned to provide complete upper-tropospheric coverage from this data source, with data set quality close to that of operational cloud motion winds. Multispectral water vapor observations were collected and processed from several different geostationary satellites. The tracking and quality control algorithms were tuned and refined based on ground-truth comparisons and case studies involving impact on numerical model analyses and forecasts. The results have shown the water vapor motion winds are of good quality, complement the cloud motion wind data, and can have a positive impact in NWP on many meteorological scales.

Velden, Christopher

1995-01-01

112

Descent motions of the Huygens probe as measured by the Surface Science Package (SSP): Turbulent evidence for a cloud layer  

Microsoft Academic Search

The Huygens probe underwent vigorous short-period motions during its parachute descent through the atmosphere of Saturn's moon Titan in January 2005, at least some of which were excited by the Titan environment. Several sensors in the Huygens Surface Science Package (SSP) detect these motions, indicating the transition to the smaller stabilizer parachute, the changing probe spin rate, aerodynamic buffeting, and

Ralph D. Lorenz; John C. Zarnecki; Martin C. Towner; Mark R. Leese; Andrew J. Ball; Brijen Hathi; Axel Hagermann; Nadeem A. L. Ghafoor

2007-01-01

113

MISR Level 2 Cloud Product Versioning  

Atmospheric Science Data Center

... Cloud Fractions, Support Vector Machine (SVM) Scene Classifiers Beta: SVM Cirrus Fraction MISR maturity level definitions | Quality ... ASCM. Improved Coarse Consensus Cloud Classifier. SVM Cirrus Mask masked out over land. Fixed normalization errors in Cloud ...

2014-08-22

114

Cloud Modeling  

NASA Technical Reports Server (NTRS)

Numerical cloud models have been developed and applied extensively to study cloud-scale and mesoscale processes during the past four decades. The distinctive aspect of these cloud models is their ability to treat explicitly (or resolve) cloud-scale dynamics. This requires the cloud models to be formulated from the non-hydrostatic equations of motion that explicitly include the vertical acceleration terms since the vertical and horizontal scales of convection are similar. Such models are also necessary in order to allow gravity waves, such as those triggered by clouds, to be resolved explicitly. In contrast, the hydrostatic approximation, usually applied in global or regional models, does allow the presence of gravity waves. In addition, the availability of exponentially increasing computer capabilities has resulted in time integrations increasing from hours to days, domain grids boxes (points) increasing from less than 2000 to more than 2,500,000 grid points with 500 to 1000 m resolution, and 3-D models becoming increasingly prevalent. The cloud resolving model is now at a stage where it can provide reasonably accurate statistical information of the sub-grid, cloud-resolving processes poorly parameterized in climate models and numerical prediction models.

Tao, Wei-Kuo; Moncrieff, Mitchell; Einaud, Franco (Technical Monitor)

2001-01-01

115

Symmetries of particle motion  

E-print Network

We define affine transport lifts on the tangent bundle by associating a transport rule for tangent vectors with a vector field on the base manifold. The aim is to develop tools for the study of kinetic/ dynamical symmetries in relativistic particle motion. The transport lift unifies and generalises the various existing lifted vector fields, with clear geometric interpretations. We find the affine dynamical symmetries of free particle motion, and compare this to previous results and to the alternative concept of "matter symmetry".

Roy Maartens; David Taylor

1997-12-11

116

The effect of parent internal motion on photofragment rotational distributions: Vector correlation of angular momenta and C2v symmetry breaking in dissociation of AB2 molecules  

NASA Astrophysics Data System (ADS)

A semiclassical calculation is presented that fully accounts for the angular momentum disposal in photodissociation of triatomic molecules. Rotational distributions are calculated for O2(3?-g) produced by the visible photolysis of ozone, O2(1?g) by the UV photolysis of ozone, and OH by the 157 nm dissociation of water, to illustrate the effects of parent internal motion on fragment rotational distributions in the dissociation of C2v geometry molecules. A simple, but realistic, impulsive model of the energy release is used to describe the dissociation dynamics. The calculations are carried out for parent molecules at room temperature, as well as at the low temperatures characteristic of molecular beams. The contributions to the diatomic fragment rotational distribution from both parent triatom rotation and zero-point bending vibration are computed. Comparison of the calculated distributions with experimentally measured distributions indicates that the spread in rotational and bending vibrational angular momenta of the parent molecule can account for all or nearly all of the spread in final J of the diatomic photofragment. However, the rotational distributions of the diatomic photofragment reveal a strong vector correlation between the diatom angular momentum produced by the dissociative energy release, and the angular momentum associated with the in-plane rotation. The correlation is such that only half of all the photofragment states allowed by energy and angular momentum conservation are actually produced with appreciable probability. Of two energy degenerate photofragment states, corresponding to breaking of one or the other nominally equivalent bonds in the AB2 molecule, the one with the smaller orbital angular momentum/recoil linear momentum is strongly favored. This is explained by larger Franck-Condon overlap in the photoexcitation for the state of lower recoil angular momentum. The correlation involves selection of which of the two nominally equivalent bonds will break in the photodissociation of an AB2 triatom of C2v geometry, and thus represents a symmetry breaking mechanism in such a photodissociation.

Levene, Harold B.; Valentini, James J.

1987-09-01

117

Closed Large Cell Clouds  

Atmospheric Science Data Center

... View Larger Image The shape and size of cellular patterns within marine stratocumulus cloud layers can change ... When the cell centers are cloudy and the main sinking motion is concentrated at cell boundaries, the cells are referred to as ...

2013-04-19

118

Exploring acceleration through vectors  

NSDL National Science Digital Library

This in class worksheet is designed to get students to think about and manipulate different accelerations in their head. Students work together with written descriptions of velocity and acceleration and draw the vectors in part one, and then turn that around in part two where they write descriptions of a car's motion based on the vector pictures they are given.

119

INTERSTELLAR CLOUDS BY SEARCHLIGHT  

SciTech Connect

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

2009-04-15

120

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

121

Cloud-tracked winds for the first Mars Global Surveyor Mapping year  

Microsoft Academic Search

We have measured winds using cloud motion in consecutive Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide-angle global map swaths taken during the first mapping year (Ls 135 -360 -111 ). We present a total of ~11,200 wind vectors collected in the north polar region during Ls 135 -195 (late summer\\/early fall) and Ls 20 -55 (mid spring), and

Huiqun Wang; Andrew P. Ingersoll

2003-01-01

122

Cloud-tracked winds for the first Mars Global Surveyor mapping year  

Microsoft Academic Search

We have measured winds using cloud motion in consecutive Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide-angle global map swaths taken during the first mapping year (Ls 135360111). We present a total of ?11,200 wind vectors collected in the north polar region during Ls 135195 (late summer\\/early fall) and Ls 2055 (mid spring) and in the south polar region

Huiqun Wang; Andrew P. Ingersoll

2003-01-01

123

Interactive Motion Segmentation Claudia Nieuwenhuis1  

E-print Network

-Nuremberg). motion vectors (Figure 1 shows a water vortex with motion vectors pointing in all directions alongInteractive Motion Segmentation Claudia Nieuwenhuis1 , Benjamin Berkels2 , Martin Rumpf2 , Daniel, Germany {berkels,rumpf}@ins.uni-bonn.de Abstract. Interactive motion segmentation is an important task

Rumpf, Martin

124

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

125

Low Cloud Type over the Ocean from Surface Observations. Part III: Relationship to Vertical Motion and the Regional Surface Synoptic Environment  

Microsoft Academic Search

Composite large-scale dynamical fields contemporaneous with low cloud types observed at midlatitude Ocean Weather Station (OWS) C and eastern subtropical OWS N are used to establish representative relationships between low cloud type and the synoptic environment. The composites are constructed by averaging meteo- rological observations of surface wind and sea level pressure from volunteering observing ships (VOS) and analyses of

Joel R. Norris; Stephen A. Klein

2000-01-01

126

Cloud Services Cloud Services  

E-print Network

of the services as well as support. These business-ready services will allow users and groups in the UniversityCloud Services Cloud Services In 2012 UCD IT Services launched an exciting new set of cloud access These optional services are available to University staff and affiliates of the University

127

Acoustic vector solitons.  

PubMed

A theory of an acoustic vector soliton of self-induced transparency is constructed. By using the perturbative reduction method the magnetic Bloch equations and the equation of motion for the displacement field for the small area pulse are reduced to a system of two coupled nonlinear Schrdinger equations. The shape of an acoustic vector soliton with the sum and difference of the frequencies is presented. Explicit analytical expressions for the parameters of an acoustic vector soliton are obtained as well as simulations of an acoustic vector soliton presented with realistic parameters which can be reached in experiments. It is shown that the vector soliton in the special case can be reduced to the breather solution, and these nonlinear waves have different profiles. PMID:23005248

Adamashvili, G T

2012-06-01

128

Clouds as Turbulent Density Fluctuations: Implications for Pressure Confinement and Spectral Line Data Interpretation  

NASA Astrophysics Data System (ADS)

We examine the idea that diffuse H I and giant molecular clouds and their substructure form as density fluctuations induced by large-scale interstellar turbulence. We do this by closely investigating the topology of the velocity, density, and magnetic fields within and at the boundaries of the clouds emerging in high-resolution two-dimensional simulations of the interstellar medium (ISM) including self-gravity, magnetic fields, parameterized heating and cooling, and a simple model for star formation. We find that the velocity field is continuous across cloud boundaries for a hierarchy of clouds of progressively smaller sizes. Cloud boundaries defined by a density-threshold criterion are found to be quite arbitrary, with no correspondence to any actual physical boundary, such as a density discontinuity. Abrupt velocity jumps are coincident with the density maxima, which indicates that the clouds are formed by colliding gas streams. This conclusion is also supported by the fact that the volume and surface kinetic terms in the Eulerian virial theorem for a cloud ensemble are comparable in general and by the topology of the magnetic field, which exhibits bends and reversals where the gas streams collide. However, no unique trend of alignment between density and magnetic features is observed. Both sub- and super-Alfvnic motions are observed within the clouds. In light of these results, we argue that thermal pressure equilibrium is irrelevant for cloud confinement in a turbulent medium, since inertial motions can still distort or disrupt a cloud, unless it is strongly gravitationally bound. Turbulent pressure confinement appears self-defeating because turbulence contains large-scale motions that necessarily distort Lagrangian cloud boundaries or equivalently cause flux through Eulerian boundaries. We then discuss the compatibility of the present scenario with observational data. We find that density-weighted velocity histograms are consistent with observational line profiles of comparable spatial and velocity resolution, exhibiting similar FWHMs and similar multicomponent structure. An analysis of the regions contributing to each velocity interval indicates that the histogram ``features'' do not come from isolated ``clumps'' but rather from extended regions throughout a cloud, which often have very different total velocity vectors. Finally, we argue that the scenario presented here may also be applicable to small scales with larger densities (molecular clouds and their substructure, up to at least n~103-105 cm-3) and conjecture that quasi-hydrostatic configurations cannot be produced from turbulent fluctuations unless the thermodynamic behavior of the flow becomes nearly adiabatic. We demonstrate, using appropriate cooling rates, that this will not occur except for very small compressions (<~10-2 pc) or until protostellar densities are reached for collapse.

Ballesteros-Paredes, Javier; Vzquez-Semadeni, Enrique; Scalo, John

1999-04-01

129

Interactive Motion Segmentation Claudia Nieuwenhuis1  

E-print Network

vectors (Figure 1 shows a water vortex with motion vectors pointing in all directions along the currentInteractive Motion Segmentation Claudia Nieuwenhuis1 , Benjamin Berkels2 , Martin Rumpf2 of Bonn, Germany {berkels,rumpf}@ins.uni-bonn.de Abstract. Interactive motion segmentation is an important

Cremers, Daniel

130

Cold, Clouds, and Snowflakes  

NSDL National Science Digital Library

Snow and ice are both precipitation, that is, the processes that remove water from clouds. Clouds, regions of the atmosphere with high relative humidity, are made of droplets of water and perhaps bits of ice. Even though water is much denser than air, these droplets and ice crystals are small enough to be suspended by random upward air motion. When these droplets or crystals join together, gravity overcomes the suspending force and we have precipitation. In this lesson, students will investigate NASA satellite data to determine geographical areas where wintry precipitation may have occurred based on cloud top temperature. They will explore the relationship between the amount of water vapor and the temperature of clouds, as well as snowflake shapes and cloud temperature.

131

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

132

Qualitative Analysis of Cloud Computing Risks and Framework for the Rationalization and Mitigation of Cloud Risks  

Microsoft Academic Search

Cloud computing is a popular subject across the IT industry, but risks associated with this new technology and delivery model are not yet well understood. This research investigates, in a qualitative fashion, the vectors that contribute to cloud computing risks in the areas of security, business, and compliance. The focus of this research is on the identification of risk vectors

Maria Azua Himmel

2012-01-01

133

Probing Uranus' Atmosphere With Discrete Cloud Observations  

NASA Astrophysics Data System (ADS)

We propose NIRI observations of Uranus with filters that can vertically locate discrete cloud features and cloud band spatial variations with high S/N imaging that can identify many more cloud features than previously observed. This will allow us to build a two-dimensional map of discrete cloud pressures as well as track cloud motions in regions previously undersampled or not visible. This will constrain models of cloud composition and of the mixing ratios of parent gases. It will also constrain models of meridional circulation cells by locating regions of upwelling motions. Of particular interest is the northern high latitude regions coming into better view. In the south methane is depleted in the upper troposphere, which should inhibit convection if the depletion is due to downwelling motions. The failure to detect discrete cloud features supports that model. Observations in the north polar regions will define whether there is currently a large seasonal asymmetry.

Sromovsky, Lawrence; Fry, Patrick

2011-08-01

134

Probing Uranus' Atmosphere With Discrete Cloud Observations  

NASA Astrophysics Data System (ADS)

We propose NIRI observations of Uranus with filters that can vertically locate discrete cloud features and cloud band spatial variations with high S/N imaging that can identify many more cloud features than previously observed. This will allow us to build a two-dimensional map of discrete cloud pressures as well as track cloud motions in regions previously undersampled or not visible. This will constrain models of cloud composition and of the mixing ratios of parent gases. It will also constrain models of meridional circulation cells by locating regions of upwelling motions. Of particular interest is the northern high latitude regions coming into better view. In the south methane is depleted in the upper troposphere, which should inhibit convection if the depletion is due to downwelling motions. The failure to detect discrete cloud features supports that model. Observations in the north polar regions will define whether there is currently a large seasonal asymmetry.

Sromovsky, Lawrence; Fry, Patrick

2012-08-01

135

Seeding-Opportunity Recognition in Winter Orographic Clouds  

Microsoft Academic Search

Detailed measurements of supercooled cloud water, precipitation, cloud-top temperature and vertical air motion in winter orographic clouds are used to develop criteria for the seedability of those clouds. Winter orographic clouds over the upwind mountain base with cloud-top temperatures between 0 and 22C are found to be primarily composed of supercooled water and are therefore seedable. The supercooled water concentration

Geoffrey E. Hill

1980-01-01

136

On the accuracy of approximation of a small celestial body motion using intermediate perturbed orbits calculated from two position vectors and three observations  

NASA Astrophysics Data System (ADS)

We examine intermediate perturbed orbits proposed by the first author previously, defined from the two position vectors and three angular coordinates of a small celestial body. It is shown theoretically, that at a small reference time interval covering the measurements the approximation accuracy of real movements by these orbits corresponds approximately to the third order of osculation. The smaller reference interval of time, the better this correspondence. Laws of variation of the methodical errors in constructing intermediate orbits subject to the length of reference time interval are deduced. According to these laws, the convergence rate of the methods to the exact solution (upon reducing the reference interval of time) is higher by two orders of magnitude than in the case of conventional methods using the Keplerian unperturbed orbit. The considered orbits are among the most accurate in set of orbits of their class determined by the order of osculation. The theoretical results are validated by numerical examples.

Shefer, V. A.; Shefer, O. V.

2015-01-01

137

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

138

Search Cloud  

MedlinePLUS

... Topics Drugs & Supplements Videos & Cool Tools ESPAOL Search Cloud To use the sharing features on this page, ... of Top 110 zoloft Share the MedlinePlus search cloud with your users by embedding our search cloud ...

139

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

140

Turbulence Decay and Cloud Core Relaxation in Molecular Clouds  

NASA Astrophysics Data System (ADS)

The turbulent motion within molecular clouds is a key factor controlling star formation. Turbulence supports molecular cloud cores from evolving to gravitational collapse and hence sets a lower bound on the size of molecular cloud cores in which star formation can occur. On the other hand, without a continuous external energy source maintaining the turbulence, such as in molecular clouds, the turbulence decays with an energy dissipation time comparable to the dynamic timescale of clouds, which could change the size limits obtained from Jean's criterion by assuming constant turbulence intensities. Here we adopt scaling relations of physical variables in decaying turbulence to analyze its specific effects on the formation of stars. We find that the decay of turbulence provides an additional approach for Jeans' criterion to be achieved, after which gravitational infall governs the motion of the cloud core. This epoch of turbulence decay is defined as cloud core relaxation. The existence of cloud core relaxation provides a more complete understanding of the effect of the competition between turbulence and gravity on the dynamics of molecular cloud cores and star formation.

Gao, Yang; Xu, Haitao; Law, Chung K.

2015-02-01

141

A Porn Video Detecting Method Based on Motion Features Using HMM  

Microsoft Academic Search

This paper proposes a method of identified reciprocating motion in pornographic video from other human action using Hidden Markov Model (HMM). The motion vectors are obtained by decoding the compressed MPEG video. Then the feature vectors are extracted by calculating the direction and the magnitude of the motion vectors. The feature vectors are fed to Hidden Markov Model for training

Zhiyi Qu; Yanmin Liu; Ying Liu; Kang Jiu; Yong Chen

2009-01-01

142

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.

Jeff White

2004-01-01

143

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

144

A method for reciprocating motion detection in porn video based on motion features  

Microsoft Academic Search

This paper presents a new algorithm for detecting the human's reciprocating motion in pornographic videos. First, the motion vector is extracted from mpeg video stream and pretreated so that the motion features are extracted by analyzing the motion rule of the objectionable videos. Then the whole videos are detected through setting a threshold. Experimental results demonstrate that the correct recognition

Qu Zhiyi; Liu Yanmin; Liu Ying; Jiu Kang; Chen Yong

2009-01-01

145

Reducing rate\\/complexity in video coding by motion estimation with block adaptive accuracy  

Microsoft Academic Search

Classical block-based motion-compensated video coders need to find and code a motion field with one motion vector per image block. All motion vectors are computed and encoded with the same fixed accuracy, typically 1 or one-half pixel accuracy. Higher motion vector accuracies have been shown to significantly reduce the total bit rate in some video sequences, but motion estimation at

Jordi Ribas-Corbera; David L. Neuhoff

1996-01-01

146

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

147

Studies of radiative effects for polar stratospheric clouds  

NASA Technical Reports Server (NTRS)

Data from the Antarctic Ozone Experiment of 1987 are used to model the radiative effects of polar stratospheric clouds. Heating and cooling rates are examined, showing that the heating and/or cooling rates within a polar stratospheric cloud depend on particle size, composition, optical depth of the cloud, solar angle, and temperature profile. The rates for an optically thin Type I cloud are too small to drive vertical motions in the stratosphere, while optically thin Type II clouds cause a stratospheric cooling.

Kinne, S.; Toon, O. B.

1989-01-01

148

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.

149

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

2007-06-28

150

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

151

Low Clouds  

Atmospheric Science Data Center

... and reddening of the hues in the foreground. Stereoscopic analysis of the data from multiple MISR cameras indicates that the cloud tops ... formats available at JPL July 23, 2007 - Trend of decreasing global cloud height during the last decade. ...

2013-04-19

152

Vector quantization  

Microsoft Academic Search

A vector quantizer is a system for mapping a sequence of continuous or discrete vectors into a digital sequence suitable for communication over or storage in a digital channel. The goal of such a system is data compression: to reduce the bit rate so as to minimize communication channel capacity or digital storage memory requirements while maintaining the necessary fidelity

Robert M. Gray

1984-01-01

153

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

154

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

155

An Inexpensive Mechanical Model for Projectile Motion  

ERIC Educational Resources Information Center

As experienced physicists, we see the beauty and simplicity of projectile motion. It is merely the superposition of uniform linear motion along the direction of the initial velocity vector and the downward motion due to the constant acceleration of gravity. We see the kinematic equations as just the mathematical machinery to perform the

Kagan, David

2011-01-01

156

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.

2004-12-14

157

Mesoscale wake clouds in Skylab pictures.  

NASA Technical Reports Server (NTRS)

The recognition of cloud patterns formed in the wake of orographic obstacles was investigated using pictures from Skylab, for the purpose of estimating atmospheric motions. The existence of ship-wake-type wave clouds in contrast to vortex sheets were revealed during examination of the pictures, and an attempt was made to characterize the pattern of waves as well as the transition between waves and vortices. Examples of mesoscale cloud patterns which were analyzed photogrammetrically and meteorologically are presented.

Fujita, T. T.; Tecson, J. J.

1974-01-01

158

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!

Dray, Tevian

2006-01-01

159

Cloning vector  

DOEpatents

A vector comprising a filamentous phage sequence containing a first copy of filamentous phage gene X and other sequences necessary for the phage to propagate is disclosed. The vector also contains a second copy of filamentous phage gene X downstream from a promoter capable of promoting transcription in a bacterial host. In a preferred form of the present invention, the filamentous phage is M13 and the vector additionally includes a restriction endonuclease site located in such a manner as to substantially inactivate the second gene X when a DNA sequence is inserted into the restriction site.

Guilfoyle, Richard A. (Madison, WI); Smith, Lloyd M. (Madison, WI)

1994-01-01

160

Cloning vector  

DOEpatents

A vector comprising a filamentous phage sequence containing a first copy of filamentous phage gene X and other sequences necessary for the phage to propagate is disclosed. The vector also contains a second copy of filamentous phage gene X downstream from a promoter capable of promoting transcription in a bacterial host. In a preferred form of the present invention, the filamentous phage is M13 and the vector additionally includes a restriction endonuclease site located in such a manner as to substantially inactivate the second gene X when a DNA sequence is inserted into the restriction site. 2 figures.

Guilfoyle, R.A.; Smith, L.M.

1994-12-27

161

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

162

EDITORIAL: Focus on Cloud Physics FOCUS ON CLOUD PHYSICS  

NASA Astrophysics Data System (ADS)

Cloud physics has for a long time been an important segment of atmospheric science. It is common knowledge that clouds are crucial for our understanding of weather and climate. Clouds are also interesting by themselves (not to mention that they are beautiful). Complexity is hidden behind the common picture of these beautiful and interesting objects. The typical school textbook definition that a cloud is 'a set of droplets or particles suspended in the atmosphere' is not adequate. Clouds are complicated phenomena in which dynamics, turbulence, microphysics, thermodynamics and radiative transfer interact on a wide range of scales, from sub-micron to kilometres. Some of these interactions are subtle and others are more straightforward. Large and small-scale motions lead to activation of cloud condensation nuclei, condensational growth and collisions; small changes in composition and concentration of atmospheric aerosol lead to significant differences in radiative properties of the clouds and influence rainfall formation. It is justified to look at a cloud as a composite, nonlinear system which involves many interactions and feedback. This system is actively linked into a web of atmospheric, oceanic and even cosmic interactions. Due to the complexity of the cloud system, present-day descriptions of clouds suffer from simplifications, inadequate parameterizations, and omissions. Sometimes the most fundamental physics hidden behind these simplifications and parameterizations is not known, and a wide scope of view can sometimes prevent a 'microscopic', deep insight into the detail. Only the expertise offered by scientists focused on particular elementary processes involved in this complicated pattern of interactions allows us to shape elements of the puzzle from which a general picture of clouds can be created. To be useful, every element of the puzzle must be shaped precisely. This often creates problems in communication between the sciences responsible for shaping elements of the puzzle, and those which combine them. Scales, assumptions and the conditions used in order to describe a particular single process of interest must be consistent with the conditions in clouds. The papers in this focus issue of New Journal of Physics collectively demonstrate (i) the variation in scientific approaches towards investigating cloud processes, (ii) the various stages of shaping elements of the puzzle, and (iii) some attempts to put the pieces together. These papers present just a small subset of loosely arranged elements in an initial stage of puzzle creation. Addressed by this issue is one of the important problems in our understanding of cloud processesthe interaction between cloud particles and turbulence. There is currently a gap between the cloud physics community and scientists working in wind tunnels, on turbulence theory and particle interactions. This collection is intended to narrow this gap by bringing together work by theoreticians, modelers, laboratory experimentalists and those who measure and observe actual processes in clouds. It forms a collage of contributions showing various approaches to cloud processes including: theoretical works with possible applications to clouds (Bistagnino and Boffetta, Gustavsson et al), an attempt to construct a phenomenological description of clouds and rain (Lovejoy and Schertzer), simplified models designed to parameterize turbulence micro- and macro-effects (Celani et al, Derevyanko et al), focused theoretical research aimed at particular cloud processes (Ayala et al, parts I and II, Wang et al), laboratory and modeling studies of complex cloud processes (Malinowski et al). This collage is far from being complete but, hopefully, should give the reader a representative impression of the current state of knowledge in the field. We hope it will be useful to all scientists whose work is inspired by cloud processes. Focus on Cloud Physics Contents The development of ice in a cumulus cloud over southwest England Yahui Huang, Alan M Blyth, Philip R A Brown, Tom W Choularton,

Falkovich, Gregory; Malinowski, Szymon P.

2008-07-01

163

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

164

Seeing Motion  

NSDL National Science Digital Library

Explore your own straight-line motion using a motion sensor to generate distance versus time graphs of your own motion. Learn how changes in speed and direction affect the graph, and gain an understanding of how motion can be represented on a graph.

2012-07-19

165

Reciprocal Vectors  

NASA Astrophysics Data System (ADS)

Reciprocal vectors and barycentric coordinates are well-established concepts in various scientific fields, where lattices and grids are essential, e.g., in solid state physics, crystallography, in the numerical analysis of partial differential equations using finite elements, and also in computer graphics and visualisation. In preparation of the Cluster mission, Chanteur [1998] in Chapter 14 of ISSI SR-001 adopted reciprocal vectors to construct estimators for spatial derivatives from four-point measurements, to perform error analysis, and to write down the spatial aliasing condition for four-point wave analysis techniques in a very transparent form. Reciprocal vectors also entered the study on the ac- curacy of plasma moment derivatives, described in Chapter 17 of ISSI SR-001 [Vogt and Paschmann, 1998]. As will be shown below, by using the least squares approach presented in Chapter 12 of ISSI SR-001 [Harvey, 1998], reciprocal vectors are a convenient means in discontinuity analysis to express boundary parameters in terms of crossing times. This chapter is intended to provide a conceptual introduction to reciprocal vectors, and to emphasise their importance for the analysis of data from the Cluster spacecraft mission. It is organised as follows: The crossing times approach to boundary analysis is presented in Section 4.2 as a way to motivate the use of reciprocal vectors; some of their most important properties are briefly addressed in Section 4.3; then Section 4.4 deals with various aspects of the spatial gradient reconstruction problem; magnetic curvature estimation is reviewed in Section 4.5, while Section 4.6 contains a discussion on the errors of boundary analysis and curvature estimation. Finally, in Section 4.7 we suggest a way to generalise the reciprocal vector concept to cases where the number of spacecraft, N, is not four.

Vogt, Joachim; Paschmann, Gotz; Chanteur, Grard

166

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

167

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

168

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.

169

Observe Clouds  

NSDL National Science Digital Library

If you observe clouds in a portion of the sky, you may notice that they are not static. Clouds are composed of tiny particles of water and are constantly changing and moving. This video lets viewers observe clouds forming, moving, and changing shape. The segment is one minute thirty-three seconds in length. A background essay and list of discussion questions are also provided.

170

Cloud Types  

NSDL National Science Digital Library

This NASA website uses Macromedia Flash Player to educate users about clouds. After a short introduction, students can learn about four levels of clouds: low, mid, high, and multi. The website describes how to determine cloud level as well. Throughout the tutorial, students can listen to the explanations while viewing informative images. Users can also choose to view the text associated with the audio. While this tutorial was created for schools participating in the S'COOL project, everyone can learn a great deal about clouds from this website.

171

Navigational Vectors  

NSDL National Science Digital Library

This is a high school instructional unit that features nine lessons relating to vectors. Students build understanding of vector properties as they learn airplane navigation. Problem-based learning activities include reading real-time weather maps, tracking airplanes flying in U.S. skies, calculating vector components, analyzing effects of wind velocity, and completing training segments similar to a private pilot certification program. Participants have access to help from experts at the Polaris Career Center. Comprehensive teacher guides, student guides, reference materials, and assessments are included. This resource was developed by the Center for Innovation in Science and Engineering Education (CIESE). Participation is cost-free; additional options are available for registered users.

2008-12-10

172

Fast sub-pixel motion estimation having lower complexity  

Microsoft Academic Search

This paper presents fast sub-pixel motion estimation having less computational complexity. The proposed methods are based on mathematical models of the motion compensated errors for moving picture compression. The methods need no interpolation from the integer-pixel search results. In order to decide the coefficients of the models, the motion compensated errors of the neighboring pixels around motion vectors are used.

Jechang Jeong

2003-01-01

173

Vector carpets  

SciTech Connect

Previous papers have described a general method for visualizing vector fields that involves drawing many small ``glyphs`` to represent the field. This paper shows how to improve the speed of the algorithm by utilizing hardware support for line drawing and extends the technique from regular to unstructured grids. The new approach can be used to visualize vector fields at arbitrary surfaces within regular and unstructured grids. Applications of the algorithm include interactive visualization of transient electromagnetic fields and visualization of velocity fields in fluid flow problems.

Dovey, D.

1995-03-22

174

Satellite photography as a means of evaluating the equations of vertical motion  

E-print Network

of evaluating computed vertical-. motion fields and should eventually contribute to improvement of the procedures used to compute vertical motions. A lag, or "trailing effect, " was noted in the rela- tion between the vertical-motion patterns and the cloud... distribution. The regions of cloudiness often were dis- placed from the centers of upward motion. This effect seemed particularly evident for rapidly moving vertical- motion patterns. The cloud activity was most frequently displaced in the direction from...

Hansen, John

1963-01-01

175

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

176

Cloud Control  

ERIC Educational Resources Information Center

Your learning curriculum needs a new technological platform, but you don't have the expertise or IT equipment to pull it off in-house. The answer is a learning system that exists online, "in the cloud," where learners can access it anywhere, anytime. For trainers, cloud-based coursework often means greater ease of instruction resulting in greater

Weinstein, Margery

2012-01-01

177

Cloud Cover  

ERIC Educational Resources Information Center

This article features a major statewide initiative in North Carolina that is showing how a consortium model can minimize risks for districts and help them exploit the advantages of cloud computing. Edgecombe County Public Schools in Tarboro, North Carolina, intends to exploit a major cloud initiative being refined in the state and involving every

Schaffhauser, Dian

2012-01-01

178

Cloud Control  

ERIC Educational Resources Information Center

For many IT shops, the cloud offers an opportunity not only to improve operations but also to align themselves more closely with their schools' strategic goals. The cloud is not a plug-and-play proposition, however--it is a complex, evolving landscape that demands one's full attention. Security, privacy, contracts, and contingency planning are all

Ramaswami, Rama; Raths, David; Schaffhauser, Dian; Skelly, Jennifer

2011-01-01

179

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

180

Pipeline vectorization  

Microsoft Academic Search

This paper presents pipeline vectorization, amethod for synthesizing hardware pipelines based on softwarevectorizing compilers. The method improves eciencyand ease of development of hardware designs, particularlyfor users with little electronics design experience. We proposeseveral loop transformations to customize pipelinesto meet hardware resource constraints, while maximizingavailable parallelism. For run-time recongurable systems,we apply hardware specialization to increase...

Markus Weinhardt; Wayne Luk

2001-01-01

181

Diurnal polar motion  

NASA Technical Reports Server (NTRS)

An analytical theory is developed to describe diurnal polar motion in the earth which arises as a forced response due to lunisolar torques and tidal deformation. Doodson's expansion of the tide generating potential is used to represent the lunisolar torques. Both the magnitudes and the rates of change of perturbations in the earth's inertia tensor are included in the dynamical equations for the polar motion so as to account for rotational and tidal deformation. It is found that in a deformable earth with Love's number k = 0.29, the angular momentum vector departs by as much as 20 cm from the rotation axis rather than remaining within 1 or 2 cm as it would in a rigid earth. This 20 cm separation is significant in the interpretation of submeter polar motion observations because it necessitates an additional coordinate transformation in order to remove what would otherwise be a 20 cm error source in the conversion between inertial and terrestrial reference systems.

Mcclure, P.

1973-01-01

182

Ice Motion Over Lake Vostok  

Microsoft Academic Search

Abstract Ice motion,over Lake Vostok is measured using,repeat-pass Synthetic,Aperture Radar (SAR) interferometry. The coverage of the lake and the components,of the vector field are resolved using ten overlapping data takes from ascending and descending,look directions. Seventy-day temporal baselines provide the sensitivity required to observe the range of ice motion,(0-6 m\\/yr) over the lake and ,the adjacent ice sheet. It is

R. Kwok; M. J. Siegert; F. D. Carsey

1999-01-01

183

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

184

Motion Sickness  

MedlinePLUS

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

185

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-Alfvnic internal motions on the level of a few hundred km s-1.

Krause, Martin; Schartmann, Marc; Burkert, Andreas

2012-10-01

186

Plate motion  

SciTech Connect

The motion of tectonic plates on the earth is characterized in a critical review of U.S. research from the period 1987-1990. Topics addressed include the NUVEL-1 global model of current plate motions, diffuse plate boundaries and the oceanic lithosphere, the relation between plate motions and distributed deformations, accelerations and the steadiness of plate motions, the distribution of current Pacific-North America motion across western North America and its margin, plate reconstructions and their uncertainties, hotspots, and plate dynamics. A comprehensive bibliography is provided. 126 refs.

Gordon, R.G. (USAF, Geophysics Laboratory, Hanscom AFB, MA (United States))

1991-01-01

187

Presentation entitled Fluid motion in a cylindrical container subject to  

E-print Network

: In the atmosphere and even the oceans the vortex motion is 2D as long as the thickness layer of the fluid is small developing a 3D motion out of the 2D . 2D von Karman Vortex street clouds Experimental investigations urged . 4 L. Zaidouny #12;Geophysics: In the atmosphere and the oceans the vortex motion may be considered 2

Shihadeh, Alan

188

Vector representation of trade cumulus thermodynamic fluxes  

NASA Technical Reports Server (NTRS)

A tephigram of BOMEX averaged thermodynamic flux vectors, developed from two tradewind budgets, is presented. The parametric model, which is utilized to represent the fluxes in the tradewind layer of the product as a mass flux and a cloud-environment difference, is examined. A table of mean structure and fluxes of a dataset for the BOMEX ship array, and the Bowen ratio and convective mass flux for a nonmixing and a cloud-top mixing model is provided. The fluxes which are displayed in a simple vector format, using the saturation point notation of Betts (1982) reveal a coupling of fluxes and the relationship between Bowen ratio and height. It is concluded that with good tradewind budget data about the statistics of cloud mixing and radiative-convective coupling can be expressed.

Betts, A. K.

1985-01-01

189

Cloud Games  

NSDL National Science Digital Library

Play these two matching games from the Web Weather for Kids site to pair cloud images with their names/types! Developed by the University Corporation for Atmospheric Research, this site requires Java.

University Corporation for Atmospheric Research - Education and Outreach Programs

2010-01-01

190

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

2007-10-16

191

Anisotropic universes with conformal motion  

E-print Network

By imposing natural geometrical and kinematical conditions on a conformal Killing vector in Bianchi I spacetime, we show that a class of axisymmetric metrics admits a conformal motion. This class contains new exact solutions of Einstein's equations, including anisotropic radiation universes that isotropise at late times.

Roy Maartens; Conrad Mellin

1996-02-09

192

Successive elimination algorithm for motion estimation  

Microsoft Academic Search

The correspondence presents a fast exhaustive search algorithm for motion estimation. The basic idea is to obtain the best estimate of the motion vectors by successively eliminating the search positions in the search window and thus decreasing the number of matching evaluations that require very intensive computations. Simulation results demonstrate that although the performance of the proposed algorithm is the

Wenhua Li; Ezzatollah Salari

1995-01-01

193

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...

194

CloudSat Studies Clouds (Artist's Concept)  

NASA Technical Reports Server (NTRS)

This artist's concept shows NASA's CloudSat spacecraft and its Cloud Profiling Radar using microwave energy to observe cloud particles and determine the mass of water and ice within clouds. The mission will collect information about the vertical structure of clouds that will help answer key questions about how they form, evolve and affect our weather, climate and water supply.

2005-01-01

195

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

196

An Ego-Motion Detection System Employing Directional-Edge-Based Motion Field Representations  

NASA Astrophysics Data System (ADS)

In this paper, a motion field representation algorithm based on directional edge information has been developed. This work is aiming at building an ego-motion detection system using dedicated VLSI chips developed for real time motion field generation at low powers[1],[2]. Directional edge maps are utilized instead of original gray-scale images to represent local features of an image and to detect the local motion component in a moving image sequence. Motion detection by edge histogram matching has drastically reduced the computational cost of block matching, while achieving a robust performance of the ego-motion detection system under dynamic illumination variation. Two kinds of feature vectors, the global motion vector and the component distribution vectors, are generated from a motion field at two different scales and perspectives. They are jointly utilized in the hierarchical classification scheme employing multiple-clue matching. As a result, the problems of motion ambiguity as well as motion field distortion caused by camera shaking during video capture have been resolved. The performance of the ego-motion detection system was evaluated under various circumstances, and the effectiveness of this work has been verified.

Hao, Jia; Shibata, Tadashi

197

Cloud Computing Fundamentals  

Microsoft Academic Search

\\u000a In the introductory chapter we define the concept of cloud computing and cloud services, and we introduce layers and types\\u000a of cloud computing. We discuss the differences between cloud computing and cloud services. New technologies that enabled cloud\\u000a computing are presented next. We also discuss cloud computing features, standards, and security issues. We introduce the key\\u000a cloud computing platforms, their

Borko Furht

2010-01-01

198

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 ...

Ms. Stewart

2010-03-24

199

CLOUD CHEMISTRY.  

SciTech Connect

Clouds present substantial concentrations of liquid-phase water, which can potentially serve as a medium for dissolution and reaction of atmospheric gases. The important precursors of acid deposition, SO{sub 2} and nitrogen oxides NO and NO{sub 2} are only sparingly soluble in clouds without further oxidation to sulfuric and nitric acids. In the case of SO{sub 2} aqueous-phase reaction with hydrogen peroxide, and to lesser extent ozone, are identified as important processes leading to this oxidation, and methods have been described by which to evaluate the rates of these reactions. The limited solubility of the nitrogen oxides precludes significant aqueous-phase reaction of these species, but gas-phase reactions in clouds can be important especially at night.

SCHWARTZ,S.E.

2001-03-01

200

Neptune's clouds  

NASA Technical Reports Server (NTRS)

The bright cirrus-like clouds of Neptune change rapidly, often forming and dissipating over periods of several to tens of hours. In this sequence Voyager 2 observed cloud evolution in the region around the Great Dark Spot (GDS). The surprisingly rapid changes which occur separating each panel shows that in this region Neptune's weather is perhaps as dynamic and variable as that of the Earth. However, the scale is immense by our standards -- the Earth and the GDS are of similar size -- and in Neptune's frigid atmosphere, where temperatures are as low as 55 degrees Kelvin (-360 F), the cirrus clouds are composed of frozen methane rather than Earth's crystals of water ice. The Voyager Mission is conducted by JPL for NASA's Office of Space Science and Applications

1999-01-01

201

Fusion of LIDAR Data and Large-scale Vector Maps for Building Reconstruction  

Microsoft Academic Search

LIDAR data contains plenty of height information, while vector maps preserve accurate building boundaries. From the viewpoint of data fusion, we integrate LIDAR data and large-scale vector maps to perform building modeling. The proposed scheme comprises six major steps: (1) preprocessing of LIDAR data and vector maps, (2) extraction of point clouds that belong to a building, (3) construction of

Liang-Chien Chen; Chih-Yi Kuo; Jiann-Yeou Rau; Chi-Heng Hsieh

202

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

203

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.

204

Motion Simulator  

NASA Technical Reports Server (NTRS)

Visitors to StenniSphere can feel the motion of a ride to Mars with a ride on StenniSphere's full motion simulator. The simulator is the only attraction at StenniSphere for which there is a charge. Adult rides are $4 and children ride for $3. Group discounts are also available.

2000-01-01

205

Cloud Computing Adam Barker  

E-print Network

Cloud Computing 1 Adam Barker #12;Overview · Introduction to Cloud computing · Enabling technologies · Di erent types of cloud: IaaS, PaaS and SaaS · Cloud terminology · Interacting with a cloud: management consoles · Launching an instance · Connecting to an instance · Running your application · Clouds

St Andrews, University of

206

Event monitoring via local motion abnormality detection in non-linear subspace Ioannis Tziakosa,1  

E-print Network

motion vectors extracted over a Region of Interest (ROI) as features and a non-linear, graph] Probability distribution Adam et al. [1] Frame Object detection Graph co-clustering Zhong et al. [34] PCA + SVM Sudo et al. [26] Object + motion Mixture of Gaussian HMM Andrade et al. [2] Motion vectors

Cavallaro, Andrea

207

Cloud Identification  

NSDL National Science Digital Library

In this online, interactive module, students learn about the ten common cloud types and how they are formed and how to identify different cloud types on satellite images. The module is part of an online course for grades 7-12 in satellite meteorology, which includes 10 interactive modules. The site also includes lesson plans developed by teachers and links to related resources. Each module is designed to serve as a stand-alone lesson, however, a sequential approach is recommended. Designed to challenge students through the end of 12th grade, middle school teachers and students may choose to skim or skip a few sections.

2012-08-03

208

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

209

Image transfer through cirrus clouds. II. Wave-front segmentation and imaging.  

PubMed

A hybrid technique to simulate the imaging of space-based objects through cirrus clouds is presented. The method makes use of standard Huygens-Fresnel propagation beyond the cloud boundary and a novel vector trace approach within the cloud. At the top of the cloud, the wave front is divided into an array of input gradient vectors, which are in turn transmitted through the cloud model by use of the Coherent Illumination Ray Trace and Imaging Software for Cirrus. At the bottom of the cloud, the output vector distribution is used to reconstruct a wave front that continues propagating to the ground receiver. Images of the object as seen through cirrus clouds with different optical depths are compared with a diffraction-limited image. Turbulence effects from the atmospheric propagation are not included. PMID:12510928

Landesman, Barbara T; Matson, Charles L

2002-12-20

210

Stellar Encounters with the Oort Cloud Based on Hipparcos Data  

NASA Technical Reports Server (NTRS)

We have combined Hipparcos proper motion and parallax data for nearby stars with ground-based radial velocity measurements to find stars which may have passed (or will pass) close enough to the Sun to perturb the Oort cloud.

Garcia-Sanchez, J.; Preston, R. A.; Jones, D. L.; Weissman, P. R.; Lestrade, J. F.; Latham, D. W.; Stefanik, R. P.

1998-01-01

211

A global survey of cloud overlap based on CALIPSO and CloudSat measurements  

NASA Astrophysics Data System (ADS)

Using 2B-CLDCLASS-LIDAR (radar-lidar) cloud classification and 2B-FLXHR-LIDAR radiation products from CloudSat over 4 years, this study evaluates the co-occurrence frequencies of different cloud types, analyzes their along-track horizontal scales and cloud radiative effects (CREs), and utilizes the vertical distributions of cloud types to evaluate cloud-overlap assumptions. The statistical results show that high clouds, altostratus (As), altocumulus (Ac) and cumulus (Cu) tend to coexist with other cloud types. However, stratus (St) (or stratocumulus, Sc), nimbostratus (Ns) and convective clouds are much more likely to exhibit individual features than other cloud types. On average, altostratus-over-stratus/stratocumulus cloud systems have a maximum horizontal scale of 17.4 km, with a standard deviation of 23.5 km. Altocumulus-over-cumulus cloud types have a minimum scale of 2.8 km, with a standard deviation of 3.1 km. By considering the weight of each multilayered cloud type, we find that the global mean instantaneous net CREs of multilayered cloud systems during the daytime are approximately -41.3 and -50.2 W m-2, which account for 40.1 and 42.3% of the global mean total net CREs at the top of the atmosphere (TOA) and at the surface, respectively. The radiative contributions of high-over-altocumulus and high-over-stratus/stratocumulus (or cumulus) in the all multilayered cloud systems are dominant due to their frequency. Considering the overlap of cloud types, the cloud fraction based on the random overlap assumption is underestimated over vast oceans, except in the west-central Pacific Ocean warm pool. Obvious overestimations mainly occur over tropical and subtropical land masses. In view of a lower degree of overlap than that predicted by the random overlap assumption to occur over the vast ocean, particularly poleward of 40 S, the study therefore suggests that a linear combination of minimum and random overlap assumptions may further improve the predictions of actual cloud fractions for multilayered cloud types (e.g., As + St/Sc and Ac + St/Sc) over the Southern Ocean. The establishment of a statistical relationship between multilayered cloud types and the environmental conditions (e.g., atmospheric vertical motion, convective stability and wind shear) would be useful for parameterization design of cloud overlap in numerical models.

Li, J.; Huang, J.; Stamnes, K.; Wang, T.; Lv, Q.; Jin, H.

2015-01-01

212

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

213

Motion and force control for multiple cooperative manipulators  

Microsoft Academic Search

The authors address the problem of motion and force control of multiple robot arms manipulating an object. A general control paradigm that decouples the motion and force control problems is introduced. For motion control, different control strategies are constructed on the basis of control input variables. There are three natural choices: joint torques, arm tip force vectors, and the acceleration

John T. Wen; K. Kreutz

1989-01-01

214

Interstellar Gas Flow Vector and Temperature Determination over 5 Years of IBEX Observations  

NASA Astrophysics Data System (ADS)

The Interstellar Boundary Explorer (IBEX) observes the interstellar neutral gas flow trajectories at their perihelion in Earth's orbit every year from December through early April, when the Earth's orbital motion is into the oncoming flow. These observations have defined a narrow region of possible, but very tightly coupled interstellar neutral flow parameters, with inflow speed, latitude, and temperature as well-defined functions of inflow longitude. The best- fit flow vector is different by ? 3 and lower by ? 3 km/s than obtained previously with Ulysses GAS, but the temperature is comparable. The possible coupled parameter space reaches to the previous flow vector, but only for a substantially higher temperature (by ? 2000 K). Along with recent pickup ion observations and including historical observations of the interstellar gas, these findings have led to a discussion, whether the interstellar gas flow into the solar system has been stable or variable over time. These intriguing possibilities call for more detailed analysis and a longer database. IBEX has accumulated observations over six interstellar flow seasons. We review key observations and refinements in the analysis, in particular, towards narrowing the uncertainties in the temperature determination. We also address ongoing attempts to optimize the flow vector determination through varying the IBEX spacecraft pointing and discuss related implications for the local interstellar cloud and its interaction with the heliosphere.

Mbius, E.; Bzowski, M.; Fuselier, S. A.; Heirtzler, D.; Kubiak, M. A.; Kucharek, H.; Lee, M. A.; Leonard, T.; McComas, D. J.; Schwadron, N.; Sok?, J. M.; Wurz, P.

2015-01-01

215

Complex Clouds  

Atmospheric Science Data Center

... View Larger Image The complex structure and beauty of polar clouds are highlighted by these images acquired by the Multi-angle ... cyclonic circulation over the Southern Indian Ocean, to the north of Enderbyland, East Antarctica. The image at left was created by ...

2013-04-16

216

THE LAW OF VECTOR FIELDS Daniel H. Gottlieb  

E-print Network

with the same acceleration, or Kepler's * *laws governing the motion of the planets, or the daily movements THE LAW OF VECTOR FIELDS Daniel H. Something fantastically beautiful. This something is the existence of a few general laws or principles which

217

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

218

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

219

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

220

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. Editor's Note: Modeling is a powerful way for students to relate the math formula to the physical process under study. This lesson allows learners to develop hand-crafted "flipbook" models of motion before they advance to computer modeling. In each challenge, data is provided so the animations can be computationally accurate.

Ted Latham

221

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.

222

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

223

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

224

Vectors: Tip to Tail  

NSDL National Science Digital Library

In this lesson students will learn the characteristics and appropriate use of vectors. They will find the magnitude and direction of vectors, they will add and subtract vectors and use an interactive website to practice what they have learned.

Sharon Linamen

2012-07-23

225

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

226

Cloud in cloud: approaches and implementations  

Microsoft Academic Search

Facilitated by the development of virtual machine (VM) technology, distributed computing and high-speed internet, cloud computing has been gradually adopted in industry and in education to deliver on-demand services and applications remotely. In this paper, a cloud-in-cloud model, useful for technical training and research, is discussed. We describe cloud-in-cloud infrastructures in three primary configurations. The Type A configuration refers to

Peng Li; Lee W. Toderick

2010-01-01

227

How Does the Global-Scale Atmosphere Circulation Produce Clouds?  

NASA Technical Reports Server (NTRS)

Although clouds are produced by "micro-scale" processes, these processes operate as a response to global-scale atmospheric motions to produce the complex geographic distribution of clouds on Earth. One way to attack this larger-scale problem is to combine global-scale satellite observations of cloud property variations with global-scale determinations of the atmospheric circulation. Such a global data analysis can be used to describe the mean characteristics of clouds and their variations for comparison with global circulation models, to identify systematic relations among observed cloud properties and atmospheric motions, or to estimate, directly, the derivative relations of the processes at work using statistical life-cycle-composites of cloud system evolution. Another approach is to find what characteristics of the global atmospheric circulation are revealed in observed global-scale cloud variations. For the first time this type of analysis is possible with the advent of global, satellite-based cloud (ISCCP), precipitation (microwave-based), and water vapor (merged infrared and microwave) datasets, together with global wind datasets (ECMWF and NCEP re-analyses), all of which resolve features at least down to the upper end of the mesoscale and cover more than a decade. We report on some preliminary attempts to identify quantitative relationships between atmospheric motions and cloud properties that are relevant to cloud processes. Three examples are given: (1) cloud variations at the smallest scales and what they reveal about the nature of small-scale turbulence in the atmospheric boundary layer, (2) cloud variations at "moderate" weather-scales and what they reveal about meteorological storm systems, and (3) cloud variations at the largest scales and what they indicate about interannual variations of climate.

Rossow, William B.

1999-01-01

228

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

229

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.

230

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

231

Deep Convective Clouds  

NSDL National Science Digital Library

Convective clouds are clouds that develop vertically appearing like big stacks of clouds. One very common example is cumulonimbus clouds. Convective clouds are commonly connected to stormy weather. Monthly Cloud Coverage for Deep Convective Cloud data can be used to predict patterns in weather. The specific pattern associated with this data is tracking and predicting thunderstorms. In this lesson, the students will take a look at the Monthly Cloud Coverage for Deep Convective Cloud data, and name one month of the year 'Thunderstorm Season' for their continent.

232

Toward Securing Sensor Clouds  

E-print Network

Computing Cloud Computing Tower-mount Antenna Tower-mount Antenna Wireless Bridge Security Threats 1. CloudToward Securing Sensor Clouds Apu Kapadia, Steven Myers, XiaoFeng Wang and Geoffrey Fox School Computer Mini Computer External Storage External Storage Router Router Router Router Cloud Computing Cloud

233

Cloud Computing For Bioinformatics  

E-print Network

Cloud Computing For Bioinformatics #12;Cloud Computing: what is it? · Cloud Computing is a distributed infrastructure where resources, software, and data are provided in an on-demand fashion. · Cloud Computing abstracts infrastructure from application. · Cloud Computing should save you time the way software

Ferrara, Katherine W.

234

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

235

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

236

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

237

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.

238

Storm and Clouds  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Yesterday's storm front was moving westward, today's moves eastward. Note the thick cloud cover and beautifully delineated cloud tops.

Image information: VIS instrument. Latitude 72.1, Longitude 308.3 East (51.7 West). 40 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

239

Does scattered radiation undergo bluing within clouds?  

NASA Astrophysics Data System (ADS)

Airborne spectral radiative data are used for estimation of bluing of radiation within clouds. The kind of vector with three components (irradiance or radiance at UV, visible and near IR channels) is considered and its transformation within cloud is analyzed. A similar procedure has used for the case of clear atmosphere. Russian spectral observation of upward and downward fluxes and NASA observation with Cloud Absorption Radiometer (CAR) of diffused intensity in 8 spectral channels are taken for consideration in cloudy and clear atmosphere. Spectral dependence of the scattering coefficient in clouds was revealed for retrieved optical parameters from radiative observations of both kinds. Possible explanation is proposed that confirms mutual influence of molecular and Mie multiple scattering in the cloudy media.

Melnikova, I.; Simakina, T.; Vasilyev, A.; Gatebe, C.; Varotsos, C.

2013-05-01

240

Cloud Infrastructure & Applications - CloudIA  

Microsoft Academic Search

The idea behind Cloud Computing is to deliver Infrastructure-as-a-Services and Software-as-a-Service over the Internet on\\u000a an easy pay-per-use business model. To harness the potentials of Cloud Computing for e-Learning and research purposes, and\\u000a to small- and medium-sized enterprises, the Hochschule Furtwangen University establishes a new project, called Cloud Infrastructure\\u000a & Applications (CloudIA). The CloudIA project is a market-oriented cloud infrastructure

Anthony Sulistio; Christoph Reich; Frank Doelitzscher

2009-01-01

241

Dust cloud manipulation in microgravity experiments  

NASA Astrophysics Data System (ADS)

The European Space Agencys 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

242

Magnetohydrodynamics of Cloud Collisions in a Multiphase Interstellar Medium  

NASA Astrophysics Data System (ADS)

We extend previous studies of the physics of interstellar cloud collisions by beginning an investigation of the role of magnetic fields through two-dimensional magnetohydrodynamical (MHD) numerical simulations. In particular, we study head-on collisions between equal mass, mildly supersonic, diffuse clouds similar to those in our previous study. Here we include a moderate magnetic field, corresponding to ?=pg/pb=4, and two limiting field geometries, with the field lines parallel (aligned) and perpendicular (transverse) to the colliding cloud motion. We explore both adiabatic and radiative (?=?rad/?coll~=0.38) cases, and we simulate collisions between clouds evolved through prior motion in the intercloud medium. In addition to the collision of evolved identical clouds (symmetric cases), we also study collisions of clouds that are initially identical but have different evolutionary ages (asymmetric cases). Depending on their geometry, magnetic fields can significantly alter the outcome of the collisions compared to the hydrodynamic (HD) case. (1) In the aligned case, adiabatic collisions, like their HD counterparts, are very disruptive independently of the symmetry. However, when radiative processes are taken into account, partial coalescence takes place even in the asymmetric case, unlike the HD calculations. (2) In the transverse case, the effects of the magnetic field are even more dramatic, with remarkable differences between unevolved and evolved clouds. Collisions between (initially adjacent) unevolved clouds are almost unaffected by magnetic fields. However, the interaction with the magnetized intercloud gas during precollision evolution produces a region of very high magnetic energy in front of the cloud. In collisions between evolved clouds with transverse field geometry, this region acts like a bumper, preventing direct contact between the clouds and eventually reversing their motion. The elasticity, defined as the ratio of the final to the initial kinetic energy of each cloud, is about 0.5-0.6 in the cases we considered. This behavior is found in both adiabatic and radiative cases.

Miniati, Francesco; Ryu, Dongsu; Ferrara, Andrea; Jones, T. W.

1999-01-01

243

Ad hoc cloud computing  

E-print Network

Commercial and private cloud providers offer virtualized resources via a set of co-located and dedicated hosts that are exclusively reserved for the purpose of offering a cloud service. While both cloud models appeal to ...

McGilvary, Gary Andrew

2014-11-27

244

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

245

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

246

Vector-Borne Diseases  

NSDL National Science Digital Library

This online encyclopedia article discusses vector-borne diseases. It defines vectors as the transmitters of disease-causing organisms that carry the pathogens from one host to another. The article reviews the biological range of vectors, the transmission and types of vector-borne diseases, patterns of occurrence and existing control measures.

Harvey Artsob

247

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.

Duane Friend

248

LBNL 38220/PEP-II AP 96-03/CBP Note-173 THE ELECTRON-CLOUD INSTABILITY IN PEP-II*  

E-print Network

-charged beam creates a cloud of electrons in the vacuum chamber. This cloud couples the transverse motionsLBNL 38220/PEP-II AP 96-03/CBP Note-173 1 THE ELECTRON-CLOUD INSTABILITY IN PEP-II* M. A. Furman the magnitude and shape of the electron cloud density distribution depend sensitively. We pay particular

Furman, Miguel

249

Vector Interpolative Logic  

E-print Network

Abstract: Vector interpolative logic (I-logic) is a consistent generalization of vector classical logic, so that the components of analyzed I-logic vectors have values from the real interval [0, 1]. All laws of classical logic and as a consequence, vector classical logic too, are preserved in the vector I- logic. This result is not possible in the frame of conventional fuzzy and/or MV- logic approaches.

Dragan Radojevi?; Zvonko Mari?

250

Vector Lane Threading  

Microsoft Academic Search

Multi-lane vector processors achieve excellent computa- tional throughput for programs with high data-level paral- lelism (DLP). However, application phases without signif- icant DLP are unable to fully utilize the datapaths in the vector lanes. In this paper, we propose vector lane thread- ing (VLT), an architectural enhancement that allows idle vector lanes to run short-vector or scalar threads. VLT- enhanced

Suzanne Rivoire; Rebecca Schultz; Tomofumi Okuda; Christos Kozyrakis

2006-01-01

251

A Multithreaded Vector Coprocessor  

Microsoft Academic Search

A multithreaded vector co-processor design is described. It is intended to be placed with its private vector memory, on an expansion board, linked to the scalar processor and its cache-based memory hierarchy. The vector co-processor can run up to 8 vector tasks (threads) in parallel. Vector registers can be accessed either as independent sets of scalar values or as array

Bernard Goossens

1997-01-01

252

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

253

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

254

Uranus at equinox: Cloud morphology and dynamics  

E-print Network

As the 7 December 2007 equinox of Uranus approached, ring and atmosphere observers produced a substantial collection of observations using the 10-m Keck telescope and the Hubble Space Telescope. Those spanning the period from 7 June 2007 through 9 September 2007 we used to identify and track cloud features, determine atmospheric motions, characterize cloud morphology and dynamics, and define changes in atmospheric band structure. We confirmed the existence of the suspected northern hemisphere prograde jet, locating its peak near 58 N, and extended wind speed measurements to 73 N. For 28 cloud features we obtained extremely high wind-speed accuracy through extended tracking times. The new results confirm a small N-S asymmetry in the zonal wind profile, and the lack of any change in the southern hemisphere between 1986 (near solstice) and 2007 (near equinox) suggests that the asymmetry may be permanent rather than seasonally reversing. In the 2007 images we found two prominent groups of discrete cloud features ...

Sromovsky, Lawrence; Hammel, Heidi; Ahue, William; de Pater, Imke; Rages, Kathy; Showalter, Mark; van Dam, Marcos

2015-01-01

255

Reading the Clouds: CloudSat Poster  

NSDL National Science Digital Library

This poster illustrates and describes types of high-, low-, and mid-altitude clouds. Poster back has article and activity related to Earth's water cycle, as well as a cloud identification quiz and a water cycle crossword puzzle.

2012-11-15

256

Cloud Infrastructure & Applications - CloudIA  

NASA Astrophysics Data System (ADS)

The idea behind Cloud Computing is to deliver Infrastructure-as-a-Services and Software-as-a-Service over the Internet on an easy pay-per-use business model. To harness the potentials of Cloud Computing for e-Learning and research purposes, and to small- and medium-sized enterprises, the Hochschule Furtwangen University establishes a new project, called Cloud Infrastructure & Applications (CloudIA). The CloudIA project is a market-oriented cloud infrastructure that leverages different virtualization technologies, by supporting Service-Level Agreements for various service offerings. This paper describes the CloudIA project in details and mentions our early experiences in building a private cloud using an existing infrastructure.

Sulistio, Anthony; Reich, Christoph; Doelitzscher, Frank

257

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-2d" target="_blank">Motion in 2D. Editor's Note: This lesson provides guided instruction to help students stay on task as they explore vector quantities with the simulation. It then takes the learner to the next level: can they apply what they learned to perform the calculations to find vector resultants?

2013-02-05

258

Method and system for non-linear motion estimation  

NASA Technical Reports Server (NTRS)

A method and system for extrapolating and interpolating a visual signal including determining a first motion vector between a first pixel position in a first image to a second pixel position in a second image, determining a second motion vector between the second pixel position in the second image and a third pixel position in a third image, determining a third motion vector between one of the first pixel position in the first image and the second pixel position in the second image, and the second pixel position in the second image and the third pixel position in the third image using a non-linear model, determining a position of the fourth pixel in a fourth image based upon the third motion vector.

Lu, Ligang (Inventor)

2011-01-01

259

Dynamics of Exozodiacal Clouds  

E-print Network

The inner Solar System contains a cloud of small (1-100 micron) dust grains created when small bodies-asteroids, comets, and Kuiper belt objects-collide and outgas. This dust cloud, the zodiacal cloud probably has extrasolar analogs, exozodiacal clouds. Exozodiacal clouds are related to debris disks, clouds of rocks and dust orbiting main sequence stars thought to represent the debris left over from planet formation. Some debris disks appear to contain distinct inner clouds that could be considered massive exozodiacal clouds (e.g. Koerner et al. 1998, Absil et al. 2006). This white paper addresses the need for future theoretical work on the dynamics of exozodiacal clouds. This theoretical work should help us discover new planets and understand exozodiacal clouds as astrophysical noise. So far, observations of nearby stars have not provided good constraints on the structures of exozodiacal clouds. But future observations probably will demand a better theoretical understanding of these systems.

M. Kuchner; C. Stark; O. Absil; J. -C. Augereau; P. Thebault

2007-07-09

260

Venus Cloud Patterns (colorized and filtered)  

NASA Technical Reports Server (NTRS)

This picture of Venus was taken by the Galileo spacecrafts Solid State Imaging System on February 14, 1990, at a range of almost 1.7 million miles from the planet. A highpass spatial filter has been applied in order to emphasize the smaller scale cloud features, and the rendition has been colorized to a bluish hue in order to emphasize the subtle contrasts in the cloud markings and to indicate that it was taken through a violet filter. The sulfuric acid clouds indicate considerable convective activity, in the equatorial regions of the planet to the left and downwind of the subsolar point (afternoon on Venus). They are analogous to 'fair weather clouds' on Earth. The filamentary dark features visible in the colorized image are here revealed to be composed of several dark nodules, like beads on a string, each about 60 miles across. The Galileo Project is managed for NASA's Office of Space Science and Applications by the Jet Propulsion Laboratory; its mission is to study Jupiter and its satellites and magnetosphere after multiple gravity assist flybys at Venus and Earth. These images of the Venus clouds were taken by Galileo's Solid State Imaging System February 13, 1990, at a range of about 1 million miles. The smallest detail visible is about 20 miles. The two right images show Venus in violet light, the top one at a time six hours later than the bottom one. They show the state of the clouds near the top of Venus's cloud deck. A right to left motion of the cloud features is evident and is consistent with westward winds of about 230 mph. The two left images show Venus in near infrared light, at the same times as the two right images. Sunlight penetrates through the clouds more deeply at the near infrared wavelengths, allowing a view near the bottom of the cloud deck. The westward motion of the clouds is slower (about 150 mph) at the lower altitude. The clouds are composed of sulfuric acid droplets and occupy a range of altitudes from 30 to 45 miles. The images have been spatially filtered to bring out small scale details and de-emphasize global shading. The filtering has introduced artifacts (wiggly lines running north/south) that are faintly visible in the infrared image. The Galileo Project is managed for NASA's Office of Space Science and Applications by the Jet Propulsion Laboratory; its mission is to study Jupiter and its satellites and magnetosphere after multiple gravity assist flybys at Venus and Earth.

1990-01-01

261

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

262

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.

Fu-Kwun Hwang

2004-10-27

263

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 inputsnormalized 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.

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

2014-10-01

264

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

265

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.

266

MotionExplorer: exploratory search in human motion capture data based on hierarchical aggregation.  

PubMed

We present MotionExplorer, an exploratory search and analysis system for sequences of human motion in large motion capture data collections. This special type of multivariate time series data is relevant in many research fields including medicine, sports and animation. Key tasks in working with motion data include analysis of motion states and transitions, and synthesis of motion vectors by interpolation and combination. In the practice of research and application of human motion data, challenges exist in providing visual summaries and drill-down functionality for handling large motion data collections. We find that this domain can benefit from appropriate visual retrieval and analysis support to handle these tasks in presence of large motion data. To address this need, we developed MotionExplorer together with domain experts as an exploratory search system based on interactive aggregation and visualization of motion states as a basis for data navigation, exploration, and search. Based on an overview-first type visualization, users are able to search for interesting sub-sequences of motion based on a query-by-example metaphor, and explore search results by details on demand. We developed MotionExplorer in close collaboration with the targeted users who are researchers working on human motion synthesis and analysis, including a summative field study. Additionally, we conducted a laboratory design study to substantially improve MotionExplorer towards an intuitive, usable and robust design. MotionExplorer enables the search in human motion capture data with only a few mouse clicks. The researchers unanimously confirm that the system can efficiently support their work. PMID:24051792

Bernard, Jrgen; Wilhelm, Nils; Krger, Bjrn; May, Thorsten; Schreck, Tobias; Kohlhammer, Jrn

2013-12-01

267

The Cloud Appreciation Society  

NSDL National Science Digital Library

The Cloud Appreciation Society believes that "clouds are Nature's poetry" and, therefore, "pledges to fight 'blue-sky thinking'." Visitors can find out about the latest cloud related news and events. The website offers a forum for users to ask cloud-related questions and communicate with other cloud enthusiasts. Anyone in the UK can join the society for free and membership will soon be expanding to other areas of the world. Everyone should check out the numerous fascinating pictures in the cloud gallery. Individuals can also contribute their cloud photographs to the continually growing collection. This site is also reviewed in the March 4, 2005_NSDL Physical Sciences Report_.

268

Quantication and analysis of respiratory motion from 4D MRI  

NASA Astrophysics Data System (ADS)

It is well known that respiratory motion affects image acquisition and also external beam radiotherapy (EBRT) treatment planning and delivery. However often the existing approaches for respiratory motion management are based on a generic view of respiratory motion such as the general movement of organ, tissue or fiducials. This paper thus aims to present a more in depth analysis of respiratory motion based on 4D MRI for further integration into motion correction in image acquisition or image based EBRT. Internal and external motion was first analysed separately, on a per-organ basis for internal motion. Principal component analysis (PCA) was then performed on the internal and external motion vectors separately and the relationship between the two PCA spaces was analysed. The motion extracted from 4D MRI on general was found to be consistent with what has been reported in literature.

Aizzuddin Abd Rahni, Ashrani; Lewis, Emma; Wells, Kevin

2014-11-01

269

Elementary GLOBE: Cloud Fun  

NSDL National Science Digital Library

A learning activity for the "Do You Know That Clouds Have Names?" book in the Elementary GLOBE series. Each student will be given the opportunity to create their own cumulus cloud out of white paper and mount it on blue paper. Students will also 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. The purpose of the activity is to help students identify cumulus clouds and observe the weather conditions on days that they see cumulus clouds. Students will learn about a cumulus cloud's shape and appearance, how to verbally describe cumulus clouds, and what the weather is generally like when these clouds appear in the sky.

2008-12-01

270

Cloud-tracked Winds for the First MGS Mapping Year  

NASA Astrophysics Data System (ADS)

We have measured winds using cloud motion in consecutive Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle global map swaths taken during the first mapping year (Ls 135 -360 -111 ). We present a total of 11,200 wind vectors collected in the north polar region during Ls 135 -195 (late summer/early fall) and Ls 20 -55 (mid spring), and in the south polar region during Ls 337 -10 (late summer/early fall). For cases with good coverage, we also present the derived mean zonal and meridional winds and the associated eddies. The speed of the zonal winds in 60 N-70 N increases at 0.6 m/s/ Ls in late northern summer, and that in 60 S-70 S increases at a rate of 0.7 m/s/ Ls in late southern summer. The latitudinal distribution of zonal wind within 50 N-75 N from mid northern summer to early northern fall indicates that winds at higher latitudes are generally weaker than those at lower latitudes, but the rate of increase with time is faster at higher latitudes. There is a cyclonic gyre in the 90 W-0 -30 E sector in the north polar region. There are large-scale waves in the weekly mean meridional wind and in the bi-weekly mean eddy momentum flux and eddy kinetic energy fields in the north polar region from mid to late summer. The cloud-tracked winds in the north are generally consistent with winds calculated by general circulation model at the water condensation level derived from MGS Thermal Emission Spectrometer (TES) observations, but appear stronger than the gradient winds derived from TES assuming no flow at the surface.

Wang, H.; Ingersoll, A.

2003-05-01

271

Motion estimation with variable velocity bandwidth  

NASA Astrophysics Data System (ADS)

A new phase-based motion algorithm is introduced. The estimation is performed such that only non-aliased temporal frequencies are included in the calculation of the translation vector describing the displacement of an object in a digital video sequence. A full description of the algorithm is presented. It is based on using a two-dimensional fast Fourier transform in two consecutive video fields or frames. Simulation results are included to illustrate the capabilities of the algorithm in an object-tracking application featuring fast frame-to-frame motion. It is shown that the proposed algorithm out-performs a conventional phase-based motion estimation algorithm.

Crinon, Regis J.; Kolodziej, Wojciech J.

1996-02-01

272

Malaria Vector Species  

NSDL National Science Digital Library

A sub-page of the extremely informative VectorBase. This is a worldwide listing of malaria vectors divided into 12 geographic regions following the 1957 classic The Epidemiology and Control of Malaria by MacDonald.

0000-00-00

273

Understanding Singular Vectors  

ERIC Educational Resources Information Center

matrix yields a surprisingly simple, heuristical approximation to its singular vectors. There are correspondingly good approximations to the singular values. Such rules of thumb provide an intuitive interpretation of the singular vectors that helps explain why the SVD is so

James, David; Botteron, Cynthia

2013-01-01

274

CERES CLoud Effects  

NSDL National Science Digital Library

This computer-generated animation depicts the Clouds and the Earth's Radiant Energy System (CERES) instrument in operation. CERES measures the energy at the top of the atmosphere and estimates energy levels in the atmosphere and at the Earth's surface. Using information from very high resolution cloud-imaging instruments on the same spacecraft, CERES also will determine cloud properties, including cloud amount, altitude, thickness, and the size of the cloud particles.

1997-06-06

275

The Oort cloud  

NASA Technical Reports Server (NTRS)

Views of the large-scale structure of the solar system, consisting of the Sun, the nine planets and their satellites, changed when Oort demonstrated that a gigantic cloud of comets (the Oort cloud) is located on the periphery of the solar system. The following subject areas are covered: (1) the Oort cloud's mass; (2) Hill's cloud mass; (3) angular momentum distribution in the solar system; and (4) the cometary cloud around other stars.

Marochnik, Leonid S.; Mukhin, Lev M.; Sagdeev, Roald Z.

1991-01-01

276

1014 IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 36, NO. 4, AUGUST 2008 Dust-Cloud Dynamics in a Complex  

E-print Network

condi- tions are needed to observe a cloud of injected particles filling up the whole discharge chamber1014 IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 36, NO. 4, AUGUST 2008 Dust-Cloud Dynamics Abstract--The motion of a dust-particle cloud in the afterglow of a complex plasma is reported. It is shown

Boyer, Edmond

277

The effect of non-Markovian cloud patterns on the design of a regulator for a solar-powered boiler  

NASA Astrophysics Data System (ADS)

This paper provides the regulator synthesis equations for the steam temperature regulator in a solar-powered boiler. The primary source of disturbance is produced by the motion of clouds across the field of mirrors which focus solar energy on the boilers. To permit flexibility in describing a variety of cloud conditions, the cloud model is non-Markov.

Sworder, D. D.; Zondervan, K. L.

278

Vector Piezoresponse Force Microscopy  

Microsoft Academic Search

A novel approach for nanoscale imaging and characterization of the orientation dependence of electromechanical properties---vector piezoresponse force microscopy (Vector PFM)---is described. The relationship between local electromechanical response, polarization, piezoelectric constants, and crystallographic orientation is analyzed in detail. The image formation mechanism in vector PFM is discussed. Conditions for complete three-dimensional (3D) reconstruction of the electromechanical response vector and evaluation of

Sergei V. Kalinin; Brian J. Rodriguez; Stephen Jesse; Junsoo Shin; Arthur P. Baddorf; Pradyumna Gupta; Himanshu Jain; David B. Williams; Alexei Gruverman

2006-01-01

279

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

280

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

2011-10-01

281

Vector Microprocessors Krste Asanovic  

E-print Network

Vector Microprocessors by Krste Asanovi´c B.A. (University of Cambridge) 1987 A dissertation 1998 #12;Vector Microprocessors Copyright 1998 by Krste Asanovi´c #12;1 Abstract Vector Microprocessors microprocessor imple- mentations targeting a much broader range of applications. I present the design

Asanoviæ, Krste

282

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

283

Nonviral Vector Systems  

Microsoft Academic Search

Gene therapy requires efficient vectors for delivering therapeutic genes. Advances in developments of nonviral vectors have\\u000a been established for improving the efficiency of gene delivery. This chapter describes different nonviral methods as well\\u000a as their applications. Some new directions in developing nonviral vectors are also discussed.

Pui-yan Lee; Leaf Huang

284

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

285

Action: Forcing Energy to Predict Motion  

NASA Astrophysics Data System (ADS)

In this paper we use scalar energy, rather than vector force and momentum, to predict how a particle will move. The result is a quantity called action. Action and its relatives undergird Newton's laws and transcend them, also predicting motion in the quantum world and in the curved spacetime of general relativity. An example exhibits action in action.

Neuenschwander, Dwight E.; Taylor, Edwin F.; Tuleja, Slavomir

2006-03-01

286

Motion and force control of robot manipulators  

Microsoft Academic Search

In this paper we present a unified approach for the control of manipulator motions and active forces based on the operational space formulation. The end-effector dynamic model is used in the development of a control system in which the generalized operational space end-effector forces are selected as the command vector. This formulation provides a framework for natural and efficient integration

Oussama Khatib; Joel Burdick

1986-01-01

287

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.

288

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

289

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

290

Shocking Changes to Molecular Clouds  

NASA Astrophysics Data System (ADS)

Supersonic motions are commonly observed in molecular clouds as evidenced by larger-than-thermal line widths measured in most species. The shocks that ensue can profoundly effect these clouds, not only dynamically, but chemically. Because shocks compress and heat the gas, chemical reactions that are extremely slow at typical molecular cloud temperatures (T ~ 10-30 K) can proceed rapidly in the wake of a shock. In many cases, compositional changes brought on by a passing shock can endure long after the gas has cooled and returned to its pre-shock state. We have used a coupled time-dependent chemical and dynamical model to investigate the lifetime of such chemical relics in the wake of non-dissociative shocks. Using a Monte Carlo cloud simulation, we explore the effects of stochastic shock activity on molecular gas over a cloud lifetime. Particular attention is paid to the chemistry of H_2O and O_2, two molecules which are predicted to have abundances that are significantly affected by shock-heated gas. Both pure gas-phase and gas-grain chemistry are considered. In agreement with previous studies, we find that shocks with velocities in excess of 10 km s(-1) can chemically process all oxygen not locked in CO into H_2O on timescales of a shock passage time ( ~ \\:few hundred years). For pure gas-phase models, the high water abundance lingers for ~ (4-7) x 10(5) yr, independent of the gas density. A density dependence for the lifetime of H_2O is found in gas-grain models as the water molecules deplete onto grains at the depletion timescale. We demonstrate that the time-averaged abundance of H_2O and O_2 (as well as other tracers, such as SiO and CH_3OH) is a sensitive function of the frequency of shocks. As such, the abundance of H_2O, and to a lesser extent O_2, can be used to trace the shock history in molecular clouds. Equally important, we find that depletion of shock-produced water onto grains can be quite large and is comparable to that observed in molecular clouds. This offers an alternative method to create water-ice mantles without resorting to grain surface chemistry. Observationally, a combination of space-based (for H_2O and O_2) and ground-based (for SiO, CH_3OH, and others) telescopes will be needed to investigate these predictions.

Melnick, Gary J.

1998-05-01

291

Local Group Proper Motion Dynamics  

NASA Astrophysics Data System (ADS)

Our knowledge of the dynamics and masses of galaxies in the Local Group has long been limited by the fact that only line-of-sight velocities were observationally accessible. This introduces significant degeneracies in dynamical models, which can only be resolved by measuring also the velocity components perpendicular to the line of sight. However, beyond the solar neighborhood, the corresponding proper motions have generally been too small to measure. This has changed dramatically over the past decade, especially due to the angular resolution and stability available on the Hubble Space Telescope. Proper motions can now be reliably measured throughout the Local Group, as illustrated by, e.g., the work of the HSTPROMO collaboration. In this review, I summarize the importance of proper motions for Local Group science, and I describe the current and future observational approaches and facilities available to measure proper motions. I highlight recent results on various Milky Way populations (globular clusters, the bulge, the metal-poor halo, hypervelocity stars, and tidal streams), dwarf satellite galaxies, the Magellanic Clouds and the Andromeda System.

van der Marel, Roeland P.

2015-04-01

292

Airborne observations of electric fields around growing and decaying cumulus clouds  

NASA Technical Reports Server (NTRS)

Airborne electric field data were gathered in an atmospheric electrification study near Cape Canaveral, FL. A Learjet 36A was instrumented with eight electric field meters (mills) and five different particle probes. The local electric field enhancements at each field mill site were determined under lab conditions and verified using in-flight data. The overdetermined system of eight equations (one for each field mill) was solved using a weighted least squares algorithm to compute the magnitude and direction of the ambient electric field. The signal processing system allowed the measured data to be expressed in terms of earth coordinates, regardless of the attitude of the aircraft. Thus, it was possible to take maximum advantage of the Learjet's speed and maneuverability in studying the electric field structure in the vicinity of the clouds. Data gathered while circling just outside the boundary of a growing cumulus cloud show a nonsymmetric pattern of electric field strength. Field intensity grew rapidly over a period of less than 10 minutes. The observed direction of the ambient electric field vector can be explained by an ascending motion of the charge centers of a classic tripole model of a thunderstorm.

Giori, K. L.; Nanevicz, J. E.

1991-01-01

293

Rotations with Rodrigues' vector  

NASA Astrophysics Data System (ADS)

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 to be a fundamental matrix that is used to express the components of the angular velocity, the rotation matrix and the angular momentum vector. The Hamiltonian formalism of rotational dynamics in terms of this vector uses the same matrix. The quantization of the rotational dynamics is performed with simple rules if one uses Rodrigues' vector and similar formal expressions for the quantum operators that mimic the Hamiltonian classical dynamics.

Pia, E.

2011-09-01

294

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

295

3D nonrigid motion analysis under small deformations  

Microsoft Academic Search

We present a novel method for estimating motion parameters and point correspondences between 3D surfaces under small nonrigid motion. A vector point function is utilized as the motion parameter, called the displacement function. Differential-geometric changes of surfaces are then used in tracking small deformations. Discriminant (of first fundamental form), unit-normal and Gaussian curvature are the invariant differential-geometric parameters that have

Chandra Kambhamettu; Dmitry Goldgof; Matthew He; Pavel Laskov

296

3D nonrigid motion analysis under small deformations  

Microsoft Academic Search

We present a novel method for estimating motion parameters and point correspondences between 3D surfaces under small nonrigid motion. A vector point function is utilized as the motion parameter, called the displacement function. Differential-geometric changes of surfaces are then used in tracking small deformations. Discriminant (of first fundamental form), unit-normal and Gaussian curvature are the invariant differential-geometric parameters that have

Chandra Kambhamettu; Dmitry B. Goldgof; Matthew He; Pavel Laskov

2003-01-01

297

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

298

A limited hardware resources efficient motion estimation algorithm  

Microsoft Academic Search

This paper describes a new motion estimation search strategy that exploits spatio-temporal correlation of motion vector field to estimate any kind of sequences containing low\\/high spatial details and slow\\/fast moving objects. The proposed algorithm dynamically changes its searching strategy between a modified genetic search and a N-step search accordingly to the scene motion complexity and the specified processing power budget.

Mombers Friederich; Dogimont Stephanie

2000-01-01

299

Fractal Structure of Molecular Clouds  

E-print Network

Compelling evidence exists to show that the structure of molecular clouds is fractal in nature. In this paper, the author reiterates this view and, in addition, asserts that not only is cloud geometry fractal, but that they also have a common characteristic - they are similar in shape to the Horsehead nebula in Orion. This shape can be described by the Julia function f(x)= z^2 + c,where both z and c are complex quantities and c = -0.745429 + 0.113008i. The dynamical processes responsible for the production of these clouds seem to be turbulence followed by Brownian motion till high densities are reached, at which point structure formation is dictated by gravity. The author presents image analysis of four varied examples, namely those of the Horsehead nebula, Eagle nebula, Rosette nebula and Paley I nebula to prove her hypothesis. The images of these nebulae are analyzed for their box dimension using fractal analysis software and comparisons are made with the given Julia set.

Srabani Datta

2001-05-02

300

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

301

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.

Jeffrey Nunn

302

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, Ccile; Jenkins, Edward B.

2014-07-01

303

Vegetation forcing and convective motion  

SciTech Connect

A large irrigated vegetation area in a semiarid or relatively dry location is a strong surface forcing of thermal circulations. Several observational studies have found that such thermally induced mesoscale circulation may contribute to the triggering and development of convective clouds. In the western United States, extensive areas of irrigated farmland are surrounded by hot, dry surfaces, such as a steppe. Substantial gradients of sensible heating in the horizontal direction lead to a {open_quotes}farm breeze{close_quotes} circulation from the cooler agricultural area to the warmer steppes found at Boardman, Oregon. These thermally forced circulations may trigger convection by the related convergence and updraft motion under favorable atmospheric conditions. The role of vegetative covering in convective motion is investigated using a mesoscale numerical model. Two- and three-dimensional simulations are described. The effects of atmospheric stability, moisture in the lower atmosphere, moisture in the upper atmosphere, and horizontal heating scale on thermally induced clouds are studied. The horizontal scale of inhomogeneity is also studied using the two-dimensional model. Finally, a realistic vegetation distribution similar to that of the Boardman Regional Flux Experiment is used in the three-dimensional simulations.

Hong, X.; Leach, M.J.; Raman, S. [North Carolina State Univ., Raleigh, NC (United States)

1995-04-01

304

Explicit prediction of ice clouds in general circulation models  

NASA Astrophysics Data System (ADS)

Although clouds play extremely important roles in the radiation budget and hydrological cycle of the Earth, there are large quantitative uncertainties in our understanding of their generation, maintenance and decay mechanisms, representing major obstacles in the development of reliable prognostic cloud water schemes for General Circulation Models (GCMs). Recognizing their relative neglect in the past, both observationally and theoretically, this work places special focus on ice clouds. A recent version of the UCLA - University of Utah Cloud Resolving Model (CRM) that includes interactive radiation is used to perform idealized experiments to study ice cloud maintenance and decay mechanisms under various conditions in term of: (1) background static stability, (2) background relative humidity, (3) rate of cloud ice addition over a fixed initial time-period and (4) radiation: daytime, nighttime and no-radiation. Radiation is found to have major effects on the life-time of layer-clouds. Optically thick ice clouds decay significantly slower than expected from pure microphysical crystal fall-out (taucld = 0.9--1.4 h as opposed to no-motion taumicro = 0.5--0.7 h). This is explained by the upward turbulent fluxes of water induced by IR destabilization, which partially balance the downward transport of water by snowfall. Solar radiation further slows the ice-water decay by destruction of the inversion above cloud-top and the resulting upward transport of water. Optically thin ice clouds, on the other hand, may exhibit even longer life-times (>1 day) in the presence of radiational cooling. The resulting saturation mixing ratio reduction provides for a constant cloud ice source. These CRM results are used to develop a prognostic cloud water scheme for the UCLA-GCM. The framework is based on the bulk water phase model of Ose (1993). The model predicts cloud liquid water and cloud ice separately, and which is extended to split the ice phase into suspended cloud ice (predicted) and falling snow (diagnosed) components. An empirical parameterization of the effect of upward turbulent water fluxes in cloud layers is obtained from the CRM simulations by (1) identifying the time-scale of conversion of cloud ice to snow as the key parameter, and (2) regressing it onto cloud differential IR heating and environmental static stability. The updated UCLA-GCM achieves close agreement with observations in global mean top of atmosphere fluxes (within 1--4 W/m2). Artificially suppressing the impact of cloud turbulent fluxes reduces the global mean ice water path by a factor of 3 and produces errors in each of solar and IR fluxes at the top of atmosphere of about 5--6 W/m2.

Kohler, Martin

1999-11-01

305

FIV vector systems.  

PubMed

Why is feline immunodeficiency virus (FIV) such an appealing candidate for gene therapy vector development? Phylogenetic analysis suggests FIV is only distantly related to the primate lentiviruses, and despite repeated exposure, neither seroconversion nor other detectable evidence of human infection occurs. FIV naturally infects diverse Felidae worldwide, including the domestic cat. Here, the disease progression parallels the immunodeficiency caused by HIV, and for that reason, FIV and the cat provide an excellent model for anti-virals and AIDS vaccine research. Simple genome organization also facilitates vector development and analysis: FIV has only three accessory/regulatory proteins. To overcome FIV's cat-specific tropism, feline vectors are equipped with hybrid LTRs, since the FIV LTR shows low activity in human cells. Recombinant FIV vectors generate titers comparable to other lentiviral systems, are capable of incorporating heterologous envelopes and efficiently transduce dividing and nondividing cells in the presence and absence of the accessory proteins in vitro. Compared to HIV vectors, FIV vector development is still in its infancy, but initial in vivo data in various species and tissues indicate long-term gene expression at therapeutic levels, and thus FIV vectors hold great promise. Future efficacy studies in animal models and primates will determine the FIV vectors' suitability for gene therapy. The design of recombinant FIV vectors incorporates safety features described for primate lentiviral vectors with the benefit that biosafety testing of FIV vectors can occur in the natural host. Currently, FIV vectors are generated in a transient fashion, but the availability of a stable producer system amenable to better characterization and scale-up will considerably increase the potential for use of FIV vectors in the clinic. PMID:12465464

Sauter, S L; Gasmi, M

2001-11-01

306

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.

307

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

2006-08-03

308

Cloud Computing for radiologists.  

PubMed

Cloud computing is a concept wherein a computer grid is created using the Internet with the sole purpose of utilizing shared resources such as computer software, hardware, on a pay-per-use model. Using Cloud computing, radiology users can efficiently manage multimodality imaging units by using the latest software and hardware without paying huge upfront costs. Cloud computing systems usually work on public, private, hybrid, or community models. Using the various components of a Cloud, such as applications, client, infrastructure, storage, services, and processing power, Cloud computing can help imaging units rapidly scale and descale operations and avoid huge spending on maintenance of costly applications and storage. Cloud computing allows flexibility in imaging. It sets free radiology from the confines of a hospital and creates a virtual mobile office. The downsides to Cloud computing involve security and privacy issues which need to be addressed to ensure the success of Cloud computing in the future. PMID:23599560

Kharat, Amit T; Safvi, Amjad; Thind, Ss; Singh, Amarjit

2012-07-01

309

Visual motion integration is mediated by directional ambiguities in local motion signals.  

PubMed

The output of primary visual cortex (V1) is a piecemeal representation of the visual scene and the response of any one cell cannot unambiguously guide sensorimotor behavior. It remains unsolved how subsequent stages of cortical processing combine ("pool") these early visual signals into a coherent representation. We (Webb et al., 2007, 2011) have shown that responses of human observers on a pooling task employing broadband, random dot motion can be accurately predicted by decoding the maximum likelihood direction from a population of motion-sensitive neurons. Whereas Amano et al. (2009) found that the vector average velocity of arrays of narrowband, two-dimensional (2-d) plaids predicts perceived global motion. To reconcile these different results, we designed two experiments in which we used 2-d noise textures moving behind spatially distributed apertures and measured the point of subjective equality between pairs of global noise textures. Textures in the standard stimulus moved rigidly in the same direction, whereas their directions in the comparison stimulus were sampled from a set of probability distributions. Human observers judged which noise texture had a more clockwise (CW) global direction. In agreement with Amano and colleagues, observers' perceived global motion coincided with the vector average stimulus direction. To test if directional ambiguities in local motion signals governed perceived global direction, we manipulated the fidelity of the texture motion within each aperture. A proportion of the apertures contained texture that underwent rigid translation and the remainder contained dynamic (temporally uncorrelated) noise to create locally ambiguous motion. Perceived global motion matched the vector average when the majority of apertures contained rigid motion, but with increasing levels of dynamic noise shifted toward the maximum likelihood direction. A class of population decoders utilizing power-law non-linearities can accommodate this flexible pooling. PMID:24302910

Rocchi, Francesca; Ledgeway, Tim; Webb, Ben S

2013-01-01

310

Method of artificial luminous clouds for investigating the regularities of the space-time gas-dust cloud evolution  

Microsoft Academic Search

Large-area cameras with a field of vision of 30-45 deg were used to record the spatial structure of gas-dust cloud formations. The exposure time was prescribed by a controlling device in cycles of exposures from 0.5 to 7 sec, with intervals between exposures of 0.5 to 3 sec. Motion-picture cameras without image intensifiers allowed cloud recording of 0.1 sec time

L. A. Andreeva; T. V. Buzdygar; V. F. Garbuzenko; I. V. Dorokhova; O. F. Kliuev; A. V. Kosenkova; S. G. Pasynkov; Iu. I. Portniagin; A. A. Shidlovskii

1992-01-01

311

Personal Cloud Computing Security Framework  

Microsoft Academic Search

Cloud computing is an evolving term these days. It describes the advance of many existing IT technologies and separates application and information resources from the underlying infrastructure. Personal Cloud is the hybrid deployment model that is combined private cloud and public cloud. By and large, cloud orchestration does not exist today. Current cloud service is provided by web browser or

Sang-Ho Na; Jun-Young Park; Eui-nam Huh

2010-01-01

312

Local correction of non-periodic motion in computed tomography  

NASA Astrophysics Data System (ADS)

This paper presents a new iterative motion correction technique composed of motion estimation in projection space, motion segmentation in image space, and motion compensation within an analytical filtered-backprojection (FBP) image reconstruction algorithm. The motion is estimated by elastic registration of acquired projections on reference projections. Reference projections are sampled from the image, reconstructed in a previous iteration step. To apply the motion compensation locally, the image regions significantly affected by motion are segmented. First the perceived motion is identified in projection space by computing the absolute difference between acquired line integrals and reference line integrals. Then, differences are reconstructed in image space, and the image is regularized with a pipeline of standard image processing operators. The result of this procedure is a normalized motion map, associating each image element with a measure of the local motion detected there. The estimated displacement vectors in projection space and the reconstructed motion map in image space are then used by an adaptive motion-compensated FBP algorithm to reconstruct a sharper image. Results are shown qualitatively and quantitatively for reconstructions from realistic projections, simulated from clinical patient data. Since the method does not assume any periodicity of the motion model, it can correct reconstruction artifacts due to unstructured patient motion, such as breath-hold failure, abdominal contractions, and nervous movements.

Schretter, Colas; Neukirchen, Christoph; Rose, Georg; Bertram, Matthias

2009-02-01

313

Dynamic Cloud Resource Reservation via Cloud Brokerage  

E-print Network

service cost. These strategies leverage dynamic programming and approximate algorithms to rapidly handleDynamic Cloud Resource Reservation via Cloud Brokerage Wei Wang, Di Niu, Baochun Li, Ben Liang dynamic strategies for the broker to make instance reservations with the objective of minimizing its

Li, Baochun

314

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

315

Head in the Clouds  

NSDL National Science Digital Library

In this activity, learners create a CloudSpotter wheel and record the different types of clouds they observe twice daily over several days. Use this activity to teach learners how to identify different types of clouds as well as improve their observation skills. If possible, plan this lesson within four days of an upcoming cold front. This will help maximize the variety of clouds the learners will observe. This resource also includes tips about foggy weather safety.

2013-04-10

316

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

317

SGP and TWP (Manus) Ice Cloud Vertical Velocities  

SciTech Connect

Daily netcdf-files of ice-cloud dynamics observed at the ARM sites at SGP (Jan1997-Dec2010) and Manus (Jul1999-Dec2010). The files include variables at different time resolution (10s, 20min, 1hr). Profiles of radar reflectivity factor (dbz), Doppler velocity (vel) as well as retrieved vertical air motion (V_air) and reflectivity-weighted particle terminal fall velocity (V_ter) are given at 10s, 20min and 1hr resolution. Retrieved V_air and V_ter follow radar notation, so positive values indicate downward motion. Lower level clouds are removed, however a multi-layer flag is included.

Kalesse, Heike

2013-06-27

318

SGP and TWP (Manus) Ice Cloud Vertical Velocities  

DOE Data Explorer

Daily netcdf-files of ice-cloud dynamics observed at the ARM sites at SGP (Jan1997-Dec2010) and Manus (Jul1999-Dec2010). The files include variables at different time resolution (10s, 20min, 1hr). Profiles of radar reflectivity factor (dbz), Doppler velocity (vel) as well as retrieved vertical air motion (V_air) and reflectivity-weighted particle terminal fall velocity (V_ter) are given at 10s, 20min and 1hr resolution. Retrieved V_air and V_ter follow radar notation, so positive values indicate downward motion. Lower level clouds are removed, however a multi-layer flag is included.

Kalesse, Heike

319

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

320

Branchless vectorized median filtering  

Microsoft Academic Search

Median filtering is an important tool in signal or image processing. Based on the vector capabilities of modern hardware, which allows for vectorized min, max and mask operations, we provide a median algorithm of complexity O(NM) that is both branchless and vectorized. In contrast to conventional fast median filters, whose run-time is data-dependent and that can operate only on scalar

M. Kachelriess

2009-01-01

321

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 (4.830.1 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

322

Security in the cloud.  

PubMed

As more provider organizations look to the cloud computing model, they face a host of security-related questions. What are the appropriate applications for the cloud, what is the best cloud model, and what do they need to know to choose the best vendor? Hospital CIOs and security experts weigh in. PMID:21863719

Degaspari, John

2011-08-01

323

Cloud computing security  

Microsoft Academic Search

Cloud computing is a paradigm rapidly being embraced by government and industry as a solution for cost-savings, scalability, and collaboration. While a multitude of applications and services are available commercially for cloud-based solutions, research in this area has yet to fully embrace the full spectrum of potential challenges facing cloud computing. This tutorial aims to provide researchers with a fundamental

Dongwan Shin; William R. Claycomb; Vincent E. Urias

2010-01-01

324

Research Cloud Computing Recommendations  

E-print Network

Research Cloud Computing Recommendations SRCPAC December 3, 2014 #12;Mandate and Membership SRCPAC convened this committee in Sept 2014 to investigate the role that cloud computing should play in our & Academic Affairs (Social Work) #12;Questions discussed · What cloud resources are available? · Which kinds

Qian, Ning

325

Cloud Computing Explained  

ERIC Educational Resources Information Center

While many talk about the cloud, few actually understand it. Three organizations' definitions come to the forefront when defining the cloud: Gartner, Forrester, and the National Institutes of Standards and Technology (NIST). Although both Gartner and Forrester provide definitions of cloud computing, the NIST definition is concise and uses

Metz, Rosalyn

2010-01-01

326

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

327

Measuring Cloud Coverage  

NSDL National Science Digital Library

This lesson reviews clouds and uses fractions to describe cloud coverage, demonstrating how math and science work together. By using math and science to describe clouds, the lesson provides students with several means of communication (fractions and meteorological terms) to describe a meteorological situation.

328

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.

Alistair Fraser

329

Vectorized Monte Carlo  

SciTech Connect

Examination of the global algorithms and local kernels of conventional general-purpose Monte Carlo codes shows that multigroup Monte Carlo methods have sufficient structure to permit efficient vectorization. A structured multigroup Monte Carlo algorithm for vector computers is developed in which many particle events are treated at once on a cell-by-cell basis. Vectorization of kernels for tracking and variance reduction is described, and a new method for discrete sampling is developed to facilitate the vectorization of collision analysis. To demonstrate the potential of the new method, a vectorized Monte Carlo code for multigroup radiation transport analysis was developed. This code incorporates many features of conventional general-purpose production codes, including general geometry, splitting and Russian roulette, survival biasing, variance estimation via batching, a number of cutoffs, and generalized tallies of collision, tracklength, and surface crossing estimators with response functions. Predictions of vectorized performance characteristics for the CYBER-205 were made using emulated coding and a dynamic model of vector instruction timing. Computation rates were examined for a variety of test problems to determine sensitivities to batch size and vector lengths. Significant speedups are predicted for even a few hundred particles per batch, and asymptotic speedups by about 40 over equivalent Amdahl 470V/8 scalar codes arepredicted for a few thousand particles per batch. The principal conclusion is that vectorization of a general-purpose multigroup Monte Carlo code is well worth the significant effort required for stylized coding and major algorithmic changes.

Brown, F.B.

1981-01-01

330

Comparative study of motion estimation for low-bit-rate video coding  

Microsoft Academic Search

Typical motion estimation for block-based video coding schemes consists of two parts: the one at integer pixel accuracy and the other at half pixel accuracy. In this paper, integer pixel motion estimation algorithms are first discussed in terms of three technical categories: search step, search pattern and decision of the initial motion vector. With the development of the efficiency of

Cheng Du; Yun He

2000-01-01

331

Image-based motion estimation for cardiac CT via image registration  

NASA Astrophysics Data System (ADS)

Images reconstructed from tomographic projection data are subject to motion artifacts from organs that move during the duration of the scan. The effect can be reduced by taking the motion into account in the reconstruction algorithm if an estimate of the deformation exists. This paper presents the estimation of the three-dimensional cardiac motion by registering reconstructed images from cardiac quiet phases as a first step towards motion-compensated cardiac image reconstruction. The non-rigid deformations of the heart are parametrized on a coarse grid on the image volume and are interpolated with cubic b-splines. The optimization problem of finding b-spline coefficients that best describe the observed deformations is ill-posed due to the large number of parameters and the resulting motion vector field is sensitive to the choice of initial parameters. Particularly challenging is the task to capture the twisting motion of the heart. The motion vector field from a dynamic computer phantom of the human heart is used to initialize the transformation parameters for the optimization process with realistic starting values. The results are evaluated by comparing the registered images and the obtained motion vector field to the case when the registration is performed without using prior knowledge about the expected cardiac motion. We find that the registered images are similar for both approaches, but the motion vector field obtained from motion estimation initialized with the phantom describes the cardiac contraction and twisting motion more accurately.

Cammin, J.; Taguchi, K.

2010-03-01

332

CO Imaging of Molecular Clouds with Optical HII Regions  

NASA Astrophysics Data System (ADS)

(12) CO and (13) CO J=1-0 images of molecular clouds associated with the optical HII regions S140, S155, and S235 made with the FCRAO 15 beam array receiver are presented. These images reveal a complex environment resulting from the interaction of the HII regions with the ambient cloud material. Cloud properties are compared to those derived from surveys of the Galactic Plane and other imaging studies of the molecular interstellar medium. These images emphasize that most of the kinetic energy is contained within the clump to clump motions on size scales greater than several pc.

Heyer, M. H.; Carpenter, J.; Ladd, E. F.

1993-12-01

333

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

334

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

NASA Astrophysics Data System (ADS)

Retrieving 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

335

Singular Vectors, Metrics, and Adaptive Observations.  

NASA Astrophysics Data System (ADS)

Singular vectors of the linearized equations of motion have been used to study the instability properties of the atmosphere-ocean system and its related predictability. A third use of these singular vectors is proposed here: as part of a strategy to target adaptive observations to `sensitive' parts of the atmosphere. Such observations could be made using unmanned aircraft, though calculations in this paper are motivated by the upstream component of the Fronts and Atlantic Storm-Track Experiment. Oceanic applications are also discussed. In defining this strategy, it is shown that there is, in principle, no freedom in the choice of inner product or metric for the singular vector calculation. However, the correct metric is dependent on the purpose for making the targeted observations (to study precursor developments or to improve forecast initial conditions). It is argued that for predictability studies, where both the dynamical instability properties of the system and the specification of the operational observing network and associated data assimilation system are important, the appropriate metric will differ from that appropriate to a pure geophysical fluid dynamics (GFD) problem. Based on two different sets of calculations, it is argued that for predictability studies (but not for GFD studies), a first-order approximation to the appropriate metric can be based on perturbation energy. The role of observations in data assimilation procedures (constraining large scales more than small scales) is fundamental in understanding reasons for the requirement for different metrics for the two classes of problems. An index-based tensor approach is used to make explicit the role of the metric.The strategy for using singular vectors to target adaptive observations is discussed in the context of other possible approaches, specifically, based on breeding vectors, potential vorticity diagnosis, and sensitivity vectors. The basic premises underlying the use of breeding and singular vectors are discussed. A comparison of the growth rates of breeding and singular vectors is made using a T21 quasigeostrophic model.Singular vectors and subjective potential vorticity (PV) diagnosis are compared for a particular case study. The areas of sensitivity indicated by the two methods only partially agree. Reasons for disagreement hinge around the fact that subjective PV diagnosis emphasizes Lagrangian advection, whereas singular vector analysis emphasizes wave propagation. For the latter, areas of sensitivity may be associated with regions of weak PV gradient, for example, mid to lower troposphere. Amplification of singular vectors propagating from regions of weak PV gradient to regions of strong PV gradient is discussed in terms of pseudomomentum conservation. Evidence is shown that analysis error may be as large in the lower midtroposphere as in the upper troposphere.

Palmer, T. N.; Gelaro, R.; Barkmeijer, J.; Buizza, R.

1998-02-01

336

Cloud microstructure studies  

NASA Technical Reports Server (NTRS)

Over two thousand individual cloud droplet size distributions were measured with an optical cloud particle spectrometer flown on the NASA Convair 990 aircraft. Representative droplet spectra and liquid water content, L (gm/cu m) were obtained for oceanic stratiform and cumuliform clouds. For non-precipitating clouds, values of L range from 0.1 gm/cu m to 0.5 gm/cu m; with precipitation, L is often greater than 1 gm/cu m. Measurements were also made in a newly formed contrail and in cirrus clouds.

Blau, H. H., Jr.; Fowler, M. G.; Chang, D. T.; Ryan, R. T.

1972-01-01

337

THE WATER CYCLE/ CLOUDS  

NSDL National Science Digital Library

Students will learn about the water cycle and how it works. You will explore many resources to find out many new factors about the water cycle. What is the water cycle? National water cycle Name the 4 water parts of the water cycle? Weather wonders Where are 3 places that the water cycle exists- What happens after condensation? animated water cycle Name 4 types of clouds? What is the highest level cloud called? Which cloud is associated with powerful thunderstorms? Cloud Types What do clouds have to do with the water cycle? National water cycle What is ...

Ms.Brown

2009-04-06

338

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

339

Estimating Cloud Cover  

NSDL National Science Digital Library

Working in pairs or small groups, students use construction paper to simulate cloud cover. They estimate the percentage of cloud cover represented by torn pieces of paper on a contrasting background and assign a cloud cover classification to the simulations created by their classmates. Students gain experience estimating cloud cover, evaluating the accuracy of estimates, and using fractions and percentages. This learning activity is from the Atmosphere chapter of the GLOBE Teacher's Guide, and is supported by the GLOBE Cloud Cover Protocol. GLOBE (Global Learning and Observation to Benefit the Environment) is a worldwide, hands-on, K-12 school-based science education program.

340

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.

George Tselioudis

1997-01-01

341

Magnetic structures inside boundary layers of magnetic clouds  

NASA Astrophysics Data System (ADS)

We analyze 23 magnetic cloud boundary layers (BLs) in Feb. 1995-Oct. 1998 and find that: (1) the distribution functions of fluctuations in the southward field component inside the boundary layer, ?BzL, is very different from ?BzS in the background solar wind and ?BzM inside the cloud, with the enhancement in the fluctuation amplitude and the variation of the magnitude and direction of the average field. (2) in the maximum variance plane (MVP) composed of the maximum and medium variance directions, the walk of the tips of the magnetic field vectors in the BL could be classified into two types based on: (a) field vectors vibrate along a circle arc, which is possibly related with Alfven fluctuations inside the BL; (b) field vectors walk randomly in the MVP, which could be correlated with the turbulence inside the BL. (3) In the ?-? plane, fields inside the BL exhibits a `U' or inverse `U' shape with a spacing of about 180 degree in the azimuthal angle, which indicate the existence of a field reverse region and are often associated with the Alfvenic fluctuations. The results above suggest that the cloud's BL owns the magnetic structure different from that in the solar wind and cloud body, which is a manifestation for the interaction of the magnetic cloud (MC) with the solar wind (SW).

Wei, Fengsi; Liu, Rui; Feng, Xueshang; Zhong, Dingkun; Yang, Fang

2003-12-01

342

Semi-supervised Cloud Screening with Laplacian SVM  

E-print Network

machine (SVM) is further reg- ularized with the un-normalized graph Laplacian, thus leadingSemi-supervised Cloud Screening with Laplacian SVM Luis Gomez-Chova, Gustavo Camps-Valls, Jordi Mu-supervised classi- fication framework based on kernel methods and graph theory. In particular, the support vector

Camps-Valls, Gustavo

343

A Hierarchical Modeling Study of the Interactions Among Turbulence, Cloud Microphysics, and Radiative Transfer in the Evolution of Cirrus Clouds  

NASA Technical Reports Server (NTRS)

This project used a hierarchy of cloud resolving models to address the following science issues of relevance to CRYSTAL-FACE: What ice crystal nucleation mechanisms are active in the different types of cirrus clouds in the Florida area and how do these different nucleation processes influence the evolution of the cloud system and the upper tropospheric humidity? How does the feedback between supersaturation and nucleation impact the evolution of the cloud? What is the relative importance of the large-scale vertical motion and the turbulent motions in the evolution of the crystal size spectra? How does the size spectra impact the life-cycle of the cloud, stratospheric dehydration, and cloud radiative forcing? What is the nature of the turbulence and waves in the upper troposphere generated by precipitating deep convective cloud systems? How do cirrus microphysical and optical properties vary with the small-scale dynamics? How do turbulence and waves in the upper troposphere influence the cross-tropopause mixing and stratospheric and upper tropospheric humidity? The models used in this study were: 2-D hydrostatic model with explicit microphysics that can account for 30 size bins for both the droplet and crystal size spectra. Notably, a new ice crystal nucleation scheme has been incorporated into the model. Parcel model with explicit microphysics, for developing and evaluating microphysical parameterizations. Single column model for testing bulk microphysics parameterizations

Curry, Judith; Khvorostyanov, V. I.

2005-01-01

344

Homogeneous ice nucleation and supercooled liquid water in orographic wave clouds  

Microsoft Academic Search

This study investigates ice nucleation mechanisms in cold lenticular wave clouds, a cloud type characterized by quasi-steady-state air motions and microphysical properties. It is concluded that homogeneous ice nucleation is responsible for the ice production in these clouds at temperatures below about -33[degrees]C. The lack of ice nucleation observed above -33[degrees]C indicates a dearth of ice-forming nuclei, and hence heterogeneous

Andrew J. Heymsfield; Larry M. Miloshevich

1993-01-01

345

Periodic variation of Oort Cloud flux and cometary impacts on the Earth and Jupiter  

Microsoft Academic Search

Time variation in impact probability is studied by assuming that the periodic flux of the Oort Cloud comets within 15au arises from the motion of the Sun with respect to the Galactic mid-plane. The periodic flux clearly shows up in the impact rate of the captured Oort Cloud cometary population, with a phase shift caused by the orbital evolution. Depending

P. Nurmi; M. J. Valtonen; J. Q. Zheng

2001-01-01

346

Community Cloud Computing  

E-print Network

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 challenge...

Marinos, Alexandros

2009-01-01

347

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

348

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

349

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

350

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

351

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

352

Electron Cloud Effect in the Linear Colliders  

SciTech Connect

Beam induced multipacting, driven by the electric field of successive positively charged bunches, may arise from a resonant motion of electrons, generated by secondary emission, bouncing back and forth between opposite walls of the vacuum chamber. The electron-cloud effect (ECE) has been observed or is expected at many storage rings [1]. In the beam pipe of the Damping Ring (DR) of a linear collider, an electron cloud is produced initially by ionization of the residual gas and photoelectrons from the synchrotron radiation. The cloud is then sustained by secondary electron emission. This electron cloud can reach equilibrium after the passage of only a few bunches. The electron-cloud effect may be responsible for collective effects as fast coupled-bunch and single-bunch instability, emittance blow-up or incoherent tune shift when the bunch current exceeds a certain threshold, accompanied by a large number of electrons in the vacuum chamber. The ECE was identified as one of the most important R&D topics in the International Linear Collider Report [2]. Systematic studies on the possible electron-cloud effect have been initiated at SLAC for the GLC/NLC and TESLA linear colliders, with particular attention to the effect in the positron main damping ring (MDR) and the positron Low Emittance Transport which includes the bunch compressor system (BCS), the main linac, and the beam delivery system (BDS). We present recent computer simulation results for the main features of the electron cloud generation in both machine designs. Thus, single and coupled-bunch instability thresholds are estimated for the GLC/NLC design.

Pivi, M

2004-09-13

353

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

354

Intracellular trafficking of nonviral vectors  

Microsoft Academic Search

Nonviral vectors continue to be attractive alternatives to viruses due to their low toxicity and immunogenicity, lack of pathogenicity, and ease of pharmacologic production. However, nonviral vectors also continue to suffer from relatively low levels of gene transfer compared to viruses, thus the drive to improve these vectors continues. Many studies on vectorcell interactions have reported that nonviral vectors bind

L K Medina-Kauwe; J Xie; S Hamm-Alvarez

2005-01-01

355

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

356

LBNL-40256/CBP Note-224/PEP-II AP Note 97.07 THE ELECTRON-CLOUD INSTABILITY IN PEP-II: AN UPDATE  

E-print Network

origin is an electron cloud [1] in the vacuum chamber that couples the transverse motion of successiveLBNL-40256/CBP Note-224/PEP-II AP Note 97.07 1 THE ELECTRON-CLOUD INSTABILITY IN PEP-II: AN UPDATE-II collider arising from the interaction of the positron beam with the accumulated electron cloud. We estimate

Furman, Miguel

357

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

2014-12-01

358

Speed tuning of motion segmentation and discrimination  

NASA Technical Reports Server (NTRS)

Motion transparency requires that the visual system distinguish different motion vectors and selectively integrate similar motion vectors over space into the perception of multiple surfaces moving through or over each other. Using large-field (7 degrees x 7 degrees) displays containing two populations of random-dots moving in the same (horizontal) direction but at different speeds, we examined speed-based segmentation by measuring the speed difference above which observers can perceive two moving surfaces. We systematically investigated this 'speed-segmentation' threshold as a function of speed and stimulus duration, and found that it increases sharply for speeds above approximately 8 degrees/s. In addition, speed-segmentation thresholds decrease with stimulus duration out to approximately 200 ms. In contrast, under matched conditions, speed-discrimination thresholds stay low at least out to 16 degrees/s and decrease with increasing stimulus duration at a faster rate than for speed segmentation. Thus, motion segmentation and motion discrimination exhibit different speed selectivity and different temporal integration characteristics. Results are discussed in terms of the speed preferences of different neuronal populations within the primate visual cortex.

Masson, G. S.; Mestre, D. R.; Stone, L. S.

1999-01-01

359

Cloud Computing Security: From Single to Multi-clouds  

Microsoft Academic Search

The use of cloud computing has increased rapidly in many organizations. Cloud computing provides many benefits in terms of low cost and accessibility of data. Ensuring the security of cloud computing is a major factor in the cloud computing environment, as users often store sensitive information with cloud storage providers but these providers may be untrusted. Dealing with \\

Mohammed A. AlZain; Eric Pardede; Ben Soh; James A. Thom

2012-01-01

360

THE CALIFORNIA MOLECULAR CLOUD  

SciTech Connect

We present an analysis of wide-field infrared extinction maps of a region in Perseus just north of the Taurus-Auriga dark cloud complex. From this analysis we have identified a massive, nearby, but previously unrecognized, giant molecular cloud (GMC). Both a uniform foreground star density and measurements of the cloud's velocity field from CO observations indicate that this cloud is likely a coherent structure at a single distance. From comparison of foreground star counts with Galactic models, we derive a distance of 450 +- 23 pc to the cloud. At this distance the cloud extends over roughly 80 pc and has a mass of {approx} 10{sup 5} M{sub sun}, rivaling the Orion (A) molecular cloud as the largest and most massive GMC in the solar neighborhood. Although surprisingly similar in mass and size to the more famous Orion molecular cloud (OMC) the newly recognized cloud displays significantly less star formation activity with more than an order of magnitude fewer young stellar objects than found in the OMC, suggesting that both the level of star formation and perhaps the star formation rate in this cloud are an order of magnitude or more lower than in the OMC. Analysis of extinction maps of both clouds shows that the new cloud contains only 10% the amount of high extinction (A{sub K} > 1.0 mag) material as is found in the OMC. This, in turn, suggests that the level of star formation activity and perhaps the star formation rate in these two clouds may be directly proportional to the total amount of high extinction material and presumably high density gas within them and that there might be a density threshold for star formation on the order of n(H{sub 2}) {approx} a few x 10{sup 4} cm{sup -3}.

Lada, Charles J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Lombardi, Marco [European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748, Garching (Germany); Alves, Joao F., E-mail: clada@cfa.harvard.ed, E-mail: mlombard@eso.or, E-mail: jalves@caha.e [Calar Alto Observatory, C/Jesus Durban Remon, 2-2, 04004 Almeria (Spain)

2009-09-20

361

A study of the Orion cometary cloud L1616  

E-print Network

With its cometary appearance and a reflection nebula near its edge facing some bright Orion stars, the Lynd's cloud L1616 shows ample evidence for being affected by one or more of these massive stars. To estimate its mass and star formation efficiency as well as to determine if it is gravitationally bound, we mapped this cloud in J=1${\\rightarrow}$0 transitions of $^{12}$CO and $^{13}$CO. It is found that the distribution of the emission in the line {\\it wings} show clear evidence for substantial mass motions. Also, the ``virial'' mass of the cloud is found to be five times the actual cloud mass determined from the $^{13}$CO column density map. It is argued that this cloud has abnormally high star formation efficiency and is possibly disintegrating. The morphology and the location of the cloud indicate that it is being affected by the star ${\\epsilon}$ Orionis which is also possibly responsible for the cloud's unusual star formation efficiency. Over a range of values of the relevant parameters, the star is found to quantitatively satisfy the requirements of being the cause of the observed characteristics of the cloud.

B. Ramesh

1995-05-27

362

Scanning Cloud Radar Observations at the ARM sites  

NASA Astrophysics Data System (ADS)

Recently, the DOE Atmospheric Radiation Measurement (ARM) program upgraded its fixed and mobile facilities with the acquisition of state-of-the-art scanning, dual-wavelength, polarimetric, Doppler cloud radars. The scanning ARM cloud radars (SACR's) are the most expensive and significant radar systems at all ARM sites and eight SACR systems will be operational at ARM sites by the end of 2013. The SACR's are the primary instruments for the detection of 3D cloud properties (boundaries, volume cloud fractional coverage, liquid water content, dynamics, etc.) beyond the soda-straw (profiling) limited view. Having scanning capabilities with two frequencies and polarization allows more accurate probing of a variety of cloud systems (e.g., drizzle and shallow, warm rain), better correction for attenuation, use of attenuation for liquid water content retrievals, and polarimetric and dual-wavelength ratio characterization of non-spherical particles for improved ice crystal habit identification. Examples of SACR observations from four ARM sites are presented here: the fixed sites at Southern Great Plains (SGP) and North Slope of Alaska (NSA), and the mobile facility deployments at Graciosa Island, Azores and Cape Cod, Massachusetts. The 3D cloud structure is investigated both at the macro-scale (20-50 km) and cloud-scale (100-500 m). Doppler velocity measurements are corrected for velocity folding and are used either to describe the in-cloud horizontal wind profile or the 3D vertical air motions.

Kollias, P.; Clothiaux, E. E.; Shupe, M.; Widener, K.; Bharadwaj, N.; Miller, M. A.; Verlinde, H.; Luke, E. P.; Johnson, K. L.; Jo, I.; Tatarevic, A.; Lamer, K.

2012-12-01

363

Quadratic exponential vectors  

SciTech Connect

We give a necessary and sufficient condition for the existence of a quadratic exponential vector with test function in L{sup 2}(R{sup d}) intersection L{sup {infinity}}(R{sup d}). We prove the linear independence and totality, in the quadratic Fock space, of these vectors. Using a technique different from the one used by Accardi et al. [Quantum Probability and Infinite Dimensional Analysis, Vol. 25, p. 262, (2009)], we also extend, to a more general class of test functions, the explicit form of the scalar product between two such vectors.

Accardi, Luigi; Dhahri, Ameur [Volterra Center, University of Roma Tor Vergata, Via Columbia 2, 00133 Roma (Italy)

2009-12-15

364

Cloud computing and security challenges  

Microsoft Academic Search

Cloud Computing recently emerged as a promising solution to information technology (IT) management. IT managers look to cloud computing as a means to maintain a flexible and scalable IT infrastructure that enables business agility. In this paper Cloud Computing services including data storage service, cloud computing operating system and software as a service will be introduced, Cloud Computing security challenges

Huiming Yu; Nakia Powell; Dexter Stembridge; Xiaohong Yuan

2012-01-01

365

Security threats in cloud computing  

Microsoft Academic Search

Cloud computing is set of resources and services offered through the Internet. Cloud services are delivered from data centers located throughout the world. Cloud computing facilitates its consumers by providing virtual resources via internet. General example of cloud services is Google apps, provided by Google and Microsoft SharePoint. The rapid growth in field of cloud computing also increases severe security

Farhan Bashir Shaikh; Sajjad Haider

2011-01-01

366

Taxonomy of cloud computing services  

Microsoft Academic Search

Cloud computing is a highly discussed topic, and many big players of the software industry are entering the development of cloud services. Several companies want to explore the possibilities and benefits of cloud computing, but with the amount of cloud computing services increasing quickly, the need for a taxonomy framework rises. This paper describes the available cloud computing services, and

C. N. Hoefer; G. Karagiannis

2010-01-01

367

Elliptical Motion and Generating Elliptical Rotation Matrices  

E-print Network

Elliptical rotation is the motion of a point on an ellipse through some angle about a vector. The purpose of this paper is to examine the generation of elliptical rotations and to interpret the motion of a point on an elipsoid using elliptic inner product and elliptic vector product. To generate an elliptical rotation matrix, first we define an elliptical ortogonal matrix and an elliptical skew symmetric matrix using the associated inner product. Then we use elliptic versions of the famous Rodrigues, Cayley, and Householder methods to construct an elliptical rotation matrix. Finally, we define elliptic quaternions and generate an elliptical rotation matrix using those quaternions. Each method is proven and is provided with several numerical examples.

Mustafa Ozdemir

2015-03-25

368

Titan's South Polar Cloud  

NASA Astrophysics Data System (ADS)

Cassini/ISS cameras detected a newly formed large cloud in the south polar region of Titan on 2012-178 (June 27). Images of this cloud in the continuum filters at 889 nm (MT3) and 935 nm (CB3) clearly reveal different characteristics relative to the'detached haze' layer that extends over all south latitudes. Figure 1 shows I/F at 889 nm, where the cloud patch is observed beyond the latitude -77 and with values of the SZA higher than 90. In this work, we analyze different MT3/CB3 images taken by ISS cameras, in order to characterize the optical properties of this cloud as well as its altitude. We first analyze images in the MT3 filter at different angles of observation in order to have some constraints on the altitude of the cloud, and subsequently the cloud optical properties are estimated by using radiative transfer simulations.

Toledo, D.; Rannou, P.; West, R. A.; Lavvas, P.; Del Genio, A. D.; Barbara, J. M.; Roy, M.; Turtle, E. P.

2014-04-01

369

Introduction to Clouds  

NSDL National Science Digital Library

This site gives students an opportunity to explore storm clouds and climate change through the use of National Aeronautic and Space Administration (NASA) climate research data obtained through satellite imaging. The challenge is to investigate actual scientific research data on clouds and storms, and make the resulting observations and interpretations available to NASA research scientists for review. The interactive site will allow students to discover what the major types of clouds produced by storms are and whether these clouds help to cool or warm the Earth's surface. Storms are the major producers of clouds in the Earth's atmosphere, so students investigate the relationship between the types of clouds in order to make their conclusions.

370

THE LAW OF VECTOR FIELDS Daniel H. Gottlieb  

E-print Network

with the same acceleration, or Kepler's laws governing the motion of the planets, or the daily movementsTHE LAW OF VECTOR FIELDS Daniel H. Gottlieb 1. Introduction. When I was 13, the intellectual world. Something fantastically beautiful. This something is the existence of a few general laws or principles which

371

THE LAW OF VECTOR FIELDS Daniel H. Gottlieb  

E-print Network

to the Earth with the same acceleration, or Kepler's laws governing the motion of the planets, or the dailyTHE LAW OF VECTOR FIELDS Daniel H. Gottlieb 1. Introduction. When I was 13, the intellectual world of a few general laws or principles which imply mathematically most of the known facts of Physics

372

Cloud computing: from hype to reality: fast tracking cloud adoption  

Microsoft Academic Search

Cloud computing is one of the most talked about and to an extent hyped technologies in the recent years. As per Gartner, cloud computing is one of the top 10 technology initiatives for this year. Cloud computing is at the \\

Ramkumar Dargha

2012-01-01

373

Ammonia Clouds on Jupiter  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site] Click on the image for movie of Ammonia Ice Clouds on Jupiter

In this movie, put together from false-color images taken by the New Horizons Ralph instrument as the spacecraft flew past Jupiter in early 2007, show ammonia clouds (appearing as bright blue areas) as they form and disperse over five successive Jupiter 'days.' Scientists noted how the larger cloud travels along with a small, local deep hole.

2007-01-01

374

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.

David Robison

375

Cloud and surface textural features in polar regions  

NASA Technical Reports Server (NTRS)

The study examines the textural signatures of clouds, ice-covered mountains, solid and broken sea ice and floes, and open water. The textural features are computed from sum and difference histogram and gray-level difference vector statistics defined at various pixel displacement distances derived from Landsat multispectral scanner data. Polar cloudiness, snow-covered mountainous regions, solid sea ice, glaciers, and open water have distinguishable texture features. This suggests that textural measures can be successfully applied to the detection of clouds over snow-covered mountains, an ability of considerable importance for the modeling of snow-melt runoff. However, broken stratocumulus cloud decks and thin cirrus over broken sea ice remain difficult to distinguish texturally. It is concluded that even with high spatial resolution imagery, it may not be possible to distinguish broken stratocumulus and thin clouds from sea ice in the marginal ice zone using the visible channel textural features alone.

Welch, Ronald M.; Kuo, Kwo-Sen; Sengupta, Sailes K.

1990-01-01

376

Targeted adenoviral vectors  

NASA Astrophysics Data System (ADS)

The practical implementation of gene therapy in the clinical setting mandates gene delivery vehicles, or vectors, capable of efficient gene delivery selectively to the target disease cells. The utility of adenoviral vectors for gene therapy is restricted by their dependence on the native adenoviral primary cellular receptor for cell entry. Therefore, a number of strategies have been developed to allow CAR-independent infection of specific cell types, including the use of bispecific conjugates and genetic modifications to the adenoviral capsid proteins, in particular the fibre protein. These targeted adenoviral vectors have demonstrated efficient gene transfer in vitro , correlating with a therapeutic benefit in preclinical animal models. Such vectors are predicted to possess enhanced efficacy in human clinical studies, although anatomical barriers to their use must be circumvented.

Douglas, Joanne T.

377

Light Vector Mesons  

E-print Network

This article reviews the current status of experimental results obtained in the measurement of light vector mesons produced in proton-proton and heavy ion collisions at different energies. The review is focused on two phenomena related to the light vector mesons; the modification of the spectral shape in search of Chiral symmetry restoration and suppression of the meson production in heavy ion collisions. The experimental results show that the spectral shape of light vector mesons are modified compared to the parameters measured in vacuum. The nature and the magnitude of the modification depends on the energy density of the media in which they are produced. The suppression patterns of light vector mesons are different from the measurements of other mesons and baryons. The mechanisms responsible for the suppression of the mesons are not yet understood. Systematic comparison of existing experimental results points to the missing data which may help to resolve the problem.

Alexander Milov

2008-12-21

378

A motion picture presentation of magnetic pulsations  

NASA Technical Reports Server (NTRS)

Using the data obtained from the IMS North American magnetometer network stations at high latitudes, a motion picture was made by a computer technique, describing time changes of Pc5 and Pi3 magnetic pulsation vectors. Examples of pulsation characteristics derived from this presentation are regional polarization changes including shifts of polarization demarcation lines, changes in the extent of an active region and its movement with time.

Suzuki, A.; Kim, J. S.; Sugura, M.; Nagano, H.

1981-01-01

379

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

380

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

381

Vectorized Finite State Automata  

Microsoft Academic Search

. We present a technique of finite state parsingbased on vectorization and describe the application of thistechnique to a well-known problem of natural language processing,that of extracting relational information from Englishtext. We define Vectorized Finite State Automata, the theoreticalmodel behind the applied system, and discuss theirsignificance.0 IntroductionOne of the persistent problems in building finite automata onthe large scale required by

Andrs Kornai

382

Relative Velocity and Vectors  

NSDL National Science Digital Library

This activity is designed to enhance student comprehension of air and wind velocity, through the use of real time flight data. Students will read about relative velocity, complete a work sheet on vectors, and then gather and analyze real world data. All of the materials, including links to sites for data collection, are provided in this learning object. After completing the activity, students will be able to define relative velocity, add and subtract vectors, and determine aircraft speed using raw data.

Weaver, David

383

A driven, trapped, laser cooled ion cloud: a forced damped oscillator  

Microsoft Academic Search

We have studied the efficiency of laser cooling on clouds of magnesium and beryllium ions held in a Penning trap. We applied a driving voltage to the trap electrodes to drive the ions near one of their motional resonances, and studied the difference between the phase of the applied driving voltage and that of the resultant ion motion. Just as

M. A van Eijkelenborg; K. Dholakia; M. E. M. Storkey; D. M Segal; R. C Thompson

1999-01-01

384

Lost in Cloud  

NASA Technical Reports Server (NTRS)

Cloud computing can reduce cost significantly because businesses can share computing resources. In recent years Small and Medium Businesses (SMB) have used Cloud effectively for cost saving and for sharing IT expenses. With the success of SMBs, many perceive that the larger enterprises ought to move into Cloud environment as well. Government agency s stove-piped environments are being considered as candidates for potential use of Cloud either as an enterprise entity or pockets of small communities. Cloud Computing is the delivery of computing as a service rather than as a product, whereby shared resources, software, and information are provided to computers and other devices as a utility over a network. Underneath the offered services, there exists a modern infrastructure cost of which is often spread across its services or its investors. As NASA is considered as an Enterprise class organization, like other enterprises, a shift has been occurring in perceiving its IT services as candidates for Cloud services. This paper discusses market trends in cloud computing from an enterprise angle and then addresses the topic of Cloud Computing for NASA in two possible forms. First, in the form of a public Cloud to support it as an enterprise, as well as to share it with the commercial and public at large. Second, as a private Cloud wherein the infrastructure is operated solely for NASA, whether managed internally or by a third-party and hosted internally or externally. The paper addresses the strengths and weaknesses of both paradigms of public and private Clouds, in both internally and externally operated settings. The content of the paper is from a NASA perspective but is applicable to any large enterprise with thousands of employees and contractors.

Maluf, David A.; Shetye, Sandeep D.; Chilukuri, Sri; Sturken, Ian

2012-01-01

385

MPLNET Version 3 Cloud Algorithm  

NASA Astrophysics Data System (ADS)

The Micropulse Lidar Network version 3 cloud detection algorithm is described. Differences between the new cloud algorithm and the previous version are highlighted. The algortihm uses thresholds in the derivative of the attenuated calibration profile to identify low-level clouds and the signal uncertainty to identify higher clouds. Cirrus clouds are identified using the cloud top temperature derived from NCEP reanalysis. To demonstrate the performance of the new algorithm, a multiyear vertical distribution of clouds is shown from measurements at the Goddard Space Flight Center (Greenbelt, MD) and Singapore sites. Seasonal and diurnal statistics on the cloud base, apparent top, temperature, phase, optical thinkness, and frequency of occurrence are featured.

Lewis, J. R.; Campbell, J. R.; Welton, E. J.

2013-12-01

386

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

387

Wavefront propagation and imaging through cirrus clouds  

NASA Astrophysics Data System (ADS)

The authors present a wavefront reconstruction technique for beams forward scattered and back scattered through cirrus clouds. The technique uses ray distributions from the Coherent Illumination and Ray Trace Imaging Software for Cirrus which traces the propagation and E field vectors through a 3D volume of ice crystals in the shape of columns, plates, bullets, and bullet rosettes with random positions and polydisperse sizes and orientations. The wavefronts are then propagated to a telescope receiver on the ground and imaged in the receiver focal plate. A modification transfer function for each of these images is calculated and compared to the MTF for a diffraction-limited system.

Landesman, Barbara T.; Kindilien, Peter; Matson, Charles L.

1999-12-01

388

Ultraviolet contrasts and the absorbers near the Venus cloud tops  

NASA Technical Reports Server (NTRS)

The UV measurements of the Venus atmosphere absorbers constrain the location, altitude, and identity near the Venus cloud tops. The spin-scan images observed by the Pioneer Venus orbiter spectrometer (UVS) and the cloud photopolarimeter measure contrasts in the 1990-3650 A range and at phase angles between 33 and 130 deg; the planet is darkest at the location where the UVS line of sight penetrates in the direction perpendicular to the cloud tops. SO2 absorption accounts for the contrast from 2000 to 3200 A; the persistence of contrast at longer wavelengths requires another absorber at about 75-mbar altitude. The correlation between the planetary differences and polarization does not need large-scale clearing or major vertical motions of the cloud tops as the main cause of the observed variations.

Esposito, L. W.

1980-01-01

389

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

390

The effective reference frame in perceptual judgments of motion direction.  

PubMed

The retinotopic projection of stimulus motion depends both on the motion of the stimulus and the movements of the observer. In this study, we aimed to quantify the contributions of endogenous (retinotopic) and exogenous (spatiotopic and motion-based) reference frames on judgments of motion direction. We used a variant of the induced motion paradigm and we created different experimental conditions in which the predictions of each reference frame were different. Finally, assuming additive contributions from different reference frames, we used a linear model to account for the data. Our results suggest that the effective reference frame for motion perception emerges from an amalgamation of motion-based, retinotopic and spatiotopic reference frames. In determining the percept, the influence of relative motion, defined by a motion-based reference frame, dominates those of retinotopic and spatiotopic motions within a finite region. We interpret these findings within the context of the Reference Frame Metric Field (RFMF) theory, which states that local motion vectors might have perceptual reference-frame fields associated with them, and interactions between these fields determine the selection of the effective reference frame. PMID:25536467

Agaoglu, Mehmet N; Herzog, Michael H; ?men, Haluk

2015-02-01

391

SoundCloudNav  

NSDL National Science Digital Library

For people who like to use SoundCloud to control their musical selections while working, this helpful plug-in will be a welcome find. SoundCloudNav will allow users to explore different tracks and manipulate them as they see fit. This version is compatible with all computers utilizing Google Chrome.

2012-05-10

392

Saharan Dust Cloud  

Atmospheric Science Data Center

article title: Saharan Dust Cloud Blows Westward Full Image A huge dust cloud blown westward from the Algerian desert is now wafting over the ... dramatic sunsets and possibly a light coating of red-brown dust on vehicles from Florida to Texas. This image, captured by JPL's ...

2013-04-16

393

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.

394

On Cloud Nine  

ERIC Educational Resources Information Center

Across the U.S., innovative collaboration practices are happening in the cloud: Sixth-graders participate in literary salons. Fourth-graders mentor kindergarteners. And teachers use virtual Post-it notes to advise students as they create their own television shows. In other words, cloud computing is no longer just used to manage administrative

McCrea, Bridget; Weil, Marty

2011-01-01

395

Cloud Resolving Modeling  

NASA Technical Reports Server (NTRS)

One of the most promising methods to test the representation of cloud processes used in climate models is to use observations together with cloud-resolving models (CRMs). CRMs use more sophisticated and realistic representations of cloud microphysical processes, and they can reasonably well resolve the time evolution, structure, and life cycles of clouds and cloud systems (with sizes ranging from about 2-200 km). CRMs also allow for explicit interaction between clouds, outgoing longwave (cooling) and incoming solar (heating) radiation, and ocean and land surface processes. Observations are required to initialize CRMs and to validate their results. This paper provides a brief discussion and review of the main characteristics of CRMs as well as some of their major applications. These include the use of CRMs to improve our understanding of: (1) convective organization, (2) cloud temperature and water vapor budgets, and convective momentum transport, (3) diurnal variation of precipitation processes, (4) radiative-convective quasi-equilibrium states, (5) cloud-chemistry interaction, (6) aerosol-precipitation interaction, and (7) improving moist processes in large-scale models. In addition, current and future developments and applications of CRMs will be presented.

Tao, Wei-Kuo

2007-01-01

396

Weather Fundamentals: Clouds. [Videotape].  

ERIC Educational Resources Information Center

The videos in this educational series, for grades 4-7, help students understand the science behind weather phenomena through dramatic live-action footage, vivid animated graphics, detailed weather maps, and hands-on experiments. This episode (23 minutes) discusses how clouds form, the different types of clouds, and the important role they play in

1998

397

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

398

Motion Lab: Position - Time Graphs of Motion  

NSDL National Science Digital Library

The representation depicts a position-time graph showing the motion of an object as it is moved by the user. The user can also move the object to match the motion represented on 8 different types of position-time graphs.

John M. Clement

399

A new automated approach to cloud population  

E-print Network

This thesis presents vCloud Populator, a new approach to automating the cloud population process on VMware vCloud Director. Cloud population is the process during which a cloud instance is populated with entities to reflect ...

Tam, Hoki

2012-01-01

400

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

401

On the Kinematics of Undulator Girder Motion  

SciTech Connect

The theory of rigid body kinematics is used to derive equations that govern the control and measurement of the position and orientation of undulator girders. The equations form the basis of the girder matlab software on the LCLS control system. The equations are linear for small motion and easily inverted as desired. For reference, some relevant girder geometrical data is also given. Equations 6-8 relate the linear potentiometer readings to the motion of the girder. Equations 9-11 relate the cam shaft angles to the motion of the girder. Both sets are easily inverted to either obtain the girder motion from the angles or readings, or, to find the angles and readings that would give a desired motion. The motion of any point on the girder can be calculated by applying either sets of equations to the two cam-planes and extrapolating in the z coordinate using equation 19. The formulation of the equations is quite general and easily coded via matrix and vector methods. They form the basis of the girder matlab software on the LCLS control system.

Welch, J; /SLAC; ,

2011-08-18

402

Clouds Over the North Pole  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Released 29 June 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.

Like yesterday's image, the linear 'ripples' are water-ice clouds. As spring is deepening at the North Pole these clouds are becoming more prevalent.

Image information: VIS instrument. Latitude 68.9, Longitude 135.5 East (224.5 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

403

Cloud computing security.  

SciTech Connect

Cloud computing is a paradigm rapidly being embraced by government and industry as a solution for cost-savings, scalability, and collaboration. While a multitude of applications and services are available commercially for cloud-based solutions, research in this area has yet to fully embrace the full spectrum of potential challenges facing cloud computing. This tutorial aims to provide researchers with a fundamental understanding of cloud computing, with the goals of identifying a broad range of potential research topics, and inspiring a new surge in research to address current issues. We will also discuss real implementations of research-oriented cloud computing systems for both academia and government, including configuration options, hardware issues, challenges, and solutions.

Shin, Dongwan; Claycomb, William R.; Urias, Vincent E.

2010-10-01

404

Cloud Model Bat Algorithm  

PubMed Central

Bat algorithm (BA) is a novel stochastic global optimization algorithm. Cloud model is an effective tool in transforming between qualitative concepts and their quantitative representation. Based on the bat echolocation mechanism and excellent characteristics of cloud model on uncertainty knowledge representation, a new cloud model bat algorithm (CBA) is proposed. This paper focuses on remodeling echolocation model based on living and preying characteristics of bats, utilizing the transformation theory of cloud model to depict the qualitative concept: bats approach their prey. Furthermore, Lvy flight mode and population information communication mechanism of bats are introduced to balance the advantage between exploration and exploitation. The simulation results show that the cloud model bat algorithm has good performance on functions optimization. PMID:24967425

Zhou, Yongquan; Xie, Jian; Li, Liangliang; Ma, Mingzhi

2014-01-01

405

Image to Point Cloud Method of 3D-MODELING  

NASA Astrophysics Data System (ADS)

This article describes the method of constructing 3D models of objects (buildings, monuments) based on digital images and a point cloud obtained by terrestrial laser scanner. The first step is the automated determination of exterior orientation parameters of digital image. We have to find the corresponding points of the image and point cloud to provide this operation. Before the corresponding points searching quasi image of point cloud is generated. After that SIFT algorithm is applied to quasi image and real image. SIFT algorithm allows to find corresponding points. Exterior orientation parameters of image are calculated from corresponding points. The second step is construction of the vector object model. Vectorization is performed by operator of PC in an interactive mode using single image. Spatial coordinates of the model are calculated automatically by cloud points. In addition, there is automatic edge detection with interactive editing available. Edge detection is performed on point cloud and on image with subsequent identification of correct edges. Experimental studies of the method have demonstrated its efficiency in case of building facade modeling.

Chibunichev, A. G.; Galakhov, V. P.

2012-07-01

406

Isentropic Analysis of Convective Motions  

NASA Technical Reports Server (NTRS)

This paper analyzes the convective mass transport by sorting air parcels in terms of their equivalent potential temperature to determine an isentropic streamfunction. By averaging the vertical mass flux at a constant value of the equivalent potential temperature, one can compute an isentropic mass transport that filters out reversible oscillatory motions such as gravity waves. This novel approach emphasizes the fact that the vertical energy and entropy transports by convection are due to the combination of ascending air parcels with high energy and entropy and subsiding air parcels with lower energy and entropy. Such conditional averaging can be extended to other dynamic and thermodynamic variables such as vertical velocity, temperature, or relative humidity to obtain a comprehensive description of convective motions. It is also shown how this approach can be used to determine the mean diabatic tendencies from the three-dimensional dynamic and thermodynamic fields. A two-stream approximation that partitions the isentropic circulation into a mean updraft and a mean downdraft is also introduced. This offers a straightforward way to identify the mean properties of rising and subsiding air parcels. The results from the two-stream approximation are compared with two other definitions of the cloud mass flux. It is argued that the isentropic analysis offers a robust definition of the convective mass transport that is not tainted by the need to arbitrarily distinguish between convection and its environment, and that separates the irreversible convective overturning fromoscillations associated with gravity waves.

Pauluis, Olivier M.; Mrowiec, Agnieszka A.

2013-01-01

407

Particle migration in suspensions by thermocapillary or electrophoretic motion  

NASA Technical Reports Server (NTRS)

Two problems of similar mathematical structure are presented: the thermocapillary motion of bubbles and the electrophoresis of colloidal particles. For both problems, it is shown that in a cloud of n particles surrounded by an infinite expanse of fluid, the velocity of each sphere under creeping flow conditions is equal to the velocity of an isolated particle, unchanged by interactions between the particles. However, when the cloud fills a container, conservation of mass shows that this result cannot continue to hold, and the average translational velocity must be calculated subject to a constraint on the mass flux. It is concluded that the average thermocapillary or electrophoretic translational velocity of a particle in the cloud is related to the effective conductivity of the cloud over the whole range of particle volume fractions, provided that the particles are identical, non-conducting and, for the thermocapillary problem, inviscid.

Acrivos, A.; Jeffrey, D. J.; Saville, D. A.

1990-01-01

408

Mycobacteriophage vector systems.  

PubMed

Successful application of molecular genetic approaches to the study of mycobacteria necessitates the introduction of recombinant DNA molecules into mycobacterial cells. Efficient methods of introducing DNA into Mycobacterium smegmatis protoplasts have been developed, and the construction of mycobacteriophage recombinant DNA vectors has been initiated. Novel Escherichia coli-Mycobacterium shuttle vectors, termed shuttle phasmids, have been constructed. These vectors were constructed by inserting E. coli cosmids into nonessential regions of mycobacteriophage DNAs. Shuttle phasmids are multifunctional vectors that replicate in E. coli as plasmids and replicate in mycobacteria as phage. The presence of the bacteriophage lambda cos sequences permits the use of the lambda in vitro packaging system for efficient cloning of additional genes into these vectors. Temperate shuttle phasmids have been constructed that can infect and lyse mycobacterial cells or lysogenize mycobacterial cells to stably integrate and express cloned DNA into mycobacterial genomes. Shuttle phasmids can be transduced into a wide variety of mycobacterial species and thus should permit the development of molecular genetic systems for the mycobacteria. PMID:2652256

Jacobs, W R; Snapper, S B; Tuckman, M; Bloom, B R

1989-01-01

409

Improving the Supervised Learning of Activity Classifiers for Human Motion Data  

E-print Network

" or "kneading dough" which could be recognized by the motion patterns and objects manipulated. Although domain-driven approaches, including supervised classifiers, such as support vector machines, hidden Markov mod- els

Sukthankar, Gita Reese

410

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

411

Repetitive Motion Disorders  

MedlinePLUS

NINDS Repetitive Motion Disorders Information Page Synonym(s): Cumulative Trauma Disorders, Repetitive Stress Injuries, Overuse Syndrome Table of Contents (click to jump to sections) What are Repetitive Motion Disorders? Is there any ...

412

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

413

Twin Clouds: An Architecture for Secure Cloud Computing (Extended Abstract)  

E-print Network

Twin Clouds: An Architecture for Secure Cloud Computing (Extended Abstract) Sven Bugiel1 , Stefan N Cloud Computing, Cryptographic Protocols, Verifiable Outsourcing, Secure Computa- tion 1 Introduction itself. When data and computation is outsourced to the cloud, prominent security risks are: malicious

Cachin, Christian

414

The proposed connection between clouds and cosmic rays: Cloud  

E-print Network

The proposed connection between clouds and cosmic rays: Cloud behaviour during the past 50 of galactic cosmic rays (GCR) and cloudiness. Here we review the evidence for such a connection from studies for the low cloud decrease predicted by the rising levels of solar activity and the low cloud­cosmic ray flux

415

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

416

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

417

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

418

Compensation of Target Motion  

NASA Astrophysics Data System (ADS)

In ion beam therapy (IBT), organ motion requires special procedures. Of general concern is the impact on the dose distribution as a result of motion-related changes in the beam's range. In addition, interplay effects can arise for scanned beam application which cannot be addressed by the so-called margins to increase the treated volume. Dedicated motion mitigation techniques and/or 4D treatment planning are required. This chapter introduces the main concepts for management of respiratory motion in IBT.

Bert, Christoph; Rietzel, Eike

419

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 ...

Carrie Benson

2013-01-31

420

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

421

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

422

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

423

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

424

Integrable four vortex motion  

Microsoft Academic Search

It follows from the Poisson brackets between constants of motion that the motion of four vortices of zero net vorticity is integrable if the total momentum vanishes. The phase space motion of this integrable case is analyzed. One stable and several unstable uniformly rotating configurations are identified.

Bruno Eckhardt

1988-01-01

425

A Motion Generator Framework  

Microsoft Academic Search

There are two broad categories of research animation system: those designed to support a particular motion synthesis tool, and those whose implementation is intended to foster a particular form of motion generator design (such as object orientation). However, neither of these approaches really provides significant assistance to the animation researcher wishing to quickly evaluate arbitrary new motion production algorithms against

Martin Preston

1996-01-01

426

EXPRESSIVE MOTION Alyssa Lees  

E-print Network

of motion capture animation, attempts have been made to extract the seemingly nebulously defined attributes of 'content' and 'style' from the motion data. Enabling quick access to highly precise data, the bene fits of motion capture for animation purposes are abundant. Yet manipulating the expressive attributes

Mohri, Mehryar

427

EXPRESSIVE MOTION Alyssa Lees  

E-print Network

of motion capture animation, attempts have been made to extract the seemingly nebulously defined attributes of 'content' and 'style' from the motion data. Enabling quick access to highly precise data, the bene- fits of motion capture for animation purposes are abundant. Yet manipulating the expressive attributes

Mohri, Mehryar

428

Intelligent compliant motion control  

Microsoft Academic Search

The role of a compliant motion scheme is to control a robot manipulator in contact with its environment. By accommodating with the interaction force, the manipulator can be used to accomplish tasks that involve constrained motions. This paper presents a new work on the compliant motion control for position-controlled manipulator. A new method for achieving efficient interaction between the manipulator

Omar M. Al-jarrah; Yuan F. Zheng

1998-01-01

429

Stereoscopic Motion Tracking System  

Microsoft Academic Search

A Stereoscopic Motion Tracking System is being developed for use with a video game system for rehabilitation of children affected by Cerebral Palsy. Two cameras will be used to track the (x, y) locationof a motion, using stereoscopic principles this data will be used to calculate the Z locationof the motion. This data will be collected for the duration of

A. Calderon; M. Dembele; B. Hossain; Y. Noor; S. Ovsiew

2011-01-01

430

Limited range of motion  

MedlinePLUS

Limited range of motion is a term meaning that a joint or body part cannot move through its normal range of motion. ... A sudden loss of range of motion may be due to: Dislocation of a joint Fracture of an elbow or other joint Septic or infected joint (hip ...

431

Camera Motion Style Transfer  

Microsoft Academic Search

When depicting both virtual and physical worlds, the viewer's impression of presence in these worlds is strongly linked to camera motion. Plausible and artist-controlled camera movement can substantially increase scene immersion. While physical camera motion exhibits subtle details of position, rotation, and acceleration, these details are often missing for virtual camera motion. In this work, we analyze camera movement using

Christian Kurz; Tobias Ritschel; Elmar Eisemann; T. Thorma?hlen; Hans-Peter Seidel

2010-01-01

432

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

433

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

434

Clouds in GEOS-5  

NASA Technical Reports Server (NTRS)

The GEOS-5 atmospheric model is being developed as a weather-and-climate capable model. It must perform well in assimilation mode as well as in weather and climate simulations and forecasts and in coupled chemistry-climate simulations. In developing GEOS-5, attention has focused on the representation of moist processes. The moist physics package uses a single phase prognostic condensate and a prognostic cloud fraction. Two separate cloud types are distinguished by their source: "anvil" cloud originates in detraining convection, and large-scale cloud originates in a PDF-based condensation calculation. Ice and liquid phases for each cloud type are considered. Once created, condensate and fraction from the anvil and statistical cloud types experience the same loss processes: evaporation of condensate and fraction, auto-conversion of liquid or mixed phase condensate, sedimentation of frozen condensate, and accretion of condensate by falling precipitation. The convective parameterization scheme is the Relaxed Arakawa-Schubert, or RAS, scheme. Satellite data are used to evaluate the performance of the moist physics packages and help in their tuning. In addition, analysis of and comparisons to cloud-resolving models such as the Goddard Cumulus Ensemble model are used to help improve the PDFs used in the moist physics. The presentation will show some of our evaluations including precipitation diagnostics.

Bacmeister, Julio; Rienecker, Michele; Suarez, Max; Norris, Peter

2007-01-01

435

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

436

Infinite cloud model of electrification by the precipitation mechanism in the presence of high rates of ion generation  

Microsoft Academic Search

We have extended a simple, infinite cloud, precipitation mechanism model of thundercloud electrification to include effects due to the presence of radioactive aerosol particles resulting from fresh debris from a nuclear explosion. These effects involve ion generation, currents due to motions of ions and charged aerosol particles, and collection of ions and aerosol particles by hydrometeors and cloud droplets. Our

J. D. Spangler; C. E. Rosenkilde

1979-01-01

437

Infinite cloud model of electrification by the precipitation mechanism in the presence of high rates of ion generation  

Microsoft Academic Search

A simple, infinite-cloud, precipitation-mechanism model of thundercloud electrification was extended to include effects due to the presence of radioactive aerosol particles. These effects involve ion generation, currents due to motions of ions and charged aerosol particles, and collection of ions and aerosol particles by hydrometeors and cloud droplets. It is concluded that an ion pair generation rate G equal to

J. D. Spangler; C. E. Rosenkilde

1978-01-01

438

The Magnetic Field Structure of Musca Dark Cloud  

NASA Astrophysics Data System (ADS)

Our goal is the study of the magnetic field (MF) structure of a pre-collapse structure of the interstellar medium - the Musca Dark Cloud (MDC), a nearby (200-250 pc), large (0.25 3) filamentary cloud. A description of the MF, together with knowledge on turbulence and gravitational forces, is key to understanding the evolution of interstellar clouds. We have obtained linear polarization measurements in the H band (1.65?m) with the Brazilian's 60 cm and 160 cm telescopes located at the OPD observatory. By combining these with our earlier optical observations (Pereyra & Magalhaes 2004), we were able to probe regions denser than what was possible in the optical. Our studies in the optical band showed that the cloud is surrounded by a MF which is well aligned with the projected small axis of the cloud. Our H-band data show in general the same tendency in the inner parts of the MDC. The comparison between the V and H bands allow us to conclude that the same type of grains are polarizing the light throughout the cloud at least up to Av 8-9, and that these are the same as those in the general ISM. Utilizing the dispersion of the polarization vectors, we estimated the MF intensity (0.02-0.16 mG) across the cloud. We compared the magnetic and gravitational energies and concluded that Musca is a subcritical cloud. From the structure function of the polarization at the H band, we obtain 0.21-0.29 pc for the range of correlation lengths of the MF in the cloud, comparable to the size of the optical condensations.

Ribeiro, N. L.; Magalhes, A. M.; Pereyra, A.; Cambresy, L.

2014-10-01

439

Cloud computing basics for librarians.  

PubMed

"Cloud computing" is the name for the recent trend of moving software and computing resources to an online, shared-service model. This article briefly defines cloud computing, discusses different models, explores the advantages and disadvantages, and describes some of the ways cloud computing can be used in libraries. Examples of cloud services are included at the end of the article. PMID:22289098

Hoy, Matthew B

2012-01-01

440

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

441

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

442

Cloud Distribution Statistics from LITE  

NASA Technical Reports Server (NTRS)

The Lidar In-Space Technology Experiment (LITE) mission has demonstrated the utility of spaceborne lidar in observing multilayer clouds and has provided a dataset showing the distribution of tropospheric clouds and aerosols. These unambiguous observations of the vertical distribution of clouds will allow improved verification of current cloud climatologies and GCM cloud parameterizations. Although there is now great interest in cloud profiling radar, operating in the mm-wave region, for the spacebased observation of cloud heights the results of the LITE mission have shown that satellite lidars can also make significant contributions in this area.

Winker, David M.

1998-01-01

443

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

444

Concord Consortium: Seeing Motion  

NSDL National Science Digital Library

This activity explores simple, straight-line motion by blending a motion sensor lab with student-generated digital graphs of distance versus time. First, learners use the online graph sketching tool to predict the motion of a person walking forward and backward over a 4-meter track in 30 seconds. Next, they try to reproduce their prediction graphs using a motion sensor to collect data. Finally, they analyze differences in slope between their original predictions and the actual data from the motion sensor. This resource is part of the Concord Consortium, a nonprofit research and development organization dedicated to transforming education through technology.

2012-04-23

445

Vector Meson Dominance  

E-print Network

Historically vector-meson physics arose along two different paths to be reviewed in Sections 1 and 2. In Section 3, the phenomenological consequences will be discussed with an emphasis on those aspects of the subject matter relevant in present-day discussions on deep inelastic scattering in the diffraction region of low values of the Bjorken variable.

Dieter Schildknecht

2005-11-08

446

Vectors Point Toward Pisa  

ERIC Educational Resources Information Center

The author shows that the set of all sequences in which each term is the sum of the two previous terms forms a vector space of dimension two. He uses this result to obtain the formula for the Fibonacci sequence and applies the same technique to other linear recursive relations. (MM)

Dean, Richard A.

1971-01-01

447

Fuzzy support vector machines  

Microsoft Academic Search

A support vector machine (SVM) learns the decision surface from two distinct classes of the input points. In many applications, each input point may not be fully assigned to one of these two classes. In this paper, we apply a fuzzy membership to each input point and reformulate the SVMs such that different input points can make different contributions to

Chun-Fu Lin; Sheng-De Wang

2002-01-01

448

Vectorizing Cartoon Animations  

Microsoft Academic Search

We present a system for vectorizing 2D raster format cartoon animations. The output animations are visually flicker free, smaller in file size, and easy to edit. We identify decorative lines separately from colored regions. We use an accurate and semantically meaningful image decomposition algorithm, supporting an arbitrary color model for each region. To ensure temporal coherence in the output, we

Song-hai Zhang; Tao Chen; Yi-fei Zhang; Shi-min Hu; Ralph R. Martin

2009-01-01

449

Vector potential methods  

NASA Technical Reports Server (NTRS)

Vector potential and related methods, for the simulation of both inviscid and viscous flows over aerodynamic configurations, are briefly reviewed. The advantages and disadvantages of several formulations are discussed and alternate strategies are recommended. Scalar potential, modified potential, alternate formulations of Euler equations, least-squares formulation, variational principles, iterative techniques and related methods, and viscous flow simulation are discussed.

Hafez, M.

1989-01-01

450

Support vector machines  

NASA Technical Reports Server (NTRS)

Support Vector Machines (SVMs) are a type of supervised learning algorith,, other examples of which are Artificial Neural Networks (ANNs), Decision Trees, and Naive Bayesian Classifiers. Supervised learning algorithms are used to classify objects labled by a 'supervisor' - typically a human 'expert.'.

Garay, Michael J.; Mazzoni, Dominic; Davies, Roger; Wagstaff, Kiri

2004-01-01

451

Vector Analysis on Fractals  

E-print Network

Post-Critically Finite fractals are self-similar structures with the boundary ... form on a vector space F of real valued functions on X, and E(u) = 0 if and ..... zero seminorm elements and completing. ... Magnetic Schrdinger operators. Classically.

Daniel J. Kelleher

2014-08-31

452

Vector Autoregressions and Reality  

Microsoft Academic Search

This article questions the statistical significance of variance decompositions and impulse response functions for unrestricted vector autoregressions. It suggests that previous authors have failed to provide confidence intervals for variance decompositions and impulse response functions. Two methods of computing such confidence intervals are developed: first, using a normal approximation; second, using bootstrapped resampling. An example from Sims's work is used

David E. Runkle

1987-01-01

453

Cloud-tracked winds for the first Mars Global Surveyor mapping year  

NASA Astrophysics Data System (ADS)

We have measured winds using cloud motion in consecutive Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide-angle global map swaths taken during the first mapping year (Ls 135-360-111). We present a total of ~11,200 wind vectors collected in the north polar region during Ls 135-195 (late summer/early fall) and Ls 20-55 (mid spring) and in the south polar region during Ls 337-10 (late summer/early fall). For cases with good coverage, we also present the derived mean zonal and meridional winds and the associated eddies. The speed of the zonal winds in 60N-70N increases at ~0.6 m/s/Ls in late northern summer, and that in 60S-70S increases at a rate of ~0.7 m/s/Ls in late southern summer. The latitudinal distribution of zonal wind within 50N-75N from mid northern summer to early northern fall indicates that winds at higher latitudes are generally weaker than those at lower latitudes, but the rate of increase with time is faster at higher latitudes. There is a cyclonic gyre in the 90W-0-30E sector in the north polar region. There are large-scale waves in the weekly mean meridional wind and in the biweekly mean eddy momentum flux and eddy kinetic energy fields in the north polar region from mid to late summer. The cloud-tracked winds in the north are generally consistent with winds calculated by general circulation model at the water condensation level derived from MGS Thermal Emission Spectrometer (TES) observations but appear stronger than the gradient winds derived from TES assuming no flow at the surface.

Wang, Huiqun; Ingersoll, Andrew P.

2003-09-01

454

A hillock and cloud model for faculae  

NASA Technical Reports Server (NTRS)

A hillock model is used here to explain facular contrasts, allowing faculae to emit more energy than the surrounding unmagnetized photosphere. For downflows, horizontal motions converge near the photosphere and many fibril flux tubes are drawn together to form a large dark area, the sunspot. For upflows, the motions diverge near the photosphere and fibril flux tubes are dispersed over a larger area associated with faculae. The upflows transport material and energy, resulting in hotter than normal temperatures, which in turn cause the gas to expand compared with its surroundings. Buoyancy thus causes a 'network' of patchy hillocks, clouds, or geysers to form which allows the sun to reradiate the energy deficit associated with sunspots by locally increasing the effective surface area of the sun beyond that of a sphere. The consequences of this model for the physical form of the facular manifestation, the appearance of faculae from earth, and the 'energy balance' in active regions are addressed.

Schatten, Kenneth H.; Mayr, Hans G.; Omidvar, Kazem; Maier, Eugene

1986-01-01

455

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

456

Soret Motion of a Charged Spherical Colloid  

E-print Network

The thermophoretic motion of a charged spherical colloidal particle and its accompanying cloud of counterions and co-ions in a temperature gradient is studied theoretically. Using the Debye-Huckel approximation, the Soret drift velocity of a weakly charged colloid is calculated analytically. For highly charged colloids, the nonlinear system of electrokinetic equations is solved numerically, and the effects of high surface potential, dielectrophoresis, and convection are examined. Our results are in good agreement with some of the recent experiments on highly charged colloids without using adjustable parameters.

Seyyed Nader Rasuli; Ramin Golestanian

2008-08-05

457

Motion-compensated two-link chain coding for binary shape sequence  

NASA Astrophysics Data System (ADS)

In this paper, we present a motion compensated two-link chain coding technique to effectively encode 2-D binary shape sequences for object-based video coding. This technique consists of a contour motion estimation and compensation algorithm and a two-link chain coding algorithm. The object contour is defined on a 6-connected contour lattice for a smoother contour representation. The contour in the current frame is first predicted by global motion and local motion based on the decoded contour in the previous frame; then, it is segmented into motion success segments, which can be predicted by the global motion or the local motion, and motion failure segments, which can not be predicted by the global and local motion. For each motion failure segment, a two-link chain code, which uses one chain code to represent two consecutive contour links, followed by an arithmetic coder is proposed for efficient coding. Each motion success segment can be represented by the motion vector and its length. For contour motion estimation and compensation, besides the translational motion model, an affine global motion model is proposed and investigated for complex global motion. We test the performance of the proposed technique by several MPEG-4 shape test sequences. The experimental results show that our proposed scheme is better than the CAE technique which is applied in the MPEG-4 verification model.

Lu, Zhitao; Pearlman, William A.

2002-01-01

458

Motion coherence affects human perception and pursuit similarly  

NASA Technical Reports Server (NTRS)

Pursuit and perception both require accurate information about the motion of objects. Recovering the motion of objects by integrating the motion of their components is a difficult visual task. Successful integration produces coherent global object motion, while a failure to integrate leaves the incoherent local motions of the components unlinked. We compared the ability of perception and pursuit to perform motion integration by measuring direction judgments