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1

Analysis of vector wind change with respect to time for Cape Kennedy, Florida  

NASA Technical Reports Server (NTRS)

Multivariate analysis was used to determine the joint distribution of the four variables represented by the components of the wind vector at an initial time and after a specified elapsed time is hypothesized to be quadravariate normal; the fourteen statistics of this distribution, calculated from 15 years of twice-daily rawinsonde data are presented by monthly reference periods for each month from 0 to 27 km. The hypotheses that the wind component changes with respect to time is univariate normal, that the joint distribution of wind component change with respect to time is univariate normal, that the joint distribution of wind component changes is bivariate normal, and that the modulus of vector wind change is Rayleigh are tested by comparison with observed distributions. Statistics of the conditional bivariate normal distributions of vector wind at a future time given the vector wind at an initial time are derived. Wind changes over time periods from 1 to 5 hours, calculated from Jimsphere data, are presented. Extension of the theoretical prediction (based on rawinsonde data) of wind component change standard deviation to time periods of 1 to 5 hours falls (with a few exceptions) within the 95 percentile confidence band of the population estimate obtained from the Jimsphere sample data. The joint distributions of wind change components, conditional wind components, and 1 km vector wind shear change components are illustrated by probability ellipses at the 95 percentile level.

Adelfang, S. I.

1978-01-01

2

Vector wind profile gust model  

NASA Technical Reports Server (NTRS)

A methodology was developed for the derivation and analysis of small scale perturbations in Jimsphere wind profiles. Gusts in various wavelength bands have been derived from these perturbations; the probability distribution of gust components and associated gust length has been shown to be accurately represented by a gamma distribution. Theoretical and observed distributions of component gust vary significantly with season, altitude, and wavelength range. The results of this study provide the basis for a vector wind model for Cape Kennedy, Florida.

Adelfang, S. I.; Evans, B. A.

1980-01-01

3

Vector wind profile gust model  

NASA Technical Reports Server (NTRS)

Work towards establishing a vector wind profile gust model for the Space Transportation System flight operations and trade studies is reported. To date, all the statistical and computational techniques required were established and partially implemented. An analysis of wind profile gust at Cape Kennedy within the theoretical framework is presented. The variability of theoretical and observed gust magnitude with filter type, altitude, and season is described. Various examples are presented which illustrate agreement between theoretical and observed gust percentiles. The preliminary analysis of the gust data indicates a strong variability with altitude, season, and wavelength regime. An extension of the analyses to include conditional distributions of gust magnitude given gust length, distributions of gust modulus, and phase differences between gust components has begun.

Adelfang, S. I.

1979-01-01

4

Wind Vectors for Hurricane Erin (WMS)  

NSDL National Science Digital Library

This visualization shows wind vectors for Hurricane Erin on September 10, 2001. Wind direction and speed are represented by the direction and speed of moving arrows, respectively. This animation represents a single measurement taken by the SeaWinds instrument on the QuikSCAT satellite, taken at 14:27:00 UTC on September 10, 2001. The WMS version of this animation which is available through the SVS Image Server (http:--aes.gsfc.nasa.gov) presents this animation with a different timestamp for each frame in order to more easily present the images as an animation. It should be noted that each frame really has a time stamp of 2001-09-10 14:27:00 UTC.

Sokolowsky, Eric; Shirah, Greg; Halverson, Jeff

2004-02-11

5

Vector wind and vector wind shear models 0 to 27 km altitude for Cape Kennedy, Florida, and Vandenberg AFB, California  

NASA Technical Reports Server (NTRS)

The techniques are presented to derive several statistical wind models. The techniques are from the properties of the multivariate normal probability function. Assuming that the winds can be considered as bivariate normally distributed, then (1) the wind components and conditional wind components are univariate normally distributed, (2) the wind speed is Rayleigh distributed, (3) the conditional distribution of wind speed given a wind direction is Rayleigh distributed, and (4) the frequency of wind direction can be derived. All of these distributions are derived from the 5-sample parameter of wind for the bivariate normal distribution. By further assuming that the winds at two altitudes are quadravariate normally distributed, then the vector wind shear is bivariate normally distributed and the modulus of the vector wind shear is Rayleigh distributed. The conditional probability of wind component shears given a wind component is normally distributed. Examples of these and other properties of the multivariate normal probability distribution function as applied to Cape Kennedy, Florida, and Vandenberg AFB, California, wind data samples are given. A technique to develop a synthetic vector wind profile model of interest to aerospace vehicle applications is presented.

Smith, O. E.

1976-01-01

6

Rapid Temporal Changes of Boundary Layer Winds  

NASA Technical Reports Server (NTRS)

The statistical distribution of the magnitude of the vector wind change over 0.25, 0.5, 1 and 2-h periods based on data from November 1999 through August 2001 is presented. The distributions of the 2-h u and v component wind changes are also presented for comparison. The wind changes at altitudes from 500 to 3000 m were measured using the Eastern Range network of five 915 MHz Doppler radar wind profilers. Quality controlled profiles were produced every 15 minutes for up to sixty gates, each representing 101 m in altitude over the range from 130 m to 6089 m. Five levels, each constituting three consecutive gates, were selected for analysis because of their significance to aerodynamic loads during the Space Shuttle ascent roll maneuver. The distribution of the magnitude of the vector wind change is found to be lognormal consistent with earlier work in the mid-troposphere. The parameters of the distribution vary with time lag, season and altitude. The component wind changes are symmetrically distributed with near-zero means, but the kurtosis coefficient is larger than that of a Gaussian distribution.

Merceret, Francis J.

2005-01-01

7

Polarimetric passive remote sensing of ocean wind vectors  

Microsoft Academic Search

This paper investigates the theory of polarimetric passive remote sensing of wind-generated sea surfaces and the potential application of polarimetric radiometry to ocean wind remote sensing. Theoretical polarimetric emission coefficients of small-scale sea surfaces are evaluated using the small perturbation method (SPM). The SPM is derived to second order and applied to the Stokes vectors of thermal emission from random

S. H. Yueh; R. Kwok; F. K. Li; S. V. Nghiem; W. J. Wilson; J. A. Kong

1994-01-01

8

Polarimetric passive remote sensing of ocean wind vectors  

Microsoft Academic Search

This paper investigates the theory of polarimetric passive remote sensing of wind-generated sea surfaces and the potential application of polarimetric radiometry to ocean wind remote sensing. Theoretical polarimetric emission coefficients of small- scale sea surfaces are evaluated using the small perturbation method (SPM). The SPM is derived to second order and applied to the Stokes vectors of thermal emission from

S. H. Yueh; R. Kwok; F. K. Li; S. V. Nghiem; W. J. Wilson; J. A. Kong

1994-01-01

9

A New Algorithm for Wind-Vector Retrieval From Scatterometers  

Microsoft Academic Search

A new efficient algorithm for retrieving wind-vector solutions from scatterometers is developed based on a criterion of minimum normalized standard deviation (NSD) of wind speed derived from backscatter measurements using a geophysical model function (GMF). Its performance has been evaluated through simulations using QSCAT-1 GMF and the QuikSCAT observational geometry. The present algorithm, named the NSD algorithm, is found to

B. S. Gohil; Abhijit Sarkar; Vijay K. Agarwal

2008-01-01

10

The Effects of Wind Driven Rain Vectors on the Stream Power of Thin Flow  

NASA Astrophysics Data System (ADS)

Stream power of a thin flow is generally explained as a function of runoff and slope under wind-free rainfall conditions, and the effect of vertically impinging raindrops on flow is always considered as a resistance to its downward movement. On the other hand, the raindrop and flow interactions for interrill erosion with wind-driven rain (WDR) differ at the impact-flow boundary. Since WDR fall trajectory varies with differences in horizontal wind velocity, both magnitude of raindrop normal and lateral stresses on flow change and a vector field is established, resulting in differentially directed lateral jets of raindrop splashes with respect to downward flows occur. Therefore, to account for these differences, a vector approach with the kinetic energy fluxes or the stream powers of raindrop splashes and flow is required instead of vector-free parameters of rainfall intensity and interrill runoff. WDR experiments were conducted to evaluate the changes in the resultant stream power (?r, J m-2 s-1) with the raindrop impact velocity vector with a two-dimensional experimental set-up in a wind tunnel. Synchronized wind and rain simulations - the rains were accompanied by the horizontal wind velocities of 0, 6, 10, 12 ms-1 - were applied to the test surfaces on windward and leeward slopes of 2, 3, 4 5, 7, 9, 11° . By this way, the diverse WDR fall trajectories with the angle of rain incidences (?o) between the wind vector and the plane of the test surface were obtained by changing slope aspect from windward to leeward. The rainfall intensity was directly measured with 20 small collectors placed over a 20 x 200 cm test pan on the inclined planes before the runs and the runoff discharges were taken every 5 min interval during 60 min WDR simulations. The results showed that the normal energy flux of WDR (?(drop)n, J m-2 s-1) was as much as 45.4 times more in the windward slope than that of the leeward although the along-surface energy flux of WDR (?(drop)s) did not change that much as ?(drop)n did with the aspect and the value was 7.7. Whereas, the considerable differences occurred in ?r with the slope aspect and the ratio as large as 259.4 was attained with the rains driven by the wind velocity of 12 ms-1 and incident on the sloping test surface of 11° . This fact indicated that the thin flow hydraulics varied significantly with the slope aspects under WDR and could bring about substantially different sediment delivery rates. Key words: stream power, WDR vectors, thin flow, lateral jets, angle of incidence

Samray, H.; Erpul, G.; Gabriels, D.; Cornelis, W. M.

2012-04-01

11

Designing Scatterometer Constellations for Sampling Global Ocean Vector Winds  

NASA Astrophysics Data System (ADS)

The rapid temporal variations in ocean vector winds make it impossible to obtain synoptic global snapshots of winds and wind stress from a single spaceborne sensor. Even when multiple sensors are present, the peculiarities of the resulting space-time sampling pattern require that significant smoothing in space and time be performed to limit spatially and temporally inhomogeneous error characteristics in the merged data. Based on the collected common experience in its member states, the World Meteorological Organization collects requirements for spatio-temporal sampling in meteorological applications such as global and regional Numerical Weather Prediction, nowcasting, and climate. An additional concern, when constructing data sets from sun-synchronous missions, is that undersampling of diurnal and sub-diurnal variability may result in aliasing of the climate data record. Indeed, examination of climatologies constructed from different satellite missions, such as NASA's QuikSCAT and EUMETSAT's ASCAT scatterometers, show systematic differences that cannot be explained as being due solely to unresolved incoherent diurnal and sub-diurnal variability. Some of these differences, especially in the tropics, are probably explained by systematic diurnal and sub-diurnal variations. Other differences may be due to the difficulty of cross-calibrating sun-synchronous satellites with different local times. Forthcoming satellite missions may offer the possibility of overcoming or mitigating the space-time sampling and calibration challenges using multiple coordinated platforms. In the next decade, there is an expectation that ocean vector winds will be measured simultaneously by multiple satellites from the European community, India, China, and the United States. The coordination and suitable merging of the data from these satellites to produce a climate data record will be a challenge to the ocean vector winds community. In this presentation, we use climatologies constructed from multiple missions (NASA's QuikSCAT and SeaWinds on ADEOS-2, EUMETSAT's ASCAT, ISRO's OSCAT) that have overlapped over significant times to assess the impact of platform sampling and calibration characteristics on constructing consistent climatologies. We also extend the statistical simulation studies by Schlax et al. (2001) to include the effects of diurnal and sub-diurnal variations. Using these methods, we will examine a variety of potential platform configurations for future planned missions and assess their potential for producing a consistent ocean vector wind climate data record.

Rodriguez, E.; Chelton, D. B.; Stoffelen, A.; Schlax, M.

2012-12-01

12

Relating the Proca Photon Mass and Cosmic Vector Potential via Solar Wind  

SciTech Connect

The effect of the Proca photon mass m{sub ph} and cosmic vector potential A{sub C} on the dynamics of solar wind is considered. For large-enough values of the parameter A{sub C}m{sub ph}{sup 2}, the solar wind structure at a distance of approx40 AU from the Sun should change significantly with respect to the actual observed flow. The absence of such deviations gives an upper bound on the parameter A{sub C}m{sub ph}{sup 2} 9 orders of magnitude less than in laboratory experiments measuring torque on a toroidal magnet.

Ryutov, D. D. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

2009-11-13

13

Vector Wind Velocity, Speed, and Mode Summaries for the Southeastern U. S.  

SciTech Connect

This report presents wind speed and direction summaries for a wide area of the Southeastern United States (including EPA Region 4) and portions of the Ohio and Mississippi River Valleys in a monthly time series format that is further broken down for eight hours of the day (01:00, 04:00, 07:00, 10:00, 13:00, 16:00, 19:00, 22:00 EST). The data used for these summaries were obtained from the International Station MeteorologicalClimate Summary (FCCA, 1996), a publicly available source of tabular data from weather stations around the world distributed through the National Climatic Data Center. The advantage of examining the data in the form presented in this report is that it is far easier to examine and understand regional and diurnal weather patterns than would be possible with the tabular data in its original format. The winds presented here can be viewed online in any of three formats through an Internet link. The first format is the traditional wind rose as used in our earlier reports f or 13 stations in the Southeast, c.f., Weber, Buckley, and Parker 2002 and Weber, Buckley, and Kurzeja 2003. The second format is the mode, or most frequent wind direction sector from the wind rose plots (i.e., the longest ''petal'' from the individual station roses). Finally, the third format depicted is the average wind vector. The average wind vector was determined by extracting the wind speed and direction for each of the 16 sectors from a station's wind record and then summing components of these vectors for the month and time of observation. Each station was then plotted on a sequence of maps for the Southeastern U.S. using ArcView software. These maps form a time series in 3-hour increments showing changes in vector wind speed and direction for each month of the year. The complete set of color figures are too numerous to be included in this report, but may be accessed by contacting one of the authors.

WEBER, ALLENH.

2004-08-18

14

Evaluation of two January - June 1992 ERS-1 AMI wind vector data sets  

NASA Technical Reports Server (NTRS)

A Jan. - Jun. 1992 10 m height wind vector field was computed with the CMOD2 model function. Freilich and Dunbar used ESA measurements of AMI (Active Microwave Instrument) sigma-naught to derive a refined model function and to produce an alternate Jan. - Jun. 1992 10 m height wind vector field, named FD data. The ESA and FD model functions and algorithms were substantially different. The FD wind vectors were in better agreement with the climatological mean wind field and with moored buoy wind measurements. The average correlation coefficients between monthly mean and daily averaged FD and moored buoy matchups of the Cartesian wind components were 0.84 and 0.74, respectively. The average root mean square differences between the monthly mean and daily averaged FD and moored buoy matchups of the Cartesian wind components were 1.25 and 3.0 m/s, respectively.

Halpern, D.; Freilich, M. H.; Dunbar, R. S.

1993-01-01

15

Validating a New Algorithm for Wind Vector Retrieval in Tropical Zachary Hargrove, UNC Asheville  

E-print Network

-Winds, and (d) the raw wind vector estimates directly from QuickSCAT. (Jones et al. 2011) (C4) (C5) (C2-C3n) (C3 are well out to sea. Estimates in wind strength are extremely important. · Scatterometers are valuable

Hennon, Christopher C.

16

Vector Fields  

NSDL National Science Digital Library

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

Ay, Tevian

2006-01-01

17

High-resolution passive polarimetric microwave mapping of ocean surface wind vector fields  

Microsoft Academic Search

The retrieval of ocean surface wind fields in both one and two dimensions is demonstrated using passive polarimetric microwave imagery obtained from a conical-scanning airborne polarimeter. The retrieval method is based on an empirical geophysical model function (GMF) for ocean surface thermal emission and an adaptive maximum likelihood (ML) wind vector estimator. Data for the GMF were obtained using the

Jeffrey R. Piepmeier; Albin J. Gasiewski

2001-01-01

18

Relationship between wind vectors and L-band radar cross sections examined using PALSAR  

Microsoft Academic Search

The relationship between ocean wind vectors and L-band normalized radar cross sections (NRCS) is examined using the Phased-Array L-band Synthetic Aperture Radar (PALSAR). We used PALSAR ScanSAR images with a wide range of incidence angles from 17deg to 43deg. More than 6,000 match-ups, each consisting of the NRCS, incidence angles, wind speeds and wind directions, were collected. The NRCS exhibits

Osamu Isoguchi; Masanobu Shimada

2007-01-01

19

Auto-correlation analysis of ocean surface wind vectors  

Microsoft Academic Search

The nature of the inherent temporal variability of surface winds is analyzed by comparison of winds obtained through different\\u000a measurement methods. In this work, an auto-correlation analysis of a time series data of surface winds measuredin situ by a deep water buoy in the Indian Ocean has been carried out. Hourly time series data available for 240 hours in the

Abhijit Sarkar; Sujit Basu; A. K. Varma; Jignesh Kshatriya

2002-01-01

20

An operational satellite scatterometer for wind vector measurements over the ocean  

NASA Technical Reports Server (NTRS)

Performance requirements and design characteristics of a microwave scatterometer wind sensor for measuring surface winds over the oceans on a global basis are described. Scatterometer specifications are developed from user requirements of wind vector measurement range and accuracy, swath width, resolution cell size and measurement grid spacing. A detailed analysis is performed for a baseline fan-beam scatterometer design, and its performance capabilities for meeting the SeaSat-A user requirements. Various modes of operation are discussed which will allow the resolution of questions concerning the effects of sea state on the scatterometer wind sensing ability and to verify design boundaries of the instrument.

Grantham, W. L.; Bracalente, E. M.; Jones, W. L.; Schrader, J. H.; Schroeder, L. C.; Mitchell, J. L.

1975-01-01

21

An algorithm for retrieval of oceanic wind vectors from the simulated Sass normalized radar cross-section measurements  

Microsoft Academic Search

A new algorithm has been proposed to recover wind vectors from the simulated Seasat A satellite scattero meter (SASS) normalized radar cross-section (NRCS) measurements exploiting the fact that all the dual polarized noise-free NRCS measurements taken in any azimuth direction should provide the same wind speed in the true direction of wind. The algorithm deals with the computation of wind

B. S. Gohil; P. C. Pandey

1985-01-01

22

Climate change impacts on wind energy: A review  

Microsoft Academic Search

Expansion of wind energy installed capacity is poised to play a key role in climate change mitigation. However, wind energy is also susceptible to global climate change. Some changes associated with climate evolution will likely benefit the wind energy industry while other changes may negatively impact wind energy developments, with such ‘gains and losses’ depending on the region under consideration.

S. C. Pryor; R. J. Barthelmie

2010-01-01

23

Global Change and Human Vulnerability to Vector-Borne Diseases  

PubMed Central

Global change includes climate change and climate variability, land use, water storage and irrigation, human population growth and urbanization, trade and travel, and chemical pollution. Impacts on vector-borne diseases, including malaria, dengue fever, infections by other arboviruses, schistosomiasis, trypanosomiasis, onchocerciasis, and leishmaniasis are reviewed. While climate change is global in nature and poses unknown future risks to humans and natural ecosystems, other local changes are occurring more rapidly on a global scale and are having significant effects on vector-borne diseases. History is invaluable as a pointer to future risks, but direct extrapolation is no longer possible because the climate is changing. Researchers are therefore embracing computer simulation models and global change scenarios to explore the risks. Credible ranking of the extent to which different vector-borne diseases will be affected awaits a rigorous analysis. Adaptation to the changes is threatened by the ongoing loss of drugs and pesticides due to the selection of resistant strains of pathogens and vectors. The vulnerability of communities to the changes in impacts depends on their adaptive capacity, which requires both appropriate technology and responsive public health systems. The availability of resources in turn depends on social stability, economic wealth, and priority allocation of resources to public health. PMID:14726459

Sutherst, Robert W.

2004-01-01

24

Comparison of Wind Vectors and Air-Sea Temperature Differences Measured during SHOWEX  

E-print Network

Comparison of Wind Vectors and Air-Sea Temperature Differences Measured during SHOWEX William J speed and direction, air temperature, and water temperature were measured from Air Sea Interaction Spar measured both water temperature and air temperature near the surface. The IR sensor gave a second

Long, David G.

25

Scanning wind-vector scatterometers with two pencil beams  

NASA Technical Reports Server (NTRS)

A scanning pencil-beam scatterometer for ocean windvector determination has potential advantages over the fan-beam systems used and proposed heretofore. The pencil beam permits use of lower transmitter power, and at the same time allows concurrent use of the reflector by a radiometer to correct for atmospheric attenuation and other radiometers for other purposes. The use of dual beams based on the same scanning reflector permits four looks at each cell on the surface, thereby improving accuracy and allowing alias removal. Simulation results for a spaceborne dual-beam scanning scatterometer with a 1-watt radiated power at an orbital altitude of 900 km is described. Two novel algorithms for removing the aliases in the windvector are described, in addition to an adaptation of the conventional maximum likelihood algorithm. The new algorithms are more effective at alias removal than the conventional one. Measurement errors for the wind speed, assuming perfect alias removal, were found to be less than 10%.

Kirimoto, T.; Moore, R. K.

1984-01-01

26

Climate change and vector-borne diseases: a regional analysis.  

PubMed Central

Current evidence suggests that inter-annual and inter-decadal climate variability have a direct influence on the epidemiology of vector-borne diseases. This evidence has been assessed at the continental level in order to determine the possible consequences of the expected future climate change. By 2100 it is estimated that average global temperatures will have risen by 1.0-3.5 degrees C, increasing the likelihood of many vector-borne diseases in new areas. The greatest effect of climate change on transmission is likely to be observed at the extremes of the range of temperatures at which transmission occurs. For many diseases these lie in the range 14-18 degrees C at the lower end and about 35-40 degrees C at the upper end. Malaria and dengue fever are among the most important vector-borne diseases in the tropics and subtropics; Lyme disease is the most common vector-borne disease in the USA and Europe. Encephalitis is also becoming a public health concern. Health risks due to climatic changes will differ between countries that have developed health infrastructures and those that do not. Human settlement patterns in the different regions will influence disease trends. While 70% of the population in South America is urbanized, the proportion in sub-Saharan Africa is less than 45%. Climatic anomalies associated with the El Niño-Southern Oscillation phenomenon and resulting in drought and floods are expected to increase in frequency and intensity. They have been linked to outbreaks of malaria in Africa, Asia and South America. Climate change has far-reaching consequences and touches on all life-support systems. It is therefore a factor that should be placed high among those that affect human health and survival. PMID:11019462

Githeko, A. K.; Lindsay, S. W.; Confalonieri, U. E.; Patz, J. A.

2000-01-01

27

Vectors  

NSDL National Science Digital Library

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

Friesen, Larry; Gillis, Anne

2008-04-18

28

vectors  

NSDL National Science Digital Library

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

Joiner, David; The Shodor Education Foundation, Inc.

29

Changes in the Wind Regime Over Northern Eurasia  

NASA Astrophysics Data System (ADS)

The wind regime of Russia varies a great deal due to the large size of the country's territory and variety of climate and terrain conditions. Changes in the regime of surface wind are of great practical importance. They can affect heat and water balance. Strong wind is one of the most hazardous meteorological event for various sectors of economy and for infrastructure. At meteorological stations wind speed and wind direction are measured at the height of 10-12 meters over the land surface with the help of wind meters or wind wanes. Due to the turbulent state of the atmosphere wind speed and wind direction in each moment of time fluctuate considerably about the average value. Therefore, the average wind speed over the period of either 2 or 10 minutes (depending on the technical capacity of the instrument used for measurements) is measured, the maximum value of wind speed (gust wind speed) in the same periods of time is determined as well as the average wind direction over the period of 2 minutes. Calculations were made on the basis of data for the period of 1980-2011. It allowed the massive scale disruption of homogeneity to be eliminated and sufficient period needed to obtain sustainable statistic characteristics to be retained. Data on average and maximum wind speed measured at 1457 stations of Russia were used. The analysis of changes in wind characteristics was made on the basis of point data and series of average characteristics obtained for 18 quasi-homogeneous climatic regions. Statistical characteristics (average and maximum values of wind speed, prevailing wind direction, values of the boundary of the 90%, 95% and 99%-confidence interval in the distribution of maximum wind speed) were obtained for all seasons and for the year as a whole. Values of boundaries of the 95% and 99%-confidence interval in the distribution of maximum wind speed were considered as indicators of extremeness of the wind regime. The trend of changes in average and maximum wind speed was assessed with a linear trend coefficient. A special attention was paid to wind changes in the Arctic where dramatic changes in surface air temperature and sea ice extent and density have been observed during the past decade. The analysis of the results allowed seasonal and regional features of changes in the wind regime on the territory of the northern part of Eurasia to be determined. The outcomes could help to provide specific recommendations to users of hydrometeorological information for making reasonable decisions to minimize losses caused by adverse wind-related weather conditions.

Bulygina, O.; Korshunova, N.; Razuvaev, V.

2012-12-01

30

Vegetation change detection for urban areas based on extended change vector analysis  

NASA Astrophysics Data System (ADS)

This study sought to develop a modified change vector analysis(CVA) using normalized multi-temporal data to detect urban vegetation change. Because of complex change in urban areas, modified CVA application based on NDVI and mask techniques can minify the effect of non-vegetation changes and improve upon efficiency to a great extent. Moreover, drawing from methods in Polar plots, the extended CVA technique measures absolute angular changes and total magnitude of perpendicular vegetation index (PVI) and two of Tasseled Cap indices (greenness and wetness). Polar plots summarized change vectors to quantify and visualize both magnitude and direction of change, and magnitude is applied to determine change pixels through threshold segmentation while direction is applied as pixel's feature to classifying change pixels through supervised classification. Then this application is performed with Landsat ETM+ imageries of Wuhan in 2002 and 2005, and assessed by error matrix, which finds that it could detect change pixels 95.10% correct, and could classify change pixels 91.96% correct in seven change classes through performing supervised classification with direction angles. The technique demonstrates the ability of change vectors in multiple biophysical dimensions to vegetation change detection, and the application can be trended as an efficient alternative to urban vegetation change detection and classification.

Yu, Hui; Jia, Yonghong

2006-10-01

31

Wind turbine concentrator design based on moist air phase change  

Microsoft Academic Search

This current article shows a procedure to improve wind turbines for kinetic energy conversion in mechanics using a new concentrating design based on moist air phase change. This concentrator presents special interest in the European Atlantic Coast because its weather is mild with a high relative humidity and its winds represent low values for wind turbines applications. Results show a

J. A. Orosa; E. J. Garcia-Bustelo; J. A. Perez

2009-01-01

32

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

33

Land-use/land-cover change detection using change-vector analysis in posterior probability space  

NASA Astrophysics Data System (ADS)

Land use/land cover change is an important field in global environmental change research. Remote sensing is a valuable data source from which land use/land cover change information can be extracted efficiently. A number of techniques for accomplishing change detection using satellite imagery have been formulated, applied, and evaluated, which can be generally grouped into two types. (1) Those based on spectral classification of the input data such as post-classification comparison and direct two-date classification; and (2) those based on radiometric change between different acquisition dates. The shortage of type 1 is cumulative error in image classification of an individual date. However, radiometric change approaches has a strict requirement for reliable image radiometry. In light of the above mentioned drawbacks of those two types of change detection methods, this paper presents a new method named change vector analysis in posterior probability space (CVAPS). Change-vector analysis (CVA) is one of the most successful radiometric change-based approaches. CVAPS approach incorporates post-classification comparison method and CVA approach, which is expected to inherit the advantages of two traditional methods and avoid their defects at the same time. CVAPS includes the following four steps. (1) Images in different periods are classified by certain classifier which can provide posterior probability output. Then, the posterior probability can be treated as a vector, the dimension of which is equal to the number of classes. (2) A procedure similar with CVA is employed. Compared with traditional CVA, new method analyzes the change vector in posterior probability space instead of spectral feature space. (3) A semiautomatic method, named Double-Window Flexible Pace Search (DFPS), is employed to determine the threshold of change magnitude. (4) Change category is discriminated by cosines of the change vectors. CVAPS approach was applied and validated by a case study of land use change detection in urban area of Shenzhen, China using multi-temporal TM data. Kappa coefficients of "change/no-change" detection and "from-to" types of change detection were employed for accuracy assessment. The experimental results show that CVAPS outperform than post-classification comparison method and can avoid cumulative error effectively. Besides, radiometric correction is not needed in this method compared with traditional CVA. Therefore, it is indicated that CVAPS is potentially useful in land-use/land-cover change detection.

Chen, Xuehong; Chen, Jin; Shen, Miaogen; Yang, Wei

2008-10-01

34

Empirical Model of Sea Surface Slope Statistics for Wind Vector Estimation Using Bistatic GPS Measurements  

NASA Astrophysics Data System (ADS)

Recently, several researchers have estimated sea surface wind speed from the cross-correlation waveform of forward scattered GPS signals. These measurement techniques apply a scattering model which integrates the reflected power over regions of the glistening surface corresponding to relative path delays within one-chip range bins. (A "chip" is the length between bit transitions in the GPS signal.) The distribution of reflected power over this glistening surface is a function of the probability density of surface slopes. An empirical model in then required to relate the surface slope statistics to the near surface wind speed (among other parameters). Thus far, retrieval methods have applied some existing empirical slope model to this problem. Katzberg (1999) adapted the Cox and Munk (1954) model, with the corrections from Wilheit (1979) to account for the larger wavelength (? ) of the GPS radiation. Garrison (2000) applied the Zavorotny and Voronovich (2000) model, which integrates the Elfouhaily (1997) wave spectrum over wave numbers smaller than a scale dividing parameter (2 ? / 3 ? ). In either case, the model for slope statistics was taken from an empirical model derived from quite different measurements, and corrected for the bistatic GPS case. In this paper, we present an independent empirical model for the probability density function (PDF) derived directly from bistatic GPS data. This model could then be used to improve wind vector retrieval algorithms for bistatic GPS data. The approach taken is to numerically invert a scattering model to determine the slope PDF which minimizes the mean square error between the model predicted waveform shape and a segment of recorded bistatic GPS data. The PDF is represented by a two-dimensional Gram-Charlier series, expanded to fourth order. The least squares minimization is applied to estimate a set of parameters including the mean square slopes, the coefficients of the Gram-Charlier series representing skewness and peakedness, and receiver calibration constants. Wind direction data, obtained from buoys, will be used to rotate the principal axes of the PDF relative to the scattering plane. After applying this rotation, the bistatic GPS waveforms are used to estimate only the shape, not the orientation, of the PDF. Experimentally determined slope PDF's will then be compared against three independent sources of wind speed data: NOAA buoys, the TOPEX/Poseidon altimeter, and the SeaWinds scatterometer on QuickSCAT. These comparisons are used to obtain an independent empirical relationship between the apparent surface slope statistics affecting bistatic L-band scattering, and the surface wind speed. At present, only cases of fully-developed seas are investigated. It is expected that some data collected in fetch-limited conditions will also have been evaluated when the paper is presented.

Garrison, J. L.; Bertuccelli, L.

2001-05-01

35

Wind energy: Developing energy, wealth, and change  

NASA Astrophysics Data System (ADS)

Wind energy has emerged as one of the fastest growing energy sources in the United States over the course of the last decade. It is the renewable energy type most readily defining clean economy leadership. An uncertain policy context, public conflicts over the impacts of turbine installations, and unsorted connections to a national green development strategy raise questions about the continued viability of wind power in the U.S. This thesis attempts to document and question some of the issues raised by wind energy expansion in the U.S. generally, but in Maine in particular, in order to explain how environmental, social, and economic benefits accrue to places hosting wind projects. The available information combined with a targeted inquiry produce insights into how the state of Maine can improve its wind development policies and outcomes.

Hopkins, Matt

36

Can antibodies against flies alter malaria transmission in birds by changing vector behavior?  

E-print Network

�vector�host system, avian malaria in pigeons transmitted by fly ectoparasites, where both two-way and three T S Host immune defense against vector. Change vector behavior. Affect disease prevalence. a r t i c l e-fly antibodies Avian malaria Vector movement a b s t r a c t Transmission of insect-borne diseases is shaped

Clayton, Dale H.

37

Change detection and classification in brain MR images using change vector analysis.  

PubMed

The automatic detection of longitudinal changes in brain images is valuable in the assessment of disease evolution and treatment efficacy. Most existing change detection methods that are currently used in clinical research to monitor patients suffering from neurodegenerative diseases--such as Alzheimer's--focus on large-scale brain deformations. However, such patients often have other brain impairments, such as infarcts, white matter lesions and hemorrhages, which are typically overlooked by the deformation-based methods. Other unsupervised change detection algorithms have been proposed to detect tissue intensity changes. The outcome of these methods is typically a binary change map, which identifies changed brain regions. However, understanding what types of changes these regions underwent is likely to provide equally important information about lesion evolution. In this paper, we present an unsupervised 3D change detection method based on Change Vector Analysis. We compute and automatically threshold the Generalized Likelihood Ratio map to obtain a binary change map. Subsequently, we perform histogram-based clustering to classify the change vectors. We obtain a Kappa Index of 0.82 using various types of simulated lesions. The classification error is 2%. Finally, we are able to detect and discriminate both small changes and ventricle expansions in datasets from Mild Cognitive Impairment patients. PMID:22256148

Simões, Rita; Slump, Cornelis

2011-01-01

38

Space vector PWM for a direct matrix converter based open-end winding ac drives with enhanced capabilities  

Microsoft Academic Search

This paper introduces a space vector PWM technique for a direct matrix converter based three-phase open-end winding AC machine drive. With the proposed PWM technique, the following simultaneous capabilities of the open-end winding drive system are achieved: 1) Machine phase voltage up to 1.5 times the input phase voltage in the linear modulation, 2) Controllable grid power factor, and 3)

Ranjan K. Gupta; Apurva Somani; Krushna K. Mohapatra; Ned Mohan

2010-01-01

39

Insights on the OAFlux ocean surface vector wind analysis merged from scatterometers and passive microwave radiometers (1987 onward)  

NASA Astrophysics Data System (ADS)

high-resolution global daily analysis of ocean surface vector winds (1987 onward) was developed by the Objectively Analyzed air-sea Fluxes (OAFlux) project. This study addressed the issues related to the development of the time series through objective synthesis of 12 satellite sensors (two scatterometers and 10 passive microwave radiometers) using a least-variance linear statistical estimation. The issues include the rationale that supports the multisensor synthesis, the methodology and strategy that were developed, the challenges that were encountered, and the comparison of the synthesized daily mean fields with reference to scatterometers and atmospheric reanalyses. The synthesis was established on the bases that the low and moderate winds (<15 m s-1) constitute 98% of global daily wind fields, and they are the range of winds that are retrieved with best quality and consistency by both scatterometers and radiometers. Yet, challenges are presented in situations of synoptic weather systems due mainly to three factors: (i) the lack of radiometer retrievals in rain conditions, (ii) the inability to fill in the data voids caused by eliminating rain-flagged QuikSCAT wind vector cells, and (iii) the persistent differences between QuikSCAT and ASCAT high winds. The study showed that the daily mean surface winds can be confidently constructed from merging scatterometers with radiometers over the global oceans, except for the regions influenced by synoptic weather storms. The uncertainties in present scatterometer and radiometer observations under high winds and rain conditions lead to uncertainties in the synthesized synoptic structures.

Yu, Lisan; Jin, Xiangze

2014-08-01

40

Time changes in gradient and observed winds  

E-print Network

equations foz the components of the grauient wind. The x- and y-components of the gradient wind equation can be derived by taking the dot product of Eq. (1) by i and by j, respectively. The compo- nents of the gradient wind in the x- and y... finite- difference technique (Carnahan et al. , 1964) over the grid system (Fig. 1, p. 13). 2) Trajectory curvature Curvature is defined as k= ~~ where Q is the angle between ds the trajectory and the x axis, and s is a distance along the trajec...

Carlson, Ronald Dale

2012-06-07

41

Detecting Changes of Thermal Environment over the Bohai Coastal Region by Spectral Change Vector Analysis  

NASA Astrophysics Data System (ADS)

Change vector analysis (CVA) is an effective approach for detecting and characterizing land-cover change by comparing pairs of multi-spectral and multi-temporal datasets over certain area derived from various satellite platforms. NDVI is considered as an effective detector for biophysical changes due to its sensitivity to red and near infrared signals, while land surface temperature (LST) is considered as a valuable indicator for changes of ground thermal conditions. Here we try to apply CVA over satellite derived LST datasets to detect changes of land surface thermal properties parallel to climate change and anthropogenic influence in a city cluster since 2001. In this study, monthly land surface temperature datasets from 2001-2008 derived from MODIS collection 5 were used to examine change pattern of thermal environment over the Bohai coastal region by using spectral change vector analysis. The results from principle component analysis (PCA) for LST show that the PC 1-3 contain over 80% information on monthly variations and these PCA components represent the main processes of land thermal environment change over the study area. Time series of CVA magnitude combined with land cover information show that greatest change occurred in urban and heavily populated area, featured with expansion of urban heat island, while moderate change appeared in grassland area in the north. However few changes were observed over large plain area and forest area. Strong signals also are related to economy level and especially the events of surface cover change, such as emergence of railway and port. Two main processes were also noticed about the changes of thermal environment. First, weak signal was detected in mostly natural area influenced by interannual climate change in temperate broadleaf forest area. Second, land surface temperature changes were controlled by human activities as 1) moderate change of LST happened in grassland influenced by grazing and 2) urban heat island was intensifier in major cities, such as Beijing and Tianjin. Further, the continual drier climate combined with human actions over past fifties years have intensified land thermal pattern change and the continuation will be an important aspects to understand land surface processes and local climate change. Land surface temperature trends from 2000-2008 over the Bohai coastal region

Hu, Y.; Jia, G.

2009-12-01

42

World Wind Tools Reveal Environmental Change  

NASA Technical Reports Server (NTRS)

Originally developed under NASA's Learning Technologies program as a tool to engage and inspire students, World Wind software was released under the NASA Open Source Agreement license. Honolulu, Hawaii based Intelesense Technologies is one of the companies currently making use of the technology for environmental, public health, and other monitoring applications for nonprofit organizations and Government agencies. The company saved about $1 million in development costs by using the NASA software.

2012-01-01

43

Effects of Local Anthropogenic Changes on Potential Malaria Vector Anopheles hyrcanus and West Nile Virus Vector Culex modestus, Camargue, France  

PubMed Central

Using historical data, we highlight the consequences of anthropogenic ecosystem modifications on the abundance of mosquitoes implicated as the current most important potential malaria vector, Anopheles hyrcanus, and the most important West Nile virus (WNV) vector, Culex modestus, in the Camargue region, France. From World War II to 1971, populations of these species increased as rice cultivation expanded in the region in a political context that supported agriculture. They then fell, likely because of decreased cultivation and increased pesticide use to control a rice pest. The species increased again after 2000 with the advent of more targeted pest-management strategies, mainly the results of European regulations decisions. An intertwined influence of political context, environmental constraints, technical improvements, and social factors led to changes in mosquito abundance that had potential consequences on malaria and WNV transmission. These findings suggest that anthropogenic changes should not be underestimated in vectorborne disease recrudescence. PMID:18258028

Poncon, Nicolas; Balenghien, Thomas; Toty, Celine; Ferre, Jean Baptiste; Thomas, Cyrille; Dervieux, Alain; L'Ambert, Gregory; Schaffner, Francis; Bardin, Olivier

2007-01-01

44

Host Life History Strategy, Species Diversity, and Habitat Influence Trypanosoma cruzi Vector Infection in Changing Landscapes  

PubMed Central

Background Anthropogenic land use may influence transmission of multi-host vector-borne pathogens by changing diversity, relative abundance, and community composition of reservoir hosts. These reservoir hosts may have varying competence for vector-borne pathogens depending on species-specific characteristics, such as life history strategy. The objective of this study is to evaluate how anthropogenic land use change influences blood meal species composition and the effects of changing blood meal species composition on the parasite infection rate of the Chagas disease vector Rhodnius pallescens in Panama. Methodology/Principal Findings R. pallescens vectors (N?=?643) were collected in different habitat types across a gradient of anthropogenic disturbance. Blood meal species in DNA extracted from these vectors was identified in 243 (40.3%) vectors by amplification and sequencing of a vertebrate-specific fragment of the 12SrRNA gene, and T. cruzi vector infection was determined by pcr. Vector infection rate was significantly greater in deforested habitats as compared to contiguous forests. Forty-two different species of blood meal were identified in R. pallescens, and species composition of blood meals varied across habitat types. Mammals (88.3%) dominated R. pallescens blood meals. Xenarthrans (sloths and tamanduas) were the most frequently identified species in blood meals across all habitat types. A regression tree analysis indicated that blood meal species diversity, host life history strategy (measured as rmax, the maximum intrinsic rate of population increase), and habitat type (forest fragments and peridomiciliary sites) were important determinants of vector infection with T. cruzi. The mean intrinsic rate of increase and the skewness and variability of rmax were positively associated with higher vector infection rate at a site. Conclusions/Significance In this study, anthropogenic landscape disturbance increased vector infection with T. cruzi, potentially by changing host community structure to favor hosts that are short-lived with high reproductive rates. Study results apply to potential environmental management strategies for Chagas disease. PMID:23166846

Gottdenker, Nicole L.; Chaves, Luis Fernando; Calzada, Jose E.; Saldana, Azael; Carroll, C. Ronald

2012-01-01

45

Climate change and vector-borne diseases: a regional analysis  

Microsoft Academic Search

likely to be observed at the extremes of the range of temperatures at which transmission occurs. For many diseases these lie in the range 14-18 o C at the lower end and about 35-40 oC at the upper end. Malaria and dengue fever are among the most important vector-borne diseases in the tropics and subtropics; Lyme disease is the most

Andrew K. Githeko; Steve W. Lindsay; Ulisses E. Confalonieri; Jonathan A. Patz

2000-01-01

46

Measuring the turbulent wind vector with a weight-shift Microlight Aircraft  

NASA Astrophysics Data System (ADS)

The Small Environmental Research Aircraft (SERA) D-MIFUs initial fields of application are aerosol / cloud and radiation transfer research. Therefore a comparatively slow (True Airspeed, TAS ~25 ms-1) but highly mobile microlight aircraft was envisaged. To broaden the application area of D-MIFU we explore whether the microlight can also be used for Eddy Covariance (EC) flux measurement. To obtain useful data sets for airborne EC a reliable turbulent Wind Vector (WV) measurement is a key requirement. Here we present methodology and results to calibrate and express performance and uncertainty of microlight based WV measurement. Specific attention is given to the influence of the flexible-wing weight-shift geometry on the WV measurement. For the WV measurement we equipped D-MIFU with a 70 cm long noseboom supporting a classical 5 hole probe and a fast 50 μm diameter thermocouple. An Inertial Navigation System (INS) supplies high accuracy ground speeds (Ï?=0.05 ms-1) and attitude angles (Ï?=0.03° , 0.1° respectively for heading). Data are stored with 10 Hz yielding a horizontal resolution of 2.5 m. The INS also allows to analyze aircraft dynamics such as 3d rotation rates and acceleration of the nacelle body. Further estimates for 3d acceleration of airfoil and noseboom are obtained at 100 Hz. The noseboom calibration coefficients under laboratory conditions were obtained by wind tunnel- and thermal bath measurements. To transfer these characteristics for in-flight conditions we carried out a series of flights with D-MIFU above the Boundary Layer under calm conditions. On basis of level flights at different power settings we were able to determine dynamic pressure-, sideslip- and attack angle offsets. Additionally forced maneuvers, such as e.g. phugoids, have been performed. By means of multivariate analysis these data are used to assess and minimize the impact of microlight nacelle and airfoil rapidly varying motions (RVM) on the WV components. In the final step of the calibration we employ a Markov Chain Monte Carlo based Bayesian optimization. Recording the posterior parameter distribution this optimizing procedure allows an integrated assessment of WV uncertainty as induced by the instrumental setup. To test whether the airborne measured WV is in agreement with ground based measurements we additionally performed flights at tall tower sites equipped with ultrasonic anemometers as well as a Sodar facility. The impact of the in-flight correction on the WV components is found to be in the order of 1 ms-1 in the horizontal and 0.1 ms-1 in the vertical. From racetrack comparisons we obtain a maximum final wind error of 0.9 ms-1 for horizontal and 0.2 ms-1 for vertical WV components before RVM correction. At that the vertical WV measurement is found to be independent from TAS. Ground truth comparisons show mean horizontal and vertical wind deviations of 0.2 ms-1, 0.1 ms-1 respectively for 10 minute averages. Deviations are independent of aircraft heading, sideslip angle respectively. From these findings we conclude that a thoroughly setup microlight aircraft is capable of measuring the WV components with an accuracy sufficient for EC applications.

Metzger, S.; Junkermann, W.; Neidl, F.; Butterbach-Bahl, K.; Schmid, H. P.; Beyrich, F.; Zheng, X. H.; Foken, T.

2009-09-01

47

IABC 83/The Winds of Change.  

ERIC Educational Resources Information Center

Drawn from a conference focusing on the changing nature of the communication function, the papers in this collection analyze and outline the professional and personal developmental techniques necessary to anticipate and capitalize upon those changes. Among the specific topics discussed in the 32 papers are the following: (1) the techniques and…

International Association of Business Communicators, San Francisco, CA.

48

Evaluation of turbulent magnetic energy spectra in the three-dimensional wave vector domain in the solar wind  

SciTech Connect

Using four-point measurements of the CLUSTER spacecraft, the energy distribution of magnetic field fluctuations in the solar wind is determined directly in the three-dimensional wave vector domain in the range 3 x 10{sup -4} rad/km < k < 3 x 10{sup -3} rad/km. The analysis method takes account of a regular tetrahedron configuration of CLUSTER and the Doppler effect. The energy distribution in the flow rest frame is anisotropic, characterized by two distinct extended structures perpendicular to the mean magnetic field and furthermore perpendicular to the flow direction. The three-dimensional distribution is averaged around the direction of the mean magnetic field direction, and then is further reduced to one-dimensional distributions in the wave number domain parallel and perpendicular to the mean magnetic field. The one-dimensional energy spectra are characterized by the power law with the index -5/3 and furthermore very close energy density between parallel and perpendicular directions to the mean magnetic field at the same wave numbers. Though the distributions and the spectra are not covered in a wide range of wave vectors, our measurements suggest that the solar wind fluctuation is anisotropic in the three-dimensional wave vector space. It is, however, rather isotropic when reduced into the parallel and perpendicular wave vector geometries due to the second anisotropy imposed by the flow direction.

Gary, S Peter [Los Alamos National Laboratory; Narita, Y [UNIV OF BRAUNSCHWEIG; Glassmeier, K H [UNIV OF BRAUNSCHWEIG; Goldstein, M L [NGSFC; Safraoui, F [NGSFC; Treumann, R A [UNIV. MUNICH

2009-01-01

49

An operational method to determine change threshold using change vector analysis  

NASA Astrophysics Data System (ADS)

Digital change detection (CD) is the computerized process of identifying changes in the state of an object, or other earthsurface features, between different dates. During the last years, a large number of change detection methods have been proposed for change detection of multiple-temporal remote sensing images. Among these, change vector analysis (CVA) is a very important and widely used method. The key of CVA is to determine change detection threshold. Change detection threshold is a very valuable key for change detection precision. In the literature, many techniques to determine change detection threshold have been proposed. However, most of them are not robust and operational since images are diverse and complex, especially to very high resolution (VHR) data (e.g. images acquired by QuickBird, IKONOS, SPOT5 and WorldView satellites). Such discrimination is usually performed by using empirical strategies or manual trial-and-error procedures, which affect both the accuracy and the reliability of the change-detection process. In this paper, we analyze the algorithm based on minimal classifying error, the algorithm based on OTSU and the algorithm based on EM. To eliminate the complexity of VHR data, an improved algorithm based on EM is proposed. Suppose the difference image meets the Mixed Gaussian distribution model. First, the grey histogram of the difference image is fitted to the Mixed Gaussian Distribution Model (MGM). Then the change detection threshold is determined by the MGM graph combing the Bayesian Criterion and the actual situation. In experiment, the semi-automatic method is effective and operational.

Zhang, Hansong; He, Jianyu Chen; Mao, Zhihua

2009-10-01

50

Climate Change Influences on Global Distributions of Dengue and Chikungunya Virus Vectors  

E-print Network

This packet presents raster data files that accompany a manuscript submitted for publication to Philosophical Transactions of the Royal Society, titled “Climate Change Influences on Global Vector Distributions for Dengue and Chikungunya Viruses...

Campbell, Lindsay P.; Luther, Caylor; Peterson, A. Townsend

2014-01-01

51

Vector Voyage!  

NSDL National Science Digital Library

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

Integrated Teaching And Learning Program

52

Combining Climatic Projections and Dispersal Ability: A Method for Estimating the Responses of Sandfly Vector Species to Climate Change  

PubMed Central

Background In the Old World, sandfly species of the genus Phlebotomus are known vectors of Leishmania, Bartonella and several viruses. Recent sandfly catches and autochthonous cases of leishmaniasis hint on spreading tendencies of the vectors towards Central Europe. However, studies addressing potential future distribution of sandflies in the light of a changing European climate are missing. Methodology Here, we modelled bioclimatic envelopes using MaxEnt for five species with proven or assumed vector competence for Leishmania infantum, which are either predominantly located in (south-) western (Phlebotomus ariasi, P. mascittii and P. perniciosus) or south-eastern Europe (P. neglectus and P. perfiliewi). The determined bioclimatic envelopes were transferred to two climate change scenarios (A1B and B1) for Central Europe (Austria, Germany and Switzerland) using data of the regional climate model COSMO-CLM. We detected the most likely way of natural dispersal (“least-cost path”) for each species and hence determined the accessibility of potential future climatically suitable habitats by integrating landscape features, projected changes in climatic suitability and wind speed. Results and Relevance Results indicate that the Central European climate will become increasingly suitable especially for those vector species with a current south-western focus of distribution. In general, the highest suitability of Central Europe is projected for all species in the second half of the 21st century, except for P. perfiliewi. Nevertheless, we show that sandflies will hardly be able to occupy their climatically suitable habitats entirely, due to their limited natural dispersal ability. A northward spread of species with south-eastern focus of distribution may be constrained but not completely avoided by the Alps. Our results can be used to install specific monitoring systems to the projected risk zones of potential sandfly establishment. This is urgently needed for adaptation and coping strategies against the emerging spread of sandfly-borne diseases. PMID:22140590

Fischer, Dominik; Moeller, Philipp; Thomas, Stephanie M.; Naucke, Torsten J.; Beierkuhnlein, Carl

2011-01-01

53

Potential contribution of wind energy to climate change mitigation  

NASA Astrophysics Data System (ADS)

It is still possible to limit greenhouse gas emissions to avoid the 2 °C warming threshold for dangerous climate change. Here we explore the potential role of expanded wind energy deployment in climate change mitigation efforts. At present, most turbines are located in extra-tropical Asia, Europe and North America, where climate projections indicate continuity of the abundant wind resource during this century. Scenarios from international agencies indicate that this virtually carbon-free source could supply 10-31% of electricity worldwide by 2050 (refs , ). Using these projections within Intergovernmental Panel on Climate Change Representative Concentration Pathway (RCP) climate forcing scenarios, we show that dependent on the precise RCP followed, pursuing a moderate wind energy deployment plan by 2050 delays crossing the 2 °C warming threshold by 1-6 years. Using more aggressive wind turbine deployment strategies delays 2 °C warming by 3-10 years, or in the case of RCP4.5 avoids passing this threshold altogether. To maximize these climate benefits, deployment of non-fossil electricity generation must be coupled with reduced energy use.

Barthelmie, R. J.; Pryor, S. C.

2014-08-01

54

SECULAR CHANGES IN ETA CARINAE'S WIND 1998-2011  

SciTech Connect

Stellar wind-emission features in the spectrum of eta Carinae have decreased by factors of 1.5-3 relative to the continuum within the last 10 years. We investigate a large data set from several instruments (STIS, GMOS, UVES) obtained between 1998 and 2011 and analyze the progression of spectral changes in direct view of the star, in the reflected polar-on spectra at FOS4, and at the Weigelt knots. We find that the spectral changes occurred gradually on a timescale of about 10 years and that they are dependent on the viewing angle. The line strengths declined most in our direct view of the star. About a decade ago, broad stellar wind-emission features were much stronger in our line-of-sight view of the star than at FOS4. After the 2009 event, the wind-emission line strengths are now very similar at both locations. High-excitation He I and N II absorption lines in direct view of the star strengthened gradually. The terminal velocity of Balmer P Cyg absorption lines now appears to be less latitude dependent, and the absorption strength may have weakened at FOS4. Latitude-dependent alterations in the mass-loss rate and the ionization structure of eta Carinae's wind are likely explanations for the observed spectral changes.

Mehner, Andrea [ESO, Alonso de Cordova 3107, Vitacura, Santiago de Chile (Chile); Davidson, Kris; Humphreys, Roberta M. [Minnesota Institute for Astrophysics, University of Minnesota, Minneapolis, MN 55455 (United States); Ishibashi, Kazunori [Global COE, Division of Particle Physics and Astrophysics, Nagoya University, Nagoya 464-8602 (Japan); Martin, John C. [Department of Physics and Astronomy, University of Illinois Springfield, Springfield, IL 62703 (United States); Ruiz, Maria Teresa [Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago de Chile (Chile); Walter, Frederick M. [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800 (United States)

2012-05-20

55

Wind of change: new insights on the ecology and evolution of pollination and mating in wind-pollinated plants  

E-print Network

REVIEW Wind of change: new insights on the ecology and evolution of pollination and mating in wind-pollinated The rich literature that characterizes the field of pollination biology has focused largely on animal- pollinated plants. At least 10 % of angiosperms are wind pollinated, and this mode of pollination has evolved

Barrett, C.H.

56

Climate change and threat of vector-borne diseases in India: are we prepared?  

Microsoft Academic Search

It is unequivocal that climate change is happening and is likely to expand the geographical distribution of several vector-borne\\u000a diseases, including malaria and dengue etc. to higher altitudes and latitudes. India is endemic for six major vector-borne\\u000a diseases (VBD) namely malaria, dengue, chikungunya, filariasis, Japanese encephalitis and visceral leishmaniasis. Over the\\u000a years, there has been reduction in the incidence of

Ramesh C. Dhiman; Sharmila Pahwa; G. P. S. Dhillon; Aditya P. Dash

2010-01-01

57

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

NASA Astrophysics Data System (ADS)

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

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

2003-12-01

58

Study of vegetation index selection and changing detection thresholds in land cover change detection assessment using change vector analysis  

NASA Astrophysics Data System (ADS)

In recent years, Vietnamese rapidly developing economy has led to speedy changes in land cover. The study of changing detection of land cover plays an important role in making the strategy of the managers. There are two main approaches in changing detection research by using remote sensing and GIS: post- classification change detection analysis approach and pre-classification changing spectral determination approach. Each has their own different advantages and disadvantages. The second one is further divided into: Image Differencing, Multi-date Principal Component Analysis (MPCA); Change Vector Analysis (CVA). In this study, researchers introduce CVA method. This method is based on two important index to show the primary feature of land cover, such as: vegetation index (NDVI-) and barren land index (-BI). Ability to apply methods of CVA has been mentioned in the studies [1, 2, 3, and 4]. However, in these studies did not mention the NDVI index selection and changing detection threshold in changing detection assessment? This paper proposes application to solve these two problems.

Nguyen, Duy; Tran, Giang

2012-07-01

59

Attraction of the cutaneous leishmaniasis vector Nyssomyia neivai (Diptera: Psychodidae) to host odour components in a wind tunnel  

PubMed Central

Background Laboratory studies of host-seeking olfactory behaviour in sandflies have largely been restricted to the American visceral leishmaniasis vector Lutzomyia longipalpis. In comparison, almost nothing is known about the chemical ecology of related species, which transmit American cutaneous leishmaniasis (ACL), due in part to difficulties in raising these insects in the laboratory. Understanding how ACL vectors locate their hosts will be essential to developing new vector control strategies to combat this debilitating disease. Methods This study examined host-odour seeking behaviour of the ACL vector Nyssomyia neivai (Pinto) (=Lutzomyia neivai) using a wind tunnel olfactometer. The primary aim was to determine whether field-collected female N. neivai would respond to host odours in the laboratory, thereby eliminating the need to maintain colonies of these insects for behavioural experiments. Responses to two key host odour components, 1-octen-3-ol and lactic acid, and a commercially-available mosquito lure (BG-Lure™) were assessed and compared relative to an air control. We also tested whether trials could be conducted outside of the normal evening activity period of N. neivai without impacting on fly behaviour, and whether the same flies could be used to assess baseline responses to air without affecting responses to octenol, thereby reducing the number of flies required for experiments. Results Octenol was found to both activate host-seeking behaviour and attract female N. neivai in the wind tunnel, while lactic acid elicited weaker responses of activation and attractiveness under identical conditions. The BG-Lure did not activate or attract N. neivai under test conditions. Further experiments showed that sandfly behaviour in the wind tunnel was not affected by time of day, such that experiments need not be restricted to nocturnal hours. Moreover, using the same flies to measure both baseline responses to air and attraction to test compounds did not affect odour-seeking behaviour. Conclusions The results of this study demonstrate that N. neivai taken from the field are suitable for use in laboratory olfactometer experiments. It is hoped this work will facilitate further research into chemical ecology of this species, and other ACL vectors. PMID:23009099

2012-01-01

60

Analysis of wind bias change with respect to time at Cape Kennedy, Florida, and Vandenberg AFB, California  

NASA Technical Reports Server (NTRS)

A statistical analysis is presented of the temporal variability of wind vectors at 1 km altitude intervals from 0 to 27 km altitude after applying a digital filter to the original wind profile data sample.

Adelfang, S. I.

1978-01-01

61

MONITORING VEGETATION REGENERATION AND DEFORESTATION USING CHANGE VECTOR ANALYSIS: MT. ST. HELENS STUDY AREA  

Microsoft Academic Search

A sophisticated method for monitoring land-cover change in a highly disturbed landscape involved change vector analysis of multitemporal Kauth-Thomas transformation data. Landsat TM data acquired after the 1980 eruption of Mt. St. Helens (1986 and 1996) were analyzed in this study. Topographic effects from the rugged terrain were removed by regressing a generated hillshade image against each band to estimate

Kristopher Kuzera

62

A supply chain diagnostic methodology: determining the vector of change  

Microsoft Academic Search

The paper presents a guide to conduct a supply chain oriented business diagnostic or ‘health check’ termed Quick Scan. The Quick Scan is a systematic approach to the collection and synthesis of qualitative and quantitative data from a supply chain. The Quick Scan approach is the initial step in a generic methodology to identifying the change management opportunities in the

M. M. Naim; P. Childerhouse; S. M. Disney; D. R. Towill

2002-01-01

63

Things fall apart: topology change from winding tachyons  

Microsoft Academic Search

We argue that closed string tachyons drive two spacetime topology changing transitions --- loss of genus in a Riemann surface and separation of a Riemann surface into two components. The tachyons of interest are localized versions of Scherk-Schwarz winding string tachyons arising on Riemann surfaces in regions of moduli space where string-scale tubes develop. Spacetime and world-sheet renormalization group analyses

Allan Adams; Xiao Liu; John McGreevy; Alex Saltman; Eva Silverstein

2005-01-01

64

Method for changing removable bearing for a wind turbine generator  

Microsoft Academic Search

A wind generator having removable change-out bearings includes a rotor and a stator, locking bolts configured to lock the rotor and stator, a removable bearing sub-assembly having at least one shrunk-on bearing installed, and removable mounting bolts configured to engage the bearing sub-assembly and to allow the removable bearing sub-assembly to be removed when the removable mounting bolts are removed.

Bharat Sampathkumaran Bagepalli; Gadre Patrick Lee; Aniruddha Dattatraya

2008-01-01

65

Estimated changes in wind speed and wind power density over the western High Plains, 1971-2000  

NASA Astrophysics Data System (ADS)

This manuscript presents the results of research on the temporal patterns in wind speed and wind power density from 1971 to 2000. The study area is across the western High Plains states east of the Rocky Mountains in an area which has a proven wind power resource. Policies and economic analyses involving the rapidly expanding wind power industry have often assumed a constant in the wind resource; however, any temporal pattern or trend in wind speeds can have a meaningful impact on the reliability of wind power as an energy resource. Using data provided by the North American Regional Climate Change Assessment Program (NARCCAP) to analyze decadal and seasonal trends of wind data, this study shows that from 1971 to 2000 there were some notable changes in the NARCCAP simulated wind velocities over the study region. Wind speed trends across the central High Plains of the USA were most notable across the western portion of the study area along the higher terrain near the front range of the Rocky Mountains. The most significant changes occurred during winter and spring when a large portion of the study area experienced the most substantial decrease in wind speed, with a 20% reduction in wind power density during spring across the western portion of the study area. During summer and fall, the trends are less noticeable, with only very small changes in the summer. Fall was the only season that saw widespread increased values of wind power density from the 1970s to 1990s, with increases of nearly 10% in some southern areas of the study area. Based upon the analysis of the data and previous literature, it is theorized that these changes could be the result of changing synoptic patterns across the study region.

Greene, J. Scott; Chatelain, Matthew; Morrissey, Mark; Stadler, Steve

2012-08-01

66

Change vector analysis method for inundation change detection using multi-temporal multi-polarized SAR images  

NASA Astrophysics Data System (ADS)

With the all-weather and day-night imaging capability, synthetic aperture radar (SAR) plays an important role in inundation extent change detection. Inundation extent change detection using SAR will be easy as a result of the dark image tones yielded by specular reflection. Change vector analysis (CVA) method, an effective change detection method, is also a valuable inundation extent change detection method. In CVA method, change magnitude and change direction can be generated separately, which can be used to determine change areas and change types. CVA method also has the ability to process any number of spectral bands and to produce detailed change information. In this paper, CVA method was applied to inundation extent change detection using multi-temporal multi-polarization ENVISAT ASAR alternative polarization images acquired on 2004-08-29, 2004-12-12 and 2005-03-27. The test site is located in Poyang Lake wetland, where land surface had different inundation extent when images were acquired. Firstly these 3 phases of images were registered together. Then the change vectors were calculated using these images. After that change magnitude and direction cosine images were produced. At last the change areas and the corresponding change type were extracted separately using decision tree method. The result indicates that CVA method has potential utility in inundation extent change detection.

Shen, Guozhuang; Guo, Huadong; Liao, Jingjuan

2007-11-01

67

Impacts of past and future climate change on wind energy resources in the United States  

Microsoft Academic Search

The links between climate change and trends in wind energy resources have important potential implications for the wind energy industry, and have received significant attention in recent studies. We have conducted two studies that provide insights into the potential for climate change to affect future wind power production. In one experiment, we projected changes in power capacity for a hypothetical

J. R. McCaa; A. Wood; S. Eichelberger; K. Westrick

2009-01-01

68

Wave-and Anemometer-Based Sea Surface Wind (WASWind) for Climate Change Analysis*  

E-print Network

Wave- and Anemometer-Based Sea Surface Wind (WASWind) for Climate Change Analysis* HIROKI TOKINAGA-based measurements of sea surface wind speed display a spurious upward trend due to increases in anemometer height (ICOADS). The Wave- and Anemometer-based Sea surface Wind (WASWind) dataset is available for wind velocity

Xie, Shang-Ping

69

Climate Change and Vector Borne Diseases on NASA Langley Research Center  

NASA Technical Reports Server (NTRS)

Increasing global temperature, weather patterns with above average storm intensities, and higher sea levels have been identified as phenomena associated with global climate change. As a causal system, climate change could contribute to vector borne diseases in humans. Vectors of concern originate from the vicinity of Langley Research Center include mosquitos and ticks that transmit disease that originate regionally, nationwide, or from outside the US. Recognizing changing conditions, vector borne diseases propagate under climate change conditions, and understanding the conditions in which they may exist or propagate, presents opportunities for monitoring their progress and mitigating their potential impacts through communication, continued monitoring, and adaptation. Personnel comprise a direct and fundamental support to NASA mission success, continuous and improved understanding of climatic conditions, and the resulting consequence of disease from these conditions, helps to reduce risk in terrestrial space technologies, ground operations, and space research. This research addresses conditions which are attributed to climatic conditions which promote environmental conditions conducive to the increase of disease vectors. This investigation includes evaluation of local mosquito population count and rainfall data for statistical correlation and identification of planning recommendations unique to LaRC, other NASA Centers to assess adaptation approaches, Center-level planning strategies.

Cole, Stuart K.; DeYoung, Russell J.; Shepanek, Marc A.; Kamel, Ahmed

2014-01-01

70

Change-vector analysis in multitemporal space: A tool to detect and categorize land-cover change processes using high temporal-resolution satellite data  

SciTech Connect

Analysis of change vectors in the multitemporal space, applied to multitemporal local area coverage imagery obtained by the Advanced Very-High Resolution Radiometer on NOAA-9 and NOAA-11 orbiting platforms, clearly reveals the nature and magnitude of land-cover change in a region of West Africa. The change vector compares the difference in the time-trajectory of a biophysical indicator, such as the normalized difference vegetation index, for two successive time periods, such as hydrological years. In establishing the time-trajectory, the indicator is composited for each pixel in a registered multidate image sequence. The change vector is simply the vector difference between successive time-trajectories, each represented as a vector in a multidimensional measurement space. The length of the change vector indicates the magnitude of the interannual change, while its direction indicates the nature of the change. A principal components analysis of change vectors for a Sudanian-Sahelian region in West Africa shows four major classes of change magnitude and four general contrasting types of change. Scene-specific changes, such as reservoir water level storage changes, are also identified. The technique is easily extended to other biophysical parameters, such as surface temperature, and can incorporate noneuclidean distance measures. Change vector analysis is being developed for application to the land-cover change product to be produced using NASA's Moderate-Resolution Imaging Spectroradiometer instrument, scheduled for flight in 1998 and 2000 on EOS-AM and -PM platforms.

Lambin, E.F. (Joint Research Center, Ispra (Italy). Inst. for Remote Sensing Applications); Strahler, A.H. (Boston Univ., MA (United States). Dept. of Geography)

1994-05-01

71

Estimating lower winds aloft at Houston, Texas, using a spatial vector regression technique  

E-print Network

of distance for different climatic zones (see Figure 1). Figure 1 shows that r? varies linearly from approximately 0. 50 at 400 n mi. to unity at zero distance. Charles (1959b), using 5 yr of serially complete wind collec- tions of the U. S. Weather Bureau... source of data on r~ s (stretch correlation coefficient between winds at the same time and station at levels "i" and "j") is a set of computations by the AWS Climatic Center, (1955-1957). Based on 3 to 10 yr of data, correlation coefficients for 50...

Zumwalt, James Tweed

2012-06-07

72

Study on growth monitoring of winter wheat based on change vector analysis  

NASA Astrophysics Data System (ADS)

The basic idea of current study of crop growth monitoring is to analyze the relation between the shape variety of NDVI curve and the condition variety of crop, calculate the feature factors, and speculate the growing condition of crop. This investigation takes five high-yield provinces as study area, including Hebei, Henan, Shandong, Anhui and Jiangsu, and takes winter wheat as study object. The ten days maximum value composite (MVC) SPOT-VEGETATION dataset, from 1999 to 2005, is used as the main remotely sensed data. Savizky-Golay filter method, which made the NDVI time-series curve disclose the change rule of winter wheat growth better, is use to eliminate the noise. And then the method of Change Vector Analysis (CVA) is applied to detect the change dynamics of winter wheat. According to the each average value of Change Vector in six years, changes, intra-annual, inter-annual and interlocal, of winter wheat have been quantified. The result shows that the method of Change Vector Analysis is effective for monitoring the winter wheat growth as a new idea, which can integrate most of the feature factors of NDVI curve.

Gu, Xiaohe; Pan, Yaozhong; Han, Lijian; Xu, Chao

2007-06-01

73

Corrections to Scatterometer Wind Vectors During Hurricane Dennis Using High Resolution NEXRAD Radar Rain Corrections  

Microsoft Academic Search

Scatterometer wind measurements in Hurricanes have excellent potential for studying ocean forcing and the forecasting of coastal storm surges and flooding potential. These observations have the advantages of wide coverage, high resolution and accuracy. However, significant errors can occur when rain causes attenuation and backscatter of the Scatterometer's microwave pencil-beam. For most of the rain conditions existing in Hurricanes, the

D. E. Weissman; Mark A. Bourassa

2006-01-01

74

Empirical Model of Sea Surface Slope Statistics for Wind Vector Estimation Using Bistatic GPS Measurements  

Microsoft Academic Search

Recently, several researchers have estimated sea surface wind speed from the cross-correlation waveform of forward scattered GPS signals. These measurement techniques apply a scattering model which integrates the reflected power over regions of the glistening surface corresponding to relative path delays within one-chip range bins. (A \\

J. L. Garrison; L. Bertuccelli

2001-01-01

75

Characteristics of wind velocity and temperature change near an escarpment-shaped road embankment.  

PubMed

Artificial structures such as embankments built during the construction of highways influence the surrounding airflow. Various types of damage can occur due to changes in the wind velocity and temperature around highway embankments. However, no study has accurately measured micrometeorological changes (wind velocity and temperature) due to embankments. This study conducted a wind tunnel test and field measurement to identify changes in wind velocity and temperature before and after the construction of embankments around roads. Changes in wind velocity around an embankment after its construction were found to be influenced by the surrounding wind velocity, wind angle, and the level difference and distance from the embankment. When the level difference from the embankment was large and the distance was up to 3H, the degree of wind velocity declines was found to be large. In changes in reference wind velocities around the embankment, wind velocity increases were not proportional to the rate at which wind velocities declined. The construction of the embankment influenced surrounding temperatures. The degree of temperature change was large in locations with large level differences from the embankment at daybreak and during evening hours when wind velocity changes were small. PMID:25136681

Kim, Young-Moon; You, Ki-Pyo; You, Jang-Youl

2014-01-01

76

State changes arising from wind transport in drylands (Invited)  

NASA Astrophysics Data System (ADS)

The importance of soil transport due to wind has been increasingly understood as a crucial aspect of ecosystem evolution in drylands. Aeolian processes impact vegetation structure, topographic characteristics, and soil properties, and aeolian transport drives important feedbacks that give rise to multiple stable states. Here, we outline the results of several field and modeling experiments that show the critical interactions that occur amongst wind, vegetation, and soils. Measurements of transport, fallout radionuclide tracing, deposition, and vegetation growth shows clearly that aeolian transport can result in significant alteration of a variety of ecosystem and soil factors. Moreover, changes to vegetation and soils from land use, invasive species, and climate change impact aeolian transport. Both simplistic and sophisticated modeling approaches indicate that transport can produce multiple stable states in dryland ecosystems, and thus can participate in large-scale reorganization of soils and vegetation. These results also indicate that manipulation of aeolian transport might provide the opportunity to step some drylands back from critical thresholds and begin the process of recovery from unwanted ecosystem states.

Okin, G. S.; D'Odorico, P.

2013-12-01

77

Projected Future Distributions of Vectors of Trypanosoma cruzi in North America under Climate Change Scenarios  

PubMed Central

Background Chagas disease kills approximately 45 thousand people annually and affects 10 million people in Latin America and the southern United States. The parasite that causes the disease, Trypanosoma cruzi, can be transmitted by insects of the family Reduviidae, subfamily Triatominae. Any study that attempts to evaluate risk for Chagas disease must focus on the ecology and biogeography of these vectors. Expected distributional shifts of vector species due to climate change are likely to alter spatial patterns of risk of Chagas disease, presumably through northward expansion of high risk areas in North America. Methodology/Principal Findings We forecast the future (2050) distributions in North America of Triatoma gerstaeckeri and T. sanguisuga, two of the most common triatomine species and important vectors of Trypanosoma cruzi in the southern United States. Our aim was to analyze how climate change might affect the future shift of Chagas disease in North America using a maximum entropy algorithm to predict changes in suitable habitat based on vector occurrence points and predictive environmental variables. Projections based on three different general circulation models (CCCMA, CSIRO, and HADCM3) and two IPCC scenarios (A2 and B2) were analyzed. Twenty models were developed for each case and evaluated via cross-validation. The final model averages result from all twenty of these models. All models had AUC >0.90, which indicates that the models are robust. Our results predict a potential northern shift in the distribution of T. gerstaeckeri and a northern and southern distributional shift of T. sanguisuga from its current range due to climate change. Conclusions/Significance The results of this study provide baseline information for monitoring the northward shift of potential risk from Chagas disease in the face of climate change. PMID:24831117

Garza, Miroslava; Feria Arroyo, Teresa Patricia; Casillas, Edgar A.; Sanchez-Cordero, Victor; Rivaldi, Chissa-Louise; Sarkar, Sahotra

2014-01-01

78

Monte Carlo studies of ocean wind vector measurements by SCATT: Objective criteria and maximum likelihood estimates for removal of aliases, and effects of cell size on accuracy of vector winds  

NASA Technical Reports Server (NTRS)

The scatterometer on the National Oceanic Satellite System (NOSS) is studied by means of Monte Carlo techniques so as to determine the effect of two additional antennas for alias (or ambiguity) removal by means of an objective criteria technique and a normalized maximum likelihood estimator. Cells nominally 10 km by 10 km, 10 km by 50 km, and 50 km by 50 km are simulated for winds of 4, 8, 12 and 24 m/s and incidence angles of 29, 39, 47, and 53.5 deg for 15 deg changes in direction. The normalized maximum likelihood estimate (MLE) is correct a large part of the time, but the objective criterion technique is recommended as a reserve, and more quickly computed, procedure. Both methods for alias removal depend on the differences in the present model function at upwind and downwind. For 10 km by 10 km cells, it is found that the MLE method introduces a correlation between wind speed errors and aspect angle (wind direction) errors that can be as high as 0.8 or 0.9 and that the wind direction errors are unacceptably large, compared to those obtained for the SASS for similar assumptions.

Pierson, W. J.

1982-01-01

79

Community-based dengue vector control: experiences in behavior change in Metropolitan Manila, Philippines  

PubMed Central

Dengue is the most important mosquito-borne disease in the Philippines, especially in Metropolitan Manila where communities are socially and economically diverse, and city governments struggle to provide basic services such as continuously available, piped water supply to residents. We examined responses to introducing water container management to control dengue vectors in two diverse communities in Masagana City: Village A (gated community) and Village B (informal settlers community). The roll out of the intervention was carried out by the study team, dengue control personnel and local health workers (BHWs). A behavioural change framework was used to describe the community responses to the introduction of a new vector control intervention - household water container management. Although, the desired outcome was not achieved during the study's timeline, observation on processes of behaviour change underscored the importance of understanding the social nature of the urban communities, often overlooked structures when dengue control program and researchers introduce new dengue control interventions. PMID:23318237

Espino, Fe; Marco, Jesusa; Salazar, Nelia P; Salazar, Ferdinand; Mendoza, Ysadora; Velazco, Aldwin

2012-01-01

80

Implications of Climate Change for Toxoptera citricida (Kirkaldy), a Disease Vector of Citrus in Florida  

Microsoft Academic Search

\\u000a Increasing temperatures, elevated CO2 levels, and changes in rainfall patterns are predicted to impact plants and insects, both harmful and beneficial. Toxoptera citricida Kirkaldy (Homoptera: Aphididae), commonly known as the brown citrus aphid (BrCA), is a cosmopolitan pest of citrus and a\\u000a highly efficient vector of citrus tristeza virus (CTV). Both the pest and the disease pose a serious threat

Jawwad A. Qureshi

81

Preliminary assessment of climate change impacts on the UK onshore wind energy resource  

E-print Network

Abstract Wind power is currently the fastest growing renewable technology and will play a significant role, the potential for changes in climate to affect the significant onshore wind resource in the United Kingdom (UK- based offshore wind, wave, tidal and biomass, the UK Government and Scottish Executive have

Harrison, Gareth

82

Assessing climate change impacts on the near-term stability of the wind energy  

E-print Network

Assessing climate change impacts on the near-term stability of the wind energy resource over- ble emissions of carbon dioxide. The wind energy resource is natu- rally a function of the climate, leading some to question the continued viability of the wind energy industry. Here we briefly articulate

Pryor, Sara C.

83

Energy Policy 36 (2008) 2333 Change in public attitudes towards a Cornish wind farm  

E-print Network

Energy Policy 36 (2008) 23­33 Viewpoint Change in public attitudes towards a Cornish wind farm independently conducted polls suggest significant public support for wind energy, there are often objections, this has seen the development of onshore wind energy to meet these targets (Strachan and Lal, 2004

84

Changing distribution patterns of canine vector borne diseases in Italy: leishmaniosis vs. dirofilariosis  

PubMed Central

Ecological and climatic changes, human and animal population dynamics are among the several factors that have favoured the spread or the (re)introduction and establishment of "novel" vector species and pathogens they transmit in previously disease-free geographical areas. As key examples of the changing pattern of distribution of canine vector borne diseases (CVBDs), the current distribution of canine leishmaniosis (CanL) by Leishmania infantum and dirofilariosis by Dirofilaria immitis causing heart worm disease (HW) in Italy is discussed on the basis of retrospective historical reports until the 90's and later on until 2009. For long time, D. immitis has been considered mainly present along the Po River Valley and northward areas, while L. infantum in south-central Italy and Sicily and Sardinia. Comparison of current available and historical data (up to 1989) confirms that HW and CanL, although with different prevalence rates, have been changing their distribution patterns in Italy as a result of many biological and ecological factors, including those related to vector distribution and introduction of new species (e.g. the Asian tiger mosquito Aedes albopictus, a competent vector of D. immitis). New autochthonous foci of HW in southern Italy (i.e. Apulia and Calabria regions) have recently been reported. Although analysing retrospective data may represent a difficult task, the "paradigm" about the dual distribution of HW and CanL in northern and southern Italy cannot yet be considered valid. The research needs for managing HW and CanL in previously uninfected areas are discussed. PMID:19426441

Otranto, Domenico; Capelli, Gioia; Genchi, Claudio

2009-01-01

85

Climate Change, Public Health, and Decision Support: The New Threat of Vector-borne Disease  

NASA Astrophysics Data System (ADS)

Climate change and vector-borne diseases constitute a massive threat to human development. It will not be enough to cut emissions of greenhouse gases-the tide of the future has already been established. Climate change and vector-borne diseases are already undermining the world's efforts to reduce extreme poverty. It is in the best interests of the world leaders to think in terms of concerted global actions, but adaptation and mitigation must be accomplished within the context of local community conditions, resources, and needs. Failure to act will continue to consign developed countries to completely avoidable health risks and significant expense. Failure to act will also reduce poorest of the world's population-some 2.6 billion people-to a future of diminished opportunity. Northrop Grumman has taken significant steps forward to develop the tools needed to assess climate change impacts on public health, collect relevant data for decision making, model projections at regional and local levels; and, deliver information and knowledge to local and regional stakeholders. Supporting these tools is an advanced enterprise architecture consisting of high performance computing, GIS visualization, and standards-based architecture. To address current deficiencies in local planning and decision making with respect to regional climate change and its effect on human health, our research is focused on performing a dynamical downscaling with the Weather Research and Forecasting (WRF) model to develop decision aids that translate the regional climate data into actionable information for users. For the present climate WRF was forced with the Max Planck Institute European Center/Hamburg Model version 5 (ECHAM5) General Circulation Model 20th century simulation. For the 21th century climate, we used an ECHAM5 simulation with the Special Report on Emissions (SRES) A1B emissions scenario. WRF was run in nested mode at spatial resolution of 108 km, 36 km and 12 km and 28 vertical levels. This model was examined relative to two mosquito vectors, both competent carriers of dengue fever, a viral, vector-borne disease. Models which incorporate public health considerations can enable decision makers to take proactive steps to mitigate the impacts and adapt to the changing environmental conditions. In this paper we provide a snapshot of our climate initiative and some examples relative to our public health practice work in vector-borne diseases to illustrate how integrated decision support could be of assistance to regional and local communities worldwide.

Grant, F.; Kumar, S.

2011-12-01

86

Risk maps for range expansion of the Lyme disease vector, Ixodes scapularis, in Canada now and with climate change  

Microsoft Academic Search

BACKGROUND: Lyme disease is the commonest vector-borne zoonosis in the temperate world, and an emerging infectious disease in Canada due to expansion of the geographic range of the tick vector Ixodes scapularis. Studies suggest that climate change will accelerate Lyme disease emergence by enhancing climatic suitability for I. scapularis. Risk maps will help to meet the public health challenge of

Nicholas H Ogden; Laurie St-Onge; Ian K Barker; Stéphanie Brazeau; Michel Bigras-Poulin; Dominique F Charron; Charles M Francis; Audrey Heagy; L Robbin Lindsay; Abdel Maarouf; Pascal Michel; François Milord; Christopher J O'Callaghan; Louise Trudel; R Alex Thompson

2008-01-01

87

Climate Change and Risk of Leishmaniasis in North America: Predictions from Ecological Niche Models of Vector and Reservoir Species  

Microsoft Academic Search

BackgroundClimate change is increasingly being implicated in species' range shifts throughout the world, including those of important vector and reservoir species for infectious diseases. In North America (México, United States, and Canada), leishmaniasis is a vector-borne disease that is autochthonous in México and Texas and has begun to expand its range northward. Further expansion to the north may be facilitated

Camila González; Ophelia Wang; Stavana E. Strutz; Constantino González-Salazar; Víctor Sánchez-Cordero; Sahotra Sarkar

2010-01-01

88

OBSERVATIONAL EVIDENCE OF CHANGING PHOTOSPHERIC VECTOR MAGNETIC FIELDS ASSOCIATED WITH SOLAR FLARES  

SciTech Connect

Recent observations have provided evidence that the solar photospheric magnetic fields could have rapid and permanent changes in both longitudinal and transverse components associated with major flares. As a result, the Lorentz force (LF) acting on the solar photosphere and solar interior could be perturbed, and the change of LF is always nearly in the downward direction. However, these rapid and permanent changes have not been systematically investigated, yet, using vector magnetograms. In this paper, we analyze photospheric vector magnetograms covering five flares to study the evolution of photospheric magnetic fields. In particular, we investigate two-dimensional spatial distributions of the changing LF. Around the major flaring polarity inversion line, the net change of the LF is directed downward in an area of {approx}10{sup 19} cm{sup 2} for X-class flares. For all events, the white-light observations show that sunspots darken in this location after flares, and magnetic fields become more inclined, which is consistent with the ideas put forward by Hudson et al. and Fisher et al., and observations.

Su, J. T.; Jing, J.; Wang, H. M. [Space Weather Research Laboratory, New Jersey Institute of Technology, University Heights, Newark, NJ 07102-1982 (United States); Mao, X. J.; Wang, X. F.; Zhang, H. Q.; Deng, Y. Y.; Guo, J.; Wang, G. P., E-mail: sjt@bao.ac.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

2011-06-01

89

Glacial Change in the Wind River Range, Wyoming, USA  

NASA Astrophysics Data System (ADS)

The upper Green River Basin (GRB) [located in the upper Colorado River Basin] and the upper Wind-Bighorn River Basin (WBRB) [located in the upper Missouri-Mississippi River Basin] are separated by the Wind River Range (WRR) of Wyoming. The WRR is an unbroken 160-kilometer barrier in west central Wyoming that is host to 63 glaciers, the largest concentration of glaciers in the American Rocky Mountains. These glaciers serve as natural water reservoirs and the continued recession of glaciers will impact agricultural water supply in the region. Previous research determined that the glaciers in the WRR contribute approximately 30% of the total streamflow volume during the critical late summer / early fall growing season. However, the previous research was limited in scope to a small number of climatic stations and limited streamflow measurements. The proposed research improves on previous research by evaluating glacial recession in the WRR using remote sensing techniques. Glacier area and terminus position for 42 glacial complexes in the WRR (from 1985 to present) will be evaluated using LANDSAT Imagery and GIS techniques. Next, for selected glaciers, aerial photograph stereopairs will also be obtained from the USGS Earth Resources, Observation and Science (EROS) Data Center in Sioux Falls, South Dakota from 1966 to present. The stereopair images will be utilized to derive the surface elevation of glaciers and calculate volume change. Traditional methods require the user to view the two photos with a stereoscope to view an object in three dimensions. Modern techniques allow this process to be completed digitally. Leica Photogrammetry suite is used to specify the spatial coordinates of each photo and create a block file, a file that consists of two or more photographs of the same area that contain spatial coordinates of each photo. Once the block file is created, the user can view the objects contained in the overlapping portions of the photos and make vertical measurements. This process allows the user to calculate changes in surface area and changes in elevation, thus volume changes can be computed. Glacier volume will also be estimated from glacier surface areas using the Bahr et al. (1997) area-volume scaling method. Finally, field data (real-time differential GPS surface survey, ground penetrating radar of ice thickness and repeat photography) from a summer 2006 site visit to Dinwoody Glacier (located on the east slope of the WRR) will be compared to previous site visits in the past 40 years. The field data will either confirm or reject observations from the remote sensing approach.

Cheesbrough, K.; Edmunds, J.; Kerr, G.; Pochop, L.; Tootle, G.

2007-12-01

90

Pressure distribution on a vectored-thrust V/STOL fighter in the transition-speed range. [wind tunnel tests to measure pressure distribution on body and wing  

NASA Technical Reports Server (NTRS)

A wind-tunnel investigation has been conducted in the Langley V/STOL tunnel with a vectored-thrust V/STOL fighter configuration to obtain detailed pressure measurements on the body and on the wing in the transition-speed range. The vectored-thrust jet exhaust induced a region of negative pressure coefficients on the lower surface of the wing and on the bottom of the fuselage. The location of the jet exhaust relative to the wing was a major factor in determining the extent of the region of negative pressure coefficients.

Mineck, R. E.; Margason, R. J.

1974-01-01

91

Things Fall Apart Topology Change from Winding Tachyons  

E-print Network

We argue that closed string tachyons drive two spacetime topology changing transitions -- loss of genus in a Riemann surface and separation of a Riemann surface into two components. The tachyons of interest are localized versions of Scherk-Schwarz winding string tachyons arising on Riemann surfaces in regions of moduli space where string-scale tubes develop. Spacetime and world-sheet renormalization group analyses provide strong evidence that the decay of these tachyons removes a portion of the spacetime, splitting the tube into two pieces. We address the fate of the gauge fields and charges lost in the process, generalize it to situations with weak flux backgrounds, and use this process to study the type 0 tachyon, providing further evidence that its decay drives the theory sub-critical. Finally, we discuss the time-dependent dynamics of this topology-changing transition and find that it can occur more efficiently than analogous transitions on extended supersymmetric moduli spaces, which are limited by modul...

Adams, A; McGreevy, J; Saltman, A; Silverstein, E

2005-01-01

92

Things Fall Apart: Topology Change from Winding Tachyons  

E-print Network

We argue that closed string tachyons drive two spacetime topology changing transitions -- loss of genus in a Riemann surface and separation of a Riemann surface into two components. The tachyons of interest are localized versions of Scherk-Schwarz winding string tachyons arising on Riemann surfaces in regions of moduli space where string-scale tubes develop. Spacetime and world-sheet renormalization group analyses provide strong evidence that the decay of these tachyons removes a portion of the spacetime, splitting the tube into two pieces. We address the fate of the gauge fields and charges lost in the process, generalize it to situations with weak flux backgrounds, and use this process to study the type 0 tachyon, providing further evidence that its decay drives the theory sub-critical. Finally, we discuss the time-dependent dynamics of this topology-changing transition and find that it can occur more efficiently than analogous transitions on extended supersymmetric moduli spaces, which are limited by moduli trapping.

A. Adams; X. Liu; J. McGreevy; A. Saltman; E. Silverstein

2005-02-02

93

Things Fall Apart: Topology Change From Winding Tachyons  

SciTech Connect

We argue that closed string tachyons drive two spacetime topology changing transitions--loss of genus in a Riemann surface and separation of a Riemann surface into two components. The tachyons of interest are localized versions of Scherk-Schwarz winding string tachyons arising on Riemann surfaces in regions of moduli space where string-scale tubes develop. Spacetime and world-sheet renormalization group analyses provide strong evidence that the decay of these tachyons removes a portion of the spacetime, splitting the tube into two pieces. We address the fate of the gauge fields and charges lost in the process, generalize it to situations with weak flux backgrounds, and use this process to study the type 0 tachyon, providing further evidence that its decay drives the theory sub-critical. Finally, we discuss the time-dependent dynamics of this topology-changing transition and find that it can occur more efficiently than analogous transitions on extended supersymmetric moduli spaces, which are limited by moduli trapping.

Adams, A.

2005-02-04

94

Detecting land-use/land-cover change in rural-urban fringe areas using extended change-vector analysis  

NASA Astrophysics Data System (ADS)

Detecting land-use/land-cover (LULC) changes in rural-urban fringe areas (RUFAs) timely and accurately using satellite imagery is essential for land-use planning and management in China. Although traditional spectral-based change-vector analysis (CVA) can effectively detect LULC change in many cases, it encounters difficulties in RUFAs because of deficiencies in the spectral information of satellite images. To detect LULC changes in RUFAs effectively, this paper proposes an extended CVA approach that incorporates textural change information into the traditional spectral-based CVA. The extended CVA was applied to three different pilot RUFAs in China with different remotely sensed data, including Landsat Thematic Mapper (TM), China-Brazil Earth Resources Satellite (CBERS) and Advanced Land Observing Satellite (ALOS) images. The results demonstrated the improvement of the extended CVA compared to the traditional spectral-based CVA with the overall accuracy increased between 4.66% and 8.00% and the kappa coefficient increased between 0.10 and 0.15, respectively. The advantage of the extended CVA lies in its integration of both spectral and textural change information to detect LULC changes, allowing for effective discrimination of LULC changes that are spectrally similar but texturally different in RUFAs. The extended CVA has great potential to be widely used for LULC-change detection in RUFAs, which are often heterogeneous and fragmental in nature, with rich textural information.

He, Chunyang; Wei, Anni; Shi, Peijun; Zhang, Qiaofeng; Zhao, Yuanyuan

2011-08-01

95

Environmental satellite data utilization: determination of wind vectors by tracking features on sequential moisture analyses derived from hyperspectral IR satellite soundings  

NASA Astrophysics Data System (ADS)

Traditional methods for deriving wind vectors from sequential geostationary satellite imagery involve the tracking of coherent clouds and moisture features in single channels (spectral bands). While this data source has proven to be important to global wind analyses, the approach is limited in two major ways: 1) The heights assigned to the vectors are not precise, leading to problems in data assimilation, and 2) Vertical profiles of the wind at a given geo-location are not provided, adding further stress to objective data assimilation (difficulty with single-level observations). A new approach to deriving winds from sequential satellite observations is being advanced at CIMSS. The method utilizes the same basic automated tracking code developed at CIMSS, however the input to the algorithm is in the form of constant-level moisture analyses derived from hyperspectral sounding information. Since the altitude of the features being tracked are already determined by the soundings/analyses, the height assignment ambiguities associated with the traditional approaches are ameliorated. Furthermore, the hyperspectral infrared (IR) information provides detailed vertical profiles of moisture where there are no clouds. This allows analyses of moisture at multiple vertical levels, which can then be used in an attempt to retrieve vertical profiles of wind. To date, the new scheme has been trialed on simulated data from GIFTS, and on one case of real data from airborne observations provided by the NAST-I instrument. From these first attempts, the "proof of concept" is successfully illustrated, and will be shown in the presentation.

Velden, Christopher

2004-10-01

96

Autonomous Mission Design and Data Fusion: Laying the groundwork for Decadal Mission swath altimetry and ocean vector winds.  

NASA Astrophysics Data System (ADS)

In the coming decade, the autonomous coordinated utilization of space, atmospheric, surface, and ocean assets, sensor webs, and data will assume more importance, as systems become more complex and tightly integrated, and as the need to know our environment with ever greater accuracy and precision becomes more acute. We have begun to address this issue with a prototype virtual ocean observatory that includes present and future NASA satellite missions (Jason-2 and QuikSCAT; and SWOT [swath altimetry] and XOVWM [ocean vector winds], respectively); atmosphere and ocean models (WRF/LAPS and ROMS, respectively); and in-situ sensors and platforms (underwater gliders). In our prototype system, the goal is to develop the architecture and implementation of the necessary software modules (e.g., automated data fusion/assimilation, and automated planning technology) to achieve adaptive in-situ sampling through feedback from space-based-assets (in this case via the SWOT simulator) thereby contributing to the orbit design during the first, experimental phase (~6-9 months) of the SWOT mission. This work is one step in the process of infusing technology into the development pipeline.

Howe, B. M.; Arabshahi, P.; Businger, S.; Chao, Y.; Chien, S.; Gray, A.

2008-12-01

97

Potential Influence of Climate Change on Vector-Borne and Zoonotic Diseases: A Review and Proposed Research Plan  

PubMed Central

Background Because of complex interactions of climate variables at the levels of the pathogen, vector, and host, the potential influence of climate change on vector-borne and zoonotic diseases (VBZDs) is poorly understood and difficult to predict. Climate effects on the nonvector-borne zoonotic diseases are especially obscure and have received scant treatment. Objective We described known and potential effects of climate change on VBZDs and proposed specific studies to increase our understanding of these effects. The nonvector-borne zoonotic diseases have received scant treatment and are emphasized in this paper. Data sources and synthesis We used a review of the existing literature and extrapolations from observations of short-term climate variation to suggest potential impacts of climate change on VBZDs. Using public health priorities on climate change, published by the Centers for Disease Control and Prevention, we developed six specific goals for increasing understanding of the interaction between climate and VBZDs and for improving capacity for predicting climate change effects on incidence and distribution of VBZDs. Conclusions Climate change may affect the incidence of VBZDs through its effect on four principal characteristics of host and vector populations that relate to pathogen transmission to humans: geographic distribution, population density, prevalence of infection by zoonotic pathogens, and the pathogen load in individual hosts and vectors. These mechanisms may interact with each other and with other factors such as anthropogenic disturbance to produce varying effects on pathogen transmission within host and vector populations and to humans. Because climate change effects on most VBZDs act through wildlife hosts and vectors, understanding these effects will require multidisciplinary teams to conduct and interpret ecosystem-based studies of VBZD pathogens in host and vector populations and to identify the hosts, vectors, and pathogens with the greatest potential to affect human populations under climate change scenarios. PMID:20576580

Mills, James N.; Gage, Kenneth L.; Khan, Ali S.

2010-01-01

98

Changing climate and changing vector-borne disease distribution: The example of Dirofilaria in Europe  

Microsoft Academic Search

Climatic changes, together with an increase in the movement of dogs across Europe, have caused an increase in the geographical range of Dirofilaria infections. The present paper is focuses on northeastern European countries, where survey data have shown an increase of Dirofilaria repens infections both in animals and humans. A growing degree day-based forecast model has been developed to predict

Claudio Genchi; Michele Mortarino; Laura Rinaldi; Giuseppe Cringoli; Giorgio Traldi; Marco Genchi

2011-01-01

99

Localization of Changes in a Model Winding Based on Terminal Measurements: Experimental Study  

Microsoft Academic Search

By using some properties of driving-point functions and adopting an iterative circuit synthesis approach, the location, extent, and type of change introduced in a model winding could be identified, based on terminal measurements. In this study, a model winding was used. From knowledge of its measured short-circuit and open-circuit natural frequencies, and pertinent winding data, an equivalent circuit was synthesized

K. Ragavan; L. Satish

2007-01-01

100

Wind shear measuring on board an airliner  

NASA Technical Reports Server (NTRS)

A measurement technique which continuously determines the wind vector on board an airliner during takeoff and landing is introduced. Its implementation is intended to deliver sufficient statistical background concerning low frequency wind changes in the atmospheric boundary layer and extended knowledge about deterministic wind shear modeling. The wind measurement scheme is described and the adaptation of apparatus onboard an A300 airbus is shown. Preliminary measurements made during level flight demonstrate the validity of the method.

Krauspe, P.

1984-01-01

101

Sensitivity of Southern Ocean overturning to wind stress changes: Role of surface restoring time scales  

NASA Astrophysics Data System (ADS)

The influence of different surface restoring time scales on the response of the Southern Ocean overturning circulation to wind stress changes is investigated using an idealised channel model. Regardless of the restoring time scales chosen, the eddy-induced meridional overturning circulation (MOC) is found to compensate for changes of the direct wind-driven Eulerian-mean MOC, rendering the residual MOC less sensitive to wind stress changes. However, the extent of this compensation depends strongly on the restoring time scale: residual MOC sensitivity increases with decreasing restoring time scale. Strong surface restoring is shown to limit the ability of the eddy-induced MOC to change in response to wind stress changes and as such suppresses the eddy compensation effect. These model results are consistent with qualitative arguments derived from residual-mean theory and may have important implications for interpreting past and future observations.

Zhai, Xiaoming; Munday, David R.

2014-12-01

102

Study of light-induced vector changes in the local atomic structure of AsSe glasses by EXAFS  

E-print Network

Study of light-induced vector changes in the local atomic structure of As­Se glasses by EXAFS G changes in the local structure of As­Se glasses using extended X-ray ab- sorption fine structure (EXAFS

Drabold, David

103

Estimated Effects of Projected Climate Change on the Basic Reproductive Number of the Lyme Disease Vector Ixodes scapularis  

PubMed Central

Background: The extent to which climate change may affect human health by increasing risk from vector-borne diseases has been under considerable debate. Objectives: We quantified potential effects of future climate change on the basic reproduction number (R0) of the tick vector of Lyme disease, Ixodes scapularis, and explored their importance for Lyme disease risk, and for vector-borne diseases in general. Methods: We applied observed temperature data for North America and projected temperatures using regional climate models to drive an I. scapularis population model to hindcast recent, and project future, effects of climate warming on R0. Modeled R0 increases were compared with R0 ranges for pathogens and parasites associated with variations in key ecological and epidemiological factors (obtained by literature review) to assess their epidemiological importance. Results: R0 for I. scapularis in North America increased during the years 1971–2010 in spatio-temporal patterns consistent with observations. Increased temperatures due to projected climate change increased R0 by factors (2–5 times in Canada and 1.5–2 times in the United States), comparable to observed ranges of R0 for pathogens and parasites due to variations in strains, geographic locations, epidemics, host and vector densities, and control efforts. Conclusions: Climate warming may have co-driven the emergence of Lyme disease in northeastern North America, and in the future may drive substantial disease spread into new geographic regions and increase tick-borne disease risk where climate is currently suitable. Our findings highlight the potential for climate change to have profound effects on vectors and vector-borne diseases, and the need to refocus efforts to understand these effects. Citation: Ogden NH, Radojevi? M, Wu X, Duvvuri VR, Leighton PA, Wu J. 2014. Estimated effects of projected climate change on the basic reproductive number of the Lyme disease vector Ixodes scapularis. Environ Health Perspect 122:631–638;?http://dx.doi.org/10.1289/ehp.1307799 PMID:24627295

Radojevic?, Milka; Wu, Xiaotian; Duvvuri, Venkata R.; Leighton, Patrick A.; Wu, Jianhong

2014-01-01

104

Operation of a wind turbine-flywheel energy storage system under conditions of stochastic change of wind energy.  

PubMed

The paper presents the issues of a wind turbine-flywheel energy storage system (WT-FESS) operation under real conditions. Stochastic changes of wind energy in time cause significant fluctuations of the system output power and as a result have a negative impact on the quality of the generated electrical energy. In the author's opinion it is possible to reduce the aforementioned effects by using an energy storage of an appropriate type and capacity. It was assumed that based on the technical parameters of a wind turbine-energy storage system and its geographical location one can determine the boundary capacity of the storage, which helps prevent power cuts to the grid at the assumed probability. Flywheel energy storage was selected due to its characteristics and technical parameters. The storage capacity was determined based on an empirical relationship using the results of the proposed statistical and energetic analysis of the measured wind velocity courses. A detailed algorithm of the WT-FESS with the power grid system was developed, eliminating short-term breaks in the turbine operation and periods when the wind turbine power was below the assumed level. PMID:25215326

Tomczewski, Andrzej

2014-01-01

105

Seasonal changes in the apparent position of the Sun as elementary applications of vector operations  

NASA Astrophysics Data System (ADS)

Many introductory courses in physics face an unpleasant chicken-and-egg problem. One might choose to introduce students to physical quantities such as velocity, acceleration, and momentum in over-simplified one-dimensional applications before introducing vectors and their manipulation; or one might first introduce vectors as mathematical objects and defer demonstration of their physical utility. This paper offers a solution to this pedagogical problem: elementary vector operations can be used without mechanics concepts to understand variations in the solar latitude, duration of daylight, and orientation of the rising and setting Sun. I show how sunrise and sunset phenomena lend themselves to exercises with scalar products, vector products, unit vectors, and vector projections that can be useful for introducing vector analysis in the context of physics.

Levine, Jonathan

2014-11-01

106

Scatterometer Ocean Surface Winds Provide Observational Evidence for Changes in the Hadley Cell  

NASA Astrophysics Data System (ADS)

Recent evidence suggests that the tropics have expanded over the last few decades by a very rough 1 degree per decade. This is considered to be an atmospheric response to the observed tropical ocean warming trend (e.g. Quan et al., 2004). If continued, the expansion of the tropics (the Hadley cell) could have a substantial impact on water resources and the ecology of the sub-tropics. Until now, the understanding of the mechanisms that govern the changing width of the tropics has been confined to models and proxies (e.g. Johanson and Fu, 2009; Hu and Fu 2007 (OLR); Lu et al. 2007 (precipitation /evaporation estimates) because of the unavailability of systematic observations of the large-scale circulation. Ocean surface vector winds, derived from scatterometer observations, provide for the first time an accurate depiction of the large-scale circulation and allow the study of the Hadley cell evolution through analysis of its surface branch. The launch of NASA's QuikSCAT in 1999 marked the beginning of routine global observations of the surface winds and provided a consistent 10-year record. The launches of ASCAT on METOP in 2006 and the ISRO's OceanSAT-2 in 2010 will assure the continuation of the climate data record of near-surface winds over the oceans. In this study we use the observations from QuikSCAT. We determine the extent of the Hadley cell as defined by the subtropical zero-crossing of the zonally-averaged zonal wind component (the separation between the midlatitude westerlies and the easterly winds in the tropics). We study the time series of 1-year running averages, 260 in total and offset from each other by two weeks. Our preliminary studies revealed a couple of interesting results: - The first half of the 10-year record shows two distinct cycles in the width of the Hadley cell while the later part of the record shows a steady increase in that width, as has been shown by others. The magnitude of the width-increase is very close to what has been reported by others (~1 deg/decade, both south and north, for a total of about 2 deg/decade). - The two cycles in the 1999-2004 time period are likely a reflection of the modulation of the Hadley cell by the La Nina(1999)/El Nino (2002) events that dominated this period - Segregating the data by ocean basins show rather different evolution of the Pacific Hadley cell versus that in the Atlantic. - Analyzing the time series of 3-month running averages reveals the seasonal variation of the extent and the width of the Hadley cell. It indicates a trend for pole-ward expansion of the northern Hadley cell branch during the boreal winter. This result is consistent with an earlier finding by Quan et al. (2004) that the winter Hadley cell has been increasing in intensity since 1950. Next, we look into a more detailed analysis to relate these preliminary findings to a more in-depth investigation of the relation between the Hadley cell strength and the El Nino/ La Nina episodes. In the future we will relate the scatterometer-defined Hadley cell characteristics and tendencies to such from precipitation observations.

Hristova-Veleva, S. M.; Haddad, Z.; Rodriguez, E.; Stiles, B. W.; Turk, F. J.; Seo, E.

2012-12-01

107

An appraisal of the full geomagnetic vector in wind-blown sediments - does it have a future? (Invited)  

NASA Astrophysics Data System (ADS)

Recent progress in the relative paleointensity (RPI) studies of the loess and paleosol deposits of China demonstrate the applicability of the technique in some sections. The PRI record of the Lingtai section (Pan et al., 2001) is mostly comparable to the reference curves of Valet et al. (2005) and Channel et al. (2009). Climate driven chemical alterations of remnant magnetization signal is additionally suggested as an explanation to the intervals of dissimilarities. The newest results of Yang et al. (2012) reveal more complex situations. At the Baoji section, where pedogenesis is relatively weak, the RPI results might possibly suggest a reflection of global paleointensity variations. The record from the Xifeng section, where pedogenesis is stronger, does not reveal any interpretable results. Studies of the Luochuan section suggest that chemical remnant magnetization is strongly linked to the pedogenesis process implying serious constrains on the interpretation of the high resolution paleomagnetic records from the paleosol and the underlying loess intervals (Liu and Zhang, 2013). At the same time, recent paleomagnetic and mineral magnetic investigations indicate that the Alaskan loess is an excellent geomagnetic direction recorder in the upper Matuyama and Brunhes epoch (Evans et al., 2011). The fine structure of the geomagnetic field can be accurately evaluated for the intervals, which are reliably dated with modern techniques (Jensen, 2013). The strong magnetic signal carried by magnetite from the igneous rock sources overwrites complexities caused by the pedogenesis process, therefore our newly obtained Alaskan geomagnetic record is the first candidate for both reliable paleointensity data set from the wind-blown sediments and the fine structure of the full geoomagnetic vector (inclination, declination, RPI). High resolution geochronology and high latitude position of the Alaskan loess help resolving the fine features of the geomagnetic excursions which are present in the record. Example of the Alaska loess magnetic record (Gold Hill section) to illustrate the Brunhes-Matuyama boundary interval. Lithological column darker layers represent soils. Inclination, declination, normalized RPI parameters are compared to SINT-2000 (Valet et al., 2005). Inclination and declination are from Evans et al. (2011); lithological column is from Jensen et al. (2011).

Kravchinsky, V. A.

2013-12-01

108

20% Wind Energy - Diversifying Our Energy Portfolio and Addressing Climate Change (Brochure)  

SciTech Connect

This brochure describes the R&D efforts needed for wind energy to meet 20% of the U.S. electrical demand by 2030. In May 2008, DOE published its report, 20% Wind Energy by 2030, which presents an in-depth analysis of the potential for wind energy in the United States and outlines a potential scenario to boost wind electric generation from its current production of 16.8 gigawatts (GW) to 304 GW by 2030. According to the report, achieving 20% wind energy by 2030 could help address climate change by reducing electric sector carbon dioxide (CO2) emissions by 825 million metric tons (20% of the electric utility sector CO2 emissions if no new wind is installed by 2030), and it will enhance our nation's energy security by diversifying our electricity portfolio as wind energy is an indigenous energy source with stable prices not subject to fuel volatility. According to the report, increasing our nation's wind generation could also boost local rural economies and contribute to significant growth in manufacturing and the industry supply chain. Rural economies will benefit from a substantial increase in land use payments, tax benefits and the number of well-paying jobs created by the wind energy manufacturing, construction, and maintenance industries. Although the initial capital costs of implementing the 20% wind scenario would be higher than other generation sources, according to the report, wind energy offers lower ongoing energy costs than conventional generation power plants for operations, maintenance, and fuel. The 20% scenario could require an incremental investment of as little as $43 billion (net present value) more than a base-case no new wind scenario. This would represent less than 0.06 cent (6 one-hundredths of 1 cent) per kilowatt-hour of total generation by 2030, or roughly 50 cents per month per household. The report concludes that while achieving the 20% wind scenario is technically achievable, it will require enhanced transmission infrastructure, streamlined siting and permitting regimes, improved reliability and operability of wind systems, and increased U.S. wind manufacturing capacity. To meet these challenges, the DOE Wind Energy Program will continue to work with industry partners to increase wind energy system reliability and operability and improve manufacturing processes. The program also conducts research to address transmission and grid integration issues, to better understand wind resources, to mitigate siting and environmental issues, to provide information to industry stakeholders and policy makers, and to educate the future generations.

Not Available

2008-05-01

109

Tangential discontinuities in the solar wind - Correlated field and velocity changes and the Kelvin-Helmholtz instability  

NASA Technical Reports Server (NTRS)

Three-dimensional Helios plasma and field data are used to investigate the relative changes in direction of the velocity and magnetic field vectors across tangential discontinuities (TDs) in the solar wind at solar distances of 0.29-0.50 AU. It is found for TDs with large Delta-v and (Delta-B)/B that Delta-v and Delta-B are closely aligned with each other, in agreement with the unexpected results of previous studies of TDs observed at 1 AU and beyond. It is shown that this effect probably results from the destruction by the Kelvin-Helmholtz instability of TDs for which Delta-v and Delta-B are not aligned. The observed decrease in the number of interplanetary discontinuities with increasing solar distance may be associated with the growth of the Kelvin-Helmholtz instability with decreasing Alfven speed.

Neugebauer, M.; Alexander, C. J.; Schwenn, R.; Richter, A. K.

1986-01-01

110

The dependence of S-band sea surface brightness and temperature on wind vector at normal incidence  

SciTech Connect

Aircraft measurements of the S-band sea surface brightness temperature at nadir as a function of wind speed and wind direction were carried out in various regions in 1985--1989. Data set of 65 circular flights was analyzed. It is shown that for water temperature recovering the wind direction is to be taken into account. This paper considers the relationship between S-band sea surface brightness temperature at nadir view angle and near surface wind speed as well as wind direction. The information of radiometer and scatterometer aircraft data set (RSAD) obtained at Space Research Institute was used. The 1985--1989 aircraft experiments in Pacific Ocean near Kamchatka peninsula and in Barents Sea were analyzed. The S-band radiometer data were used for the investigation due to their potential application of water temperature recovering and in this case the precise knowledge of wind speed dependence is very important.

Trokhimovski, Y.G. [NOAA/ERL/ETL/ET5, Boulder, CO (United States)] [NOAA/ERL/ETL/ET5, Boulder, CO (United States); Bolotnikova, G.A.; Grechko, S.I.; Kuzmin, A.V. [IKI RAN, Moscow (Russian Federation)] [IKI RAN, Moscow (Russian Federation); Etkin, V.S.

1995-07-01

111

Effect of sudden solar wind dynamic pressure changes at subauroral latitudes: Change in magnetic field  

SciTech Connect

The observations obtained during the International Magnetospheric Study (IMS) from the magnetometers of the IGS network extending from Cambridge, England, to Tromso, Norway, are used to study the response of subauroral current systems to sudden changes in solar wind dynamic pressure. Observations show that the response is very strong at subauroral latitudes. The preliminary response in the H component is a brief, small increase in the dayside moring sector and a decrease in the afternoon and night sectors. The main response in the horizontal field (the H and D components) is toward the pole except in the dayside morning sector. The inferred ionospheric current is mainly a circulatory system flowing counterclockwise when viewed form the north pole everywhere at subauroral latitudes except the dayside morning sector. 29 refs., 12 figs.

Le, G.; Russell, C.T.; Petrinec, S.M.; Ginskey, M. (Univ. of California, Los Angeles (United States))

1993-03-01

112

Analyses of possible changes in intense and extreme wind speeds over northern Europe under climate change scenarios  

Microsoft Academic Search

Dynamical downscaling of ECHAM5 using HIRHAM5 and RCA3 for a northern European domain focused on Scandinavia indicates sustained\\u000a extreme wind speeds with long recurrence intervals (50 years) and intense winds are not likely to evolve out of the historical\\u000a envelope of variability until the end of C21st. Even then, significant changes are indicated only in the SW of the domain\\u000a and

S. C. PryorR; R. J. Barthelmie; N. E. Clausen; M. Drews; N. MacKellar; E. Kjellström

2010-01-01

113

Wind-tunnel investigation of the powered low-speed longitudinal aerodynamics of the Vectored-Engine-Over (VEO) wing fighter configuration  

NASA Technical Reports Server (NTRS)

A wind-tunnel investigation incorporating both static and wind-on testing was conducted in the Langley 4- by 7-Meter Tunnel to determine the effects of vectored thrust along with spanwise blowing on the low-speed aerodynamics of an advanced fighter configuration. Data were obtained over a large range of thrust coefficients corresponding to takeoff and landing thrust settings for many nozzle configurations. The complete set of static thrust data and the complete set of longitudinal aerodynamic data obtained in the investigation are presented. These data are intended for reference purposes and, therefore, are presented without analysis or comment. The analysis of the thrust-induced effects found in the investigation are not discussed.

Paulson, J. W.; Whitten, P. D.; Stumpfl, S. C.

1982-01-01

114

S. C. Pryor R. J. Barthelmie E. Kjellstro m Potential climate change impact on wind energy resources in northern  

E-print Network

S. C. Pryor � R. J. Barthelmie � E. Kjellstro¨ m Potential climate change impact on wind energy of climate change on the feasibility and pre- dictability of renewable energy sources including wind energy on near-surface flow and hence wind energy density across northern Europe. It is shown that: Simulated

Pryor, Sara C.

115

Power balancing in variable speed wind-energy systems using vector control of front-end converters  

Microsoft Academic Search

This paper presents a novel power balance control method for wind energy systems feeding an isolated grid. The system is based on a variable-speed wind energy conversion system (WECS) connected to an AC load using a power converter. An energy storage system, connected to the AC load using an additional converter, is used to balance the power generated by the

Roberto Cárdenas; Rubén Peña; Marcelo Pérez; Fernando Vargas; Greg Asher; Jon Clare

2005-01-01

116

Supervised Change Detection in VHR Images Using Support Vector Machines and Contextual Information  

NASA Astrophysics Data System (ADS)

One of the recent challenges in environmental studies is how to include and exploit multitemporal information from multispectral very high resolution (VHR) images. This problem is also known as change detection (CD). Nowadays, many approaches, both supervised and unsupervised, are known and the selection of the method depends strongly on the application, the scope of the study and on available time. In the present research an accurate multiclass supervised method based on Support Vector Machines (SVM) for multitemporal remotely sensed image classification is proposed. SVM is a method issued from the statistical learning theory, known for its good generalization abilities and its performance when dealing with high dimensional spaces. Moreover, its sparse solution provides a final model depending only on a few patterns with an associated nonzero weights (support vectors), and resulting in an optimal regularized complexity. The final decision is obtained with a linear separation of data in an induced kernel feature space, corresponding to a nonlinear classification in the input space. When dealing with CD in VHR imagery, misclassified patterns are often caused by the high variance of the information at pixel level, caused by noise and by the influence of the high spatial resolution. Considering a precise coregistration, the variance at object level is high both in space and in time. The usefulness of adding such information is in smoothing, following an object based or a texture based criteria, the interclass variance and increasing the intraclass variance. By adding such information the classifier can better perform when predicting the class of pixels, because of the neighborhood information that was intrinsically extrapolated by the filtering. In the proposed approach, the behavior of mathematical morphology and morphological profiles obtained with different parameters are studied in a CD setting. The series of features are extracted both on the multispectral images and on the panchromatic images covering the scene at different time. Finally, the model is developed by directly applying multitemporal classification on the multitemporal image, looking for both stable and changed classes. Accurate multiclass CD with VHR optical imagery is a very powerful tool when analyzing city sprawl evolution and urbanization regimes, or when the resolution of the images allows a fine analysis of a multitemporal phenomenon (natural hazards, post catastrophe assessment, risk maps…). The real case study deals with a multitemporal image issued from two QuickBird scenes of the city of Zurich, Switzerland. This work is supported by the SNFS Project No. 200021-126505 "KernelCD".

Volpi, Michele; Kanevski, Mikhail

2010-05-01

117

Modelling potential changes in marine biogeochemistry due to large-scale offshore wind farms  

NASA Astrophysics Data System (ADS)

Large-scale renewable energy generation by offshore wind farms may lead to changes in marine ecosystem processes through the following mechanism: 1) wind-energy extraction leads to a reduction in local surface wind speeds; 2) these lead to a reduction in the local wind wave height; 3) as a consequence there's a reduction in SPM resuspension and concentrations; 4) this results in an improvement in under-water light regime, which 5) may lead to increased primary production, which subsequently 6) cascades through the ecosystem. A three-dimensional coupled hydrodynamics-biogeochemistry model (GETM_ERSEM) was used to investigate this process for a hypothetical wind farm in the central North Sea, by running a reference scenario and a scenario with a 10% reduction (as was found in a case study of a small farm in Danish waters) in surface wind velocities in the area of the wind farm. The ERSEM model included both pelagic and benthic processes. The results showed that, within the farm area, the physical mechanisms were as expected, but with variations in the magnitude of the response depending on the ecosystem variable or exchange rate between two ecosystem variables (3-28%, depending on variable/rate). Benthic variables tended to be more sensitive to the changes than pelagic variables. Reduced, but noticeable changes also occurred for some variables in a region of up to two farm diameters surrounding the wind farm. An additional model run in which the 10% reduction in surface wind speed was applied only for wind speeds below the generally used threshold of 25 m/s for operational shut-down showed only minor differences from the run in which all wind speeds were reduced. These first results indicate that there is potential for measurable effects of large-scale offshore wind farms on the marine ecosystem, mainly within the farm but for some variables up to two farm diameters away. However, the wave and SPM parameterisations currently used in the model are crude and need to be further tested and refined. Also, potential counter-acting processes such as possible increases in SPM concentrations due to turbulence generated by the wind-turbine foundations may need to be included for more accurate simulations. Moreover, it is unclear to what extent these results would be valid for areas where different hydrodynamic characteristics may predominate, e.g. with summer stratification or strong tidal currents. Finally, an assessment would need to be carried out of how beneficial or detrimental these potential changes might be from various social-economic and ecosystem-management points of view.

van der Molen, Johan; Rees, Jon; Limpenny, Sian

2013-04-01

118

EMERGENCE OF A NEW NEOTROPICAL MALARIA VECTOR FACILITATED BY HUMAN MIGRATION AND CHANGES IN LAND USE  

Microsoft Academic Search

In a region of northeastern Amazonia, we find a species previously of minor importance, Anopheles marajoara, to be the principal malaria vector. In a total of five collections during 1996-97 in three replicated sites near the city of Macapa´, Amapastate, this species occurs in much greater abundance compared with the presumed vector Anopheles darlingi. Also, a significantly higher proportion of

JAN E. CONN; RICHARD C. WILKERSON; RAIMUNDO T. L. DE SOUZA; CARL D. SCHLICHTING; ROBERT A. WIRTZ; MARINETE M. POVOA

2002-01-01

119

Mars Pathfinder Landing Site: Evidence for a Change in Wind Regime from Lander and Orbiter Data  

NASA Technical Reports Server (NTRS)

Surface features related to the wind are observed in the vicinity of the Mars Pathfinder (MPR landing site data from the lander and in data from orbit by the Viking Orbiter and Mars Global Surveyor missions. Features seen from the surface include wind tails associated with small rocks, barchanoid duneforms, ripplelike patterns, and ventifact flutes cut into some rocks. Features seen from orbit include wind tails associated with impact craters, ridges inferred to be duneforms, and modified crater rims interpreted to have been eroded and mantled by windblown material. The orientations of these features show two prevailing directions. One is inferred to represent winds from the northeast, which is consistent with strongest winds predicted by a general circulation model to occur during the Martian northern winter under current conditions. A second wind blowing from the ESE was responsible for modifying the crater rims and cutting some of the ventifacts. The two wind regimes could reflect a change in climate related to Mars' obliquity or some other, unknown factor. Regardless of the cause, the MPF area has been subjected to a complex pattern of winds and supply of small particles, and the original surface formed by sedimentary processes from Tiu and Ares Vallis flooding events has been modified by repeated burial and exhumation.

Greeley, Ronald; Kraft, Michael D.; Kuzmin, Ruslan O.; Bridges, Nathan T.

2000-01-01

120

Responding to a Changing Energy Industry : 2007 Wind Energy Business Plan  

E-print Network

Energy Group clients who are comfortable with our technical services and may want to expand our role into detailed engineering and construction. The Wind Energy Team has organized current and prospective clients into the following categories... EMGT 835 FIELD PROJECT: Responding to a Changing Energy Industry 2007 Wind Energy Business Plan By Ryan J. Jacobson, P.E. Master of Science The University of Kansas Fall Semester, 2007 An EMGT Field Project report submitted...

Jacobson, Ryan J.

2007-12-14

121

Winds of Change: How Black Holes May Shape Galaxies  

NASA Astrophysics Data System (ADS)

New observations from NASA's Chandra X-ray Observatory provide evidence for powerful winds blowing away from the vicinity of a supermassive black hole in a nearby galaxy. This discovery indicates that "average" supermassive black holes may play an important role in the evolution of the galaxies in which they reside. For years, astronomers have known that a supermassive black hole grows in parallel with its host galaxy. And, it has long been suspected that material blown away from a black hole - as opposed to the fraction of material that falls into it -- alters the evolution of its host galaxy. A key question is whether such "black hole blowback" typically delivers enough power to have a significant impact. Powerful relativistic jets shot away from the biggest supermassive black holes in large, central galaxies in clusters like Perseus are seen to shape their host galaxies, but these are rare. What about less powerful, less focused galaxy-scale winds that should be much more common? "We're more interested here in seeing what an "average"-sized supermassive black hole can do to its galaxy, not the few, really big ones in the biggest galaxies," said Dan Evans of the Massachusetts Institute of Technology who presented these results at the High Energy Astrophysics Division of the American Astronomical Society meeting in Kona, Hawaii. Evans and his colleagues used Chandra for five days to observe NGC 1068, one of the nearest and brightest galaxies containing a rapidly growing supermassive black hole. This black hole is only about twice as massive as the one in the center of our Galaxy, which is considered to be a rather ordinary size. The X-ray images and spectra obtained using Chandra's High Energy Transmission Grating Spectrometer (HETGS) showed that a strong wind is being driven away from the center of NGC 1068 at a rate of about a million miles per hour. This wind is likely generated as surrounding gas is accelerated and heated as it swirls toward the black hole. A portion of the gas is pulled into the black hole, but some of it is blown away. High energy X-rays produced by the gas near the black hole heat the ouflowing gas, causing it to glow at lower X-ray energies. This Chandra study by Evans and his colleagues is much deeper than previous X-ray observations. It allowed them to make a high-definition map of the cone-shaped volume lit up by the black hole and its winds. By combining measurement of the velocity of the clouds with estimates of the density of the gas, Evans and his colleagues showed that each year several times the mass of the Sun is being deposited out to large distances, about 3,000 light years from the black hole. The wind may carry enough energy to heat the surrounding gas and suppress extra star formation. "We have shown that even these middle-of-the-road black holes can pack a punch," said Evans. "I think the upshot is that these black holes are anything but ordinary." Further Chandra HETGS studies of other nearby galaxies will examine the impact of other AGN outflows, leading to improvements in our understanding of the evolution of both galaxies and black holes. "In the future, our own Galaxy's black hole may undergo similar activity, helping to shut down the growth of new stars in the central region of the Milky Way," said Evans. These new results provide a key comparison to previous work performed at Georgia State University and the Catholic University of America with the Hubble Space Telescope's STIS instrument. NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass. More information, including images and other multimedia, can be found at: http://chandra.harvard.edu and http://chandra.nasa.gov

2010-03-01

122

Uncertainty Analysis of High Resolution Ocean Surface Wind Vector Earth System Data Records, Phase 1: Time Series Homogeneity with Derivative Fields  

NASA Astrophysics Data System (ADS)

Three Earth System Data Records representing an assimilated analysis of satellite derived ocean surface wind vector retrievals are evaluated to assess uncertainty and suitability as a Climate Data Record (CDR). Two of the data sets utilize a Numerical Weather Prediction (NWP) derived background analysis wind field for gap-filling at 6-hourly intervals; the two datasets assimilate identical satellite data, but differ in how the data are assimilated as well as which background wind field was chosen. The third data set is pre-averaged at monthly intervals and approximates a merged satellite-only data set with no background filling. The satellite data sources for each data set have been thoroughly cross-calibrated and quality controlled to help provide for stability in the time series and reduction of sensor-to-sensor bias. Derivative fields, such as the curl, are used as a proxy for uncertainty in this initial assessment. Results from each data set suggest that the uncertainty as described by the curl is non-homogeneous with time. In particular, two distinct points in the time series, both representing minima and maxima in the number of observations respectively, show uniquely different surface features and spatial resolutions. Dynamical features that resemble transient storms, eddies, and currents are clearly visible during the year representing the maxima, but remain unrecognizable during the minima. The scales that are well resolved can be seen through spectral analysis of the curl fields, despite the fields having very similar wind speed spectra compared to the relatively poor scale-resolving fields, which suggests that the most signficant source of the wind vector uncertainty is in the directional component. Qualitatively, each ESDR meets the international standards for a CDR, which includes meeting common metadata standards. These metadata standards we've examined, namely Climate and Forecasting (CF), are more than capable of accounting for dataset uncertainties at the granule level, although we would hope that data centers and metadata clearing houses would also be willing to host this valuable information at the dataset level.

Moroni, D. F.; Bourassa, M. A.; Hughes, P. J.

2012-12-01

123

Integration of remotely-sensed raster data with a vector-based geographical information system for land-use change detection  

Microsoft Academic Search

Methods of land-use change detection are different for raster and vector data types because of the differences in structures of the two data types. Since large amounts of land-use data (derived from existing maps and aerial photographs) are stored in vector format in a Geographical Information System (GIS), there is a need to develop a change detection algorithm for use

N. M. MATTIKALLI

1995-01-01

124

Changing patterns of West Nile virus transmission: altered vector competence and host susceptibility  

PubMed Central

West Nile virus (WNV) is a flavivirus (Flaviviridae) transmitted between Culex spp. mosquitoes and avian hosts. The virus has dramatically expanded its geographic range in the past ten years. Increases in global commerce, climate change, ecological factors and the emergence of novel viral genotypes likely play significant roles in the emergence of this virus; however, the exact mechanism and relative importance of each is uncertain. Previously WNV was primarily associated with febrile illness of children in endemic areas, but it was identified as a cause of neurological disease in humans in 1994. This modulation in disease presentation could be the result of the emergence of a more virulent genotype as well as the progression of the virus into areas in which the age structure of immunologically naïve individuals makes them more susceptible to severe neurological disease. Since its introduction to North America in 1999, a novel WNV genotype has been identified that has been demonstrated to disseminate more rapidly and with greater efficiency at elevated temperatures than the originally introduced strain, indicating the potential importance of temperature as a selective criteria for the emergence of WNV genotypes with increased vectorial capacity. Even prior to the North American introduction, a mutation associated with increased replication in avian hosts, identified to be under adaptive evolutionary pressure, has been identified, indicating that adaptation for increased replication within vertebrate hosts could play a role in increased transmission efficiency. Although stable in its evolutionary structure, WNV has demonstrated the capacity for rapidly adapting to both vertebrate hosts and invertebrate vectors and will likely continue to exploit novel ecological niches as it adapts to novel transmission foci. PMID:19406093

Brault, Aaron C.

2009-01-01

125

Climate change impact of wind energy availability in the Eastern Mediterranean using the regional climate model PRECIS  

Microsoft Academic Search

Global near-surface wind fields are projected to change as a result of climate change. An enhanced knowledge of the changes in wind energy availability in the twenty-first century is essential for improving the development of wind energy production. We use the PRECIS regional model over the East Mediterranean to dynamically downscale the results of the Had3CM Atmosphere-Ocean coupled Global Circulation

A. Bloom; V. Kotroni; K. Lagouvardos

2008-01-01

126

Drag Forces, Neutral Wind and Electric Conductivity Changes in the Ionospheric E Region  

E-print Network

The neutrals in the Earth environment are in fact free and subjected to drag forces (by ions). In this study we show that drag or friction forces in the ionosphere-thermosphere system initiate changes in the plasma flow, neutral wind, and the conductivity, as well. Ions and electrons embedded in neutral wind field of velocity u acquire drifts perpendicular both to the initial neutral wind velocity and to the ambient magnetic field producing a perpendicular electric current. This perpendicular electric current is defined by a conductivity derived previously and the polarization electric field u x B. Self-consistently, the free neutrals acquires an additional neutral velocity component perpendicular to the initial neutral wind velocity u. The Pedersen and Hall currents wane within a specific time inversely proportional to neutral-ion collision frequency. These findings are relevant to a better understanding of electric current generation, distribution and closure in weakly ionized plasmas where charged particle...

Nenovski, Petko

2014-01-01

127

Changes in the wind stress variation with the warm pool SST increase over the western Pacific  

NASA Astrophysics Data System (ADS)

The western Pacific warm pool is conventionally defined as an area where SST is higher than 28C. SST values exhibits a simple thermodynamic energy balance between evaporative heat loss and radiative energy input. Ocean dynamics in the warm-pool act on the eastward expansion of warm SST through equatorial wave-induced zonal advection, and it also plays a key role to maintain the warm-pool SST through the poleward Ekman transport at the surface layer. The strong east-west migration of the warm-pool in the equatorial western Pacific is closely linked to surface current variation driven by the ENSO-related surface winds. Anomalous easterly (westerly) trade winds force the thermocline depth. The trade winds also induce the Ekman upwelling associated the Coriolis effects, which brings the cold water to surface layer in the eastern Pacific. Recent studies have suggested that the warm-pool SST is increasing over the last century. Warmer SST may change surface winds, which in turn change ocean currents connecting the western tropical Pacific Ocean with the eastern tropical Pacific Ocean. In this study, we examine long-term changes in the center of the wind stress with the SST increase in the warm-pool region for the period 1950-2011. The SSTs are obtained from the Hadley Centre SST dataset, ERSST (Extended Reconstructed SST v3b), SODA (Simple Ocean Data Assimilation, version 2.2.4) data set.

Lee, Yoon-Kyoung; Yeh, Sang-Wook; Kwon, MinHo; Moon, Byung-Kwon

2014-05-01

128

An Ill Wind? Climate Change, Migration, and Health  

PubMed Central

Background: Climate change is projected to cause substantial increases in population movement in coming decades. Previous research has considered the likely causal influences and magnitude of such movements and the risks to national and international security. There has been little research on the consequences of climate-related migration and the health of people who move. Objectives: In this review, we explore the role that health impacts of climate change may play in population movements and then examine the health implications of three types of movements likely to be induced by climate change: forcible displacement by climate impacts, resettlement schemes, and migration as an adaptive response. Methods: This risk assessment draws on research into the health of refugees, migrants, and people in resettlement schemes as analogs of the likely health consequences of climate-related migration. Some account is taken of the possible modulation of those health risks by climate change. Discussion: Climate-change–related migration is likely to result in adverse health outcomes, both for displaced and for host populations, particularly in situations of forced migration. However, where migration and other mobility are used as adaptive strategies, health risks are likely to be minimized, and in some cases there will be health gains. Conclusions: Purposeful and timely policy interventions can facilitate the mobility of people, enhance well-being, and maximize social and economic development in both places of origin and places of destination. Nevertheless, the anticipated occurrence of substantial relocation of groups and communities will underscore the fundamental seriousness of human-induced climate change. PMID:22266739

Barnett, Jon

2012-01-01

129

Wind extremes in the North Sea Basin under climate change: An ensemble study of 12 CMIP5 GCMs  

NASA Astrophysics Data System (ADS)

Coastal safety may be influenced by climate change, as changes in extreme surge levels and wave extremes may increase the vulnerability of dunes and other coastal defenses. In the North Sea, an area already prone to severe flooding, these high surge levels and waves are generated by low atmospheric pressure and severe wind speeds during storm events. As a result of the geometry of the North Sea, not only the maximum wind speed is relevant, but also wind direction. Climate change could change maximum wind conditions, with potentially negative effects for coastal safety. Here, we use an ensemble of 12 Coupled Model Intercomparison Project Phase 5 (CMIP5) General Circulation Models (GCMs) and diagnose the effect of two climate scenarios (rcp4.5 and rcp8.5) on annual maximum wind speed, wind speeds with lower return frequencies, and the direction of these annual maximum wind speeds. The 12 selected CMIP5 models do not project changes in annual maximum wind speed and in wind speeds with lower return frequencies; however, we do find an indication that the annual extreme wind events are coming more often from western directions. Our results are in line with the studies based on CMIP3 models and do not confirm the statement based on some reanalysis studies that there is a climate-change-related upward trend in storminess in the North Sea area.

Winter, R. C.; Sterl, A.; Ruessink, B. G.

2013-02-01

130

UNDERSTANDING REGIONAL PATTERNS OF VECTOR-BORNE INFECTIOUS DISEASE IN A CHANGING ENVIRONMENT  

E-print Network

under scenarios of global warming and deforestation. With different mosquito vectors and habitat on malaria in the Amazon Basin, and the effects of landscape fragmentation on Lyme disease in the United and deforestation, do not yet extended beyond isolated research locations, a limitation which my dissertation

Wisconsin at Madison, University of

131

Native American Support Programs Task Force Changing Winds: Service to Native American Students  

E-print Network

Native American Support Programs Task Force Changing Winds: Service to Native American Students and Communities in Montana Final Report of the MSU Native American Support Programs Task Force Submitted To Shelly Hogan #12;Native American Support Programs Task Force Contents EXECUTIVE SUMMARY

Dyer, Bill

132

Temporal Changes in Wind as Objects for Evaluating Mesoscale Numerical Weather Prediction  

E-print Network

continuous in space and time. Such continuity suggests that displaying maps of surface wind changes with high complex information about a model's performance with predictions of the atmo- sphere's future state on weather forecasts. For example, at the test ranges operated by the U.S. Army Test and Evaluation Command

Knievel, Jason Clark

133

Winds of Change: Charting the Course for IT in the Twenty-First Century  

ERIC Educational Resources Information Center

In the spring of 2005, the author, the retiring president of EDUCAUSE, was asked to be the keynote speaker at the EDUCAUSE Western Regional Conference. The conference theme was "Winds of Change: Charting the Course for Technology in Challenging Times." What that brought to his mind was the era of the great sailing ships of the eighteenth and…

Hawkins, Brian L.

2007-01-01

134

Climate Change and Risk of Leishmaniasis in North America: Predictions from Ecological Niche Models of Vector and Reservoir Species  

PubMed Central

Background Climate change is increasingly being implicated in species' range shifts throughout the world, including those of important vector and reservoir species for infectious diseases. In North America (México, United States, and Canada), leishmaniasis is a vector-borne disease that is autochthonous in México and Texas and has begun to expand its range northward. Further expansion to the north may be facilitated by climate change as more habitat becomes suitable for vector and reservoir species for leishmaniasis. Methods and Findings The analysis began with the construction of ecological niche models using a maximum entropy algorithm for the distribution of two sand fly vector species (Lutzomyia anthophora and L. diabolica), three confirmed rodent reservoir species (Neotoma albigula, N. floridana, and N. micropus), and one potential rodent reservoir species (N. mexicana) for leishmaniasis in northern México and the United States. As input, these models used species' occurrence records with topographic and climatic parameters as explanatory variables. Models were tested for their ability to predict correctly both a specified fraction of occurrence points set aside for this purpose and occurrence points from an independently derived data set. These models were refined to obtain predicted species' geographical distributions under increasingly strict assumptions about the ability of a species to disperse to suitable habitat and to persist in it, as modulated by its ecological suitability. Models successful at predictions were fitted to the extreme A2 and relatively conservative B2 projected climate scenarios for 2020, 2050, and 2080 using publicly available interpolated climate data from the Third Intergovernmental Panel on Climate Change Assessment Report. Further analyses included estimation of the projected human population that could potentially be exposed to leishmaniasis in 2020, 2050, and 2080 under the A2 and B2 scenarios. All confirmed vector and reservoir species will see an expansion of their potential range towards the north. Thus, leishmaniasis has the potential to expand northwards from México and the southern United States. In the eastern United States its spread is predicted to be limited by the range of L. diabolica; further west, L. anthophora may play the same role. In the east it may even reach the southern boundary of Canada. The risk of spread is greater for the A2 scenario than for the B2 scenario. Even in the latter case, with restrictive (contiguous) models for dispersal of vector and reservoir species, and limiting vector and reservoir species occupancy to only the top 10% of their potential suitable habitat, the expected number of human individuals exposed to leishmaniasis by 2080 will at least double its present value. Conclusions These models predict that climate change will exacerbate the ecological risk of human exposure to leishmaniasis in areas outside its present range in the United States and, possibly, in parts of southern Canada. This prediction suggests the adoption of measures such as surveillance for leishmaniasis north of Texas as disease cases spread northwards. Potential vector and reservoir control strategies—besides direct intervention in disease cases—should also be further investigated. PMID:20098495

Gonzalez, Camila; Wang, Ophelia; Strutz, Stavana E.; Gonzalez-Salazar, Constantino; Sanchez-Cordero, Victor; Sarkar, Sahotra

2010-01-01

135

Q-Winds satellite hurricane wind retrievals and H*Wind comparisons  

E-print Network

1 Q-Winds satellite hurricane wind retrievals and H*Wind comparisons Pet Laupattarakasem and W This paper presents a new hurricane ocean vector wind (OVW) product known as Q-Winds produced from the SeaWinds for tropical cyclones. SeaWinds OVW retrievals are presented for ten hurricane passes with near

Hennon, Christopher C.

136

Winds  

NSDL National Science Digital Library

In this problem-based learning (PBL) scenario, students prepare a presentation for investors showing how their fishing company has a significant advantage because it locates upwelling zones and fishing areas using TRMM (Tropical Rainfall Measuring Mission) and other satellite data. Prior to launching the PBL, students learn about wind: the topics of air pressure, coriolis effect, upwelling and the role of differential heating on the atmosphere are explored in classroom demonstrations. Materials required include a beaker, coffee grounds, drinking straw, balloon, flashlight, and turntable. The resource includes teacher background information, glossary, assessment rubric, and an appendix introducing problem-based learning.

137

Uncovering spider silk nanocrystalline variations that facilitate wind-induced mechanical property changes.  

PubMed

Spider major ampullate (MA) silk varies in mechanical properties when spun in different environments. Amino acid compositional changes induced by variations in MaSp1 and MaSp2 expression, and various biochemical and physiological glandular processes induce silk property variability. Quantifying the contributions of these mechanisms on silk variability may facilitate the development of silk biomimetics. Wind is a medium that induces variations in MA silk mechanics. We exposed the spider Cyclosa mulmeinensis to wind and measured the amino acid composition, tensile mechanics, and crystalline structure of its MA silk using HPLC, tensile tests, and X-ray diffraction. We found the mechanical properties of MA silks from spiders exposed to wind to differ from unexposed spiders. The amino acid compositions did not differ, but X-ray diffraction found a lower crystal density and greater ?-sheet alignment relative to the fiber axis in the silks of spiders exposed to wind. We found no evidence that the mechanical property variations were a product of profound changes to the alignment of the protein within the amorphous region. We conclude that variations in the density and alignment of the crystalline ?-sheets, probably accompanied by some alignment change in the amorphous region as a result of "stretching" during spinning of the silk, probably explains the mechanical property variations that we found across treatment subgroups. As C. mulmeinensis MA silk increases both in strength and elasticity when the spiders are exposed to wind, bioengineers may consider it as a model for the development of high-performance silk biomimetics. PMID:23947397

Blamires, Sean J; Wu, Chao-Chia; Wu, Chung-Lin; Sheu, Hwo-Shuenn; Tso, I-Min

2013-10-14

138

Recent changes in measured wind in the NE Atlantic and variability of correlation with NAO  

NASA Astrophysics Data System (ADS)

The paper deals with wind measurements, recorded since the 1950s, at twelve meteorological stations along a transect near the westernmost European border, between 64° and 44° N. Extreme wind speed tends to decrease sharply near the northern boundary (at Reykjavick), near the middle of the study area (at Shannon and Valentia) and near the southern boundary (at Brest and Cap Ferret), to increase at Thorshavn, with less significant trends at the other stations. Average wind speeds confirm the above tendencies, with an additional increasing speed at Lerwick, Kirkwall, Malin Head, Belle-Ile and Cap Ferret. To compare changes in wind activity, the data have been subdivided into three periods: until 1975, 1976-1992 and 1993-2008. Frequencies have been computed also for the "winter" (October to March) period, per quadrants, and for occurrences exceeding the speed of 15 m s-1. At Reykjavick a recent increase in the frequency of strong winds has occurred from various directions. Between 62° N (Thorshavn) and 59° N (Kirkwall) strong wind has been increasing since 1975. Minor changes can be observed at Stornoway, whereas at Malin Head the greatest increase for southerlies and westerlies is observed during the 1976-1992 period. At Belmullet, the frequency of strong southerlies has almost doubled since 1992, while at Shannon and Valentia it remains quite low. Finally at Brest and Belle-Ile, westerlies are predominant among winds >15 m s-1. Important changes in time and latitude appear in the correlation with the NAO (North Atlantic Oscillation) index. The highest correlation coefficients, calculated with monthly or seasonal means between the early 1950s and 1975, are observed from between 58° N (Stornoway) and Iceland, whereas low positive coefficients are reported more south. During the period 1976-1992, when increasing NAO index is predominant, positive correlation improves southwards as far as 54° (Belmullet) with some improvement also at Shannon and Valentia, while it remains low or even negative near the French Atlantic coast. Finally in the 1993-2008 period, correlation improves for all the stations south of 54° N (Belmullet), while it weakens more north.

Pirazzoli, P. A.; Tomasin, A.; Ullmann, A.

2010-10-01

139

Wind of change: new insights on the ecology and evolution of pollination and mating in wind-pollinated plants  

PubMed Central

Background The rich literature that characterizes the field of pollination biology has focused largely on animal-pollinated plants. At least 10 % of angiosperms are wind pollinated, and this mode of pollination has evolved on multiple occasions among unrelated lineages, and hence this discrepancy in research interest is surprising. Here, the evolution and functional ecology of pollination and mating in wind-pollinated plants are discussed, a theoretical framework for modelling the selection of wind pollination is outlined, and pollen capture and the occurrence of pollen limitation in diverse wind-pollinated herbs are investigated experimentally. Scope and Conclusions Wind pollination may commonly evolve to provide reproductive assurance when pollinators are scarce. Evidence is presented that pollen limitation in wind-pollinated plants may not be as common as it is in animal-pollinated species. The studies of pollen capture in wind-pollinated herbs demonstrate that pollen transfer efficiency is not substantially lower than in animal-pollinated plants as is often assumed. These findings challenge the explanation that the evolution of few ovules in wind-pollinated flowers is associated with low pollen loads. Floral and inflorescence architecture is crucial to pollination and mating because of the aerodynamics of wind pollination. Evidence is provided for the importance of plant height, floral position, and stamen and stigma characteristics in promoting effective pollen dispersal and capture. Finally, it is proposed that geitonogamous selfing may alleviate pollen limitation in many wind-pollinated plants with unisexual flowers. PMID:19218583

Friedman, Jannice; Barrett, Spencer C. H.

2009-01-01

140

Engineering changes to the 0.1m cryogenic wind tunnel at Southampton University  

NASA Technical Reports Server (NTRS)

The more important changes to the 0.1 m cryogenic wind tunnel since its completion in 1977 are outlined. These include detailed improvements in the fan drive to allow higher speeds, and the provision of a test section leg suitable for use with a magnetic suspension and balance system. The instrumentation, data logging, data reduction and tunnel controls were also improved and modernized. A tunnel performance summary is given.

Goodyer, M. J.

1984-01-01

141

Effects on winter circulation of short and long term solar wind changes  

NASA Astrophysics Data System (ADS)

Indices of the North Atlantic Oscillation and the Arctic Oscillation show correlations on the day-to-day timescale with the solar wind speed (SWS). Minima in the indices were found on days of SWS minima during years of high stratospheric aerosol loading. The spatial distribution of surface pressure changes during 1963-2011 with day-to-day changes in SWS shows a pattern resembling the NAO. Such a pattern was noted for year-to-year variations by Boberg and Lundstedt (2002), who compared NAO variations with the geo-effective solar wind electric field (the monthly average SWS multiplied by the average southward component, i.e., negative Bz component, of the interplanetary magnetic field). The spatial distribution of the correlations of geopotential height changes in the troposphere and stratosphere with the SWS; the geo-effective electric field (SWS?Bz); and the solar 10.7 cm flux suggests that solar wind inputs connected to the troposphere via the global electric circuit, together with solar ultraviolet irradiance acting on the stratosphere, affect regional atmospheric dynamics.

Zhou, Limin; Tinsley, Brian; Huang, Jing

2014-12-01

142

[Changes in vectors of endogenously generated ion currents in light-induced germination of turions of Spirodela polyrrhiza].  

PubMed

Nondormant turions of Spirodela polyrhiza (L.) Schleiden were utilized to investigate endogenous ion currents in light-induced germination and early growing processes of higher plants. A small outward current was detected at the ventral side of the turions near the pocket containing the most developed sprout primordium. After a light pulse, the direction of the endogenous current changed from outward to inward. These ion currents are most likely conditioned by unspecific diffusion of cations (probably H+) inside the cell. Three-day-old sprouts of Spirodela showed the highest inward current near the sprout base which decreases toward its edge. Newly formed sprouts demonstrated a strong gravity effect (bending), which was preceded by a lowering of the Z-component of vectors close to the sprout base after a change of the turion fixation. PMID:12298209

Sokolovski?, S G; Appenroth, K J

2002-01-01

143

Responses of wind erosion to climate-induced vegetation changes on the Colorado Plateau  

PubMed Central

Projected increases in aridity throughout the southwestern United States due to anthropogenic climate change will likely cause reductions in perennial vegetation cover, which leaves soil surfaces exposed to erosion. Accelerated rates of dust emission from wind erosion have large implications for ecosystems and human well-being, yet there is poor understanding of the sources and magnitude of dust emission in a hotter and drier climate. Here we use a two-stage approach to compare the susceptibility of grasslands and three different shrublands to wind erosion on the Colorado Plateau and demonstrate how climate can indirectly moderate the magnitude of aeolian sediment flux through different responses of dominant plants in these communities. First, using results from 20 y of vegetation monitoring, we found perennial grass cover in grasslands declined with increasing mean annual temperature in the previous year, whereas shrub cover in shrublands either showed no change or declined as temperature increased, depending on the species. Second, we used these vegetation monitoring results and measurements of soil stability as inputs into a field-validated wind erosion model and found that declines in perennial vegetation cover coupled with disturbance to biological soil crust resulted in an exponential increase in modeled aeolian sediment flux. Thus the effects of increased temperature on perennial plant cover and the correlation of declining plant cover with increased aeolian flux strongly suggest that sustained drought conditions across the southwest will accelerate the likelihood of dust production in the future on disturbed soil surfaces. PMID:21368143

Munson, Seth M.; Belnap, Jayne; Okin, Gregory S.

2011-01-01

144

Responses of wind erosion to climate-induced vegetation changes on the Colorado Plateau  

USGS Publications Warehouse

Projected increases in aridity throughout the southwestern United States due to anthropogenic climate change will likely cause reductions in perennial vegetation cover, which leaves soil surfaces exposed to erosion. Accelerated rates of dust emission from wind erosion have large implications for ecosystems and human well-being, yet there is poor understanding of the sources and magnitude of dust emission in a hotter and drier climate. Here we use a two-stage approach to compare the susceptibility of grasslands and three different shrublands to wind erosion on the Colorado Plateau and demonstrate how climate can indirectly moderate the magnitude of aeolian sediment flux through different responses of dominant plants in these communities. First, using results from 20 y of vegetation monitoring, we found perennial grass cover in grasslands declined with increasing mean annual temperature in the previous year, whereas shrub cover in shrublands either showed no change or declined as temperature increased, depending on the species. Second, we used these vegetation monitoring results and measurements of soil stability as inputs into a field-validated wind erosion model and found that declines in perennial vegetation cover coupled with disturbance to biological soil crust resulted in an exponential increase in modeled aeolian sediment flux. Thus the effects of increased temperature on perennial plant cover and the correlation of declining plant cover with increased aeolian flux strongly suggest that sustained drought conditions across the southwest will accelerate the likelihood of dust production in the future on disturbed soil surfaces.

Munson, S.M.; Belnap, J.; Okin, G.S.

2011-01-01

145

Modeling of the Thermal State Change of Blast Furnace Hearth With Support Vector Machines  

Microsoft Academic Search

For the economic operation of a blast furnace, the thermal state change of a blast furnace hearth (BFH), often repre- sented by the change of the silicon content in hot metal, needs to be strictly monitored and controlled. For these purposes, this paper has taken the tendency prediction of the thermal state of BFH as a binary classification problem and

Chuanhou Gao; Ling Jian; Shihua Luo

2012-01-01

146

Centennial changes in North Pacific anoxia linked to tropical trade winds  

USGS Publications Warehouse

Climate warming is expected to reduce oxygen (O2) supply to the ocean and expand its oxygen minimum zones (OMZs). We reconstructed variations in the extent of North Pacific anoxia since 1850 using a geochemical proxy for denitrification (?15N) from multiple sediment cores. Increasing ?15N since ~1990 records an expansion of anoxia, consistent with observed O2 trends. However, this was preceded by a longer declining ?15N trend that implies that the anoxic zone was shrinking for most of the 20th century. Both periods can be explained by changes in winds over the tropical Pacific that drive upwelling, biological productivity, and O2 demand within the OMZ. If equatorial Pacific winds resume their predicted weakening trend, the ocean’s largest anoxic zone will contract despite a global O2 decline.

Deutsch, Curtis; Berelson, William; Thunell, Robert; Weber, Thomas; Tems, Caitlin; McManus, James; Crusius, John; Ito, Taka; Baumgartner, Timothy; Ferreira, Vicente; Mey, Jacob; van Geen, Alexander

2014-01-01

147

Change in Hamiltonian General Relativity from the Lack of a Time-like Killing Vector Field  

E-print Network

In General Relativity in Hamiltonian form, change has seemed to be missing, defined only asymptotically, or otherwise obscured at best, because the Hamiltonian is a sum of first-class constraints and a boundary term and thus supposedly generates gauge transformations. Attention to the gauge generator G of Rosenfeld, Anderson, Bergmann, Castellani et al., a specially tuned sum of first-class constraints, facilitates seeing that a solitary first-class constraint in fact generates not a gauge transformation, but a bad physical change in electromagnetism (changing E) or GR. The change spoils the Lagrangian constraints in terms of the physically relevant velocities rather than auxiliary canonical momenta. While Maudlin has defended change in GR much as G. E. Moore resisted skepticism, there remains a need to exhibit the technical flaws in the argument. Insistence on Hamiltonian-Lagrangian equivalence, a theme emphasized by Mukunda, Castellani, Sugano, Pons, Salisbury, Shepley and Sundermeyer among others, holds th...

Pitts, J Brian

2014-01-01

148

Responses of Wind Erosion to Climate-Induced Vegetation Changes on the Colorado Plateau  

NASA Astrophysics Data System (ADS)

Projected increases in aridity throughout the southwestern United States due to anthropogenic climate change will likely cause reductions in perennial vegetation cover, which leaves soil surfaces exposed to erosion. Accelerated rates of dust emission from wind erosion have large implications for ecosystems and human well-being, yet there is poor understanding of the sources and magnitude of dust emission in a hotter and drier climate. Here we use a two-stage approach to compare the susceptibility of grasslands and three different shrublands to wind erosion on the Colorado Plateau and demonstrate how climate can indirectly moderate the magnitude of aeolian sediment flux through different responses of dominant plants in these communities. First, using results from 20 years of vegetation monitoring, we found perennial grass cover in grasslands declined with increasing mean annual temperature in the previous year, whereas shrub cover in shrublands either showed no change or declined as temperature increased, depending on the species. Second, we used these vegetation monitoring results and measurements of soil stability as inputs into a field-validated wind erosion model and found that declines in perennial vegetation cover coupled with disturbance to biological soil crust resulted in an exponential increase in modeled aeolian sediment flux. Thus the effects of increased temperature on perennial plant cover and the correlation of declining plant cover with increased aeolian flux strongly suggest that sustained drought conditions across the southwest will accelerate the likelihood of dust production in the future on disturbed soil surfaces.; Perennial grasses and all perennial vegetation canopy cover (top panel) and modeled aeolian sediment flux (bottom panel) at five wind speeds (15.0, 17.5, 20.0, 22.5, and 25.0 ms-1) in relationship to mean annual temperature in the previous year in perennial grasslands across the Colorado Plateau, USA.

Munson, S. M.; Belnap, J.; Okin, G. S.

2012-12-01

149

Wind power: Addressing wildlife impacts, assessing effects on tourism, and examining the link between climate change perceptions and support  

NASA Astrophysics Data System (ADS)

As the world's most rapidly growing source of energy, wind power has vast potential for mitigating climate change and advancing global environmental sustainability. Yet, the challenges facing wind energy remain both complex and substantial. Two such challenges are: 1) wildlife impacts; and 2) perceived negative effects on tourism. This dissertation examines these challenges in a multi-paper format, and also investigates the role that climate change perceptions play in garnering public support for wind power. The first paper assesses optimal approaches for addressing wind power's wildlife impacts. Comparative analysis reveals that avian mortality from turbines ranks far behind avian mortality from a number of other anthropogenic sources. Additionally, although bats have recently emerged as more vulnerable to wind turbines than birds, they are generally less federally protected. The Migratory Bird Treaty Act (MBTA) protects over 800 bird species, regardless of their threatened or endangered status. Moreover, it criminalizes the incidental take of birds without a permit and simultaneously grants no permits for such incidental take, thereby creating a legal conundrum for the wind industry. An examination of the legislative and case history of the MBTA, however, reveals that wind operators are not likely to be prosecuted for incidental take if they cooperate with the U.S. Fish & Wildlife Service (FWS) and take reasonable steps to reduce siting and operational impacts. Furthermore, this study's analysis reveals modest wildlife impacts from wind power, in comparison with numerous other energy sources. Scientific-research, legal, and policy recommendations are provided to update the present legal and regulatory regime under the MBTA and to minimize avian and bat impacts. For instance, FWS should: establish comprehensive federal guidelines for wind facility siting, permitting, monitoring, and mitigation; and promulgate regulations under the MBTA for the issuance of incidental take permits at wind facilities. Equal protections for bats are also recommended. In examining the potential effect of offshore wind power on coastal tourism, the second paper reports the findings of a summer 2007 survey of over 1,000 out-of-state tourists at Delaware beaches. Randomly sampled beachgoers were shown photo-simulations of wind turbines at increasing distances from shore and asked how each simulation would affect visitation. With wind turbines located six miles offshore, approximately one-quarter would switch to a different beach. This stated avoidance, however, diminishes with increasing wind project distance from shore. Additionally, stated avoidance of a beach with turbines six miles offshore is exceeded by: avoidance of a beach with an equidistant, inland, fossil fuel power plant; attraction to a beach in order to see turbines six miles offshore; and the likelihood of paying for an offshore wind boat tour. Further, logistic regression modeling reveals that neither trip cost nor income significantly influences the likelihood of visiting a beach with offshore wind. These findings suggest that to limit beach avoidance, offshore wind developers could site wind facilities further from shore, particularly in areas with high recreational use. Moreover, with wind turbines six miles offshore serving more as an attraction than as a deterrent, offshore wind development may, in fact, bolster local tourism revenues. The third study examines public perceptions of climate change and the link between those perceptions and support for wind power, both in general and with respect to specific offshore sites. Analyzing data from five surveys, this research uncovers low climate awareness and concern levels overall. Respondents demonstrate a poor understanding of climate change impacts and of how to effectively address climate change. In accordance with the New Ecological Paradigm, still fewer are concerned about climate change. The issue ranks 6th in Delaware and 8th in Cape Cod as a reason for local project support, behind such issues as energy independence

Lilley, Meredith Blaydes

150

Climate Change and Vector-borne Diseases: An Economic Impact Analysis of Malaria in Africa  

PubMed Central

A semi-parametric econometric model is used to study the relationship between malaria cases and climatic factors in 25 African countries. Results show that a marginal change in temperature and precipitation levels would lead to a significant change in the number of malaria cases for most countries by the end of the century. Consistent with the existing biophysical malaria model results, the projected effects of climate change are mixed. Our model projects that some countries will see an increase in malaria cases but others will see a decrease. We estimate projected malaria inpatient and outpatient treatment costs as a proportion of annual 2000 health expenditures per 1,000 people. We found that even under minimal climate change scenario, some countries may see their inpatient treatment cost of malaria increase more than 20%. PMID:21556186

Egbendewe-Mondzozo, Aklesso; Musumba, Mark; McCarl, Bruce A.; Wu, Ximing

2011-01-01

151

Effect of sudden solar wind dynamic pressure changes at subauroral latitudes - Time rate of change of magnetic field  

NASA Astrophysics Data System (ADS)

The observations obtained during the IMS from the IGS magnetometer chain extending from Cambridge, England, to Tromso, Norway are used to study the time rate of change of the magnetic field at subauroral latitudes at the time of interplanetary shock passages. The time rate of change of the H component maximizes in the high latitude dayside sector. For these typical interplanetary shocks, the dayside value of time rate of change can be as high as 3 nT/sec at Tromso and 1 nT/sec at York. The time rate of change in the dayside roughly depends on the change of square root of solar wind dynamic pressure. The largest of these time rates of change are similar to but slightly smaller than those known to cause disruptive disturbances in power distribution and communication systems. Thus, the daytime effects of sudden impulses may be equal to or greater than the nighttime effects associated with substorms as measured by their impact on terrestrial systems.

Le, G.; Russell, C. T.

1993-01-01

152

Electrostatic Solitary Waves in the Solar Wind: Evidence for Instability at Solar Wind Current Sheets  

NASA Technical Reports Server (NTRS)

A strong spatial association between bipolar electrostatic solitary waves (ESWs) and magnetic current sheets (CSs) in the solar wind is reported here for the first time. This association requires that the plasma instabilities (e.g., Buneman, electron two stream) which generate ESWs are preferentially localized to solar wind CSs. Distributions of CS properties (including shear angle, thickness, solar wind speed, and vector magnetic field change) are examined for differences between CSs associated with ESWs and randomly chosen CSs. Possible mechanisms for producing ESW-generating instabilities at solar wind CSs are considered, including magnetic reconnection.

Malaspina, David M.; Newman, David L.; Wilson, Lynn Bruce; Goetz, Keith; Kellogg, Paul J.; Kerstin, Kris

2013-01-01

153

National Assessment of Shoreline Change: A GIS compilation of vector shorelines and associated shoreline change data for the sandy shorelines of Kauai, Oahu, and Maui, Hawaii  

USGS Publications Warehouse

Sandy ocean beaches are a popular recreational destination, and often are surrounded by communities that consist of valuable real estate. Development is increasing despite the fact that coastal infrastructure may be repeatedly subjected to flooding and erosion. As a result, the demand for accurate information regarding past and present shoreline changes is increasing. Working with researchers from the University of Hawaii, investigators with the U.S. Geological Survey's National Assessment of Shoreline Change Project have compiled a comprehensive database of digital vector shorelines and shoreline-change rates for the islands of Kauai, Oahu, and Maui, Hawaii. No widely accepted standard for analyzing shoreline change currently exists. Current measurement and rate-calculation methods vary from study to study, precluding the combination of study results into statewide or regional assessments. The impetus behind the National Assessment was to develop a standardized method for measuring changes in shoreline position that is consistent from coast to coast. The goal was to facilitate the process of periodically and systematically updating the measurements in an internally consistent manner. A detailed report on shoreline change for Kauai, Maui, and Oahu that contains a discussion of the data presented here is available and cited in the Geospatial Data section of this report.

Romine, Bradley M.; Fletcher, Charles H.; Genz, Ayesha S.; Barbee, Matthew M.; Dyer, Matthew; Anderson, Tiffany R.; Lim, S. Chyn; Vitousek, Sean; Bochicchio, Christopher; Richmond, Bruce M.

2012-01-01

154

Enhancing a GIS Cellular Automata model of land use change using Support Vector Machine  

Microsoft Academic Search

Cellular Automata (CA) are dynamic mathematical systems (which are discrete in time and space, operate in uniform regular lattice, and are characterized by local interaction) that can be used with GIS to simulate land use change. Common cellular automata calibration is based on linear logistic regression. Linear models, however, are susceptible to over-fitting; especially when applied to nonlinearly separable data.

O. Okwuashi; Peter Nwilo; J. McConchie; E. Eyo

2009-01-01

155

Dynamic changes of spatial functional network connectivity in healthy individuals and schizophrenia patients using independent vector analysis.  

PubMed

Recent work on both task-induced and resting-state functional magnetic resonance imaging (fMRI) data suggests that functional connectivity may fluctuate, rather than being stationary during an entire scan. Most dynamic studies are based on second-order statistics between fMRI time series or time courses derived from blind source separation, e.g., independent component analysis (ICA), to investigate changes of temporal interactions among brain regions. However, fluctuations related to spatial components over time are of interest as well. In this paper, we examine higher-order statistical dependence between pairs of spatial components, which we define as spatial functional network connectivity (sFNC), and changes of sFNC across a resting-state scan. We extract time-varying components from healthy controls and patients with schizophrenia to represent brain networks using independent vector analysis (IVA), which is an extension of ICA to multiple data sets and enables one to capture spatial variations. Based on mutual information among IVA components, we perform statistical analysis and Markov modeling to quantify the changes in spatial connectivity. Our experimental results suggest significantly more fluctuations in patient group and show that patients with schizophrenia have more variable patterns of spatial concordance primarily between the frontoparietal, cerebellar and temporal lobe regions. This study extends upon earlier studies showing temporal connectivity differences in similar areas on average by providing evidence that the dynamic spatial interplay between these regions is also impacted by schizophrenia. PMID:24418507

Ma, Sai; Calhoun, Vince D; Phlypo, Ronald; Adal?, Tülay

2014-04-15

156

Estimating Flare-Related Photospheric Lorentz Force Vector Changes Within Active Regions  

NASA Astrophysics Data System (ADS)

It is shown that expressions for the global Lorentz force associated with a flaring active region derived by Fisher {\\it et al.} (2012) can be used to estimate the Lorentz force changes for strong fields in large structures over photospheric subdomains within active regions. Gary's~(2001) model for the stratified solar atmosphere is used to demonstrate that in large-scale structures with typical horizontal magnetic length scale $\\gg 300$~km and with strong magnetic fields ($\\ge 1$~kG at the $\\tau =1$ opacity layer at 5000~\\AA), the Lorentz force acting on the photosphere may be approximated by a surface integral based on photospheric boundary data alone. These conditions cover many of the sunspot fields and major neutral lines that have been studied using Fisher {\\it et al.}'s (2012) expressions over the past few years. The method gives a reasonable estimate of flare-related Lorentz force changes based on photospheric magnetogram observations provided that the Lorentz force changes associated with the flare have a lasting effect on the observed fields, and are not immediately erased by post-flare equilibration processes.

Petrie, G. J. D.

2014-10-01

157

Response of Saturn's Current Sheet Structure to Changes in the Solar Wind Dynamic Pressure and IMF  

NASA Astrophysics Data System (ADS)

Using our global MHD model of Saturn’s magnetosphere, we investigate the location, shape and motion of Saturn’s current sheet under a variety of situations. Our global MHD model self consistently treats the entire magnetosphere and includes magnetospheric plasma sources from a major disk-like source from Enceladus and the rings and a secondary toroidal plasma source from Titan. The model produces solutions which are not constrained to be symmetric therefore the results are quite useful in trying to extend previous models that have been generated using Cassini data. Because we can carefully control the inputs to our MHD model, we do not have to worry about separating variations due to local time, varying upstream conditions, spacecraft motion or changes in the mass loading rate that often make interpreting the data complicated. We will present results for both steady state, as well as time varying solar wind conditions. Simulations with constant solar wind conditions allow us to study the effect that upsteam dynamic pressure has on both the shape and size of the current sheet. In addition, we will present results from simulations that include sudden changes in the solar wind dynamics pressure as well as the IMF direction. These simulations will allow us to study the current sheet response and to look for features such as current sheet flapping. Our previous studies have shown that the current sheet in our model does in fact reproduce the “bowl-like” behavior expect at most local times. However, at dusk, the current sheet is often quite warped. We will examine the cause of this warping and under what conditions it occurs.

Hansen, K. C.; Jia, X.; Gombosi, T. I.

2010-12-01

158

A Change of Inertia-Supporting the Thrust Vector Control of the Space Launch System  

NASA Technical Reports Server (NTRS)

The Space Launch System (SLS) is America's next launch vehicle. To utilize the vehicle more economically, heritage hardware from the Space Transportation System (STS) will be used when possible. The Solid Rocket Booster (SRB) actuators could possibly be used in the core stage of the SLS. The dynamic characteristics of the SRB actuator will need to be tested on an Inertia Load Stand (ILS) that has been converted to Space Shuttle Main Engine (SSME). The inertia on the pendulum of the ILS will need to be changed to match the SSME inertia. In this testing environment an SRB actuator can be tested with the equivalent resistence of an SSME.

Dziubanek, Adam J.

2012-01-01

159

Climate Change and Vector Borne Diseases: Getting A Grip on Control  

NASA Astrophysics Data System (ADS)

Pathogens that are transmitted by arthropods to humans kill millions of people a year and have long been identified as systems likely affected by climate change. Despite this, there has been a long controversy of how to evaluate the responses of these infectious disease systems to climatic conditions so that meaningful programmatic dcisions can be made. We briefly review the rationale for overall expectations, using them to identify both the temporal and spatial resolution needed for decision making and then discuss progress to date, using the world global malaria eradication program as an example.

Glass, G. E.; Ellis, H.

2011-12-01

160

Cost-competitive incentives for wind energy development in China: institutional dynamics and policy changes  

Microsoft Academic Search

This paper presents an overview of the development of wind power in China. The factors that affect the directions of wind power development are analyzed. It examines the economics of windfarm development and compares it with conventional energy sources. The major constraints in wind technology development, and defects of the current policies, are discussed. It points out that wind power

Wen-Qiang Liu; Lin Gan; Xi-Liang Zhang

2002-01-01

161

Feline Leukemia Virus Integrase And Capsid Packaging Functions Do Not Change The Insertion Profile Of Standard Moloney Retroviral Vectors  

PubMed Central

Adverse events linked to perturbations of cellular genes by vector insertion reported in gene therapy trials and animal models have prompted attempts to better understand the mechanisms directing viral vector integration. The integration profiles of vectors based on MLV, ASLV, SIV, and HIV have all been shown to be non-random, and novel vectors with a safer integration pattern have been sought. Recently we developed a producer cell line called CatPac that packages standard MoMLV vectors with FeLV gag, pol and env gene products. We now report the integration profile of this vector, asking if the FeLV integrase and capsid proteins could modify the MoMLV integration profile, potentially resulting in a less genotoxic pattern. We transduced rhesus macaque CD34+ hematopoietic progenitor cells with CatPac or standard MoMLV vectors, and determined their integration profile by LAM-PCR. We obtained 184 and 175 unique integration sites (IS) respectively for CatPac and standard MoMLV vectors, and these were compared to 10 000 in silico-generated random IS. The integration profile for CatPac vector was similar to MoMLV and equally non-random, with a propensity for integration near transcription start sites and in highly dense gene regions. We found an IS for CatPac vector localized 715 nucleotides upstream of LMO-2, the gene involved in the ALL developed by X-SCID patients treated via gene therapy using MoMLV vectors. In conclusion, we found that replacement of MoMLV env, gag, and pol gene products with FeLV did not alter the basic integration profile. Thus there appears to be no safety advantage for this packaging system. However, considering the stability and efficacy of CatPac vectors, further development is warranted, utilizing potentially safer vector backbones, for instance those with a SIN configuration. PMID:20237508

Metais, Jean-Yves; Topp, Shana; Doty, Raymond T.; Borate, Bhavesh; Nguyen, Anh-Dao; Wolfsberg, Tyra G.; Abkowitz, Janis L.; Dunbar, Cynthia E.

2010-01-01

162

Numerical modeling on air quality in an urban environment with changes of the aspect ratio and wind direction.  

PubMed

Due to heavy traffic emissions within an urban environment, air quality during the last decade becomes worse year by year and hazard to public health. In the present work, numerical modeling of flow and dispersion of gaseous emissions from vehicle exhaust in a street canyon were investigated under changes of the aspect ratio and wind direction. The three-dimensional flow and dispersion of gaseous pollutants were modeled using a computational fluid dynamics (CFD) model which was numerically solved using Reynolds-averaged Navier-Stokes (RANS) equations. The diffusion flow field in the atmospheric boundary layer within the street canyon was studied for different aspect ratios (W/H=1/2, 3/4, and 1) and wind directions (?=90°, 112.5°, 135°, and 157.5°). The numerical models were validated against wind tunnel results to optimize the turbulence model. The numerical results agreed well with the wind tunnel results. The simulation demonstrated that the minimum concentration at the human respiration height within the street canyon was on the windward side for aspect ratios W/H=1/2 and 1 and wind directions ?=112.5°, 135°, and 157.5°. The pollutant concentration level decreases as the wind direction and aspect ratio increase. The wind velocity and turbulence intensity increase as the aspect ratio and wind direction increase. PMID:23192299

Yassin, Mohamed F

2013-06-01

163

Wind Tunnel Test of an RPV with Shape-Change Control Effector and Sensor Arrays  

NASA Technical Reports Server (NTRS)

A variety of novel control effector concepts have recently emerged that may enable new approaches to flight control. In particular, the potential exists to shift the composition of the typical aircraft control effector suite from a small number of high authority, specialized devices (rudder, aileron, elevator, flaps), toward larger numbers of smaller, less specialized, distributed device arrays. The concept envisions effector and sensor networks composed of relatively small high-bandwidth devices able to simultaneously perform a variety of control functions using feedback from disparate data sources. To investigate this concept, a remotely piloted flight vehicle has been equipped with an array of 24 trailing edge shape-change effectors and associated pressure measurements. The vehicle, called the Multifunctional Effector and Sensor Array (MESA) testbed, was recently tested in NASA Langley's 12-ft Low Speed wind tunnel to characterize its stability properties, control authorities, and distributed pressure sensitivities for use in a dynamic simulation prior to flight testing. Another objective was to implement and evaluate a scheme for actively controlling the spanwise pressure distribution using the shape-change array. This report describes the MESA testbed, design of the pressure distribution controller, and results of the wind tunnel test.

Raney, David L.; Cabell, Randolph H.; Sloan, Adam R.; Barnwell, William G.; Lion, S. Todd; Hautamaki, Bret A.

2004-01-01

164

Effects of wind variability on scatterometry at low wind speeds  

Microsoft Academic Search

The dependence of the normalized radar cross section of the sea on wind variability within the resolution cell is examined by considering probability distributions of cross sections and wind vectors. If a threshold wind speed exists below which backscatter is negligible for steady winds, variability of the wind over the resolution cell is shown to cause significant backscatter at mean

William J. Plant

2000-01-01

165

QBO cycle identified by changes in height profile of the zonal winds: new regularities  

Microsoft Academic Search

The vertical wind profiles in the equatorial atmosphere for 1953–2003 have been examined to study the regularities of the wind reversal in quasi-biennial oscillations (QBO) cycle. The detail analysis of rotation in the stratospheric wind profiles reveals that the quiet periods alternate with active periods, characterized by strong disturbing winds. The stage with the easterly winds above 20–30hPa and westerly

I. Gabis; O. A. Troshichev

2005-01-01

166

Expression changes in tolerant murine cardiac allografts after gene therapy with a lentiviral vector expressing alpha1,3 galactosyltransferase.  

PubMed

Comparison of intragraft gene expression changes in tolerant cardiac allograft models may provide the basis for identifying pathways involved in graft survival. Our laboratory has previously demonstrated that tolerance to the gal alpha1,3 gal epitope, the major target of rejection of wild-type pig hearts in human cardiac transplantation, can be achieved after transplantation with bone marrow transduced with a lentiviral vector expressing alpha1,3 galactosyltransferase. We now present intracardiac gene expression changes associated with long-term tolerance in this model. Biotin-labeled cRNA was hybridized to Affymetrix GeneChip 430 2.0 Mouse Genome Arrays. Data were subjected to functional annotation analysis to identify genes of known function in which expression was increased or decreased by at least 2-fold (t-test, P < .05) in tolerant gal+/+ wild-type hearts as compared to transplanted syngeneic controls. Tolerant hearts demonstrated increased expression of genes associated with the stress response, modulation of immune function and cell survival (HSPa9a, CD56, and Akt1s1), and decreased expression of several immunoregulatory genes (CD209, CD26, and PDE4b). These data suggest that tolerance may be associated with activation of immunomodulatory and survival pathways. PMID:17175215

Evans, J M; Doki, T; Fischer-Lougheed, J; Davicioni, E; Kearns-Jonker, M

2006-12-01

167

Assessing Southern Hemisphere Westerly Wind Changes during the Last Glacial Maximum using Paleo-data Synthesis (Invited)  

NASA Astrophysics Data System (ADS)

Changes in the strength and position of Southern Hemisphere westerly winds during the last glacial cycle have been invoked to explain glacial-interglacial climate fluctuations. However, neither paleo models nor paleodata agree on the magnitude, or even the sign, of the change in wind strength and latitude during the Last Glacial Maximum (LGM), compared to the recent past. This study synthesizes paleo-environmental data that have been used to infer changes in winds during the LGM compared with the late Holocene. These compilations include changes in terrestrial moisture, dust deposition, and ocean productivity, along with summaries of previously published information on sea surface temperatures (SSTs) and ocean dynamics in the Southern Hemisphere. Our compilations of terrestrial moisture from 94 sites and dust deposition from 87 sites show generally drier conditions for the LGM between 0 and 40S, with wetter conditions along the west coasts and drying along the east coasts of continents. LGM dust deposition rates ranged from 2 to 4.5 times higher over the Southern Ocean and about 13 times higher over the Antarctic continent. For the oceans, reconstructed changes in SSTs show maximum cooling (>4 °C) in the modern-day Subantarctic Zone, coincident with a region of enhanced export production during the LGM compared with today. We find that any hypothesis of LGM wind and climate change needs to provide a plausible explanation for increased moisture on the west coast of continents, cooler temperatures and higher productivity in the Subantarctic Zone, and reductions in Agulhas leakage around southern Africa. Our comparison suggests that an overall strengthening, an equatorward displacement, or no change at all in winds could all be interpreted as consistent with observations. If a single cause related to the southern westerlies is sought for all the evidence presented, then an equatorward displacement or strengthening of the winds would be consistent with the largest proportion of the data evidence. However, other processes, such as weakening or poleward shifts in winds, a weakened hydrological cycle, extended sea-ice cover, and changed buoyancy fluxes, cannot be ruled out as potential explanations of observed changes in moisture, surface temperature, and productivity. We contend that resolving the position and strength of westerly winds during the LGM remains elusive based on data reconstructions alone. However, we believe that these data reconstructions of environmental conditions can be used in conjunction with model simulations to identify which processes best represent westerly wind conditions during the LGM.

Kohfeld, K. E.; Graham, R. M.; De Boer, A. M.; Wolff, E. W.; Sime, L. C.; Le Quere, C.; Bopp, L.

2013-12-01

168

Pharmacological analysis of calcium transients in response to gravity vector change in Arabidopsis hypocotyls and petioles.  

NASA Astrophysics Data System (ADS)

Plants regulate their growth and morphology in response to gravity field known as gravitropism in general In the process of gravitropism gravity sensing will form the critical earliest event which is supposed to take place in specialized cells statocytes such as columella cells and shoot endodermal cells Although gravistimulation is assumed to be converted into certain intracellular signals the underlying transduction mechanisms have hardly been explored One of the potential candidates for the intracellular signals is an increase in the cytoplasmic free calcium concentration Ca 2 c Here we measured Ca 2 c changes induced by gravistimulation in seedlings of Arabidopsis thaliana expressing aequorin as a calcium reporter When a plate of seedlings was turned through 180 r Ca 2 c transiently increased within 50 s and decayed exponentially with a time constant of ca 60 s The amplitude of the Ca 2 c increase was independent of the angular velocity of the rotation The Ca 2 c increase was reversibly blocked by extracellularly applied potential mechanosensitive channel blockers La 3 Gd 3 or a Ca 2 chelator BAPTA indicating that it arose from Ca 2 -influx via Ca 2 -permeable channel s on the plasma membrane Furthermore the Ca 2 c increase was attenuated by actin-disrupting drugs latrunculin B cytochalasin B but not by microtuble-disrupting drugs oryzalin nocodazole indicating that the activation of

Toyota, M.; Furuichi, T.; Tatsumi, H.; Sokabe, M.

169

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

170

Wind Characterization for the Assessment of Collision Risk During Flight Level Changes  

NASA Technical Reports Server (NTRS)

A model of vertical wind gradient is presented based on National Oceanic and Atmospheric Administration (NOAA) wind data. The objective is to have an accurate representation of wind to be used in Collision Risk Models (CRM) of aircraft procedures. Depending on how an aircraft procedure is defined, wind and the different characteristics of the wind will have a more severe or less severe impact on distances between aircraft. For the In-Trail Procedure, the non-linearity of the vertical wind gradient has the greatest impact on longitudinal distance. The analysis in this paper extracts standard deviation, mean, maximum, and linearity characteristics from the NOAA data.

Carreno, Victor; Chartrand, Ryan

2009-01-01

171

The Structural Changes of Tropical Cyclones Upon Interaction with Vertical Wind Shear  

NASA Technical Reports Server (NTRS)

The Fourth Convection and Moisture Experiment (CAMEX-4) provided a unique opportunity to observe the distributions and document the roles of important atmospheric factors that impact the development of the core asymmetries and core structural changes of tropical cyclones embedded in vertical wind shear. The state-of-the-art instruments flown on the NASA DC-8 and ER-2, in addition to those on the NOAA aircraft, provided a unique set of observations that documented the core structure throughout the depth of the tropical cyclone. These data have been used to conduct a combined observational and modeling study using a state-of-the-art, high- resolution mesoscale model to examine the role of the environmental vertical wind shear in producing tropical cyclone core asymmetries, and the effects on the structure and intensity of tropical cyclones.The scientific objectives of this study were to obtain in situ measurements that would allow documentation of the physical mechanisms that influence the development of the asymmetric convection and its effect on the core structure of the tropical cyclone.

Ritchie, Elizabeth A.

2003-01-01

172

Two Models Switched Predictive Pitch Control for Wind Turbine Based on Improved Incremental SVR  

Microsoft Academic Search

Model predictive control arithmetic was used for wind turbine pitch control, whose nonlinear model was identified by support vector regression (SVR). But the model of wind turbine could be changed in fieldwork, so incremental learning algorithm was adopted for SVR online identification. In order to shorten the calculation time of SVR online identification, the improved sequential minimal optimization (SMO) algorithm

Lin Yonggang; Li Wei; Cui Baoling; Liu Hongwei

2006-01-01

173

Spatial and temporal changes in Lutzomyia longipalpis abundance, a Leishmania infantum vector in an urban area in northeastern Argentina  

PubMed Central

This study aimed to analyse changes in the spatial distribution of Lutzomyia longipalpis in Posadas, an urban area located in northeastern Argentina. Data were obtained during the summer of 2007 and 2009 through two entomological surveys of peridomiciles distributed around the city. The abundance distribution pattern for 2009 was computed and compared with the previous pattern obtained in 2007, when the first human visceral leishmaniasis cases were reported in the city. Vector abundance was also examined in relation to micro and macrohabitat characteristics. In 2007 and 2009, Lu. longipalpis was distributed among 41.5% and 31% of the households in the study area, respectively. In both years, the abundance rates at most of the trapping sites were below 30 Lu. longipalpis per trap per night; however, for areas exhibiting 30-60 Lu. longipalpis and more than 60 Lu. longipalpis, the areas increased in both size and number from 2007-2009. Lu. longipalpis was more abundant in areas with a higher tree and bush cover (a macrohabitat characteristic) and in peridomiciles with accumulated unused material (a microhabitat characteristic). These results will help to prioritise and focus control efforts by defining which peridomiciles display a potentially high abundance of Lu. longipalpis. PMID:24271040

Fernandez, Maria Soledad; Santini, Maria Soledad; Cavia, Regino; Sandoval, Adolfo Enrique; Perez, Adriana Alicia; Acardi, Soraya; Salomon, Oscar Daniel

2013-01-01

174

Impact of WRF Physics and Grid Resolution on Low-level Wind Prediction: Towards the Assessment of Climate Change Impact on Future Wind Power  

SciTech Connect

The Weather Research and Forecast (WRF) model is used in short-range simulations to explore the sensitivity of model physics and horizontal grid resolution. We choose five events with the clear-sky conditions to study the impact of different planetary boundary layer (PBL), surface and soil-layer physics on low-level wind forecast for two wind farms; one in California (CA) and the other in Texas (TX). Short-range simulations are validated with field measurements. Results indicate that the forecast error of the CA case decreases with increasing grid resolution due to the improved representation of valley winds. Besides, the model physics configuration has a significant impact on the forecast error at this location. In contrast, the forecast error of the TX case exhibits little dependence on grid resolution and is relatively independent of physics configuration. Therefore, the occurrence frequency of lowest root mean square errors (RMSEs) at this location is used to determine an optimal model configuration for subsequent decade-scale regional climate model (RCM) simulations. In this study, we perform two sets of 20-year RCM simulations using the data from the NCAR Global Climate Model (GCM) simulations; one set models the present climate and the other simulates the future climate. These RCM simulations will be used to assess the impact of climate change on future wind energy.

Chin, H S; Glascoe, L; Lundquist, J; Wharton, S

2010-02-24

175

Efficacy of child abuse and neglect prevention messages in the Florida Winds of Change campaign.  

PubMed

Public awareness campaigns have been included in universal, communitywide, and programmatic approaches aimed at preventing child abuse and neglect. More evaluation of campaign effects is needed to identify their place on the continuum of evidence-based programs. This article reports on an efficacy study of the Florida Winds of Change campaign using a randomized experimental design. Investigators conducted an online survey of a web-based panel of Florida residents with children 18 years of age or younger living in the home. Six outcomes were measured at baseline and a 30-day follow-up. Three outcomes referred to knowledge of child development, child disciplinary techniques, and community resources for parents. Prevention attitudes or beliefs, motivation, and action were also assessed. Respondents were exposed to three public service announcements and a selection of parent resource material. Logistic regression models revealed that exposure to campaign messages was associated with significant increases in all but one of the campaign outcomes. PMID:22206348

Evans, W Douglas; Falconer, Mary Kay; Khan, Munziba; Ferris, Christie

2012-01-01

176

Combined Wind Vector and Sea State Impact on Ocean Nadir-Viewing Ku- and C-Band Radar Cross-Sections  

PubMed Central

The authors report the first results in studying the polarization anisotropy of the microwave backscatter from nadir observations provided by Jason-1 altimeter in both Ku- and C-band. A small but clear wind direction signal for wind speeds above 6 m/s is revealed. These azimuthal variations of radar cross-section increase with increasing wind speed up to 14 m/s. The signatures then level off at higher winds. These results extend, for the first time, recent theoretical improved scattering approximation, and point some similarities between scattering and emission mechanisms at nadir. The observed directional effect can thus be interpreted as a signature of the curvature anisotropy of wind-generated short-scale waves. Sensitivities to both wind speed and sea state are also reported in the present analysis.

Tran, Ngan; Chapron, Bertrand

2006-01-01

177

Spatially-Explicit Simulation Modeling of Ecological Response to Climate Change: Methodological Considerations in Predicting Shifting Population Dynamics of Infectious Disease Vectors  

PubMed Central

Poikilothermic disease vectors can respond to altered climates through spatial changes in both population size and phenology. Quantitative descriptors to characterize, analyze and visualize these dynamic responses are lacking, particularly across large spatial domains. In order to demonstrate the value of a spatially explicit, dynamic modeling approach, we assessed spatial changes in the population dynamics of Ixodes scapularis, the Lyme disease vector, using a temperature-forced population model simulated across a grid of 4 × 4 km cells covering the eastern United States, using both modeled (Weather Research and Forecasting (WRF) 3.2.1) baseline/current (2001–2004) and projected (Representative Concentration Pathway (RCP) 4.5 and RCP 8.5; 2057–2059) climate data. Ten dynamic population features (DPFs) were derived from simulated populations and analyzed spatially to characterize the regional population response to current and future climate across the domain. Each DPF under the current climate was assessed for its ability to discriminate observed Lyme disease risk and known vector presence/absence, using data from the US Centers for Disease Control and Prevention. Peak vector population and month of peak vector population were the DPFs that performed best as predictors of current Lyme disease risk. When examined under baseline and projected climate scenarios, the spatial and temporal distributions of DPFs shift and the seasonal cycle of key questing life stages is compressed under some scenarios. Our results demonstrate the utility of spatial characterization, analysis and visualization of dynamic population responses—including altered phenology—of disease vectors to altered climate. PMID:24772388

Dhingra, Radhika; Jimenez, Violeta; Chang, Howard H.; Gambhir, Manoj; Fu, Joshua S.; Liu, Yang; Remais, Justin V.

2014-01-01

178

Possible changes in the return period of loss associated with European wind storms in a future climate  

NASA Astrophysics Data System (ADS)

Possible changes in return periods of European wind storms in a future climate are investigated based on transient GCM simulations. The intensity of a storm is quantified by the associated estimated loss, which is derived using the storm loss model originally developed by Klawa and Ulbrich (2003). We adapted this method to estimate losses for individual storms. With that aim, we use daily maximum wind speeds to compute the estimated loss for each storm considering exceedences of the local 98th wind percentile. If a storm affects Europe during more than one day, the largest daily loss is considered. The total estimated loss for a single storm is then given by the sum estimated loss values for all grid points affected by the storm. We focus our investigation on the European countries which are often affected by winter storms (Germany, France, Netherlands, Belgium, Denmark, United Kingdom and Ireland). The method is first tested for wind storm losses based on ERA40 data. Results reveal that the method is able to estimate well the spatial extension and ranking of losses associated with historical storms. We use robust Extreme Value Analysis (EVA) techniques which fit an extreme value distribution to data above a high threshold to estimate the return periods of storm losses. In order to estimate possible changes in return periods of storm loss in a future climate, GCM data for recent (20C, 1960-2000) and future climate conditions (SRES A1B and A2, 2001-2100) is considered. Results of our study show that both the number and intensity of loss from wind storms increases under future climate conditions. In particular, several storms are detected with estimated losses exceeding three times the largest events for recent climate conditions. Consequently, a significant shortening of return periods of European wind storm losses is identified at the end of the 21st century. This implies higher risk of occurrence of damaging wind events over Europe.

Karremann, Melanie K.; Pinto, Joaquim G.; Klawa, Matthias; Della-Marta, Paul M.; Stowasser, Markus

2010-05-01

179

Land-Based Wind Potential Changes in the Southeastern United States (Presentation)  

SciTech Connect

Recent advancements in utility-scale wind turbine technology and pricing have vastly increased the potential land area where turbines can be deployed in the United States. This presentation quantifies the new developable land potential (e.g., capacity curves), visually identifies new areas for possible development (e.g., new wind resource maps), and begins to address deployment barriers to wind in new areas for modern and future turbine technology.

Roberts, J. O.

2013-09-01

180

Potential impacts of topography and prevailing wind direction on future precipitation changes in Japan  

NASA Astrophysics Data System (ADS)

To investigate future changes in summertime precipitation amounts over the Japanese islands and their relations to the topographical heights, this study analyzed 20 km horizontal grid-spacing regional climate model downscalings of MIROC3.2-hires 20C3M and SRES-A1B scenario data for the periods of 1981-2000 and 2081-2100. Results indicate the remarkable increases in June-July-August mean daily precipitation in the west and south sides (windward sides) of the mountainous regions, especially in western Japan where heavy rainfall is frequently observed in the recent climate. The remarkable increases in summertime precipitation are likely to occur not only in high altitude areas but also at low altitudes. The occurrence frequencies of precipitation greater than 100 mm/day would also increase in such areas. The intensification of southwesterly moist air flows in the lower troposphere is considered to be one of the main causes of those precipitation changes because the intensified southwesterly moist air flows impinging on the western and southern slopes of the mountains can generate stronger upslope flows and well-developed clouds, leading to increased precipitation. Also, the results show that future precipitation changes in the lee sides of the mountainous regions (e.g., the Tokyo metropolitan area) would be comparatively small. These results indicate large influences of topography and prevailing wind direction on future precipitation changes. Acknowledgments: This study was conducted as part of the research subject "Vulnerability and Adaptation to Climate Change in Water Hazard Assessed Using Regional Climate Scenarios in the Tokyo Region' (National Research Institute for Earth Science and Disaster Prevention; PI: Koji Dairaku) of Research Program on Climate Change Adaptation (RECCA) and was supported by the SOUSEI Program, funded by Ministry of Education, Culture, Sports, Science and Technology, Government of Japan. We thank the regional climate modeling groups (MRI/NIED/Univ. Tsukuba) for producing and making available their model output. Their work was supported by the Environment Research and Technology Development Fund (S5-3) of the Ministry of the Environment, Japan.

Tsunematsu, N.; Dairaku, K.; Hirano, J.

2013-12-01

181

Catastrophic wind damage to North American forests and the potential impact of climate change  

Microsoft Academic Search

Catastrophic winds from tornadoes and downbursts are a major cause of natural disturbance in forests of eastern North America, accounting for thousands of hectares of disturbed area annually. Wind disturbance shows substantial regional variation, decreasing from the mid-west to the east and from the south-east to New England. In terms of the relative importance among these types of storms, more

Chris J Peterson

2000-01-01

182

Structural changes of the follicular cells during developmental stages of the malaria vector mosquitoes Anopheles pharoensis (Diptera: Culicidae) in Egypt.  

PubMed

The structure modulation of follicular cells and the ovarian changes during fourth larval instar and pupal stage of the malaria vector mosquitoes Anopheles pharoensis Theobald were investigated using the light and electron microscopy. The generative organs consist of a pair of polytrophic ovaries (OV), which are oblong, spindle-shaped bodies, lying dorsolaterally and occupying the region from the mid-fifth to the mid-sixth abdominal segment in the fourth larval instar, while in the pupal stage, each ovary (OV) is situated in the haemocoel of the sixth abdominal segment. It is an oblong body slightly larger in diameter; the lumen of the calyx becomes wider and central, and the pedicel (P) consists of one row of compact discoidal cells; meanwhile, in the fourth larval instar, the pedicel is without a lumen and consists of two rows of discoidal cells which are arranged as a short column between the follicle and calyx. The mean volume of the follicle in the fourth larval instar is 9.078?±?3.0178 ?m(3), meanwhile in the pupal stage being 12.051?±?2.427 ?m(3). The germarium (G) decreases in size in the pupal stage and contains a group of cells from which the oogonia differentiate, follicular cells which are similar to trophocytes, undifferentiated into one oocyte (O), which will develop into an egg and it is statistically the smallest one measured (0.058?±?0.0041 ?m(3), 0.303?±?0.0086 ?m(3)) in fourth larval instar and pupal stage, respectively as compared to the others within the follicle which will be accompanied as nurse cells (NC). The follicle is enclosed by a mononuclear flattened cells (follicular membrane), which have distinct boundaries. The vitellarium is differentiated into primary (F1) and secondary follicles (F2) in the pupal stage. The Golgi apparatus (GA) appears as discrete bits which are restricted to the perinuclear zone. The mitochondria (M) in the fourth larval instar are in the form of granules and short rods. They are perinuclearly distributed, forming a ring that surrounds the comparatively large nucleus. In the pupal stage, a similar condition to that described for the larva is observed, but with an increase in size and numbers, due to breaking up of rods into granules. PMID:25241910

Yamany, Abeer S; Adham, Fatma K; Mehlhorn, Heinz

2014-11-01

183

Aerobiology of Artemisia airborne pollen in Murcia (SE Spain) and its relationship with weather variables: annual and intradiurnal variations for three different species. Wind vectors as a tool in determining pollen origin  

NASA Astrophysics Data System (ADS)

Detailed results from a 2-year survey of airborne pollen concentrations of Artemisia in Murcia are presented. Three consecutive pollen seasons of Artemisia occurring each year, related to three different species (A.campestris, A.herba-alba and A.barrelieri), were observed. A winter blooming of Artemisia could explain the incidence of subsequent pollinosis in the Murcia area. With regard to meteorological parameters, mathematical analyses showed relationships between daily pollen concentrations of Artemisia in summer-autumn and precipitations that occurred 6-8 weeks before. The cumulative percentage of insolation from 1 March seemed to be related to blooming onsets. Once pollination has begun, meteorological factors do not seem to influence pollen concentrations significantly. Intradiurnal patterns of pollen concentrations were similar for late summer and winter species (A. campestris and A.barrelieri). During autumn blooming (A.herba-alba), the intradiurnal pattern was particularly erratic. Theoretical values of wind run were obtained for each pollen season by the graphical sum of hourly wind vectors. When theoretical wind run was mapped onto the vegetation pattern, supposed pollen source locations were obtained for each hour. By comparing supposed hourly pollen origins with the intradiurnal patterns of pollen concentrations, it can be seen that this simple model explains variations in mean pollen concentrations throughout the day.

Giner, M. Munuera; Carrión García, José S.; García Sellés, Javier

184

Aerobiology of Artemisia airborne pollen in Murcia (SE Spain) and its relationship with weather variables: annual and intradiurnal variations for three different species. Wind vectors as a tool in determining pollen origin.  

PubMed

Detailed results from a 2-year survey of airborne pollen concentrations of Artemisia in Murcia are presented. Three consecutive pollen seasons of Artemisia occurring each year, related to three different species (A. campestris, A. herba-alba and A. barrelieri), were observed. A winter blooming of Artemisia could explain the incidence of subsequent pollinosis in the Murcia area. With regard to meteorological parameters, mathematical analyses showed relationships between daily pollen concentrations of Artemisia in summer-autumn and precipitations that occurred 6-8 weeks before. The cumulative percentage of insolation from 1 March seemed to be related to blooming onsets. Once pollination has begun, meteorological factors do not seem to influence pollen concentrations significantly. Intradiurnal patterns of pollen concentrations were similar for late summer and winter species (A. campestris and A. barrelieri). During autumn blooming (A. herba-alba), the intradiurnal pattern was particularly erratic. Theoretical values of wind run were obtained for each pollen season by the graphical sum of hourly wind vectors. When theoretical wind run was mapped onto the vegetation pattern, supposed pollen source locations were obtained for each hour. By comparing supposed hourly pollen origins with the intradiurnal patterns of pollen concentrations, it can be seen that this simple model explains variations in mean pollen concentrations throughout the day. PMID:10552308

Munuera Giner, M; Carrión García, J S; García Sellés, J

1999-10-01

185

Using Eulerian and Lagrangian Approaches to Investigate Wind-Driven Changes in the Southern Ocean Abyssal Circulation  

NASA Astrophysics Data System (ADS)

This study uses a global ocean eddy-permitting climate model to explore the export of abyssal water from the Southern Ocean and its sensitivity to projected twenty-first-century poleward-intensifying Southern Ocean wind stress. The authors investigate the abyssal flow pathways and transport using a combination of Lagrangian and Eulerian techniques. In an Eulerian format, the equator- and poleward flows within similar abyssal density classes are increased by the wind stress changes, making it difficult to explicitly diagnose changes in the abyssal export in a meridional overturning circulation framework. Lagrangian particle analyses are used to identify the major export pathways of Southern Ocean abyssal waters and reveal an increase in the number of particles exported to the subtropics from source regions around Antarctica in response to the wind forcing. Both the Lagrangian particle and Eulerian analyses identify transients as playing a key role in the abyssal export of water from the Southern Ocean. Wind-driven modifications to the potential energy component of the vorticity balance in the abyss are also found to impact the Southern Ocean barotropic circulation.

Spence, Paul; van Sebille, Erik; Saenko, Oleg; England, Matthew

2014-05-01

186

Analysis of Change in the Wind Speed Ratio according to Apartment Layout and Solutions  

PubMed Central

Apartment complexes in various forms are built in downtown areas. The arrangement of an apartment complex has great influence on the wind flow inside it. There are issues of residents' walking due to gust occurrence within apartment complexes, problems with pollutant emission due to airflow congestion, and heat island and cool island phenomena in apartment complexes. Currently, the forms of internal arrangements of apartment complexes are divided into the flat type and the tower type. In the present study, a wind tunnel experiment and computational fluid dynamics (CFD) simulation were performed with respect to internal wind flows in different apartment arrangement forms. Findings of the wind tunnel experiment showed that the internal form and arrangement of an apartment complex had significant influence on its internal airflow. The wind velocity of the buildings increased by 80% at maximum due to the proximity effects between the buildings. The CFD simulation for relaxing such wind flows indicated that the wind velocity reduced by 40% or more at maximum when the paths between the lateral sides of the buildings were extended. PMID:24688430

Hyung, Won-gil; Kim, Young-Moon; You, Ki-Pyo

2014-01-01

187

Analysis of change in the wind speed ratio according to apartment layout and solutions.  

PubMed

Apartment complexes in various forms are built in downtown areas. The arrangement of an apartment complex has great influence on the wind flow inside it. There are issues of residents' walking due to gust occurrence within apartment complexes, problems with pollutant emission due to airflow congestion, and heat island and cool island phenomena in apartment complexes. Currently, the forms of internal arrangements of apartment complexes are divided into the flat type and the tower type. In the present study, a wind tunnel experiment and computational fluid dynamics (CFD) simulation were performed with respect to internal wind flows in different apartment arrangement forms. Findings of the wind tunnel experiment showed that the internal form and arrangement of an apartment complex had significant influence on its internal airflow. The wind velocity of the buildings increased by 80% at maximum due to the proximity effects between the buildings. The CFD simulation for relaxing such wind flows indicated that the wind velocity reduced by 40% or more at maximum when the paths between the lateral sides of the buildings were extended. PMID:24688430

Hyung, Won-gil; Kim, Young-Moon; You, Ki-Pyo

2014-01-01

188

Rapid changes in mixed layer stratification driven by submesoscale instabilities and winds  

E-print Network

Submesoscale eddies generated by baroclinic instability of upper ocean fronts lead to rapid restratification of the mixed layer on a time scale of days. This restratification can be opposed by a down-front wind stress ...

Ferrari, Raffaele

189

The quasi-biennial oscillation in the equatorial stratosphere: Seasonal regularity in zonal wind changes, discrete QBO-cycle period and prediction of QBO-cycle duration  

Microsoft Academic Search

The changes of vertical wind structure in equatorial stratosphere in course of Quasi-Biennial Oscillation (QBO) demonstrates\\u000a the evident seasonal dependence. The easterly wind regime descending from the middle to lower stratosphere always includes\\u000a the stationary period—the stagnation stage. At stagnation stage the bottom boundary of the easterly wind is located in different\\u000a QBO-cycles at different altitude in the range from

I. P. Gabis; O. A. Troshichev

2011-01-01

190

The quasi-biennial oscillation in the equatorial stratosphere: Seasonal regularity in zonal wind changes, discrete QBO-cycle period and prediction of QBO-cycle duration  

Microsoft Academic Search

The changes of vertical wind structure in equatorial stratosphere in course of Quasi-Biennial Oscillation (QBO) demonstrates the evident seasonal dependence. The easterly wind regime descending from the middle to lower stratosphere always includes the stationary period---the stagnation stage. At stagnation stage the bottom boundary of the easterly wind is located in different QBO-cycles at different altitude in the range from

I. P. Gabis; O. A. Troshichev

2011-01-01

191

Changing Snow Cover and Stream Discharge in the Western United States - Wind River Range, Wyoming  

NASA Technical Reports Server (NTRS)

Earlier onset of springtime weather has been documented in the western United States over at least the last 50 years. Because the majority (>70%) of the water supply in the western U.S. comes from snowmelt, analysis of the declining spring snowpack has important implications for the management of water resources. We studied ten years of Moderate-Resolution Imaging Spectroradiometer (MODIS) snow-cover products, 40 years of stream discharge and meteorological station data and 30 years of snow-water equivalent (SWE) SNOw Telemetry (SNOTEL) data in the Wind River Range (WRR), Wyoming. Results show increasing air temperatures for.the 40-year study period. Discharge from streams in WRR drainage basins show lower annual discharge and earlier snowmelt in the decade of the 2000s than in the previous three decades. Changes in streamflow may be related to increasing air temperatures which are probably contributing to a reduction in snow cover, although no trend of either increasingly lower streamflow or earlier snowmelt was observed within the decade of the 2000s. And SWE on 1 April does not show an expected downward trend from 1980 to 2009. The extent of snow cover derived from the lowest-elevation zone of the WRR study area is strongly correlated (r=0.91) with stream discharge on 1 May during the decade of the 2000s. The strong relationship between snow cover and streamflow indicates that MODIS snow-cover maps can be used to improve management of water resources in the drought-prone western U.S.

Hall, Dorothy K.; Foster, James L.; DiGirolamo, Nicolo E.; Barton, Jonathan S.; Riggs, George A.

2011-01-01

192

The Effects of Climate Change and Globalization on Mosquito Vectors: Evidence from Jeju Island, South Korea on the Potential for Asian Tiger Mosquito (Aedes albopictus) Influxes and Survival from Vietnam Rather Than Japan  

PubMed Central

Background Climate change affects the survival and transmission of arthropod vectors as well as the development rates of vector-borne pathogens. Increased international travel is also an important factor in the spread of vector-borne diseases (VBDs) such as dengue, West Nile, yellow fever, chikungunya, and malaria. Dengue is the most important vector-borne viral disease. An estimated 2.5 billion people are at risk of infection in the world and there are approximately 50 million dengue infections and an estimated 500,000 individuals are hospitalized with dengue haemorrhagic fever annually. The Asian tiger mosquito (Aedes albopictus) is one of the vectors of dengue virus, and populations already exist on Jeju Island, South Korea. Currently, colder winter temperatures kill off Asian tiger mosquito populations and there is no evidence of the mosquitos being vectors for the dengue virus in this location. However, dengue virus-bearing mosquito vectors can inflow to Jeju Island from endemic area such as Vietnam by increased international travel, and this mosquito vector's survival during colder winter months will likely occur due to the effects of climate change. Methods and Results In this section, we show the geographical distribution of medically important mosquito vectors such as Ae. albopictus, a vector of both dengue and chikungunya viruses; Culex pipiens, a vector of West Nile virus; and Anopheles sinensis, a vector of Plasmodium vivax, within Jeju Island, South Korea. We found a significant association between the mean temperature, amount of precipitation, and density of mosquitoes. The phylogenetic analyses show that an Ae. albopictus, collected in southern area of Jeju Island, was identical to specimens found in Ho Chi Minh, Vietnam, and not Nagasaki, Japan. Conclusion Our results suggest that mosquito vectors or virus-bearing vectors can transmit from epidemic regions of Southeast Asia to Jeju Island and can survive during colder winter months. Therefore, Jeju Island is no longer safe from vector borne diseases (VBDs) due to the effects of globalization and climate change, and we should immediately monitor regional climate change to identify newly emerging VBDs. PMID:23894312

Jeong, Ji Yeon; Yoo, Seung Jin; Koh, Young-Sang; Lee, Seogjae; Heo, Sang Taek; Seong, Seung-Yong; Lee, Keun Hwa

2013-01-01

193

Q&A on "Impacts of Wind Farms on Land Surface Temperature" Published by Nature Climate Change on April 29, 2012  

E-print Network

1 Q&A on "Impacts of Wind Farms on Land Surface Temperature" Published by Nature Climate Change? This study presents the first observational evidence of wind farm impacts on land surface temperature with spatial detail using satellite data. What is land surface temperature? Land surface temperature is how hot

Zhou, Liming

194

Changing vessel routes could significantly reduce the cost of future offshore wind projects.  

PubMed

With the recent emphasis on offshore wind energy Coastal and Marine Spatial Planning (CMSP) has become one of the main frameworks used to plan and manage the increasingly complex web of ocean and coastal uses. As wind development becomes more prevalent, existing users of the ocean space, such as commercial shippers, will be compelled to share their historically open-access waters with these projects. Here, we demonstrate the utility of using cost-effectiveness analysis (CEA) to support siting decisions within a CMSP framework. In this study, we assume that large-scale offshore wind development will take place in the US Mid-Atlantic within the next decades. We then evaluate whether building projects nearshore or far from shore would be more cost-effective. Building projects nearshore is assumed to require rerouting of the commercial vessel traffic traveling between the US Mid-Atlantic ports by an average of 18.5 km per trip. We focus on less than 1500 transits by large deep-draft vessels. We estimate that over 29 years of the study, commercial shippers would incur an additional $0.2 billion (in 2012$) in direct and indirect costs. Building wind projects closer to shore where vessels used to transit would generate approximately $13.4 billion (in 2012$) in savings. Considering the large cost savings, modifying areas where vessels transit needs to be included in the portfolio of policies used to support the growth of the offshore wind industry in the US. PMID:24794388

Samoteskul, Kateryna; Firestone, Jeremy; Corbett, James; Callahan, John

2014-08-01

195

Wind Engineering  

NASA Technical Reports Server (NTRS)

Dr. Jack Cermak, Director of Fluid Dynamics and Diffusion Laboratory, developed the first wind tunnel to simulate the changing temperatures, directions and velocities of natural winds. In this work, Cermak benefited from NASA technology related to what is known as the atmospheric boundary layer (ABL).

1983-01-01

196

Climate change projected fire weather sensitivity: CaliforniaSanta Ana wind occurrence  

SciTech Connect

A new methodbased on global climate model pressuregradients was developed for identifying coastal high-wind fire weatherconditions, such as the Santa Ana Occurrence (SAO). Application of thismethod for determining southern California Santa Ana wind occurrenceresulted in a good correlation between derived large-scale SAOs andobserved offshore winds during periods of low humidity. The projectedchange in the number of SAOs was analyzed using two global climatemodels, one a low temperature sensitivity and the other amiddle-temperature sensitivity, both forced with low and high emissionscenarios, for three future time periods. This initial analysis showsconsistent shifts in SAO events from earlier (September-October) to later(November-December) in the season, suggesting that SAOs may significantlyincrease the extent of California coastal areas burned by wildfires, lossof life, and property.

Miller, Norman L.; Schlegel, Nicole J.

2006-01-01

197

Tandem Cascade Thrust Vectoring Research Program.  

National Technical Information Service (NTIS)

Continuous thrust vectoring from horizontal through vertical, to reversed thrust can be accomplished by the use of one or two cascades in series, each employing variable camber airfoils. An experimental wind tunnel evaluation of three types of variable ca...

J. R. Erwin, D. E. Clark, R. G. Giffin, J. G. Kirkpatrick

1964-01-01

198

On the Winds of Change Impact of Renewables on Electricity Markets [Guest Editorial  

Microsoft Academic Search

Renewable energy technologies are being welcomed in many countries worldwide because of their minor or nonimpact on the environment, as compared to the adverse impact of traditional fossil fuel generation alternatives. Although renewable energy in the form of hydroelectricity has been present since the dawn of electricity, the emphasis is presently on nonconventional renewables, such as wind and solar technologies.

H. Rudnick; L. A. Barroso

2010-01-01

199

18 IEEE power & energy magazine september/october 2010 on the winds of change  

E-print Network

fuel technologies, although it is very technologically dependent. Solar energy, for example, requires of electricity, the emphasis is presently on noncon- ventional renewables, such as wind and solar technologies, they are still not at the technological and economical state to compete with traditional ones such as natural gas

Dixon, Juan

200

VOL. 66, NO. 4 (DECEMBER 2013) P. 448458 Changing Daily Wind Speeds on Alaska's North Slope  

E-print Network

to hunt bowhead whale (Balaena mysticetus) during spring and caribou (Rangifer tarandus) during summer. We printemps, et du caribou (Rangifer tarandus) � l'�t�. Nous avons int�gr� les observations des chasseurs au with wind conditions suitable for safely hunting bowhead whales and caribou. The statistical analysis

201

Solar wind and substorm-related changes in the lobes of the geomagnetic tail  

Microsoft Academic Search

Variations in the magnetic energy density in the lobes of the geomagnetic tail appear to be fundamentally associated with magnetospheric substorms. Thus in this paper the relationship of the tail lobe energy density to solar wind dynamic pressure, the north-south component of the interplanetary magnetic field, and substorm expansion onsets is investigated. Enhanced lobe energy densities are observed to follow

Michael N. Caan; Robert L. McPherron; Christopher T. Russell

1973-01-01

202

Atmospheric transparency changes associated with solar wind-induced atmospheric electricity variations  

Microsoft Academic Search

Variations in atmospheric transmission of several percent in nominally clear air are found to accompany solar wind events associated with variations on the day-to-day timescale in the flow of vertical current density (Jz) in the global electric circuit. The effect has been observed only for stations at high latitudes (>55°N). Increases in transmission are present when inferred Jz decreases occurred

V. C. Roldugin; B. A. Tinsley

2004-01-01

203

Variations of Jovian aurora induced by changes in solar wind dynamic pressure  

Microsoft Academic Search

The jovian aurora contains a persistent main oval encircling each magnetic pole, which is associated with the upward field-aligned currents in the corotation enforcement current system. It has been suggested by two recent studies that the brightness of the main oval should become temporarily dimmer ~ 1 hr after arrival of a shock wave in the solar wind, compressing the

Bin Gong

2005-01-01

204

The change in Cosmic rays intensity variation with the Solar wind velocity variation  

Microsoft Academic Search

GRAPES-3 experiment is situated at Ooty in South India 76.7 East 11.4 North. Effective ob- servation area of our muon telescopes is 560 m 2 . They are the largest detector in the world of its kind. There were several reports that increase of the solar wind velocity suppresses the intensity of cosmic rays. But there are few which studied

Y. HAYASHI; K. HAYASHI; S. KAWAKAMI; T. MATSUYAMA; M. MINAMINO; T. OKUDA; S. OGIO; A. OSHIMA; N. SHIMIZU; S. K GUPTA; A. IYER; P. JANGADEESAN; S. KARTHIKEYAN; P. K MOHANTY; S. D MORRIS; P. K NAYAK; B. S RAO; K. C RAVINDRAN; H. TANAKA; S. C TONWAR; S. SHIBATA; I. MORISHITA

205

Climate change negotiations and first-mover advantages: the case of the wind turbine industry  

Microsoft Academic Search

Individual EU member countries, such as Denmark and Germany, may have a rational economic interest in creating comparative advantages for renewable energy sources in order to capitalise on their first-mover advantages in these industries. We demonstrate that different means of implementing the Kyoto Agreement affect the potential to market new renewable technologies, e.g. wind turbines, to other countries subsequent to

Urs Steiner Brandt; Gert Tinggaard Svendsen

2006-01-01

206

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

207

Vector quantization  

NASA Technical Reports Server (NTRS)

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

Gray, Robert M.

1989-01-01

208

Learning curves and changing product attributes: the case of wind turbines  

E-print Network

Bank) for providing us with our initial data set. 1 Many studies have used the concept of learning curves to assess cost evolutions of, for instance, coal-fired power plants (Joskow and Rose, 1985), ethanol production (Goldemberg, 1996), PV... wind energy provided at higher tower heights. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.000 0.200 0.400 0.600 0.800 1.000 1.200 1.400 Wind Energy/Swept Area (-/m^2) kW /S w ep t A re a (k W /m ^2 ) dy/dx*x/y = 0.3 Figure 1 Relation between rated power...

Coulomb, Louis; Neuhoff, Karsten

2006-03-14

209

Migrating swans profit from favourable changes in wind conditions at low altitude  

Microsoft Academic Search

Because energy reserves limit flight range, wind assistance may be of crucial importance for migratory birds. We tracked eight Bewick’s swans Cygnus columbianus bewickii, using 95-g satellite transmitters with altimeters and activity sensors, during their spring migration from Denmark to northern Russia in 1996. During the 82 occasions where a swan’s location was recorded in flight, average flight altitude was

Marcel Klaassen; Jan H. Beekman; Jari Kontiokorpi; Roef J. W. Mulder; Bart A. Nolet

2004-01-01

210

Decadal Changes of Wind Stress over the Southern Ocean Associated with Antarctic Ozone Depletion  

Microsoft Academic Search

Using 40-yr ECMWF Re-Analysis (ERA-40) data and in situ observations, the positive trend of Southern Ocean surface wind stress during two recent decades is detected, and its close linkage with spring Antarctic ozone depletion is established. The spring Antarctic ozone depletion affects the Southern Hemisphere lower-stratospheric circulation in late spring\\/early summer. The positive feedback involves the strengthen- ing and cooling

Xiao-Yi Yang; Rui Xin Huang; Dong Xiao Wang

2007-01-01

211

Assessment of possible changes in return period and ranking of losses associated with European wind storms in a future climate  

NASA Astrophysics Data System (ADS)

Winter storms are one of the major natural hazards affecting Europe. Possible changes in return periods and ranking of European wind storms in a future climate are investigated based on transient GCM simulations. The intensity of a storm is quantified by the associated estimated loss, which is derived using the storm loss model originally developed by Klawa and Ulbrich (2003), here adapted to estimate losses for individual storms. Daily maximum wind speeds are used to compute the estimated loss for each storm considering exceedences of the local 98th wind percentile. If a storm affects Europe during more than one day, the largest daily loss is considered. The total estimated loss for a single storm is then given by the sum estimated loss values for all grid points affected by the storm. We focus our investigation on Western and Central Europe, particularly in the "core Europe" countries (Germany, France, Netherlands, Belgium, Denmark, United Kingdom and Ireland). The method is first tested for wind storm losses based on ERA40 data. Results reveal that the method is able to estimate well the spatial extension and ranking of losses associated with historical storms. We use robust Extreme Value Analysis (EVA) techniques which fit an extreme value distribution to data above a high threshold to estimate the return periods of storm losses. In order to estimate possible changes in return periods and rankings of storm loss in a future climate, GCM data for recent (20C, 1960-2000) and future climate conditions (SRES A1B and A2, 2001-2100) is considered. Results show that both the number and intensity of extreme losses increases under future climate conditions. There is a strong shift of storm loss rankings, with a present day top 1 becoming a rank 6 (A1B) or rank 8 (A2) event. In particular, we found storms with estimated losses exceeding almost two times the largest events identified for the 20th century. Accordingly, a significant shortening of return periods of European wind storm losses is found for the end of the 21th century, particularly for the A1B-scenario. This indicates an enhanced risk of occurrence of destructive winter storms over Europe.

Karremann, M. K.; Pinto, J. G.; Klawa, M.; Della-Marta, P. M.; Stowasser, M.

2010-09-01

212

Studentsâ Consistency of Graphical Vector Addition Method on 2-D Vector Addition Tasks  

NSDL National Science Digital Library

In a series of ten two-dimensional graphical vector addition questions with varying visual representations, most students stuck to a single solution method, be it correct or incorrect. Changes to the visual representation include placing vectors on a grid, making the vectors arrangements symmetric, varying the separation between vectors, and reversing the direction of either vector. We discuss the questions asked of students and their responses, emphasizing the results of one student who did change solution methods during an interview.

Hawkins, Jeffrey M.; Thompson, John R.; Wittmann, Michael C.

2010-01-19

213

Wind turbine wake aerodynamics  

Microsoft Academic Search

The aerodynamics of horizontal axis wind turbine wakes is studied. The contents is directed towards the physics of power extraction by wind turbines and reviews both the near and the far wake region. For the near wake, the survey is restricted to uniform, steady and parallel flow conditions, thereby excluding wind shear, wind speed and rotor setting changes and yawed

L. J. Vermeer; J. N. Sørensen; A. Crespo

2003-01-01

214

Variations of Jovian aurora induced by changes in solar wind dynamic pressure  

NASA Astrophysics Data System (ADS)

The jovian aurora contains a persistent main oval encircling each magnetic pole, which is associated with the upward field-aligned currents in the corotation enforcement current system. It has been suggested by two recent studies that the brightness of the main oval should become temporarily dimmer ~ 1 hr after arrival of a shock wave in the solar wind, compressing the magnetosphere abruptly, because the difference between the angular velocity of the plasma in the magnetosphere and the rigid planetary rotational speed becomes smaller. But recent observations at Jupiter and Saturn have reported the opposite: the auroral oval brightens, and moves poleward, after the arrival of a solar wind shock. In this thesis, I will quantitatively include the flywheel effect of the neutral gas in the ionosphere in the coupling current system to explain this discrepancy and show that the corotation enforcement current should reverse and strengthen after a compression, and thereby temporarily cause the main oval to become brighter and move poleward. I will also show the differences between the night side and the day side in steady state and after a compression event by applying two different magnetic field models fitted from observations, and try to qualitatively explain the dawn-dusk asymmetry by introducing a region-1 current system analogous to that at Earth, which arises from the detailed interaction between solar wind and magnetosphere. Generally, I expect the day side sector of the main oval to brighten more than the night side sector, and the dawn sector to brighten more than the dusk sector.

Gong, Bin

2005-12-01

215

Wind Scanner: A full-scale Laser Facility for Wind and Turbulence Measurements around large Wind Turbines  

E-print Network

Turbines Torben Mikkelsen, Jakob Mann and Michael Courtney Wind Energy Department, Risø National Laboratory measurements of the wind fields engulfing today's huge wind turbines. Our aim is to measure in real- time 3D wind vector data at several hundred points every second: 1) in front of the turbine, 2) at the turbine

216

Application of satellite surface wind data to ocean wind analysis  

Microsoft Academic Search

A new set of cross-calibrated, multi-satellite ocean surface wind data is described. The principal data set covers the global ocean for the period beginning in 1987 with six-hour and 25-km resolution, and is produced by combining all ocean surface wind speed observations from SSM\\/I, AMSR-E, and TMI, and all ocean surface wind vector observations from QuikSCAT and SeaWinds. An enhanced

Robert Atlas; Joseph Ardizzone; Ross N. Hoffman

2008-01-01

217

The effects of changing winds and temperatures on the oceanography of the Ross Sea in the 21st century  

NASA Astrophysics Data System (ADS)

Ross Sea is critically important in regulating Antarctic sea ice and is biologically productive, which makes changes in the region's physical environment of global concern. We examined the effects of projected changes in atmospheric temperatures and winds on aspects of the ocean circulation likely important to primary production using a high-resolution sea ice-ocean-ice shelf model of the Ross Sea. The modeled summer sea-ice concentrations decreased by 56% by 2050 and 78% by 2100. The duration of shallow mixed layers over the continental shelf increased by 8.5 and 19.2 days in 2050 and 2100, and the mean summer mixed layer depths decreased by 12 and 44%. These results suggest that the annual phytoplankton production in the future will increase and become more diatomaceous. Other components of the Ross Sea food web will likely be severely disrupted, creating significant but unpredictable impacts on the ocean's most pristine ecosystem.

Smith, Walker O.; Dinniman, Michael S.; Hofmann, Eileen E.; Klinck, John M.

2014-03-01

218

Climate change effects on mitigation measures: The case of extreme wind events and Philippines’ biofuel plan  

Microsoft Academic Search

Biofuel production has increased dramatically over the past decade, among other to mitigate climate change. However, climate change vulnerability may currently not be sufficiently accounted for in national biofuel strategies, hence neglecting a possible link between mitigation and adaptation to climate change. To the best of our knowledge this potential link has received very little attention in the literature. One

Per M. Stromberg; Miguel Esteban; Alexandros Gasparatos

219

Late Holocene changes in precipitation in northwest Tasmania and their potential links to shifts in the Southern Hemisphere westerly winds  

NASA Astrophysics Data System (ADS)

Accurate projections of future climate changes in regions susceptible to drought depend on a good understanding of past climate changes and the processes driving them. In the absence of longer term instrumental data, paleoclimate data are needed. In this study we develop a precipitation reconstruction for Rebecca Lagoon (41°11'S, 144°41'E), northwest Tasmania. First, the relationship between scanning reflectance spectroscopy measurements of sediment cores in the visible spectrum (380-730 nm) and instrumental precipitation record (1912-2009) was used to develop a model to reconstruct precipitation back in time. Results showed that the ratio of reflectance between 660 and 670 nm (i.e., reflectance at 660 nm/reflectance at 670 nm; a measure of pigment diagenesis) was significantly related to annual precipitation. A calibration model was developed (R = - 0.56, pauto < 0.001, RMSEP = 43.0 mm yr- 1, 5 year triangular filtered data, calibration period 1912-2009). Second, this calibration-in-time model was used to reconstruct late Holocene precipitation changes over the last ~ 3000 years. This showed relatively dry conditions from ca. 3100-2800 cal yr BP, wet conditions from ca. 2800-2400 cal yr BP, dry conditions from ca. 2400-2000 calyr BP, and variable conditions after this. Relatively wet conditions occurred from ca. 500 cal yr BP to the late AD 1800 s (ca. 50 cal. yr BP). The precipitation reconstruction indicates that conditions were relatively dry for the 20th century compared to the last ~ 3000 years. In particular, the dry period measured in recent decades is one of the most intense in at least the last 500 years. As precipitation in this region is primarily driven by the Southern Hemisphere westerly winds, these changes are discussed in terms of shifts in westerly wind strength and/or position.

Saunders, K. M.; Kamenik, C.; Hodgson, D. A.; Hunziker, S.; Siffert, L.; Fischer, D.; Fujak, M.; Gibson, J. A. E.; Grosjean, M.

2012-07-01

220

Quadraphonic Wind  

NSDL National Science Digital Library

In this activity, learners discover how the extent of various wind speeds changes in each of the four quadrants around a hurricane. Learners use data from the 'present' location of Hurricane Bill (2009) to plot the distance of various wind speeds that extend from the center of the storm. This resource includes brief background information about hurricanes and forecasting as well as an explanation of the Hurricane Bill data used in this activity and how small increases in wind speed can cause increased potential for damage.

Service, National W.

2012-12-18

221

Vectors, Change of Basis and Matrix Representation: Onto-Semiotic Approach in the Analysis of Creating Meaning  

ERIC Educational Resources Information Center

In a previous study, the onto-semiotic approach was employed to analyse the mathematical notion of different coordinate systems, as well as some situations and university students' actions related to these coordinate systems in the context of multivariate calculus. This study approaches different coordinate systems through the process of change of…

Montiel, Mariana; Wilhelmi, Miguel R.; Vidakovic, Draga; Elstak, Iwan

2012-01-01

222

Dissipation in Pulsar Winds  

E-print Network

I review the constraints placed on relativistic pulsar winds by comparing optical and X-ray images of the inner Crab Nebula on the one hand with two-dimensional MHD simulations on the other. The various proposals in the literature for achieving the low magnetisation required at the inner edge of the Nebula, are then discussed, emphasising that of dissipation in the striped-wind picture. The possibility of direct observation of the wind is examined. Based on the predicted orientation of the polarisation vector, I outline a new argument suggesting that the off-pulse component of the optical emission of the Crab pulsar originates in the wind.

J. G. Kirk

2005-04-19

223

Circular Conditional Autoregressive Modeling of Vector Fields*  

PubMed Central

As hurricanes approach landfall, there are several hazards for which coastal populations must be prepared. Damaging winds, torrential rains, and tornadoes play havoc with both the coast and inland areas; but, the biggest seaside menace to life and property is the storm surge. Wind fields are used as the primary forcing for the numerical forecasts of the coastal ocean response to hurricane force winds, such as the height of the storm surge and the degree of coastal flooding. Unfortunately, developments in deterministic modeling of these forcings have been hindered by computational expenses. In this paper, we present a multivariate spatial model for vector fields, that we apply to hurricane winds. We parameterize the wind vector at each site in polar coordinates and specify a circular conditional autoregressive (CCAR) model for the vector direction, and a spatial CAR model for speed. We apply our framework for vector fields to hurricane surface wind fields for Hurricane Floyd of 1999 and compare our CCAR model to prior methods that decompose wind speed and direction into its N-S and W-E cardinal components. PMID:24353452

Modlin, Danny; Fuentes, Montse; Reich, Brian

2013-01-01

224

Fractional Factorial Experiment Designs to Minimize Configuration Changes in Wind Tunnel Testing  

NASA Technical Reports Server (NTRS)

This paper serves as a tutorial to introduce the wind tunnel research community to configuration experiment designs that can satisfy resource constraints in a configuration study involving several variables, without arbitrarily eliminating any of them from the experiment initially. The special case of a configuration study featuring variables at two levels is examined in detail. This is the type of study in which each configuration variable has two natural states - 'on or off', 'deployed or not deployed', 'low or high', and so forth. The basic principles are illustrated by results obtained in configuration studies conducted in the Langley National Transonic Facility and in the ViGYAN Low Speed Tunnel in Hampton, Virginia. The crucial role of interactions among configuration variables is highlighted with an illustration of difficulties that can be encountered when they are not properly taken into account.

DeLoach, Richard; Cler, Daniel L.; Graham, Albert B.

2002-01-01

225

Decades-Long Changes of the Interstellar Wind Through Our Solar System  

NASA Astrophysics Data System (ADS)

The journey of the Sun through the dynamically active local interstellar medium creates an evolving heliosphere environment. This motion drives a wind of interstellar material through the heliosphere that has been measured with Earth-orbiting and interplanetary spacecraft for 40 years. Recent results obtained by NASA's Interstellar Boundary Explorer mission during 2009-2010 suggest that neutral interstellar atoms flow into the solar system from a different direction than found previously. These prior measurements represent data collected from Ulysses and other spacecraft during 1992-2002 and a variety of older measurements acquired during 1972-1978. Consideration of all data types and their published results and uncertainties, over the three epochs of observations, indicates that the trend for the interstellar flow ecliptic longitude to increase linearly with time is statistically significant.

Frisch, P. C.; Bzowski, M.; Livadiotis, G.; McComas, D. J.; Moebius, E.; Mueller, H.-R.; Pryor, W. R.; Schwadron, N. A.; Sokó?, J. M.; Vallerga, J. V.; Ajello, J. M.

2013-09-01

226

The national assessment of shoreline change: a GIS compilation of vector cliff edges and associated cliff erosion data for the California coast  

USGS Publications Warehouse

The U.S. Geological Survey has generated a comprehensive data clearinghouse of digital vector cliff edges and associated rates of cliff retreat along the open-ocean California coast. These data, which are presented herein, were compiled as part of the U.S. Geological Survey's National Assessment of Shoreline Change Project. Cliff erosion is a chronic problem along many coastlines of the United States. As coastal populations continue to grow and community infrastructures are threatened by erosion, there is increased demand for accurate information including rates and trends of coastal cliff retreat. There is also a critical need for these data to be consistent from one region to another. One objective of this work is to a develop standard, repeatable methodology for mapping and analyzing cliff edge retreat so that periodic, systematic, and internally consistent updates of cliff edge position and associated rates of erosion can be made at a national scale. This data compilation for open-ocean cliff edges for the California coast is a separate, yet related study to Hapke and others, 2006 documenting shoreline change along sandy shorelines of the California coast, which is itself one in a series that includes the Gulf of Mexico and the Southeast Atlantic coast (Morton and others, 2004; Morton and Miller, 2005). Future reports and data compilations will include coverage of the Northeast U.S., the Great Lakes, Hawaii and Alaska. Cliff edge change is determined by comparing the positions of one historical cliff edge digitized from maps with a modern cliff edge derived from topographic LIDAR (light detection and ranging) surveys. Historical cliff edges for the California coast represent the 1920s-1930s time-period; the most recent cliff edge was delineated using data collected between 1998 and 2002. End-point rate calculations were used to evaluate rates of erosion between the two cliff edges. Please refer to our full report on cliff edge erosion along the California coastline at http://pubs.usgs.gov/of/2007/1133/ for additional information regarding methods and results (Hapke and others, 2007). Data in this report are organized into downloadable layers by region (Northern, Central and Southern California) and are provided as vector datasets with accompanying metadata. Vector cliff edges may represent a compilation of data from one or more sources and the sources used are included in the dataset metadata. This project employs the Environmental Systems Research Institute's (ESRI) ArcGIS as it's Geographic Information System (GIS) mapping tool and contains several data layers (shapefiles) that are used to create a geographic view of the California coast. The vector data form a basemap comprising polygon and line themes that include a U.S. coastline (1:80,000), U.S. cities, and state boundaries.

Hapke, Cheryl; Reid, David; Borrelli, Mark

2007-01-01

227

Climate change and the potential for range expansion of the Lyme disease vector Ixodes scapularis in Canada.  

PubMed

We used an Ixodes scapularis population model to investigate potential northward spread of the tick associated with climate change. Annual degree-days >0 degrees C limits for I. scapularis establishment, obtained from tick population model simulations, were mapped using temperatures projected for the 2020s, 2050s and 2080s by two Global Climate Models (the Canadian CGCM2 and the UK HadCM3) for two greenhouse gas emission scenario enforcings 'A2'and 'B2' of the Intergovernmental Panel on Climate Change. Under scenario 'A2' using either climate model, the theoretical range for I. scapularis establishment moved northwards by approximately 200 km by the 2020s and 1000 km by the 2080s. Reductions in emissions (scenario 'B2') had little effect on projected range expansion up to the 2050s, but the range expansion projected to occur between the 2050s and 2080s was less than that under scenario 'A2'. When the tick population model was driven by projected annual temperature cycles (obtained using CGCM2 under scenario 'A2'), tick abundance almost doubled by the 2020s at the current northern limit of I. scapularis, suggesting that the threshold numbers of immigrating ticks needed to establish new populations will fall during the coming decades. The projected degrees of theoretical range expansion and increased tick survival by the 2020s, suggest that actual range expansion of I. scapularis may be detectable within the next two decades. Seasonal tick activity under climate change scenarios was consistent with maintenance of endemic cycles of the Lyme disease agent in newly established tick populations. The geographic range of I. scapularis-borne zoonoses may, therefore, expand significantly northwards as a consequence of climate change this century. PMID:16229849

Ogden, N H; Maarouf, A; Barker, I K; Bigras-Poulin, M; Lindsay, L R; Morshed, M G; O'callaghan, C J; Ramay, F; Waltner-Toews, D; Charron, D F

2006-01-01

228

Selective Vectorization for Short-Vector Instructions  

E-print Network

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

Amarasinghe, Saman

2009-12-18

229

A device for rapid determination of thermophysical properties of phase-change wind-tunnel models  

NASA Technical Reports Server (NTRS)

An experimental method for direct measurement of the thermophysical properties of wind tunnel heat transfer models was developed. The technique consists of placing the model under a bank of high intensity, radiant heaters so that the fast opening water cooled shutters, which isolate the heater bank from the model, allow a step-input heat rate to be applied. Measurements of the heat transfer rate coupled with a surface-temperature time history of the same material are sufficient to determine the material thermophysical properties. An infrared thermometer is used to measure model surface temperature and a slug calorimeter provides heat transfer rate information. The output from the infrared thermometer and calorimeter is then fed into an analog-to-digital converter which provides digitized data to a computer. This computer then calculates combined thermophysical properties and a teleprinter prints out all the data. Thus, results are available within 7 minutes of test initiation as opposed to the weeks or months required using prior techniques.

Creel, T. R., Jr.

1976-01-01

230

Changes in solar wind-magnetosphere coupling with solar cycle, season, and time relative to stream interfaces  

NASA Astrophysics Data System (ADS)

Geomagnetic activity depends on a variety of factors including solar zenith angle, solar UV, strength of the interplanetary magnetic field, speed and density of the solar wind, orientation of the Earth’s dipole, distance of the Earth from Sun, occurrence of CMEs and CIRs, and possibly other parameters. We have investigated some of these using state-dependant linear prediction filters. For a given state a prediction filter transforms a coupling function such as rectified solar wind electric field (VBs) to an output like the auroral electrojet index (AL). The area of this filter calculated from the sum of the filter coefficients measures the strength of the coupling. When the input and output are steady for a time longer than the duration of the filter the ratio of output to input is equal to this area. We find coupling strength defined in this way for Es=VBs to AL (and AU) is weakest at solar maximum and strongest at solar minimum. AL coupling displays a semiannual variation being weakest at the solstices and strongest at the equinoxes. AU coupling has only an annual variation being strongest at summer solstice. AL and AU coupling also vary with time relative to a stream interface. Es coupling is weaker after the interface, but ULF coupling is stronger. Total prediction efficiency remains about constant at the interface. The change in coupling strength with the solar cycle can be explained as an effect of more frequent saturation of the polar cap potential causing a smaller ratio of AL to Es. Stronger AL coupling at the equinoxes possibly indicates some process that makes magnetic reconnection less efficient when the dipole axis is tilted along the Earth-Sun line. Strong AU coupling at summer solstice is likely due to high conductivity in northern summer. Coupling changes at a stream interface are correlated with the presence of strong wave activity in ground and satellite measurements and may be an artifact of the method by which solar wind data are propagated.

McPherron, Robert L.; Baker, Daniel N.; Pulkkinen, T. I.; Hsu, T.-S.; Kissinger, J.; Chu, X.

2013-07-01

231

Simulation of Variable Speed Wind Generation System Using Boost Converter of Permanent Magnet Synchronous Generator  

NASA Astrophysics Data System (ADS)

This paper proposes variable-speed wind generation system using the boost converter. The proposed system has three speed control modes for the wind velocity. The control mode of low wind velocity regulates the armature current of the generator with the boost converter to control the speed of wind turbine. The control mode of middle wind velocity regulates the DC link voltage with the vector controlled inverter to control the speed of wind turbine. The control mode of high wind velocity regulates the pitch angle of the wind turbine with the pitch angle control system to control the speed of wind turbine. The hybrid of three control modes extends the variable-speed range. The proposed system simplifies the maintenance and improves the reliability and reduces the cost in compare with the variable-speed wind generation system using PWM converter. This paper describes the control strategy and modeling for simulation using Matlab Simulink of the proposed system. Also this paper describes the control strategy and modeling of variable-speed wind generation system using PWM converter. The steady state and transient responses for wind velocity changes are simulated using the Matlab Simulink. This paper verifies the fundamental performance of the system using boost converter by discussing the simulation results of the both systems.

Ohyama, Kazuhiro; Sakamoto, Tsuyoshi; Arinaga, Shinji; Yamashita, Yukio

232

Short Time Scale Changes in Underwater Irradiance in a Wind-exposed Lagoon (Vaccarès Lagoon, France): Efficiency of Infrequent Field Measurements of Water Turbidity or Weather Data to Predict Irradiance in the Water Column  

Microsoft Academic Search

High frequency water sampling in the wind-exposed Vaccarès lagoon revealed frequent and rapid changes in suspended solid (SS) concentrations in the water column. SS concentrations, sometimes higher than 800 mg l?1, were significantly correlated with antecedent wind conditions. Mean wind velocity during the 5–33 h before water sampling or maximal wind velocity during the previous 8.5–22 h were good predictors of SS concentrations

Damien Banas; Patrick Grillas; Isabelle Auby; François Lescuyer; Eric Coulet; Jean-Claude Moreteau; Bertrand Millet

2005-01-01

233

Holocene changes in a park-forest vegetation mosaic in the Wind River Range, Wyoming  

SciTech Connect

The modern mod-elevation vegetation of the Rocky Mountains is a mosaic of conifer forests and open parks dominated by sagebrush (Artemisia spp.), grasses, and other herbs. It is not known how this pattern originated or how sensitive the balance between forest and park is to disturbance. Using pollen from sediments of five small ponds in Fish Creek Park, WY (elev. 2700 m), I reconstructed the last 8000 yrs of changes in the park-forest mosaic in an are about 16 km[sup 2]. Surface samples collected from 52 ponds in the Fish Creek Park area and from forest and park sites in Wyoming and Colorado indicate that park and forest pollen assemblages can be distinguished using multivariate statistical methods and conifer:herb pollen ratios. Fossil pollen from the five sediment cores shows that the distribution of the two vegetation types on the landscape has changed through the Holocene, and that the changes in vegetation are gradual. Past changes from park to forest have apparently occurred much more slowly than changes from forest to park, suggesting that areas subjected to recent clearcutting may remain unforested for centuries.

Lynch, E.A. (Univ. of Minnesota, St. Paul, MN (United States))

1994-06-01

234

Stochastic Dynamics of Sea Surface Winds Adam Hugh Monahan  

E-print Network

Stochastic Dynamics of Sea Surface Winds Adam Hugh Monahan School of Earth and Ocean Sciences The probability distribution of sea surface winds (both vector winds and wind speed) is considered. The observed moment fields, estimated from SeaWinds scatterometer data, are shown to be characterised by non

Monahan, Adam Hugh

235

Three Dimensional Dynamic Model Based Wind Field Reconstruction from Lidar Data  

NASA Astrophysics Data System (ADS)

Using the inflowing horizontal and vertical wind shears for individual pitch controller is a promising method if blade bending measurements are not available. Due to the limited information provided by a lidar system the reconstruction of shears in real-time is a challenging task especially for the horizontal shear in the presence of changing wind direction. The internal model principle has shown to be a promising approach to estimate the shears and directions in 10 minutes averages with real measurement data. The static model based wind vector field reconstruction is extended in this work taking into account a dynamic reconstruction model based on Taylor's Frozen Turbulence Hypothesis. The presented method provides time series over several seconds of the wind speed, shears and direction, which can be directly used in advanced optimal preview control. Therefore, this work is an important step towards the application of preview individual blade pitch control under realistic wind conditions. The method is tested using a turbulent wind field and a detailed lidar simulator. For the simulation, the turbulent wind field structure is flowing towards the lidar system and is continuously misaligned with respect to the horizontal axis of the wind turbine. Taylor's Frozen Turbulence Hypothesis is taken into account to model the wind evolution. For the reconstruction, the structure is discretized into several stages where each stage is reduced to an effective wind speed, superposed with a linear horizontal and vertical wind shear. Previous lidar measurements are shifted using again Taylor's Hypothesis. The wind field reconstruction problem is then formulated as a nonlinear optimization problem, which minimizes the residual between the assumed wind model and the lidar measurements to obtain the misalignment angle and the effective wind speed and the wind shears for each stage. This method shows good results in reconstructing the wind characteristics of a three dimensional turbulent wind field in real-time, scanned by a lidar system with an optimized trajectory.

Raach, Steffen; Schlipf, David; Haizmann, Florian; Cheng, Po Wen

2014-06-01

236

Medical Education In the Anatomical Sciences: The Winds of Change Continue to Blow  

NSDL National Science Digital Library

This article describes a follow up survey identifying the changes over a decade in medical curriculum. Directors of medical schools responded to questions pertaining to total course hours, lab hours, lecture hours, lab is integrated or stand alone, and laboratory experience. Outcomes of differences over time are discussed.

Dr. Jennifer M McBride (Cleveland Clinic, Lerner College of Medicine of Case Western Reserve University, Surgery)

2009-11-01

237

CHANGES OF SYSTEM OPERATION COSTS DUE TO LARGE-SCALE WIND INTEGRATION  

E-print Network

BARTH1 , Peter MEIBOM3 , Christoph WEBER2 , 1 University of Stuttgart, Germany 2 University of Duisburg sources. This leads to a great interest in simulation and optimization models for estimating the costs Model Institute of Energy Economics and the Rational Use of EnergyIER Changes of System Operation Costs

238

New techniques in 3D scalar and vector field visualization  

SciTech Connect

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

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

1993-05-05

239

Microenvironmental changes and plant responses due to shading and wind deflectio by solar collectors: a simulation study  

SciTech Connect

The potential microenvironmental changes at the ground surface beneath arrays of solar mirrors or collectors were investigated in a Sonoran Desert ecosystem, utilizing a simulated array of plywood panels. The simulated array consisted of twelve panels designed to exhibit a similar shape, tilt, and spacing as is expected to occur in heliostat fields of solar thermal facilities or in arrays of photovoltaic collectors. The experimental design in the study was based on comparing two microsites in the simulated array versus the open desert. Presence of the panels results in up to a 90% reduction in solar radiance during the midday period, with microsites beneath each panel receiving about 14% of the open desert irradiance over the whole day. The array of panels also effected a 14% to 60% reduction in monthly accumulated wind flow in the center of the array. The combination of reduced radiant energy input and wind deflection resulted in significantly reduced surface and soil temperatures in the heavily shaded sites, and moderately reduced surface and soil temperatures in the sunny microsites. Plant responses to a cooler, moister environment were: (1) higher diversity and survival of winter spring annuals; (2) proliferation of C/sub 3/ annuals in the summer flora versus the more typical C/sub 4/ annuals in the open; (3) greater new shoot production of shrubs; (4) greater gross photosynthesis and stomatal conductance of the two shrub species in the warm dry season, but not in the cool wet season; (5) increased leaf retention and reduction in the typical leaf polymorphic character into the dry season of the drought deciduous Ambrosia deltoidea; and, (6) invasion of the heavily shaded areas of the array by a pseudo-riparian species, Baccharis sarothroides. (WHK)

Patten, D.T.; Smith, S.D.

1980-11-01

240

Wind turbine  

DOEpatents

A wind turbine of the type having an airfoil blade (15) mounted on a flexible beam (20) and a pitch governor (55) which selectively, torsionally twists the flexible beam in response to wind turbine speed thereby setting blade pitch, is provided with a limiter (85) which restricts unwanted pitch change at operating speeds due to torsional creep of the flexible beam. The limiter allows twisting of the beam by the governor under excessive wind velocity conditions to orient the blades in stall pitch positions, thereby preventing overspeed operation of the turbine. In the preferred embodiment, the pitch governor comprises a pendulum (65,70) which responds to changing rotor speed by pivotal movement, the limiter comprising a resilient member (90) which engages an end of the pendulum to restrict further movement thereof, and in turn restrict beam creep and unwanted blade pitch misadjustment.

Cheney, Jr., Marvin C. (Glastonbury, CT)

1982-01-01

241

Abstract--A bi-objective optimization model of power and power changes generated by a wind turbine is discussed in this  

E-print Network

production. Power ramp rate (PRR) expresses the change of power for a given time interval, e.g., a minute of a photovoltaic generator by using an electric double-layer capacitor. Zheng et al. [3] applied data results at 10-min to 60-min intervals was demonstrated in their research. The operation of wind turbines

Kusiak, Andrew

242

Amazonian malaria: Asymptomatic human reservoirs, diagnostic challenges, environmentally-driven changes in mosquito vector populations, and the mandate for sustainable control strategies  

PubMed Central

Across the Americas and the Caribbean, nearly 561,000 slide-confirmed malaria infections were reported officially in 2008. The nine Amazonian countries accounted for 89% of these infections; Brazil and Peru alone contributed 56% and 7% of them, respectively. Local populations of the relatively neglected parasite P. vivax, which currently accounts for 77% of the regional malaria burden, are extremely diverse genetically and geographically structured. At a time when malaria elimination is placed on the public health agenda of several endemic countries, it remains unclear why malaria proved so difficult to control in areas of relatively low levels of transmission such as the Amazon Basin. We hypothesize that asymptomatic parasite carriage and massive environmental changes that affect vector abundance and behavior are major contributors to malaria transmission in epidemiologically diverse areas across the Amazon Basin. Here we review available data supporting this hypothesis and discuss their implications for current and future malaria intervention policies in the region. Given that locally generated scientific evidence is urgently required to support malaria control interventions in Amazonia, we briefly describe the aims of our current field-oriented malaria research in rural villages and gold-mining enclaves in Peru and a recently opened agricultural settlement in Brazil. PMID:22015425

da Silva-Nunes, Monica; Moreno, Marta; Conn, Jan E.; Gamboa, Dionicia; Abeles, Shira; Vinetz, Joseph M.; Ferreira, Marcelo U.

2012-01-01

243

Observed And Predicted Flow Variability Over The Baltic Region: Implications Of Climate Change For Wind Energy Viability  

Microsoft Academic Search

We present analysis of historical and prognostic future flow regimes in the Baltic with the perspective of the viability of wind energy. Analysis of 850 hPa wind speeds as manifest in the NCEP\\/NCAR reanalysis fields over the Baltic region indicates annual mean wind speeds over the Baltic significantly increased over the period 1953-1999 with the majority of the increase being

S. C. Pryor; R. J. Barthelmie; J. T. Schoof

2003-01-01

244

Dengue Vectors and their Spatial Distribution  

PubMed Central

The distribution of dengue vectors, Ae. aegypti and Ae. albopictus, is affected by climatic factors. In addition, since their life cycles are well adapted to the human environment, environmental changes resulting from human activity such as urbanization exert a great impact on vector distribution. The different responses of Ae. aegypti and Ae albopictus to various environments result in a difference in spatial distribution along north-south and urban-rural gradients, and between the indoors and outdoors. In the north-south gradient, climate associated with survival is an important factor in spatial distribution. In the urban-rural gradient, different distribution reflects a difference in adult niches and is modified by geographic and human factors. The direct response of the two species to the environment around houses is related to different spatial distribution indoors and outdoors. Dengue viruses circulate mainly between human and vector mosquitoes, and the vector presence is a limiting factor of transmission. Therefore, spatial distribution of dengue vectors is a significant concern in the epidemiology of the disease. Current technologies such as GIS, satellite imagery and statistical models allow researchers to predict the spatial distribution of vectors in the changing environment. Although it is difficult to confirm the actual effect of environmental and climate changes on vector abundance and vector-borne diseases, environmental changes caused by humans and human behavioral changes due to climate change can be expected to exert an impact on dengue vectors. Longitudinal monitoring of dengue vectors and viruses is therefore necessary. PMID:22500133

Higa, Yukiko

2011-01-01

245

Directional trends in thermospheric neutral winds observed at Arecibo during the past three solar cycles  

NASA Astrophysics Data System (ADS)

Since 1980, we have observed the thermospheric neutral wind at the Arecibo Observatory using a Fabry-Perot interferometer to measure the O(1D) 630 nm emission. Burnside and Tepley (1989) examined the first 8 years of this extended data set and found that there were no significant or systematic solar cycle influences on the magnitude or direction of the neutral wind field, nor on its horizontal gradients. Such affects have been observed previously at other locations around the globe, and their absence at Arecibo may have been due to the limited data set. Thus, we have extended the period of acquisition and analysis of our neutral wind measurements to include nearly three complete solar cycles (or approximately 30 years) and will present our results within the framework of the earlier work. While the earlier conclusion that no major systematic solar cycle influence on the neutral winds at Arecibo generally remains intact, we did find a slight increase in wind magnitude and a gradual, yet consistent rotation of the thermospheric neutral wind vector from a general southeast to a more eastward flow during 30 years of observation. We explain the magnitude and directional variations in terms of long-term changes in the density and temperature of the upper atmosphere and their possible dissimilar influences on each wind component that appear as a rotation of the neutral wind vector.

Tepley, C. A.; Robles, E.; García, R.; Santos, P. T.; Brum, C. M.; Burnside, R. G.

2011-06-01

246

Wind Tubes  

NSDL National Science Digital Library

In this activity, learners create and experiment with wind tubes. These tubes are a playful and inventive way to explore the effect that moving air has on objects. Construction uses everyday materials such as a fan and embroidery hoops. Itâs fun to make things fly out of or float in the tubes, and to adjust the tubes to change the way the objects fly. The activity requires a significant amount of time and resources to build and may require adult help in construction. Experimentation with the wind tubes is engaging for a wide age range of learners.

Exploratorium

2012-12-14

247

Large-scale variability of wind erosion mass flux rates at Owens Lake. 2. Role of roughness change, particle limitation, change of threshold friction velocity, and the Owen effect  

NASA Astrophysics Data System (ADS)

Variability in airborne particles larger than sand flux for distance scales larger than 200 m was observed during wind erosion episodes on the northeast side of a dry lake bed (Owens Lake). Measurements were made during erosion episodes on a ˜3-km line of wind measuring and sand flux collecting instruments. Data were selected for winds that (1) aligned with the instrument line and (2) had mean speeds cubed at 4-m heights at the beginning, middle, and end of the line that differed by less than 5% (i.e., mean wind speeds differed by less than 1.7%). Four mechanisms were determined to cause the large-scale differences in the mass flux profiles. In order of their importance, the mechanisms are as follows: (1) change of the drag coefficient (or the ratio u*/U, where u* is wind friction velocity and U is mean wind speed from place to place), this is a measure of variability in roughness height; (2) particle limitation (depletion of the loose "available" erodible material on the surface); (3) variation of the threshold friction velocity; and (4) the Owen effect (the increase of u*/U with U).

Gillette, Dale A.; Hardebeck, Ellen; Parker, Jim

1997-11-01

248

Characteristics of transformer-type superconducting fault current limiter depending on reclosing in changing the number of turns of secondary winding  

NASA Astrophysics Data System (ADS)

The amount of consumed power is increasing with industrial development and rapidly increasing population. In accidents due to increased power consumption, the fault current sharply increases. Superconducting fault current limiters (SFCL) are studied widely to limit such fault currents. In this study, the characteristics of a transformer-type SFCL are analyzed depending on reclosing in changing the number of secondary winding turns. For experiment conditions, the turn ratio of the primary and secondary windings of a transformer-type SFCL was set to 4:2 and 4:4. The voltage was incremented by 80 V from 120 V for the experiment. The circuit breaker was operated with two open times of CO-0.17 s - CO-0.17 s - CO seconds ( C; closed, O; open), respectively. Comparing the result for the experiment conditions with the case of the turn ratios of the primary and secondary windings at 4:4 and 4:2, the fault current was limited effectively in 4:2 than in 4:4 for the fault current limit ratios. With respect to the result of recovery characteristics, it was examined that the superconducting unit recovered faster when the turn ratio of the primary and secondary windings was 4:2 than 4:4. Comparing the amount of consumed power related to the recovery characteristics of the superconducting element, it was examined that the recovery time was faster in less power consumption for the superconducting unit. As such, since a transformer-type SFCL depending on reclosing in changing the number of turns of the secondary winding controls the turn ratio of the secondary winding to control fault current limiting and recovery characteristics, it can normally operate.

Choi, S. G.; Choi, H. S.; Cho, Y. S.; Park, H. M.; Jung, B. I.; Ha, K. H.

2011-11-01

249

Rapid COMMUNICATION Mean winds in the mesopause region observed by MF radars at 31° and 45°N  

NASA Astrophysics Data System (ADS)

Mean winds in the mesopause region (78-98 km) were observed in northern (45°N) and southern (31°N) Japan by MF radars. The change of the horizontal wind vector with height is illustrated by means of hodographs for solstices and equinoxes. The observations in southern Japan show a stronger meridional wind than in northern Japan. At the December solstice 1996 the meridional wind over southern Japan changes from a northward wind of around 15 ms at 78 km to a southward wind of 10 ms at 98 km height. At the March and September equinoxes the southward wind increases from around 0 to 15 ms in this region. The observed meridional wind is significantly stronger than the meridional wind of the empirical HWM93 wind model, but is in agreement with previous observations by the MU radar in Kyoto (35°N). The temporal behaviour of the mean wind hodographs is shown for the three annual cycles from 1994-1997 over southern Japan.

Hocke, K.; Igarashi, K.

1998-07-01

250

Vector Addition Calculator  

NSDL National Science Digital Library

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

Joiner, David; The Shodor Education Foundation, Inc.

251

Downscaling and predictability of historical monthly mean surface winds over a region of complex terrain and marine influence: Western Canada  

NASA Astrophysics Data System (ADS)

Surface wind is a vector quantity exhibiting high spatial and temporal variability. Consequently, it presents a challenge for methods of statistical downscaling, which are used to establish a relationship between the large-scale atmospheric flow (predictors) and local climate variables (predictands). Simple regression-based techniques, for example, used with success for smoother predictands such as temperature, may not be as effective when applied to wind. In this work, the predictability of surface wind magnitude and direction at 28 stations in Western Canada over the period 1979-2006 was assessed using NCEP-2 reanalysis fields to derive large-scale predictors. Specifically, a combined principal components (PC) analysis was employed with the wind components at 500 hPa and mean sea level pressure as input fields, and the first 5 PCs used as predictors. The predictands were either wind speed or vector wind components oriented along directions ranging from 0 to 170 degrees at 10 degree intervals. Multiple linear regression was used for the downscaling, and its robustness assessed via cross-validation with an associated Pearson R2 value. This approach might be expected to display relatively high predictability, since it is comprised almost entirely of observations. However, our findings show that often this is not the case. Overall, wind speed was poorly predicted (R2<0.5), with the exception of a handful of stations in autumn and winter. By contrast, wind components were predicted with better skill than wind speeds at nearly all stations year-round, with the highest R2 values in autumn (SON) and lowest values in summer (JJA). The predictability of wind components was found to depend upon the topographic character of the region surrounding a given station. In mountainous regions, e.g., predictive skill was strongly related to the orientation of the components, with the best predicted components oriented along topographically significant directions such as constricted valleys and ocean channels. Predictability at stations in regions of relatively flat terrain was less dependent on wind direction. The latter stations also displayed region-wide seasonal shifts in the direction of the most skillfully predicted wind component. In summary, at most stations in Western Canada, monthly mean vector wind components were more reliably predicted than wind speeds. This result complicates the assessment of local changes in mean wind speed, extremes, and wind energy under climate change that is often a desired outcome of the downscaling exercise using modelled fields as predictors. However, useful projections might still be obtained at stations where a single wind direction is dominant.

Curry, C.; van der Kamp, D.; Monahan, A. H.

2010-12-01

252

Chikungunya Virus–Vector Interactions  

PubMed Central

Chikungunya virus (CHIKV) is a mosquito-borne alphavirus that causes chikungunya fever, a severe, debilitating disease that often produces chronic arthralgia. Since 2004, CHIKV has emerged in Africa, Indian Ocean islands, Asia, Europe, and the Americas, causing millions of human infections. Central to understanding CHIKV emergence is knowledge of the natural ecology of transmission and vector infection dynamics. This review presents current understanding of CHIKV infection dynamics in mosquito vectors and its relationship to human disease emergence. The following topics are reviewed: CHIKV infection and vector life history traits including transmission cycles, genetic origins, distribution, emergence and spread, dispersal, vector competence, vector immunity and microbial interactions, and co-infection by CHIKV and other arboviruses. The genetics of vector susceptibility and host range changes, population heterogeneity and selection for the fittest viral genomes, dual host cycling and its impact on CHIKV adaptation, viral bottlenecks and intrahost diversity, and adaptive constraints on CHIKV evolution are also discussed. The potential for CHIKV re-emergence and expansion into new areas and prospects for prevention via vector control are also briefly reviewed. PMID:25421891

Coffey, Lark L.; Failloux, Anna-Bella; Weaver, Scott C.

2014-01-01

253

Cross-border transfer of climate change mitigation technologies : the case of wind energy from Denmark and Germany to India  

E-print Network

This research investigated the causal factors and processes of international development and diffusion of wind energy technology by examining private sector cross-border technology transfer from Denmark and Germany to India ...

Mizuno, Emi, Ph. D. Massachusetts Institute of Technology

2007-01-01

254

Solar Wind Magnetic Fields  

NASA Technical Reports Server (NTRS)

The magnetic fields originate as coronal fields that are converted into space by the supersonic, infinitely conducting, solar wind. On average, the sun's rotation causes the field to wind up and form an Archimedes Spiral. However, the field direction changes almost continuously on a variety of scales and the irregular nature of these changes is often interpreted as evidence that the solar wind flow is turbulent.

Smith, E. J.

1995-01-01

255

Relating high-Latitude Topside Ionospheric Vertical Electron-Density-Profile changes to Solar-Wind Parameters During Large Magnetic Storms  

NASA Astrophysics Data System (ADS)

Ten large magnetic storms (Dst < -100 nT) where high-latitude topside electron-density profiles Ne(h) could be obtained from Alouette/ISIS topside-sounder data, and where solar-wind data were available, were investigated. The former were obtained from the NASA Space Physics Data Facility (SPDF) and the latter were obtained from the NASA OMNIWeb database. Large Ne(h) changes were observed during the storms in all cases. In some cases large topside Ne(h) gradients were observed between adjacent ionograms (separated by ~ ½ minute) and even within a single ionogram (profiles separated by < 10 s). The changes in the winter profiles have a clear relationship with the solar-wind velocity Vsw in that the topside Ne(h) increases with increasing Vsw during nighttime and decreases with increasing Vsw during daytime.

Benson, R. F.; Fainberg, J.; Osherovich, V.; Truhlik, V.; Wang, Y.; Bilitza, D.; Lam, H.

2012-12-01

256

THE WAVENUMBER SPECTRA OF SCATTEROMETER-DERIVED WINDS  

E-print Network

THE WAVENUMBER SPECTRA OF SCATTEROMETER-DERIVED WINDS D. G . Long and D. D. Luke Electrical Spaceborne scatterometers are the only proven method for global all-weather measurement of vector winds/seainteraction where the time variability of the surface wind field and the wind stress curl drive the ocean; hence

Long, David G.

257

Advances in Microwave Remote Sensing: Ocean Wind Speed and Direction  

NSDL National Science Digital Library

This Webcast covers the ocean surface wind retrieval process, the basics of microwave polarization as it relates to wind retrievals, and several operational examples. Information on the development of microwave sensors used to retrieve ocean surface wind speed and the ocean surface wind vector (speed and direction) is also included.

Comet

2005-11-28

258

A twisted flow wind tunnel for testing yacht sails  

Microsoft Academic Search

The paper outlines the requirements for wind tunnel testing model yachts for sail aerodynamics investigations. It is shown that the apparent wind onto a yacht is “twisted” over the mast height, due to the vector addition of the yacht and wind velocities. The design features of a special wind tunnel built in New Zealand which can produce twisted flow in

Richard G. J. Flay

1996-01-01

259

Vectoring: Steering a Plane  

NSDL National Science Digital Library

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

Nasa

2011-08-20

260

Evapotranspiration modelling using support vector machines \\/ Modélisation de l'évapotranspiration à l'aide de ‘support vector machines’  

Microsoft Academic Search

This study investigates the accuracy of support vector machines (SVM), which are regression procedures, in modelling reference evapotranspiration (ET0). The daily meteorological data, solar radiation, air temperature, relative humidity and wind speed from three stations, Windsor, Oakville and Santa Rosa, in central California, USA, are used as inputs to the support vector machines to reproduce ET0 obtained using the FAO-56

OZGUR KI?I; MESUT ÇIMEN

2009-01-01

261

Motion filter vector quantization  

Microsoft Academic Search

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

Dariusz Blasiak; Wai-yip Chan

2002-01-01

262

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

263

An assessment of thermal, wind, and planetary wave changes in the middle and lower atmosphere due to 11-year UV flux variations  

NASA Technical Reports Server (NTRS)

Hines (1974) speculated that solar-induced modifications of the middle and upper atmosphere may alter the transmissivity of the stratosphere to upwardly propagating atmospheric waves. It was suggested that subsequent constructive or destructive interference may result in a change of phase or amplitude of these waves in the troposphere leading to weather or climate changes. The present investigation has the objective to bring together both radiative transfer and planetary wave studies in an effort to assess specifically whether Hines mechanism can be initiated by the solar ultraviolet flux variability assumed to be associated with the 11-year solar cycle. The obtained results suggest that the presently studied mechanism, which links solar-induced zonal wind changes in the stratosphere and mesosphere to planetary wave changes in the troposphere, is not strong enough to cause substantive changes in the troposphere.

Callis, L. B.; Alpert, J. C.; Geller, M. A.

1985-01-01

264

(^-L_n,g)-spaces. Length of a vector field and the angle between two vector fields  

E-print Network

The notions of length of a vector field and cosine of the angle between two vector fields over a differentiable manifold with contravariant and covariant affine connections and metrics are introduced and considered. The change of the length of a vector field and of the angle between two vector fields along a contravariant vector field are found. The introduced notions are necessary for investigations of different types of transports over a manifold of the above mentioned type.

S. Manoff

2000-02-22

265

The transduction of rat submandibular glands by an adenoviral vector carrying the human growth hormone gene is associated with limited and reversible changes at the infusion site.  

PubMed

Adenoviral vectors have been shown to efficiently deliver exogenous genes to salivary glands and have therefore been investigated as tools for the treatment of human disease. The purpose of this study was to evaluate the response of F344 rats to intraductal infusion of the right submandibular salivary gland with an adenoviral vector encoding the gene for human growth hormone (AdCMVhGH). Co-administration of hydroxychloroquine (HCQ) was used to redirect the secretion of human growth hormone (hGH) from saliva into serum. This paper documents the findings of the pathology evaluation of this National Toxicology Program study. The right submandibular salivary gland (infusion site) was the primary target organ, with microscopic lesions characteristic of a mild to moderate insult observed at 3 days post infusion in vector exposed animals. These lesions were characterized by variable degrees of acute glandular inflammation, degeneration and necrosis, with more severe lesions in the higher dose groups. Rats at 28 days post infusion had milder inflammation, degeneration and necrosis compared to day 3 rats, with variable degrees of regeneration. In conclusion, the effects on the salivary glands are reversible as indicated by the milder inflammation and degeneration in the day 28 rats concomitant with mild to moderate regeneration. Therefore, the vector appears relatively innocuous with limited tissue toxicity. [The supplemental data referenced in this paper is not printed in this issue of Toxicologic Pathology. It is available as a downloadable file in the online edition of Toxicologic Pathology, 34(4). In order to access the full article online, you must have either an individual subscription or a member subscription accessed through www.toxpath.org.]. PMID:16844666

Elmore, S; Lanning, L; Allison, N; Vallant, M; Nyska, A

2006-01-01

266

Comparison of the response of doubly fed and fixed-speed induction generator wind turbines to changes in network frequency  

Microsoft Academic Search

Synchronous and fixed-speed induction generators release the kinetic energy of their rotating mass when the power system frequency is reduced. In the case of doubly fed induction generator (DFIG)-based wind turbines, their control system operates to apply a restraining torque to the rotor according to a predetermined curve with respect to the rotor speed. This control system is not based

J. Ekanayake; N. Jenkins

2004-01-01

267

Association of Anthropogenic Land Use Change and Increased Abundance of the Chagas Disease Vector Rhodnius pallescens in a Rural Landscape of Panama  

PubMed Central

Anthropogenic disturbance is associated with increased vector-borne infectious disease transmission in wildlife, domestic animals, and humans. The objective of this study was to evaluate how disturbance of a tropical forest landscape impacts abundance of the triatomine bug Rhodnius pallescens, a vector of Chagas disease, in the region of the Panama Canal in Panama. Rhodnius pallescens was collected (n = 1,186) from its primary habitat, the palm Attalea butyracea, in five habitat types reflecting a gradient of anthropogenic disturbance. There was a high proportion of palms infested with R. pallescens across all habitat types (range = 77.1–91.4%). Results show that disturbed habitats are associated with increased vector abundance compared with relatively undisturbed habitats. Bugs collected in disturbed sites, although in higher abundance, tended to be in poor body condition compared with bugs captured in protected forest sites. Abundance data suggests that forest remnants may be sources for R. pallescens populations within highly disturbed areas of the landscape. PMID:21212205

Gottdenker, Nicole L.; Calzada, José E.; Saldaña, Azäel; Carroll, C. Ronald

2011-01-01

268

Experimental investigation of change of energy of infragavity waves in dependence on spectral characteristics of an irregular wind waves in coastal zone  

NASA Astrophysics Data System (ADS)

An infragravity waves are long waves with periods of 20 - 300 s. Most essential influence of infragarvity waves on dynamic processes is in a coastal zone, where its energy can exceed the energy of wind waves. From practical point of view, the infragravity waves are important, firstly, due to their influence on sand transport processes in a coastal zone. For example, interacting with group structure of wind waves the infragravity waves can define position of underwater bars on sandy coast. Secondly, they are responsible on formation of long waves in harbors. Main source of infragravity waves is wave group structure defined by sub-nonlinear interactions of wind waves (Longuet-Higgins, Stewart, 1962). These infragravity waves are bound with groups of wind waves and propagate with wave group velocity. Another type of infragravity waves are formed in a surf zone as a result of migration a wave breaking point (Symonds, et al., 1982). What from described above mechanisms of formation of infragravity waves prevails, till now it is unknown. It is also unknown how energy of infragravity waves depends on energy of input wind waves and how it changes during nonlinear wave transformation in coastal zone. In our work on the basis of the analysis of data of field experiment and numerical simulation a contribution of infragravity waves in total wave energy in depending on integral characteristics of an irregular wave field in the conditions of a real bathymetry was investigated. For analysis the data of field experiment "Shkorpilovtsy-2007" (Black sea) and data of numerical modeling of Boussinesq type equation with extended dispersion characteristics (Madsen et al., 1997) were used. It was revealed that infragravity waves in a coastal zone are defined mainly by local group structure of waves, which permanently changes due to nonlinearity, shoaling and breaking processes. Free infragravity waves appearing after wave breaking exist together with bound infragravity waves. There are no clear total dependences of energy of infrragravity waves from energy of wind waves and mean period of infragravity waves from mean period of wind waves. But significant wave height of infragravity waves depends on relative water depth (wave height of wind waves divided on water depth). There are different types of this dependence for breaking and non-breaking waves. The influence of peak period, significant wave height and directional spreading of initial wave spectrum on these dependences are discussed. The peculiarities of spectra of infragravity waves for non-breaking, breaking and multibreaking wind waves are shown. This work is supported by the RFBR, project 12-05-00965. References: Longuet-Higgins, M. S., R. W. Stewart, 1962. Radiation stress and mass transport in gravity waves, with an application to surf beats. J. Fluid Mech., 13, pp. 481-504. Symonds G., D.A. Huntley, A.J. Bowen, 1982. Two dimensional surf beat: long wave generation by a time-varying breakpoint. J. of Geoph. Res., 87(C), pp.492-498. Madsen P.A., Sorensen O.R., Shaffer H.A. 1997. Surf zone dynamics simulated by a Boussinesq type model. Coastal Engineering, 32, p. 255-287.

Saprykina, Yana; Divinskii, Boris

2013-04-01

269

Reduced Vector Preisach Model  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

270

Wind direction variability in Afternoon and Sunset Turbulence  

NASA Astrophysics Data System (ADS)

Understanding wind direction (WD) variability better is important for several reasons. Air pollution models need information about how variable wind direction is in different conditions (Davies and Thomson 1999). Accurate predictions of dispersion are important for human health and safety and allow for adaptation planning (Nagle et al. 2011). Other applications include horizontal diffusion, efficiency and fatigue of wind machines and air-sea interaction (Mahrt 2011). Most studies of wind direction variability have focused on nocturnal conditions because of greater variability in light winds. Modelling WD variability in transition periods when both mean wind speed and variance of the wind components are in a state of change can, however, also be very challenging and has not been the focus of earlier studies. The evening transitioning to the nocturnal boundary layer can play an important role in the diffusion process of pollutants and scalars emitted at surface and transported within the atmosphere. The Boundary Layer Late Afternoon and Sunset Turbulence (BLLAST) field campaign that took place in southern France in June and July 2011 focused on the decaying turbulence of the late afternoon boundary layer and related issues (Lothon et al. 2012). We analyse field measurements from BLLAST to investigate WD variability in the evening transition period. Standard deviations of horizontal wind direction fluctuations in the lowest 60 m of the boundary layer have been examined for dependence on mean wind speed, higher order moments and averaging time. Measurement results are interpreted using measured and idealized probability density functions of horizontal wind vectors. These are also used to develop analytical functions describing how WD variability depends on wind speed, variance and other controlling factors in the atmospheric boundary layer. References: Davies B.M., Thomson D.J., 1999. Comparison of some parameterizations of wind direction variability with observations, Atmospheric Enviroment 33, 4909-4917. Lothon M. et al., 2012. The Boundary-Layer Late Afternoon and Sunset Turbulence field experiment, Proc. of the 20th Symposium on Boundary-Layers and Turbulence, 7-13 July, Boston, MA, USA. Mahrt L., 2011. Surface Wind Direction Variability, Journal of Applied Meteorology and Climatology 50. 144-152. Nagle J.C., 2011. Adapting to Pollution, Research Roundtable on Climate Change, Adaptation, and Enviromental Law, Northwestern Law Searle Center, Legal and Regulatory Studies 7-18 April, IL, USA.

Nilsson, Erik; Lothon, Marie; Lohou, Fabienne; Mahrt, Larry

2014-05-01

271

Solar wind and the motion of dust grains  

NASA Astrophysics Data System (ADS)

In this paper, we investigate the action of solar wind on an arbitrarily shaped interplanetary dust particle. The final relativistically covariant equation of motion of the particle also contains the change of the particle's mass. The non-radial solar wind velocity vector is also included. The covariant equation of motion reduces to the Poynting-Robertson effect in the limiting case when a spherical particle is treated, when the speed of the incident solar wind corpuscles tends to the speed of light and when the corpuscles spread radially from the Sun. The results of quantum mechanics have to be incorporated into the physical considerations, in order to obtain the limiting case. If the solar wind affects the motion of a spherical interplanetary dust particle, then ?. Here, p'in and p'out are the incoming and outgoing radiation momenta (per unit time), respectively, measured in the proper frame of reference of the particle, and ? and ? are the solar wind pressure and the total scattering cross-sections, respectively. An analytical solution of the derived equation of motion yields a qualitative behaviour consistent with numerical calculations. This also holds if we consider a decrease of the particle's mass. Using numerical integration of the derived equation of motion, we confirm our analytical result that the non-radial solar wind (with a constant value of angle between the radial direction and the direction of the solar wind velocity) causes outspiralling of the dust particle from the Sun for large values of the particle's semimajor axis. The non-radial solar wind also increases the time the particle spirals towards the Sun. If we consider the periodical variability of the solar wind with the solar cycle, then there are resonances between the particle's orbital period and the period of the solar cycle.

Kla?ka, J.; Petržala, J.; Pástor, P.; Kómar, L.

2012-04-01

272

Winding for the wind  

Microsoft Academic Search

The mechanical properties and construction of epoxy-impregnated fiber-glass blades for wind turbines are discussed, along with descriptions of blades for the Mod 0A and Mod 5A WECS and design goals for a 4 kW WECS. Multicell structure combined with transverse filament tape winding reduces labor and material costs, while placing a high percentage of 0 deg fibers spanwise in the

O. Weingart

1981-01-01

273

Adding Two Vectors  

NSDL National Science Digital Library

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

Harrison, David M.

2010-08-13

274

Bottom-current and wind-pattern changes as indicated by Late Glacial and Holocene sediments from western Lake Geneva (Switzerland)  

USGS Publications Warehouse

The Late-Glacial and Holocene sedimentary history of the Hauts-Monts area (western Lake Geneva, Switzerland) is reconstructed combining high resolution seismic stratigraphy and well-dated sedimentary cores. Six reflections and seismic units are defined and represented by individual isopach maps, which are further combined to obtain a three-dimensional age-depth model. Slumps, blank areas and various geometries are identified using these seismic data. The sediment depositional areas have substantially changed throughout the lake during the end of the Late-Glacial and the Holocene. These changes are interpreted as the result of variations in the intensity of deep lake currents and the frequency of strong winds determining the distribution of sediment input from the Versoix River and from reworking of previously deposited sediments within the lacustrine basin. The identified changes in sediment distribution allowed us to reconstruct the lake's deep-current history and the evolution of dominant strong wind regimes from the Preboreal to present times.

Girardclos, S.; Baster, I.; Wildi, W.; Pugin, A.; Rachoud-Schneider, A. -M.

2003-01-01

275

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

276

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

277

Aerodynamics of Spherical Balloon Wind Sensors  

Microsoft Academic Search

A preliminary analysis of the response characteristics of spherical balloon wind sensors is presented. It is shown that smoosuperpressure spheres do, not provide accurate detailed wind profiles and that the response characteristics can be improved by the addition of roughness elements. Experimental data show that surface roughness elements on a spherical balloon stabilize the drag force vector and reduce the

James R. Scoggins; Aero-Astrodynamics Labo

1964-01-01

278

Using incoherent scatter radar to investigate the neutral wind long-term trend over Arecibo  

NASA Astrophysics Data System (ADS)

Thermospheric neutral winds can be the most important driver when modeling ionospheric densities and temperatures. Several papers in this special edition show interesting features of the neutral winds behavior during the last 30 years at the Arecibo Observatory (18.3°N, 66.75°W ˜28.25° dip latitude) using Fabry-Perot Interferometer (FPI) data. A neutral wind vector that changes its direction, becoming more dominantly eastward over the years and a meridional neutral wind component that decreases in magnitude, were found. The main goal of this work is to look for similar evidence of long-term trends in the radar derived winds that might support these recent discoveries and explore the associated ionospheric parameter measurements to look for the effects of these changing winds on the ionosphere. With this purpose in mind, Incoherent Scatter Radar (ISR) measurements of the F region vector drifts are used to derive the corresponding meridional thermospheric neutral wind along the magnetic field over Arecibo during 20 years. Major findings include a decreasing long-term trend (lowering) of the height where the F2- layer peak density occurs (hmF2), which could be related with a more increased downward flux of the ionosphere. A slight decrease in the peak density of the F2- layer (NmF2) after local midnight also was found during the period studied. The meridional wind along the magnetic field derived from ISR data also revealed a long-term trend, becoming more northward during the period studied, with a maximum variation between 02:30UT and 05:30UT.

Santos, P. T.; Brum, C. G. M.; Tepley, C. A.; Aponte, N.; González, S. A.; Robles, E.

2011-11-01

279

Sources of uncertainty in projections of twenty-first century westerly wind changes over the Amundsen Sea, West Antarctica, in CMIP5 climate models  

NASA Astrophysics Data System (ADS)

The influence of changes in winds over the Amundsen Sea has been shown to be a potentially key mechanism in explaining rapid loss of ice from major glaciers in West Antarctica, which is having a significant impact on global sea level. Here, Coupled Model Intercomparison Project Phase 5 (CMIP5) climate model data are used to assess twenty-first century projections in westerly winds over the Amundsen Sea ( U AS ). The importance of model uncertainty and internal climate variability in RCP4.5 and RCP8.5 scenario projections are quantified and potential sources of model uncertainty are considered. For the decade 2090-2099 the CMIP5 models show an ensemble mean twenty-first century response in annual mean U AS of 0.3 and 0.7 m s-1 following the RCP4.5 and RCP8.5 scenarios respectively. However, as a consequence of large internal climate variability over the Amundsen Sea, it takes until around 2030 (2065) for the RCP8.5 response to exceed one (two) standard deviation(s) of decadal internal variability. In all scenarios and seasons the model uncertainty is large. However the present-day climatological zonal wind bias over the whole South Pacific, which is important for tropical teleconnections, is strongly related to inter-model differences in projected change in U AS (more skilful models show larger U AS increases). This relationship is significant in winter (r = -0.56) and spring (r = -0.65), when the influence of the tropics on the Amundsen Sea region is known to be important. Horizontal grid spacing and present day sea ice extent are not significant sources of inter-model spread.

Bracegirdle, Thomas J.; Turner, John; Hosking, J. Scott; Phillips, Tony

2014-10-01

280

ContentsContents2828vector 1. Background to Vector Calculus  

E-print Network

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

Vickers, James

281

Forecasting Caspian Sea level changes using satellite altimetry data (June 1992-December 2013) based on evolutionary support vector regression algorithms and gene expression programming  

NASA Astrophysics Data System (ADS)

Sea level forecasting at various time intervals is of great importance in water supply management. Evolutionary artificial intelligence (AI) approaches have been accepted as an appropriate tool for modeling complex nonlinear phenomena in water bodies. In the study, we investigated the ability of two AI techniques: support vector machine (SVM), which is mathematically well-founded and provides new insights into function approximation, and gene expression programming (GEP), which is used to forecast Caspian Sea level anomalies using satellite altimetry observations from June 1992 to December 2013. SVM demonstrates the best performance in predicting Caspian Sea level anomalies, given the minimum root mean square error (RMSE = 0.035) and maximum coefficient of determination (R2 = 0.96) during the prediction periods. A comparison between the proposed AI approaches and the cascade correlation neural network (CCNN) model also shows the superiority of the GEP and SVM models over the CCNN.

Imani, Moslem; You, Rey-Jer; Kuo, Chung-Yen

2014-10-01

282

An Analysis of Path-Vector Routing Protocol Convergence Algorithms  

Microsoft Academic Search

Today's Internet uses a path vector routing protocol, BGP, for global routing. After a connectivity change, a path vector protocol tends to explore a potentially large number of alternative paths before converging on new stable paths. Several techniques for improving path vector convergence have been proposed, however there has been no comparative analysis to judge the relative merit of each

Dan Pei; UCLA CSD; Beichuan Zhang; Dan Massey; Lixia Zhang

283

Meteorology (Wind)  

Wind speed at 50 m (m/s) The average and percent difference minimum and ... are given.   Percent of time for ranges of wind speed at 50 m (percent) Percentage [frequency] of time that wind ... be adjusted to heights from 10 to 300 meters using the Gipe power law. Wind speeds may be adjusted for different terrain by selecting from ...

2014-09-25

284

Comparison of Satellite-Derived Wind Measurements with Other Wind Measurement Sensors  

NASA Technical Reports Server (NTRS)

The purpose of this paper is to compare the good data from the Jimsphere launches with the data from the satellite system. By comparing the wind speeds from the Fixed Pedestal System 16 (FPS-16) Radar/Jimsphere Wind System and NASA's 50-MHz Radar Wind Profiler, the validation of winds from Geostationary Operational Environmental Satellite 7 (GOES-7) is performed. This study provides an in situ data quality check for the GOES-7 satellite winds. Comparison was made of the flowfields in the troposphere and the lower stratosphere of case studies of pairs of Jimsphere balloon releases and Radar Wind Profiler winds during Space Shuttle launches. The mean and standard deviation of the zonal component statistics, the meridional component statistics, and the power spectral density curves show good agreement between the two wind sensors. The standard deviation of the u and v components for the STS-37 launch (consisting of five Jimsphere/Radar Wind Profiler data sets) was 1.92 and 1.67 m/s, respectively; for the STS-43 launch (there were six Jimsphere/Wind Profiler data sets) it was 1.39 and 1.44 m/s, respectively. The overall standard deviation was 1.66 m/s for the u component and 1.55 m/s tor the v component, and a standard deviation of 2.27 m/s tor the vector wind difference. The global comparison of satellite with Jimsphere balloon vector winds shows a standard deviation of 3.15 m/s for STS-43 and 4.37 m/s for STS-37. The overall standard deviation of the vector wind was 3.76 m/s, with a root-mean-square vector difference of 4.43 m/s. These data have demonstrated that this unique comparison of the Jimsphere and satellite winds provides excellent ground truth and a frame of reference during testing and validation of satellite data

Susko, Michael; Herman, Leroy

1995-01-01

285

Solar Wind Forecasting with the SOLIS-VSM  

Microsoft Academic Search

A web based solar wind forecasting resource applying a simple empirical model with SOLIS-VSM (Vector Spectromagnetograph) data is presented here. The solar wind empirical model uses the locations of coronal holes on the observed solar disk to forecast an estimated solar wind velocity at Earth. The model coefficients are estimated minimizing the difference between 10+ years of coronal hole images

S. J. Robbins; C. J. Henney; J. W. Harvey

2005-01-01

286

SWE, a comprehensive plasma instrument for the WIND spacecraft  

Microsoft Academic Search

The Solar Wind Experiment (SWE) on the WIND spacecraft is a comprehensive, integrated set of sensors which is designed to investigate outstanding problems in solar wind physics. It consists of two Faraday cup (FC) sensors; a vector electron and ion spectrometer (VEIS); a strahl sensor, which is especially configured to study the electron ‘strahl’ close to the magnetic field direction;

K. W. Ogilvie; D. J. Chornay; R. J. Fritzenreiter; F. Hunsaker; J. Keller; J. Lobell; G. Miller; J. D. Scudder; E. C. Sittler; R. B. Torbert; D. Bodet; G. Needell; A. J. Lazarus; J. T. Steinberg; J. H. Tappan; A. Mavretic; E. Gergin

1995-01-01

287

Robust Multi-loop Airborne SLAM in Unknown Wind Environments  

E-print Network

Robust Multi-loop Airborne SLAM in Unknown Wind Environments Jonghyuk Kim Department of Engineering presents a robust multi-loop airborne SLAM structure which also augments wind information. The air velocity. This can be tackled by augmenting the unknown wind velocity into the state vector of SLAM, simultaneously

Kim, Jonghyuk "Jon"

288

Change vector analysis to categorise land cover change processes using the tasselled cap as biophysical indicator: description: implementing Landsat TM and ETM to detect land cover and land use changes in the mount Cameroon region using the CVA technique with the tasselled cap as biophysical indicator.  

PubMed

The continuous extraction of wood and the conversion of forest to small- and large-scale agricultural parcels is rapidly changing the land cover of the mount Cameroon region. The changes occur at varying spatial scales most often not more than 2ha for the small-scale subsistence farms and above 10ha for the extensive agricultural plantations of cocoa and palm. Given the importance of land use and land cover data in conservation planning, accurate and efficient techniques to provide up-to-date change information are required. A number of techniques for realising the detection of land cover dynamics using remotely sensed imagery have been formulated, tested and assessed with the results varying with respect to the change scenario under investigation, the information required and the imagery applied. In this study the Change Vector Analysis (CVA) technique was implemented on multitemporal multispectral Landsat data from the Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM) sensors to monitor the dynamics of forest change in the mount Cameroon region. CVA was applied to multi-temporal data to compare the differences in the time-trajectory of the tasseled cap greenness and brightness for two successive time periods - 1987 and 2002. The tasseled cap was selected as biophysical indicator because it optimises the data viewing capabilities of vegetation, representing the basic types of land cover - vegetation, soil and water. Classes were created arbitrarily to predict the technique's potential in monitoring forest cover changes in the mount Cameroon region. The efficiency of the technique could not be fully assessed due to the inavailability of sufficient ground truth data. Assessment was based on the establishment of an error matrix of change versus no-change. The overall accuracy was 70%. The technique nevertheless demonstrated immense potentials in monitoring forest cover change dynamics especially when complemented with field studies. PMID:18193332

Siwe, Rene Ngamabou; Koch, Barbara

2008-10-01

289

Winding for the wind  

NASA Astrophysics Data System (ADS)

The mechanical properties and construction of epoxy-impregnated fiber-glass blades for wind turbines are discussed, along with descriptions of blades for the Mod 0A and Mod 5A WECS and design goals for a 4 kW WECS. Multicell structure combined with transverse filament tape winding reduces labor and material costs, while placing a high percentage of 0 deg fibers spanwise in the blades yields improved strength and elastic properties. The longitudinal, transverse, and shear modulus are shown to resist stresses exceeding the 50 lb/sq ft requirements, with constant stress resistance expected until fatigue failure is approached. Regression analysis indicates a fatigue life of 400 million operating cycles. The small WECS under prototype development features composite blades, nacelle, and tower. Rated at 5.7 kW in a 15 mph wind, the machine operates over a speed range of 9-53.9 mph and is expected to produce 16,200 kWh annually in a 10 mph average wind measured at 30 ft.

Weingart, O.

290

Winding for the wind  

NASA Technical Reports Server (NTRS)

The mechanical properties and construction of epoxy-impregnated fiber-glass blades for wind turbines are discussed, along with descriptions of blades for the Mod 0A and Mod 5A WECS and design goals for a 4 kW WECS. Multicell structure combined with transverse filament tape winding reduces labor and material costs, while placing a high percentage of 0 deg fibers spanwise in the blades yields improved strength and elastic properties. The longitudinal, transverse, and shear modulus are shown to resist stresses exceeding the 50 lb/sq ft requirements, with constant stress resistance expected until fatigue failure is approached. Regression analysis indicates a fatigue life of 400 million operating cycles. The small WECS under prototype development features composite blades, nacelle, and tower. Rated at 5.7 kW in a 15 mph wind, the machine operates over a speed range of 9-53.9 mph and is expected to produce 16,200 kWh annually in a 10 mph average wind measured at 30 ft.

Weingart, O.

1981-01-01

291

Medium Modification of Vector Mesons  

SciTech Connect

The theory of the strong interaction, Quantum Chromodynamics (QCD), has been remarkably successful in describing high-energy and short-distance-scale experiments involving quarks and gluons. However, applying QCD to low energy and large-distance scale experiments has been a major challenge. Various QCD-inspired models predict a partial restoration of chiral symmetry in nuclear matter with modifications of the properties of hadrons from their free-space values. Measurable changes such as a shift in mass and/or a change of width are predicted at normal nuclear density. Photoproduction of vector mesons off nuclei have been performed at different laboratories. The properties of the ?, ? and ? mesons are investigated either directly by measuring their mass spectra or indirectly through transparency ratios. The latest results regarding medium modifications of the vector mesons in the nuclear medium will be discussed.

Chaden Djalali, Michael Paolone, Dennis Weygand, Michael H. Wood, Rakhsha Nasseripour

2011-03-01

292

Winds of Change: Expanding the Frontiers of Flight. Langley Research Center's 75 Years of Accomplishment, 1917-1992  

NASA Technical Reports Server (NTRS)

This commemorative volume highlights in pictures and text seventy five years of accomplishments of the Langley Research Center. The introductory matter features wind tunnels and their contribution to the development of aeronautics. A chronological survey details four different periods in Langley's history. The first period, 1917-1939, is subtitled 'Perfecting the Plane' which details Langley's contribution to early aeronautics with examples from specific aircraft. The second period, 1940-1957, focuses on the development of military aircraft during and after World War II. The third period, 1958-1969, tells the story of Langley's involvement with NASA and the satellite and Apollo era. The fourth period, entitled 'Charting New Courses: 1970-1992 and Beyond', treats various new topics from aerospace planes to Mars landing, as well as older topics such as the Space Shuttle and research spinoffs.

Schultz, James

1992-01-01

293

Saturn’s Zonal Winds at Cloud Level between 2004-2013 from Cassini ISS Images  

NASA Astrophysics Data System (ADS)

We examine images of Saturn returned by Cassini orbiter’s Imaging Science Subsystem (ISS) camera between 2004 to 2013 to analyze the temporal evolution of the zonal mean wind speed as a function of latitude. Our study primarily examines the images captured in the 752-nm continuum band using the CB2 filter. Images captured using the CB2 filter sense the upper troposphere of Saturn between 350 mbar and 500 mbar (Pérez-Hoyos and Sánchez-Lavega, 2006; Sánchez-Lavega et al, 2006; García-Melendo et al, 2009). We measure the wind speed using a two-dimensional Correlation Imaging Velocimetry (CIV) technique. The wind vectors are computed using pairs of images separated in time by up to two planetary rotations, and binned in latitude to determine the zonal mean wind profile, which typically covers a limited range of latitude. To achieve pole-to-pole coverage, we systematically merge all the wind measurements during each of the calendar years in order to compile a yearly, near-global record of Saturn's zonal wind structure. Using our wind measurements, we analyze the temporal evolution of the zonal wind. We specifically focus on changes in the wind profile after the 2009 equinox; we predict that changes in the insolation pattern caused by the shifting ring shadows affect the horizontal temperature gradient, and change the zonal mean wind through the thermal wind relationship. Furthermore, we also extend the zonal wind analysis by Sayanagi et al (2013), who detected changes in the zonal wind related to the Great Storm of 2010-2011, to study the subsequent evolution of the region affected by the storm. We compare our results with previously published zonal wind profiles obtained from Voyager 1 and 2 (Sánchez-Lavega et al, 2000) and Cassini (García-Melendo et al, 2011). Out study is supported by the Cassini Project, and our investigation is funded by NASA Outer Planets Research Program grant NNX12AR38G and NSF Astronomy and Astrophysics grant 1212216 to KMS.

Blalock, John J.; Sayanagi, Kunio M.; Dyudina, Ulyana A.; Ewald, Shawn P.; Ingersoll , Andrew P.

2014-11-01

294

Experimental and numerical modeling of wind flow over complex topography  

NASA Astrophysics Data System (ADS)

Wind mapping is of utmost importance in various wind engineering, wind environment, and wind energy applications. The available wind atlases usually provide wind data with low resolutions relative to the wind turbine height and size and usually neglect the effect of topographic features with relatively large or sudden changes in elevation. Developing a cost effective methodology to predict the wind patterns and to obtain wind maps over any topographic terrain is absolutely needed for wind turbine/farm siting. As the previous analytic and empirical attempts to resolve the flow over topographic features were limited to basic geometries that hardly exist in nature, applying Particle Image Velocimetry (PIV) measurement techniques in wind tunnel and Computational Fluid Dynamics (CFD) techniques in numerical simulation of the flow over topography seems to be the best alternative solution to the problem. PIV measurements and CFD simulations are carried out on a 1:3000 scale model of complex topographic area. Three distinct topographic features are investigated: a valley, a ridge and a hill. The PIV measurements compare well with hot-wire based mean velocity profiles for the three cases. Moreover, the turbulence intensity profiles match well for flow regions without recirculation. The ridge wake region shows discrepancies between the two techniques which are attributed to the complexity of the flow in this region and limitations of both techniques. A procedure incorporating Geographic Information System (GIS) and surface modeling techniques is introduced to build the CFD model of a complex terrain starting from the existing topography maps with desired resolutions. Moreover, a new approach is made to simulate the terrain roughness up to ultimate roughness heights, by implementing arrays of bell-shaped roughness elements in the CFD model. The velocity profiles and velocity vectors were compared with the PIV measurements and were found to be in good agreement near the ground and up to the full scale height of 300m. The study shows that PIV measurements and CFD simulations can be successfully used in qualifying and quantifying the flow over complex topography consisting of a wide range of roughness heights, enabling to map the flow structure with very high spatial resolution. KEYWORDS: Wind mapping, Complex topography, Computational fluid dynamics (CFD), Particle image velocimetry (PIV).

Rasouli, Ashkan

295

A herpes simplex viral vector expressing green fluorescent protein can be used to visualize morphological changes in high-density neuronal culture.  

PubMed

High-density cultures of mammalian neurons offer a model system for studies of brain development, but the morphological features of individual neurons is difficult to ascertain. We show that a herpes virus vector expressing a bioluminescent protein allows detailed morphometric analyses of living neurons in complex culture environments. Expression of enhanced green fluorescent protein (eGFP) was constitutively driven in neurons using the herpes simplex virus amplicon system. This system allowed us to make novel observations regarding development in high-density cultures from rat hippocampus and cerebellum. After the phase of initial neurite outgrowth, maturing neurons continue to show rapid remodeling of the neurite branches (0.79 +/- 0.11 mum/h per neurite; mean +/- SEM, n=8), and displacement of the soma within the neurite arbor (1.35 +/- 0.74 mum/h). These results demonstrate that a substantial capacity for morphological plasticity persists in maturing mammalian CNS neurons after cessation of net neurite outgrowth in early development. PMID:20811504

Falk, Torsten; Strazdas, Lori A; Borders, Rebecca S; Kilani, Ramsey K; Yool, Andrea J; Sherman, Scott J

2001-04-15

296

Symbolic computer vector analysis  

NASA Technical Reports Server (NTRS)

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

Stoutemyer, D. R.

1977-01-01

297

MAC3: Vectors  

NSDL National Science Digital Library

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

Friesen, Larry; Gillis, Anne

2008-12-22

298

Society for Vector Ecology  

NSDL National Science Digital Library

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

2008-09-12

299

Wind extremes in the North Sea Basin under climate change: An ensemble study of 12 CMIP5 GCMs  

E-print Network

; accepted 27 December 2012; published 20 February 2013. [1] Coastal safety may be influenced by climate change, as changes in extreme surge levels and wave extremes may increase the vulnerability of dunes and other coastal defenses. In the North Sea, an area already prone to severe flooding, these high surge

Haak, Hein

300

Forecasting Evaluation of WindSat in the Coastal Environment  

NASA Technical Reports Server (NTRS)

WindSat has demonstrated that measurements from polarimetric space-based microwave radiometers can be used to retrieve global ocean surface vector winds. Since the date of launch in 2003, substantial incremental improvements have been made to WindSat data processing, calibration, and retrieval algorithms. The retrievals now have higher resolution, improved wind vector ambiguity removal, and enhanced capability to represent high winds. Utilization of WindSat retrievals (wind vectors, total precipitable water, rainrate and sea surface temperature) will be demonstrated in the context of operational weather forecasting applications, especially the monitoring of topographically-forced winds. Examples will be presented from various parts of the world, including inland seas, midlatitude oceans, the tropics, and the United States. We will illustrate retrievals in extreme high- and extreme low-wind regimes, both of which can be problematic. Rain contamination will be addressed. We will include a comparison of WindSat vector maps to corresponding maps from the QuikScat scatterometer. We will discuss how near-realtime data from WindSat is being transitioned to specific offices within the National Weather Service.

Lee, Thomas F.; Bettenhausen, Mike H.; Hawkins, Jeffrey D.; Richardson, Kim; Jedlovec, Gary; Smith, Matt

2012-01-01

301

The changing burden of malaria and association with vector control interventions in Zambia using district-level surveillance data, 2006-2011  

PubMed Central

Background Malaria control was strengthened in Zambia over the past decade. The two primary interventions for vector control are indoor residual spraying (IRS) and long-lasting insecticide-treated nets (LLINs). Using passive malaria surveillance data collected from 2006 to 2011 through the Zambian District Health Information System, the associations between increased coverage with LLINs and IRS and the burden of malaria in Zambia were evaluated. Methods National passive malaria surveillance data from 2006 to 2011 were analysed. A district-level, random-effects model with Poisson regression was used to explore the association between malaria cases and coverage with LLINs and IRS. Malaria cases and LLINs and IRS coverage were mapped to visualize spatiotemporal variation in malaria for each year. Results From 2006–2011, 24.6 million LLINs were distributed and 6.4 million houses were sprayed with insecticide. Coverage with LLINs was not uniformly distributed over the study period and IRS was targeted to central and southern districts where malaria transmission was low. LLIN coverage was associated with a reduction in malaria cases, although an increase in the number of malaria cases was reported in some districts over the study period. A high burden of malaria persisted in north-eastern Zambia, whereas a reduction in the number of reported malaria cases was observed in western and southern Zambia. Conclusion Enhanced and targeted interventions in north-eastern Zambia where the burden of malaria remains high, as well as efforts to sustain low malaria transmission in the south-west, will be necessary for Zambia to achieve the national goal of being malaria free by 2030. PMID:24289177

2013-01-01

302

Late Holocene changes in precipitation in northwest Tasmania and their potential links to shifts in the Southern Hemisphere westerly winds  

E-print Network

Late Holocene changes in precipitation in northwest Tasmania and their potential links to shifts for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, 7000, Australia c British), northwest Tasmania. First, the relationship between scanning reflectance spectroscopy measurements

Wehrli, Bernhard

303

The Biology and Control of Leishmaniasis Vectors  

PubMed Central

Vector control remains a key component of many anti-leishmaniasis programs and probably will remain so until an effective vaccine becomes available. Technologies similar to those used for control of adult mosquitoes, specifically interior residual sprays and insecticide-treated nets, are currently at the forefront as disease control measures. This article provides a review of literature on the biology and control of sand fly vectors of leishmaniasis in the context of changing disease risks and the realities of modern vector control. The Literature Retrieval System of the Armed Forces Pest Management Board, Washington, DC, was the primary search engine used to review the literature. PMID:20606968

Claborn, David M

2010-01-01

304

Wind Streaks  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Released 12 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.

Windstreaks are features caused by the interaction of wind and topographic landforms. The raised rims and bowls of impact craters causes a complex interaction such that the wind vortex in the lee of the crater can both scour away the surface dust and deposit it back in the center of the lee. If you look closely, you will see evidence of this in a darker 'rim' enclosing a brighter interior.

Image information: VIS instrument. Latitude 6.9, Longitude 69.4 East (290.6 West). 19 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

305

Vector Calculus Spring 1997  

E-print Network

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

Sharpley, Robert

306

Retroviruses as vectors.  

PubMed

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

Vile, R G; Russell, S J

1995-01-01

307

Hunting the Vector Hybrid  

E-print Network

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

A Donnachie; Yu S Kalashnikova

1999-01-18

308

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

309

Qualitative Vector Algebra  

Microsoft Academic Search

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

Uckun Serdar

310

Adiabatic and nonadiabatic responses of the radiation belt relativistic electrons to the external changes in solar wind dynamic pressure and interplanetary magnetic field  

NASA Astrophysics Data System (ADS)

By removing the influences of 'magnetopause shadowing' (r0>6.6RE) and geomagnetic activities, we investigated statistically the responses of magnetic field and relativistic (>0.5MeV) electrons at geosynchronous orbit to 201 interplanetary perturbations during 6 years from 2003 (solar maximum) to 2008 (solar minimum). The statistical results indicate that during geomagnetically quiet times (HSYM ?-30nT, and AE<200nT), ~47.3% changes in the geosynchronous magnetic field and relativistic electron fluxes are caused by the combined actions of the enhancement of solar wind dynamic pressure (Pd) and the southward turning of interplanetary magnetic field (IMF) (?Pd>0.4 nPa, and IMF Bz<0 nT), and only ~18.4% changes are due to single dynamic pressure increase (?Pd >0.4 nPa, but IMF Bz>0 nT), and ~34.3% changes are due to single southward turning of IMF (IMF Bz<0 nT, but |?Pd|<0.4 nPa). Although the responses of magnetic field and relativistic electrons to the southward turning of IMF are weaker than their responses to the dynamic pressure increase, the southward turning of IMF can cause the dawn-dusk asymmetric perturbations that the magnetic field and the relativistic electrons tend to increase on the dawnside (LT~00:00-12:00) but decrease on the duskside (LT~13:00-23:00). Furthermore, the variation of relativistic electron fluxes is adiabatically controlled by the magnitude and elevation angle changes of magnetic field during the single IMF southward turnings. However, the variation of relativistic electron fluxes is independent of the change in magnetic field in some compression regions during the enhancement of solar wind dynamic pressure (including the single pressure increases and the combined external perturbations), indicating that nonadiabatic dynamic processes of relativistic electrons occur there. Acknowledgments. This work is supported by NSFC (grants 41074119 and 40604018). Liuyuan Li is grateful to the staffs working for the data from GOES 8-12 satellites and OMNI database in CDAWeb.

Li, L.

2013-12-01

311

A Stochastic Unit-Commitment Model to Estimate the Costs of Changing Power Plant Operation under High Amounts of Intermittent Wind Power  

E-print Network

High Amounts of Intermittent Wind Power Integration Meibom, P.1 , Brand, H.2 , Barth, R.2 and Weber, C in several European countries. The introduction of substantial amounts of wind power in a liberalized production costs of wind power are very low, and larger amounts of frequency-responding spinning as well

312

Wind motor applications for transportation  

SciTech Connect

Motion equation for a vehicle equipped with a wind motor allows, taking into account the drag coefficients, to determine the optimal wind drag velocity in the wind motor`s plane, and hence, obtain all the necessary data for the wind wheel blades geometrical parameters definition. This optimal drag velocity significantly differs from the flow drag velocity which determines the maximum wind motor power. Solution of the motion equation with low drag coefficients indicates that the vehicle speed against the wind may be twice as the wind speed. One of possible transportation wind motor applications is its use on various ships. A ship with such a wind motor may be substantially easier to steer, and if certain devices are available, may proceed in autonomous control mode. Besides, it is capable of moving within narrow fairways. The cruise speed of a sailing boat and wind-motored ship were compared provided that the wind velocity direction changes along a harmonic law with regard to the motion direction. Mean dimensionless speed of the wind-motored ship appears to be by 20--25% higher than that of a sailing boat. There was analyzed a possibility of using the wind motors on planet rovers in Mars or Venus atmospheric conditions. A Mars rover power and motor system has been assessed for the power level of 3 kW.

Lysenko, G.P.; Grigoriev, B.V.; Karpin, K.B. [Moscow Aviation Inst. (Russian Federation)

1996-12-31

313

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

314

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

315

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

316

Vector Quantization With Emergent Codebook Structure  

NASA Technical Reports Server (NTRS)

Proposed scheme under development for transmission of vector-quantized digital video images, vector quantizer codebook updated to adapt quantizer to changing signal statistics. Intended to be realized with electronic neural network. Codebook, which consists of patterns constituting video images, will undergo training during operation and scheme will develop codebooks ordered during training. System enables coding more compact, more immune to noise, and supports variable rate compression.

Ahalt, Stanley C.; Krishnamurthy, Ashok

1993-01-01

317

Quantum mechanics without state vectors  

NASA Astrophysics Data System (ADS)

Because the state vectors of isolated systems can be changed in entangled states by processes in other isolated systems, keeping only the density matrix fixed, it is proposed to give up the description of physical states in terms of ensembles of state vectors with various probabilities, relying only on density matrices. The density matrix is defined here by the formula giving the mean values of physical quantities, which implies the same properties as the usual definition in terms of state vectors and their probabilities. This change in the description of physical states opens up a large variety of new ways that the density matrix may transform under various symmetries, different from the unitary transformations of ordinary quantum mechanics. Such new transformation properties have been explored before, but so far only for the symmetry of time translations into the future, treated as a semigroup. Here, new transformation properties are studied for general symmetry transformations forming groups, not just semigroups. Arguments that such symmetries should act on the density matrix as in ordinary quantum mechanics are presented, but all of these arguments are found to be inconclusive.

Weinberg, Steven

2014-10-01

318

Lecture outline Support vector machines  

E-print Network

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

Terzi, Evimaria

319

Lecture outline Support vector machines  

E-print Network

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

Terzi, Evimaria

320

The Analysis of Wind Seismic Noise and Algorithms of its Determination  

NASA Astrophysics Data System (ADS)

Main barrier on a way of increase quality of seismic observations is the noise oscillations of a ground owing to influence of parameters variations of an environment, which is exhibited in the broad band record. For a reduction of noise influences changes any of an environment parameter, its variations are noted. It serves for hardware or program compensation of the noise. Nowadays the numerous ways are developed for a noise level reduction made by changes of temperature, magnetic field and atmospheric pressure. It is not so difficult to conduct record-keeping of influence of ground waters level and snow coverage on long and super long periods also. Wind is high-power factor for noise producing. It was multiply noted in the scientific literature. The wind is connected to pressure, but it is not the same. The apart from of a gradient of pressure, on a field of a wind in a surface layer renders influence of the Coriolis force and friction about a surface of ground. Any obstacle, from small-scale (building, trees, wood bands and so on) up to large-scale (range of mountains), standing on a way of air flow, distorts a field of a wind. Therefore, there are zones of a wind strengthening, zone of wind shadow. It forms exposed to the wind and lee-side vortexes. The speed and the direction of the wind are influenced also by non-irregularity of vertical distribution temperature, which makes horizontal flows of an air influencing to underlying layers known as the phenomenon of turbulent viscosity. The wind has a character of a laminar flow only at low speeds. The vortexes formed by strengthening of the wind act quasi-periodic on an underlying surface, the force and period of these effects, including wind impacts in obstacles, grow with strengthening of a wind. It is size the same order, as acceleration created in atmosphere by barometric gradients. A very complex picture of seismic noise for each seismic station is created by outcome of air friction about the earth surface and impacts into obstacles. The influence of a wind direction to seismic noise is not proved. The attempts of searching of this influence came across absence of qualitative data and absence of techniques of determination of a wind operation on oscillations of a ground. It is marked the increase of a noise level with strengthening of a wind only. Any compensation of noise is not made. In the task is illuminated the state of a problem, it is discussed the applicability the existing data and techniques for research and are considered the possible approaches to the solution of a problem and requirement to experimental data. The examples of sharing of the seismic noise data, atmospheric pressure, force and direction of a wind are shown. The methodology of researches consists of two directions: it is offered to represent a wind as a vector (direction, force of a wind) and to compare it to appropriate vector of the noise, chosen from a the seismic data on direction; other method - to decompose the wind on ranges (on a direction and on a force) and separately to investigate seismic noise appropriate to each wind range.

Kislov, K. V.; Gravirov, V. V.; Labuncov, M.

2010-12-01

321

The effect of sensor sheltering and averaging techniques on wind measurements at the Shuttle Landing Facility  

NASA Technical Reports Server (NTRS)

This document presents results of a field study of the effect of sheltering of wind sensors by nearby foliage on the validity of wind measurements at the Space Shuttle Landing Facility (SLF). Standard measurements are made at one second intervals from 30-feet (9.1-m) towers located 500 feet (152 m) from the SLF centerline. The centerline winds are not exactly the same as those measured by the towers. A companion study, Merceret (1995), quantifies the differences as a function of statistics of the observed winds and distance between the measurements and points of interest. This work examines the effect of nearby foliage on the accuracy of the measurements made by any one sensor, and the effects of averaging on interpretation of the measurements. The field program used logarithmically spaced portable wind towers to measure wind speed and direction over a range of conditions as a function of distance from the obstructing foliage. Appropriate statistics were computed. The results suggest that accurate measurements require foliage be cut back to OFCM standards. Analysis of averaging techniques showed that there is no significant difference between vector and scalar averages. Longer averaging periods reduce measurement error but do not otherwise change the measurement in reasonably steady flow regimes. In rapidly changing conditions, shorter averaging periods may be required to capture trends.

Merceret, Francis J.

1995-01-01

322

Tropospheric Wind Measurements From Space: The SPARCLE Mission And Beyond  

NASA Technical Reports Server (NTRS)

For over 20 years researchers have been investigating the feasibility of profiling tropospheric vector wind velocity from space with a pulsed Doppler lidar. Efforts have included theoretical development, system and mission studies, technology development, and ground-based and airborne measurements. Now NASA plans to take the next logical step towards enabling operational global tropospheric wind profiles by demonstrating horizontal wind measurements from the Space Shuttle in early 2001 using a coherent Doppler wind lidar system.

Kavaya, Michael J.; Emmitt, G. David

1998-01-01

323

Tropospheric Wind Measurements from Space: The SPARCLE Mission and Beyond  

NASA Technical Reports Server (NTRS)

For over 20 years researchers have been investigating the feasibility of profiling tropospheric vector wind velocity from space with a pulsed Doppler lidar. Efforts have included theoretical development, system and mission studies, technology development, and ground-based and airborne measurements. Now NASA plans to take the next logical step towards enabling operational global tropospheric wind profiles by demonstrating horizontal wind measurements from the Space Shuttle in early 2001 using a coherent Doppler wind lidar system.

Kavaya, Michael J.; Emmitt, G. David

1998-01-01

324

Wind Whispers  

NSDL National Science Digital Library

The Advanced Technology Environmental and Energy Center (ATEEC) provides this presentation on the career and technical aspects of wind energy. In addition to discussing careers in wind, the presentation covers the siting of wind turbines and some electricity basics. Users must download this resource for viewing, which requires a free log-in. There is no cost to download the item.

2011-03-09

325

Toasty Wind  

NSDL National Science Digital Library

In this quick activity, learners use a toaster to investigate the source for the Earth's wind. Learners hold a pinwheel above a toaster to discover that rising heat causes wind. Use this activity to introduce learners to the process of convection as a source for wind. This resource also explains how convection causes thunderstorms and lists important thunderstorm safety tips.

Service, National W.

2012-07-24

326

Polycistronic viral vectors.  

PubMed

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

de Felipe, P

2002-09-01

327

Flow distortion by a solent sonic anemometer: Wind tunnel calibration and its assessment for flux measurements over forest and field  

SciTech Connect

Main flow distortion effects caused by the sonic probe (i.e., deflection and attenuation/amplification of the wind vector) as a function of the azimuth angle of the incoming flow were examined by means of wind tunnel measurements at four different wind speeds and 11 different elevation angles of the flow with respect to the probe. The dependence of the distortion on wind speed and elevation angle turned out to be small compared with the dependence on the azimuth angle. Based on wind tunnel data, a set of calibration coefficients for each azimuth was evaluated. Application of this calibration on wind tunnel data shows an average compensation of the flow distortion of about 61%. A comparative application of the calibration supplied by the manufacturer leads to an increase of the flow distortion effects, especially at higher wind speeds. Application of the obtained calibration on field data leads to a change of about 20% in momentum flux over forest and grass field. The flux of sensible heat changes by about 4% over forest, whereas it is hardly altered over grass.

Grelle, A.; Lindroth, A. [Swedish Univ. of Agricultural Sciences, Uppsala (Sweden)] [Swedish Univ. of Agricultural Sciences, Uppsala (Sweden)

1994-12-01

328

MAC^3: Vectors Worksheet  

NSDL National Science Digital Library

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

Friesen, Larry; Gillis, Anne

2008-12-22

329

Simulation of a vector hysteresis measurement system taking hysteresis into account by the vector Preisach model  

NASA Astrophysics Data System (ADS)

The paper deals with the numerical analysis of a rotational single sheet tester with round-shaped specimen (RRSST) which is now under construction. The measurement setup consists of an induction motor the rotor of which has been removed, and its windings have been replaced to a special two phase one which can generate homogeneous magnetic field inside the motor. The two orthogonal components of the magnetic field intensity and of the magnetic flux density vectors can be measured by H-coils and B-coils, respectively. The Finite Element Method (FEM) with the T, ?-? potential formulation has been applied in the simulations. The vector hysteresis property of the specimen has been approximated by the vector Preisach model. Finally, the nonlinear problem has been solved by the fixed-point technique. The aim of the present work is to focus on the design aspects of this kind of measurement system.

Kuczmann, Miklós

2008-02-01

330

Understanding Vector Fields.  

ERIC Educational Resources Information Center

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

Curjel, C. R.

1990-01-01

331

Climatology of extreme winds in southern California  

SciTech Connect

A climatology of annual extreme winds in southern California has been prepared. The climatology includes a description of extreme wind regions, defined on the basis of observed winds and topography. Extreme wind distribution parameters have been estimated for 46 locations using data obtained from the National Climatic Data Center. Probabilities associated with extreme winds have been estimated for these locations. The results of the analysis are generally consistent with previous estimates of extreme winds in southern California. Although in several instances the current estimates are significantly higher than previous estimates. The data examined do not indicate that there has been a significant change in the extreme wind climate of southern California.

Ramsdell, J.V.; Hubbe, J.M.; Elliott, D.L.; Holladay, C.G.

1987-01-01

332

The effect of sudden wind shear on the Earth's magnetosphere: Statistics of wind shear events and CCMC simulations of magnetotail disconnections  

NASA Astrophysics Data System (ADS)

The solar wind is filled with strong current sheets and sudden velocity shears; often the two are co-located. Sudden velocity shears at 1 AU are statistically analyzed using ACE measurements from 1998 to 2008. The occurrence rates of passage and the orientations of the shear planes are examined. For shear layers with vector velocity changes |?v| > 50 km/s, an average of ˜12 pass the Earth per day. In the fast wind, ˜60 sudden shear layers pass the Earth per day (about 2.5 per hour). To explore the effects of sudden wind shears on the Earth's magnetosphere, global magnetospheric MHD simulations with four different simulation codes are performed at the Community Coordinated Modeling Center (CCMC) with north-south and east-west wind shears. Windsock movement of the magnetotail is analyzed and comet-like disconnections of the magnetotail and magnetosheath are examined. Sudden changes in the cross-polar-cap potential and ionospheric Joule dissipation are seen as the shear layers pass the Earth. Other potential effects of sudden wind shear on the magnetosphere are discussed.

Borovsky, Joseph E.

2012-06-01

333

Full-Scale Wind-Tunnel Tests of a Propeller with the Diameter Changed by Cutting off the Blade Tips  

NASA Technical Reports Server (NTRS)

Tests were conducted in order to determine how the characteristics of a propeller are affected by cutting off the tips. The diameter of a standard 10-foot metal propeller was changed successively to 9 feet 6 inches, 9 feet 0 inches, 8 feet 6 inches, and 8 feet 0 inches. Each propeller thus formed was tested at four pitch settings using an open cockpit fuselage and a D-12 engine. A small loss in propulsive efficiency is indicated. Examples are given showing the application of the results to practical problems.

Wood, Donald H

1931-01-01

334

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

335

Vector sampling expansion  

Microsoft Academic Search

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

D. Seidner; M. Feder

2000-01-01

336

Wind jets and wind waves off the Pacific coast of northern Japan under winter monsoon captured by combined use of scatterometer, synthetic aperture radar, and altimeter  

Microsoft Academic Search

Wind jets and wind waves off the Pacific coast of northern Japan under the east Asian winter monsoon are investigated using scatterometer, synthetic aperture radar (SAR), and altimeters. First, we depict two prevailing wind flow patterns associated with the northwesterly winter monsoon. They are derived by averaging QuikSCAT wind vectors when the 850-hPa pressure level wind directions are within 260°–290°

Teruhisa Shimada; Hiroshi Kawamura

2004-01-01

337

Vector field path following for small unmanned air vehicles  

Microsoft Academic Search

This paper presents a new method for unmanned aerial vehicle path following using vector fields to represent desired ground track headings to direct the vehicle onto the desired path. The key feature of this approach is that ground track heading error and lateral following error approach zero asymptotically even in the presence of constant wind disturbances. Methods for following straight-line

Derek R. Nelson; D. B. Barber; T. W. McLain; R. W. Beard

2006-01-01

338

ValidWind applications: wind power prospecting, aerosol transport  

NASA Astrophysics Data System (ADS)

The ValidWind™ system employs an XL200 laser rangefinder to track small, lightweight, helium-filled balloons (0.33 meters, 0.015 kg). We record their trajectories (range resolution 0.5 meters) and automatically produce local wind profiles in real time. Tracking range is enhanced beyond 2 km by applying retro-reflector tape to the balloons. Aerodynamic analysis shows that ValidWind balloon motion is well coupled to the local wind within relaxation times { 1 second, due to drag forces at subcritical Reynolds numbers Re < 2×105. Such balloons are Lagrangian sensors; i.e., they move with the wind as opposed to being fixed in space. In a field campaign involving many balloons, slight variations in ground level winds at launch lead to trajectory patterns that we analyze to derive 3D maps of the vertical and horizontal wind profiles downwind of the launch area. Field campaigns are focused on likely sites for wind power generation and on facilities from which airborne particulates are emitted. We describe results of wind measurements in Utah near the cities of Clarkston, Logan, and Ogden. ValidWind is a relatively inexpensive wind sensor that is easily and rapidly transported and deployed at remote sites. It is an ideal instrument for wind prospecting to support early decisions required, for example, in siting meteorology towers. ValidWind provides high-resolution, real time characterization of the average and changing 3D wind fields in which wind power turbines and other remote sensors must operate.

Wilkerson, T.; Marchant, A.; Apedaile, T.; Scholes, D.; Simmons, J.; Bradford, B.

2010-10-01

339

Electric car with solar and wind energy may change the environment and economy: A tool for utilizing the renewable energy resource  

NASA Astrophysics Data System (ADS)

Energy and environmental issues are among the most important problems of public concern. Wind and solar energy may be one of the alternative solutions to overcome energy shortage and to reduce greenhouse gaseous emission. Using electric cars in cities can significantly improve the air quality there. Through our analyses and modeling on the basis of the National Centers for Environment Prediction data we confirm that the amount of usable solar and wind energy far exceeds the world's total energy demand, considering the feasibility of the technology being used. Storing the surplus solar and wind energy and then releasing this surplus on demand is an important approach to maintaining uninterrupted solar- and wind-generated electricity. This approach requires us to be aware of the available solar and wind energy in advance in order to manage their storage. Solar and wind energy depends on weather conditions and we know weather forecasting. This implies that solar and wind energy is predictable. In this article, we demonstrate how solar and wind energy can be forecasted. We provide a web tool that can be used by all to arrive at solar and wind energy amount at any location in the world. The tool is available at http://www.renewableenergyst.org. The website also provides additional information on renewable energy, which is useful to a wide range of audiences, including students, educators, and the general public.

Liu, Quanhua

2014-01-01

340

Implications of climate change on the distribution of the tick vector Ixodes scapularis and risk for Lyme disease in the Texas-Mexico transboundary region  

PubMed Central

Background Disease risk maps are important tools that help ascertain the likelihood of exposure to specific infectious agents. Understanding how climate change may affect the suitability of habitats for ticks will improve the accuracy of risk maps of tick-borne pathogen transmission in humans and domestic animal populations. Lyme disease (LD) is the most prevalent arthropod borne disease in the US and Europe. The bacterium Borrelia burgdorferi causes LD and it is transmitted to humans and other mammalian hosts through the bite of infected Ixodes ticks. LD risk maps in the transboundary region between the U.S. and Mexico are lacking. Moreover, none of the published studies that evaluated the effect of climate change in the spatial and temporal distribution of I. scapularis have focused on this region. Methods The area of study included Texas and a portion of northeast Mexico. This area is referred herein as the Texas-Mexico transboundary region. Tick samples were obtained from various vertebrate hosts in the region under study. Ticks identified as I. scapularis were processed to obtain DNA and to determine if they were infected with B. burgdorferi using PCR. A maximum entropy approach (MAXENT) was used to forecast the present and future (2050) distribution of B. burgdorferi-infected I. scapularis in the Texas-Mexico transboundary region by correlating geographic data with climatic variables. Results Of the 1235 tick samples collected, 109 were identified as I. scapularis. Infection with B. burgdorferi was detected in 45% of the I. scapularis ticks collected. The model presented here indicates a wide distribution for I. scapularis, with higher probability of occurrence along the Gulf of Mexico coast. Results of the modeling approach applied predict that habitat suitable for the distribution of I. scapularis in the Texas-Mexico transboundary region will remain relatively stable until 2050. Conclusions The Texas-Mexico transboundary region appears to be part of a continuum in the pathogenic landscape of LD. Forecasting based on climate trends provides a tool to adapt strategies in the near future to mitigate the impact of LD related to its distribution and risk for transmission to human populations in the Mexico-US transboundary region. PMID:24766735

2014-01-01

341

Evaluation of High Wind Speed Observations from Spaceborne and Airborne Ocean Wind Measurement Systems  

NASA Astrophysics Data System (ADS)

It is very difficult to obtain high quality in-situ wind data in the high wind speed regimes (>17m/s). Winds measured by moored small-hulled buoys become increasingly low biased as wind speeds exceed 20 m/s. Ordinary ship reported winds are of poor quality in this high wind speed range, and the better-equipped research vessels rarely sample this wind regime. Finally, marine wind fields produced by numerical weather prediction (NWP) models, including even the products of the newer "reanalysis" projects, are notoriously biased low in severe storms. The best-suited candidates to assess the performance of new wind measurements are actually other spaceborne and airborne ocean wind vector instruments (such as ASCAT and WindSat) provided their performance in high wind speed regimes are well understood. The Indian Space Research Organization (ISRO) launched the OceanSat-2 satellite on 23 September 2009. Oceansat-2 is ISRO's second in a series of satellites dedicated to ocean research. OceanSat-2 carries a microwave radar scatterometer (OSCAT) capable of measuring the ocean surface vector winds. The OSCAT operates at Ku-band (13.515 GHz) scanning the earth surface conically at 20.5 rpm using dual-polarized pencil beams with an incidence angle 48.9 degree for the horizontally polarized (H-pol) beam and 57.6 degree for the vertically polarized (V-pol) beam resulting in a swath width of 1840 km. The orbit characteristics provide global ocean coverage wind retrievals within 29 orbits or 2 days. In the paper we will present validation of high wind estimates from OSCAT measurements processed by NOAA.

Jelenak, Zorana; Chang, Paul; Soisuvarn, Seubsom; Alsweiss, Suleiman

2013-04-01

342

Wind Dynamics and Forests  

NSDL National Science Digital Library

In this activity, students will set up a model forest using plastic bottles to observe changes caused by differences in wind speed and forest density. An extension to the activity will allow students to explore the concept of evapotranspiration. From this activity students will understand that living organisms in an ecosystem can have profound effects upon the local atmosphere, changes in vegetation can have profound effects upon wind speed, and models are useful to researchers in understanding the shaping of ecosystems. The teacher's guide contains detailed background material, learning goals, alignment to national standards, grade level/time, details on materials and preparation, procedure, assessment ideas, and modifications for alternative learners.

343

EVA: an explicit vector language  

Microsoft Academic Search

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

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

1990-01-01

344

Bit vector encoding via decomposition  

Microsoft Academic Search

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

Ralph D. Jeffords

1982-01-01

345

The global impact of satellite-derived polar winds on model forecasts  

NASA Astrophysics Data System (ADS)

The use of Atmospheric Motion Vectors (AMVs) in Numerical Weather Prediction (NWP) models continues to be an important source of information in data sparse regions. These AMVs are derived from a time-sequence of images from geostationary and polar orbiting satellites. NWP centers have documented positive impact on model forecasts not only in regions where the AMVs are measured, but elsewhere as well. One example is the positive impact that the Moderate Resolution Imaging Spectroradiometer (MODIS) polar winds have on forecasts in the middle and subtropical latitudes, especially in 3 to 5 day forecasts and forecast bust situations. The MODIS winds are only derived poleward of 65° latitude. What are possible explanations for this global impact? This study investigates the hypothesis that the assimilation of polar winds modifies the flow in high latitudes near the polar jet stream and that this effect propagates to lower latitudes in extended forecasts. Using a pre-operational version of the National Centers for Environmental Prediction's (NCEP) Global Forecast System (GFS), a side-by-side experiment was run for a six week period during the late summer of 2004, with and without the MODIS polar winds. Five forecast cases within this period were examined to determine how winds in the polar regions affect the wind and geopotential height fields in the jet stream region, resulting in changes in wave propagation speed. From the five cases examined, it was determined that the addition of the polar winds modifies the mass balance in synoptic-scale waves near the polar jet streams, more consistently in data void regions. This change in mass balance is evident in differences in the ageostrophic wind, which has an effect on the speed and amplitude of baroclinic waves that extends from the jet stream into lower latitudes in later forecast times. These results reveal the substantial impact that polar-only observations have on the predictability of global weather systems.

Santek, David A.

346

On the use of QuikSCAT data for assessing wind energy resources  

NASA Astrophysics Data System (ADS)

As the land space suitable for wind turbine installations becomes saturated, the focus is on offshore sites. Advantages of such a transition include increased power production, smaller environmental and social impact and extended availability of prospective areas. Until recently installation of wind turbines was limited in coastal areas. Nowadays, the search for suitable sites is extended beyond shallow waters, in locations far offshore where available measurements of various environmental parameters are limited. Space-borne observations are ideal due to their global spatial coverage, providing information where in-situ measurements are impracticable. The most widely used satellite observations for wind vector information are obtained by scatterometers; active radars that relate radiation backscattered from the sea surface to wind. SeaWinds, the scatterometer on board the QuikSCAT platform, launched by NASA in 1999 provided information with global coverage until 2009. The potential use of this 10-year long dataset is evaluated in the present study for the characterization of wind resources in the North and Baltic Seas, where most of Europe's offshore wind farms are located. Long-term QuikSCAT data have been extensively and positively validated in open ocean and in enclosed seas. In the present study QuikSCAT rain-free observations are compared with in-situ observations from three locations in the North Sea. As the remotely sensed observations refer to neutral atmospheric stratification, the impact of stability is assessed. Mean wind characteristics along with the Weibull A and k parameters are estimated in order to obtain information regarding the variation of wind. The numerical weather prediction (NWP) model WRF (Weather Research & Forecasting) is used for comparisons against QuikSCAT. Surface winds derived from long-term WRF simulations are compared against QuikSCAT data to evaluate differences in the spatial extend. Preliminary results indicate very good agreement between satellite and in-situ observations. The mean annual wind speed at 10 meters above the sea surface is found significantly higher in the North Sea when compared to the Baltic Sea. Strong lee effects on the 10m wind speeds are observed, in particular the reduced wind speed on the east side of the British Isles as opposed to the west coast of Denmark. An intense flow channelling in the English Channel and the Baltic Sea is highlighted, along with various other effects. Comparisons between WRF and QuikSCAT show biases in the order of 0.4 m/s or lower in extended spatial scales. Higher negative biases, indicating higher QuikSCAT wind speed than the WRF-derived, are observed mainly in coastal areas where representativeness errors due to surface roughness changes are significant.

Karagali, I.; Peña, A.; Hahmann, A. N.; Hasager, C.; Badger, M.

2011-12-01

347

Distribution and Evolution of Vector Magnetic Fields in Coronal Holes  

NASA Astrophysics Data System (ADS)

Coronal holes (CHs) are low density and low temperature regions in the solar corona, and they are the sources of fast solar wind. Nowadays, many properties of CHs are far from being understood. Magnetic fields are the key to understand the solar phenomena. Therefore, we try to answer the questions relative to CHs by studying the distribution and evolution of magnetic fields, especially the vector magnetic fields, in CHs. With the observations from the SOHO, Hinode, STEREO, and SDO, we investigate some aspects of CHs in detail for the first time, such as the evolution of vector magnetic field and magnetic nonpotentiality in CHs, and obtain a series of results. (1) Response of the solar atmosphere to the magnetic field distribution and evolution in a CH. We study the magnetic fields in a CH and at the CH boundary, and present the corresponding atmospheric response of different overlying layers to the magnetic field distribution and evolution. We also quantitatively analyze the relationship between the magnetic flux density and atmospheric emissions at different wavelengths. (2) Evolution of dipoles in an equatorial CH and its effect on the decay of the CH. We investigate the evolution of dipolar magnetic fields in an equatorial CH region. In the CH, the submergence of initial loops after their emergence is observed for the first time. The area where the dipoles are located becomes a place of mixed polarities instead of the unipolar fields, resulting in the change of the overlying corona from a CH area to a quiet region. (3) Distribution of vector magnetic fields and magnetic nonpotentiality of CHs. We investigate the vector magnetic fields, current densities, and current helicities in two CHs, and compare them with two quiet regions. We find that: (i) in the areas where the large current helicities are concentrated, there are strong vertical and horizontal field elements; (ii) the mean current density in the magnetic flux concentrations with the vertical fields stronger than 100 Gs is as large as (0.012±0.001) A\\cdotm^{-2}, consistent with that in the flare productive active regions; (iii) the magnetic fields in both the CHs and the quiet regions are nonpotential. (4) SDO observations of magnetic reconnection at CH boundaries. At the CH boundaries, we find many coronal jets as the signatures of magnetic reconnection, below which the magnetic emergence and cancellation are observed. We study the shifts of CH boundaries, and prove that the magnetic reconnection at CH boundaries maintains the rigid rotation of CHs. (5) Structures and evolution of polar plumes in the north polar CH. With the total solar eclipse observations, we investigate the properties and evolution of the polar plumes. The results reveal that the plumes which are closer to the CH center are more vertical. It seems that the lifetimes of plumes are much longer than the timescale of eclipse, and there may be no short timescale oscillations. The above results are helpful for us to understand the properties of CHs, and to get more insight into the evolution of CHs and the magnetic activities in CHs. As the source of fast solar wind, CHs are one kind of triggering regions of space weather. Therefore, our results can also provide an essential physical basis and observational evidence for studying the mechanism of solar wind acceleration and the course of space weather.

Yang, S. H.

2012-11-01

348

Quality and Control of Water Vapor Winds  

NASA Technical Reports Server (NTRS)

Water vapor imagery from the geostationary satellites such as GOES, Meteosat, and GMS provides synoptic views of dynamical events on a continual basis. Because the imagery represents a non-linear combination of mid- and upper-tropospheric thermodynamic parameters (three-dimensional variations in temperature and humidity), video loops of these image products provide enlightening views of regional flow fields, the movement of tropical and extratropical storm systems, the transfer of moisture between hemispheres and from the tropics to the mid- latitudes, and the dominance of high pressure systems over particular regions of the Earth. Despite the obvious larger scale features, the water vapor imagery contains significant image variability down to the single 8 km GOES pixel. These features can be quantitatively identified and tracked from one time to the next using various image processing techniques. Merrill et al. (1991), Hayden and Schmidt (1992), and Laurent (1993) have documented the operational procedures and capabilities of NOAA and ESOC to produce cloud and water vapor winds. These techniques employ standard correlation and template matching approaches to wind tracking and use qualitative and quantitative procedures to eliminate bad wind vectors from the wind data set. Techniques have also been developed to improve the quality of the operational winds though robust editing procedures (Hayden and Veldon 1991). These quality and control approaches have limitations, are often subjective, and constrain wind variability to be consistent with model derived wind fields. This paper describes research focused on the refinement of objective quality and control parameters for water vapor wind vector data sets. New quality and control measures are developed and employed to provide a more robust wind data set for climate analysis, data assimilation studies, as well as operational weather forecasting. The parameters are applicable to cloud-tracked winds as well with minor modifications. The improvement in winds through use of these new quality and control parameters is measured without the use of rawinsonde or modeled wind field data and compared with other approaches.

Jedlovec, Gary J.; Atkinson, Robert J.

1996-01-01

349

Unsafe at Any (Wind) Speed?.  

NASA Astrophysics Data System (ADS)

The goal of this research was to examine the relative safety and stability of stationary motor vehicles exposed to severe winds. The focus was on private passenger vehicles. 1) The behavior of two instrumented storm-chase vehicles that were exposed to severe winds, 2) the behavior of 291 vehicles exposed to a tornado, and 3) the wind speed required to upset a sedan and a minivan exposed to winds in a wind tunnel were studied. A wind as strong as 47 m s1 (105 mph) has been measured by a storm-chase pickup truck and 44 m s1 (98 mph) by a storm chase sedan. The vehicles were not adversely affected by the wind. Also studied were 291 vehicles parked outdoors at homes struck by tornadoes, and the behavior of the vehicles was compared to the F-scale damage to the house. At sites with F1 or F2 damage, 72% of the vehicles were not moved by the wind and 96% were not tipped over. At sites with F3 or F4 damage, 50% were not moved by the wind and 82% were not tipped over. Wind tunnel tests on a sedan and minivan showed they were most vulnerable to upset (lifting of one tire from the ground) with wind directions near 45° and 135°, as measured from the front. When modeled with 5° of suspension tilt to the side, the sedan was found to be upset at wind speeds of 51-67 m s1 (115-150 mph), and the minivan was upset at wind speeds of 58-80 m s1 (130-180 mph). Although an underground shelter or sturdy building offer the best protection from severe winds, it is found that a vehicle may be a relatively stable place and may be safer than a mobile home or the outdoors. These findings may warrant changes to public recommendations made during tornado warnings and other severe storm situations.

Schmidlin, Thomas; Hammer, Barbara; King, Paul; Ono, Yuichi; Miller, L. Scott; Thumann, Gregory

2002-12-01

350

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

351

Evaluation of innate immunity and vector toxicity following inoculation of bovine, porcine or human adenoviral vectors in a mouse model  

PubMed Central

Nonhuman adenovirus (Ad) vectors derived from bovine Ad serotype 3 (BAd3) or porcine Ad serotype 3 (PAd3) can circumvent pre-existing immunity against human Ad (HAd). We have previously reported differential transduction of human and nonhuman cells by these Ad vectors, and their distinct receptor usage and biodistribution. To compare the induction of innate immunity, vector toxicity and vector uptake by Kupffer cells (KCs) following intravenous administration of PAd3, BAd3, or HAd5 vectors in mice, we determined mRNA expression levels of proinflammatory chemokines and cytokines, and Toll-like receptors (TLRs) in the liver and spleen. Tissue toxicity of these vectors was assessed by comparing serum levels of liver-specific enzymes, histopathology and Kupffer cell (KC) depletion. Compared to the HAd5 vector, PAd3 and BAd3 vectors were more potent stimulators of innate immune responses as indicated by enhanced mRNA expression of TLRs and proinflammatory chemokines and cytokine genes. Histopathological changes in the liver were most pronounced in HAd5-inoculated mice while BAd3- or PAd3-inoculated mice revealed mild histologic changes that were confined to early time points. Inoculation with HAd5 or PAd3 vectors resulted in a significant (P <0.05) decline of the number of KCs in the liver. Together, these results extend our previous observations regarding distinct in vivo biology of nonhuman and human Ad vectors. PMID:20659505

Sharma, Anurag; Bangari, Dinesh S.; Tandon, Manish; HogenEsch, Harm; Mittal, Suresh K.

2010-01-01

352

Changes in species richness and spatial distribution of mosquitoes (Diptera: Culicidae) inferred from museum specimen records and a recent inventory: a case study from Belgium suggests recent expanded distribution of arbovirus and malaria vectors.  

PubMed

Mosquito (Diptera: Culicidae) distribution data from a recent inventory of native and invading mosquito species in Belgium were compared with historical data from the period 1900-1960 that were retrieved from a revision of the Belgian Culicidae collection at the Royal Belgian Institute of Natural Sciences. Both data sets were used to investigate trends in mosquito species richness in several regions in Belgium. The relative change in distribution area of mosquito species was particularly important for species that use waste waters and used tires as larval habitats and species that recently shifted their larval habitat to artificial larval habitats. More importantly, several of these species are known as vectors of arboviruses and Plasmodium sp. and the apparent habitat shift of some of them brought these species in proximity to humans. Similar studies comparing current mosquito richness with former distribution data retrieved from voucher specimens from collections is therefore encouraged because they can generate important information concerning health risk assessment at both regional and national scale. PMID:23540109

Dekoninck, W; Hendrickx, F; Versteirt, V; Coosemans, M; De Clercq, E M; Hendrickx, G; Hance, T; Grootaert, P

2013-03-01

353

Vector cross product in n-dimensional vector space  

E-print Network

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

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

2013-10-19

354

Moist wind relationships  

NASA Technical Reports Server (NTRS)

The equations describing the temporal and spatial behavior of the kinematic moisture and heat flux are described. In these nonlinear equations, the contribution by diabatic processes to the large-scale flux is composed of two parts. One part is associated with a Rayleigh damping term while the other arises from temporal and spatial changes in the pressure gradient term. It was found that the influence of diabatic processes on large-scale moisture fluxes depends greatly on the degree of balance between forcing and damping terms in the governing kinematic flux equations. The existence of a near balance requires a reduction in the large-scale horizontal geostrophic wind speed. Based on an examination of the moisture flux equations, it is argued that reductions in the large-scale horizontal wind speed observed within major cumulus cloud systems help conserve large-scale moisture fluxes. The deviation of the wind from geostrophic conditions is easily estimated for a near balanced state. This wind modification induces secondary vertical circulations that contribute to convergence, creating or supporting long-lived mesoscale flows. We believe this process to be a major supporter of the mesoscale circulations observed in severe storms and squall lines. In the tropics the wind modification has an antitriptic relationship. These diagnostic findings suggest possible modifications to the wind field in the application of a cumulus parameterization, and may be important in diabatic initialization of numerical weather prediction models.

Raymond, William H.

1990-01-01

355

Moist wind relationships  

NASA Technical Reports Server (NTRS)

Equations describing the temporal and spatial behavior of the kinematic moisture and heat flux are introduced. In these nonlinear equations, the contribution by diabatic processes to the large-scale flux is composed of two parts. One part is associated with a Rayleigh damping term, while the other arises from temporal and spatial changes in the pressure gradient term. The influence of diabatic processes on the large-scale moisture fluxes depends greatly on the degree of balance between forcing and damping terms in the governing equations. The existence of a near balance requires a reduction in the large-scale horizontal geostrophic wind speed. From a scale analysis of the moisture flux equations it is argued that reductions in the large-scale horizontal wind speed, observed within major cumulus cloud systems, help conserve large-scale moisture fluxes. The deviation of the wind from geostrophic conditions is easily estimated. This wind modification induces secondary vertical circulations that contribute to the convergence, creating or supporting long-lived mesoscale flows. In the tropics the wind modification has an antitriptic relationship. These diagnostic findings suggest possible modifications to the wind field in the application of cumulus parameterization, and may be important in diabatic initialization of numerical weather prediction models.

Raymond, William H.

1993-01-01

356

Vector control in some countries of Southeast Asia: comparing the vectors and the strategies.  

PubMed

The use of information on malaria vector behaviour in vector control is discussed in relation to the area of Southeast Asia comprising Cambodia, Laos, Myanmar, Thailand and Vietnam. The major vectors in the region are Anopheles dirus, An. minimus, An. maculatus and An. sundaicus, of which An. dirus is the most important. Options for vector control and the biological features of mosquitoes, which would make them amenable to control by these measures, are listed. The methods with the greatest potential for controlling each of the four vector species are described. Experiences of vector control by residual spraying, insecticide-treated nets and larva control and of personal protection against the four vectors are outlined, and it is noted that choice of control strategy is often determined by epidemiological, economic and political considerations, whilst entomological observations may help to explain failures of control and to indicate alternative strategies. Future research needs include basic entomological field studies using the most appropriate indicators to detect changes related to rapidly changing environmental conditions, such as loss of forest and climate change. Further studies of the efficacy of insecticide-treated mosquito nets, with greater attention to study design, are needed before it can be assumed that they will work in Southeast Asia. At the same time, research to improve sustainable utilization of nets is important, bearing in mind that nets are not the only means to control malaria and should not drain resources from supervision and training, which improve access to diagnosis and treatment of malaria and other diseases. Research is needed to make decisions on whether vector control is appropriate in different environments, and, if so, how to carry it out in different health systems. Researchers need to play a greater role in making operational research (entomological, epidemiological, social, economic and health systems research) of good quality an integral component of implementation programmes. PMID:7605123

Meek, S R

1995-04-01

357

Probabilistic Path Planning of Montgolfier Balloons in Strong, Uncertain Wind Fields  

NASA Technical Reports Server (NTRS)

Lighter-than-air vehicles such as hot-air balloons have been proposed for exploring Saturn s moon Titan, as well as other bodies with significant atmospheres. For these vehicles to navigate effectively, it is critical to incorporate the effects of surrounding wind fields, especially as these winds will likely be strong relative to the control authority of the vehicle. Predictive models of these wind fields are available, and previous research has considered problems of planning paths subject to these predicted forces. However, such previous work has considered the wind fields as known a priori, whereas in practical applications, the actual wind vector field is not known exactly and may deviate significantly from the wind velocities estimated by the model. A probabilistic 3D path-planning algorithm was developed for balloons to use uncertain wind models to generate time-efficient paths. The nominal goal of the algorithm is to determine what altitude and what horizontal actuation, if any is available on the vehicle, to use to reach a particular goal location in the least expected time, utilizing advantageous winds. The solution also enables one to quickly evaluate the expected time-to-goal from any other location and to avoid regions of large uncertainty. This method is designed for balloons in wind fields but may be generalized for any buoyant vehicle operating in a vector field. To prepare the planning problem, the uncertainty in the wind field is modeled. Then, the problem of reaching a particular goal location is formulated as a Markov decision process (MDP) using a discretized space approach. Solving the MDP provides a policy of what actuation option (how much buoyancy change and, if applicable, horizontal actuation) should be selected at any given location to minimize the expected time-to-goal. The results provide expected time-to-goal values from any given location on the globe in addition to the action policy. This stochastic approach can also provide insights not accessible by deterministic methods; for example, one can evaluate variability and risk associated with different scenarios, rather than only viewing the expected outcome.

Wolf, Michael; Blackmore, James C.; Kuwata, Yoshiaki

2011-01-01

358

Offshore wind energy prospects  

Microsoft Academic Search

In last two years offshore wind energy is becoming a focal point of national and non national organizations particularly after the limitations of fossil fuel consumption, adopted by many developed countries after Kyoto conference at the end of 1997 on global climate change. North Europe is particularly interested in offshore for the limited land areas still available, due to the

Gaetano Gaudiosi

1999-01-01

359

Wind Energy Leasing Handbook  

E-print Network

Wind Energy Leasing Handbook Wind Energy Leasing Handbook E-1033 Oklahoma Cooperative Extension?..................................................................................................................... 31 What do wind developers consider in locating wind energy projects?............................................................................................ 37 How do companies and individuals invest in wind energy projects?....................................................................

Balasundaram, Balabhaskar "Baski"

360

Deviations from the ideal wind: Local and zonal-mean perspectives  

NASA Astrophysics Data System (ADS)

This contribution introduces the non-ideal wind as the deviation from a general local wind balance, the ideal wind. The ideal wind is directed along intersection lines of Bernoulli function and potential temperature surfaces. In climatological steady state, the ideal mass flux cannot participate in net mass fluxes, because the mean position of the mentioned intersection lines does not change. A conceptional proximity of the zonal-mean non-ideal wind and the residual wind as occurring in the transformed Eulerian mean (TEM) equations suggests itself. The zonal- and time-mean non-ideal wind is compared to the residual wind for the Held-Suarez test case. Similarities occur for the meridional components in the zone of Rossby wave breaking in the upper troposphere equatorward of the jet. The vertical components are similar, too. However, the vertical non-ideal wind is much stronger in the baroclinic zone. This is due to the missing vertical eddy flux of Ertel's potential vorticity (EPV) in the TEM equations. The largest differences are to be found in the boundary layer, where the non-ideal wind exhibits typical pattern of Ekman dynamics. Instantaneous non-ideal wind vectors demonstrate mass-inflow for lows and mass-outflow for highs in the boundary layer. A significant non-ideal meridional wind is associated with a filamentation of EPV in the zone of Rossby wave breaking in about 300 hPa. Strong gradients of EPV act as a transport barrier. The dynamical state index (DSI) introduced by Weber and Nevir (2008) in order to identify extreme weather events acts as a source for the divergence of the non-ideal mass flux. Hence, the DSI and the non-ideal wind could provide useful diagnostics to charaterize atmospheric dynamics from a local, zonal-mean, and time-mean perspective. Reference WEBER, T., P. NÉVIR, 2008: Storm tracks and cyclone development using the theoretical concept of the Dy- namic State Index DSI. - Tellus 60A, 1-10.

Gaßmann, Almut

2014-05-01

361

Examining the Variability of Wind Power Output in the Regulation Time Frame: Preprint  

SciTech Connect

This work examines the distribution of changes in wind power for different time scales in the regulation time frame as well as the correlation of changes in power output for individual wind turbines in a wind plant.

Hodge, B. M.; Shedd, S.; Florita, A.

2012-08-01

362

Operational behavior of a double-fed permanent magnet generator for wind turbines  

E-print Network

Greater efficiency in wind turbine systems is achieved by allowing the rotor to change its rate of rotation as the wind speed changes. The wind turbine system is decoupled from the utility grid and a variable speed operation ...

Reddy, Sivananda Kumjula

2005-01-01

363

Wind Tunnel  

NSDL National Science Digital Library

Scientists use enormous wind tunnels to test the design of planes, helicopters, even the Space Shuttle. In this simulation activity, learners create a miniature wind tunnel test by blowing air with a fan or blow dryer through a large tube, then flying paper airplanes, helicopters and other folded paper models in the "wind." Unless the source of the air is a fan that stands on its own, for example, more than one person will be needed to do the activity.This activity can be combined with the Helicopter Twirl, Parachute Drop and Boomerang activities, also found on the Lawrence Hall of Science Kids Site.

Science, Lawrence H.

2009-01-01

364

Global Winds  

NSDL National Science Digital Library

On this worksheet, students examine a diagram of global winds and learn the position of the prevailing westerlies, the polar easterlies, the trade winds, the horse latitudes and the doldrums, and that together, the uneven heating of the planet by the Sun and the Coriolis Effect are responsible for the global wind belts. The resource is part of the teacher's guide accompanying the video, NASA Why Files: The Case of the Mysterious Red Light. Lesson objectives supported by the video, additional resources, teaching tips and an answer sheet are included in the teacher's guide.

365

Stellar Winds  

NASA Astrophysics Data System (ADS)

A "stellar wind" is the continuous, supersonic outflow of matter from the surface layers of a star. Our sun has a solar wind, driven by the gas-pressure expansion of the hot (T > 106 K) solar corona. It can be studied through direct in situ measurement by interplanetary spacecraft; but analogous coronal winds in more distant solar-type stars are so tenuous and transparent that that they are difficult to detect directly. Many more luminous stars have winds that are dense enough to be opaque at certain wavelengths of the star's radiation, making it possible to study their wind outflows remotely through careful interpretation of the observed stellar spectra. Red giant stars show slow, dense winds that may be driven by the pressure from magnetohydrodyanmic waves. As stars with initial mass up to 8 M ? evolve toward the Asymptotic Giant Branch (AGB), a combination of stellar pulsations and radiative scattering off dust can culminate in "superwinds" that strip away the entire stellar envelope, leaving behind a hot white dwarf stellar core with less than the Chandrasekhar mass of ˜ ?? 1. 4M ?. The winds of hot, luminous, massive stars are driven by line-scattering of stellar radiation, but such massive stars can also exhibit superwind episodes, either as Red Supergiants or Luminous Blue Variable stars. The combined wind and superwind mass loss can strip the star's hydrogen envelope, leaving behind a Wolf-Rayet star composed of the products of earlier nuclear burning via the CNO cycle. In addition to such direct effects on a star's own evolution, stellar winds can be a substantial source of mass, momentum, and energy to the interstellar medium, blowing open large cavities or "bubbles" in this ISM, seeding it with nuclear processed material, and even helping trigger the formation of new stars, and influencing their eventual fate as white dwarves or core-collapse supernovae. This chapter reviews the properties of such stellar winds, with an emphasis on the various dynamical driving processes and what they imply for key wind parameters like the wind flow speed and mass loss rate.

Owocki, Stan

366

Edge technique Doppler lidar wind measurements with high vertical resolution  

Microsoft Academic Search

We have developed a Doppler lidar system using the edge technique and have made atmospheric lidar wind measurements. Line-of-sight wind profiles with a vertical resolution of 22 m have a standard deviation of 0.40 m s for a ten-shot average. Day and night lidar measurements of the vector wind have been made for altitudes from 200 to 2000 m. We

C. Laurence Korb; Bruce M. Gentry; S. Xingfu Li

1997-01-01

367

Heat transfer phase change paint tests of 0.0175-scale models (nos. 21-0 and 46-0) of the Rockwell International space shuttle orbiter in the AEDC tunnel B hypersonic wind tunnel (test OH25A)  

NASA Technical Reports Server (NTRS)

Tests were conducted in a hypersonic wind tunnel using various truncated space shuttle orbiter configurations in an attempt to establish the optimum model size for other tests examining body shock-wing leading edge interference effects. The tests were conducted at Mach number 8 using the phase change paint technique. A test description, tabulated data, and tracings of isotherms made from photographs taken during the test are presented.

Dye, W. H.

1975-01-01

368

Fractal vector measures and vector calculus on planar fractal domains  

Microsoft Academic Search

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

F. Mendivil; E. R. Vrscay

2002-01-01

369

Wind Surge  

NSDL National Science Digital Library

This site features an interactive applet from the University of Delaware. The applet illustrates the way water can pile up against the downwind side (of a basin) due to stresses exerted on the surface by strong wind.

Dalrymple, Robert A.; Delaware, University O.

370

Filament winding  

NASA Astrophysics Data System (ADS)

The major aspects of filament winding are discussed, emphasizing basic reinforcement and matrix materials, winding procedures, process controls, and cured composite properties. Fiberglass (E-glass and S-glass strengths are 500,000 and 665,000 psi respectively) and polyester resins are the principal reinforcement constituent materials. Graphite and aramid reinforcements are being used more frequently, primarily for the more critical pressure vessels. Matrix systems are most commonly based on epoxy as it has superior mechanical properties, fatigue behavior, and heat resistance as compard with polyesters. A fiberglass overwrap of PVC pipe is an anticipated development in on-site winding and combination winding, and the compression molding of filament wound lay-ups will be investigated. The fabrication of weight-sensitive structural components may be achieved by using such moldings.

Shibley, A. M.

371

DFIG-based wind farm electromagnetic dynamic model and impact on protection relay of transmission network  

Microsoft Academic Search

A DFIG-based wind generator electromagnetic transient model is established on the RTDS platform in this paper. Stator flux oriented vector control scheme is adopted to achieve power decoupling control in the DFIG based wind model. In order to research the impact of the wind farm on the existing protection relay of the network, this paper establishes single machine electromagnetic dynamic

Guanghui Li; Baohui Zhang; Jin Wang; Zhiqian Bo; Tony Yip; David Writer; Yu-ming Lei

2011-01-01

372

The Windvan pulsed CO2 Doppler lidar wide-area wind sensor  

Microsoft Academic Search

Wind sensing using a Doppler lidar is achieved by sensing the Doppler content of narrow frequency laser light backscattered by the ambient atmospheric aerosols. The derived radial wind components along several directions are used to generate wind vectors, typically using the Velocity Azimuth Display (VAD) method described below. Range resolved information is obtained by range gating the continuous scattered return.

Rhidian Lawrence

1990-01-01

373

Viral vectors for veterinary vaccines.  

PubMed

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

Sheppard, M

1999-01-01

374

Anisotropic Scalings of solar wind turbulence  

NASA Astrophysics Data System (ADS)

Solar wind provides a natural site for studying MHD turbulence. Recently, it has been shown that the solar wind turbulence is anisotropic: the scaling law of the 2nd-order magnetic field structure function depends on the angle between the background magnetic field and the flow velocity. Furthermore, by using a local scale-dependent 3D coordinate system, Chen et al. (2012) demonstrated that the exponent of the power spectrum of the turbulent magnetic field depends on both the vector sum and difference of the two-point solar wind magnetic fields that are being examined. This anisotropy of the solar wind turbulence may depend on various variables. In this work, as an attempt to understand the property and the origin of the anisotropic scaling, we examine the structure functions of the magnetic field for several selected periods. In particular we investigate how the anisotropy depends on the solar wind type.

Xu, F.; Zhao, L.; Li, G.

2012-12-01

375

Three-dimensional elastic lidar winds  

SciTech Connect

Maximum cross-correlation techniques have been used with satellite data to estimate winds and sea surface velocities for several years. Los Alamos National Laboratory (LANL) is currently using a variation of the basic maximum cross-correlation technique, coupled with a deterministic application of a vector median filter, to measure transverse winds as a function of range and altitude from incoherent elastic backscatter lidar data taken throughout large volumes within the atmospheric boundary layer. Hourly representations of three- dimensional wind fields, derived from elastic lidar data taken during an air-quality study performed in a region of complex terrain near Sunland Park, New Mexico, are presented and compared with results from an Environmental Protection Agency (EPA) approved laser doppler velocimeter. The wind fields showed persistent large scale eddies as well as general terrain following winds in the Rio Grande valley.

Buttler, W.T.

1996-07-01

376

Changes  

Microsoft Academic Search

Detailed case histories of long-term successional changes in vegetation are crucial for assessing ecological integrity and developing restoration objectives on prairie preserves in North America's northern Great Plains. Such documentation generally is lacking, however. We used aerial photo measurements plus records from land surveyors and other sources to document change in extent of woodland across four National Wildlife Refuges in

Ronald E. Bontrop; Masanori Kasahara

2001-01-01

377

Vectors from A to B  

NSDL National Science Digital Library

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

378

Fluidic thrust vector control  

NASA Astrophysics Data System (ADS)

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

Haloulakos, V. E.

379

Preloadable vector sensitive latch  

NASA Technical Reports Server (NTRS)

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

Acres, William R. (inventor)

1987-01-01

380

Kinematics of vector fields  

E-print Network

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

S. Manoff

2000-03-02

381

Vector Magnetograph Design  

NASA Technical Reports Server (NTRS)

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

Chipman, Russell A.

1996-01-01

382

Fractional Vector Calculus  

Microsoft Academic Search

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

Vasily E. Tarasov

383

Vector Difference Calculus  

Microsoft Academic Search

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

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

1998-01-01

384

Applications of Vector Calculus  

Microsoft Academic Search

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

Paul C. Matthews

385

Elusive vector glueball  

SciTech Connect

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

Suzuki, Mahiko

2002-05-01

386

A vector product in R  

Microsoft Academic Search

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

A. R. Walter

1996-01-01

387

Scientific processor vector file organization  

SciTech Connect

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

Lahti, A.E.

1989-10-17

388

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

389

The wind characteristics program  

Microsoft Academic Search

Wind characteristics research activities emphasize wind resource assessment, site selection and evaluation techniques, and wind characteristics for wind turbine design, performance and operations evaluation. Wind resource analysis shows the greatest area of high wind power resource is in the midsection of the U.S. High wind power is available in other sections of the country and is described in some detail

L. L. Wendell

1981-01-01

390

Construction of Solar-Wind-Like Magnetic Fields  

NASA Astrophysics Data System (ADS)

Fluctuations in the solar wind fields tend to not only have velocities and magnetic fields correlated in the sense consistent with Alfvén waves traveling from the Sun, but they also have the magnitude of the magnetic field remarkably constant despite their being broadband. This Letter provides, for the first time, a method for constructing fields with nearly constant magnetic field, zero divergence, and with any specified power spectrum for the fluctuations of the components of the field. Every wave vector, k, is associated with two polarizations; the relative phases of these can be chosen to minimize the variance of the field magnitude while retaining the “random” character of the fields. The method is applied to a case with one spatial coordinate that demonstrates good agreement with observed time series and power spectra of the magnetic field in the solar wind, as well as with the distribution of the angles of rapid changes (“discontinuities”), thus showing a deep connection between two seemingly unrelated issues. It is suggested that using this construction will lead to more realistic simulations of solar wind turbulence and of the propagation of energetic particles.

Roberts, D. Aaron

2012-12-01

391

Construction of solar-wind-like magnetic fields.  

PubMed

Fluctuations in the solar wind fields tend to not only have velocities and magnetic fields correlated in the sense consistent with Alfvén waves traveling from the Sun, but they also have the magnitude of the magnetic field remarkably constant despite their being broadband. This Letter provides, for the first time, a method for constructing fields with nearly constant magnetic field, zero divergence, and with any specified power spectrum for the fluctuations of the components of the field. Every wave vector, k, is associated with two polarizations; the relative phases of these can be chosen to minimize the variance of the field magnitude while retaining the "random" character of the fields. The method is applied to a case with one spatial coordinate that demonstrates good agreement with observed time series and power spectra of the magnetic field in the solar wind, as well as with the distribution of the angles of rapid changes ("discontinuities"), thus showing a deep connection between two seemingly unrelated issues. It is suggested that using this construction will lead to more realistic simulations of solar wind turbulence and of the propagation of energetic particles. PMID:23368180

Roberts, D Aaron

2012-12-01

392

Doppler Lidar for Wind Measurements on Venus  

NASA Technical Reports Server (NTRS)

NASA Langley Research Center has a long history of developing 2-micron laser transmitter for wind sensing. With support from NASA Laser Risk Reduction Program (LRRP) and Instrument Incubator Program (IIP), NASA Langley Research Center has developed a state-of-the-art compact lidar transceiver for a pulsed coherent Doppler lidar system for wind measurement. The transmitter portion of the transceiver employs the high-pulse-energy, Ho:Tm:LuLiF, partially conductively cooled laser technology developed at NASA Langley. The transceiver is capable of 250 mJ pulses at 10 Hz. It is very similar to the technology envisioned for coherent Doppler lidar wind measurements from Earth and Mars orbit. The transceiver is coupled to the large optics and data acquisition system in the NASA Langley VALIDAR mobile trailer. The large optics consists of a 15-cm off-axis beam expanding telescope, and a full-hemispheric scanner. Vertical and horizontal vector winds are measured, as well as relative backscatter. The data acquisition system employs frequency domain velocity estimation and pulse accumulation. It permits real-time display of the processed winds and archival of all data. This lidar system was recently deployed at Howard University facility in Beltsville, Mary-land, along with other wind lidar systems. Coherent Doppler wind lidar ground-based wind measurements and comparisons with other sensors will be presented. A simulation and data product for wind measurement at Venus will be presented.

Singh, Upendra N.; Emmitt, George D.; Yu, Jirong; Kavaya, Michael J.

2010-01-01

393

Vector representation of tourmaline compositions  

NASA Technical Reports Server (NTRS)

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

Burt, Donald M.

1989-01-01

394

Low-speed wind-tunnel test of a STOL supersonic-cruise fighter concept  

NASA Technical Reports Server (NTRS)

A wind-tunnel investigation was conducted to examine the low-speed static stability and control characteristics of a 0.10 scale model of a STOL supersonic cruise fighter concept. The concept, referred to as a twin boom fighter, was designed as a STOL aircraft capable of efficient long range supersonic cruise. The configuration name is derived from the long twin booms extending aft of the engine to the twin vertical tails which support a high center horizontal tail. The propulsion system features a two dimensional thrust vectoring exhaust nozzle which is located so that the nozzle hinge line is near the aircraft center of gravity. This arrangement is intended to allow large thrust vector angles to be used to obtain significant values of powered lift, while minimizing pitching moment trim changes. Low speed stability and control information was obtained over an angle of attack range including the stall. A study of jet induced power effects was included.

Coe, Paul L., Jr.; Riley, Donald R.

1988-01-01

395

20% Wind Energy 20% Wind Energy  

E-print Network

(government, industry, utilities, NGOs) Analyzes wind's potential contributions to energy security, economic20% Wind Energy by 2030 20% Wind Energy by 2030 #12;Presentation and Objectives Overview Background scenario for reaching 20% wind energy by 2030 and contrasts it to a scenario in which no new U.S. wind

Powell, Warren B.

396

Wind power and Wind power and  

E-print Network

Wind power and the CDM #12; Wind power and the CDM Emerging practices in developing wind power 2005 Jyoti P. Painuly, Niels-Erik Clausen, Jørgen Fenhann, Sami Kamel and Romeo Pacudan #12; WIND POWER AND THE CDM Emerging practices in developing wind power projects for the Clean Development Mechanism Energy

397

2008 WIND TECHNOLOGIES MARKET REPORT  

SciTech Connect

The U.S. wind industry experienced a banner year in 2008, again surpassing even optimistic growth projections from years past. At the same time, the last year has been one of upheaval, with the global financial crisis impacting near-term growth prospects for the wind industry, and with federal policy changes enacted to push the industry towards continued aggressive expansion. This rapid pace of development has made it difficult to keep up with trends in the marketplace. Yet, the need for timely, objective information on the industry and its progress has never been greater. This report - the third of an ongoing annual series - attempts to meet this need by providing a detailed overview of developments and trends in the U.S. wind power market, with a particular focus on 2008. As with previous editions, this report begins with an overview of key wind power installation-related trends: trends in wind capacity growth in the U.S., how that growth compares to other countries and generation sources, the amount and percentage of wind in individual states and serving specific utilities, and the quantity of proposed wind capacity in various interconnection queues in the United States. Next, the report covers an array of wind industry trends, including developments in turbine manufacturer market share, manufacturing and supply-chain investments, wind turbine and wind project size, project financing developments, and trends among wind power developers, project owners, and power purchasers. The report then turns to a discussion of wind project price, cost, and performance trends. In so doing, it reviews the price of wind power in the United States, and how those prices compare to the cost of fossil-fueled generation, as represented by wholesale power prices. It also describes trends in installed wind project costs, wind turbine transaction prices, project performance, and operations and maintenance expenses. Next, the report examines other policy and market factors impacting the domestic wind power market, including federal and state policy drivers, transmission issues, and grid integration. Finally, the report concludes with a preview of possible near- to medium-term market developments. This version of the Annual Report updates data presented in the previous editions, while highlighting key trends and important new developments from 2008. New to this edition is an executive summary of the report and an expanded final section on near- to medium-term market development. The report concentrates on larger-scale wind applications, defined here as individual turbines or projects that exceed 50 kW in size. The U.S. wind power sector is multifaceted, however, and also includes smaller, customer-sited wind turbines used to power the needs of residences, farms, and businesses. Data on these applications are not the focus of this report, though a brief discussion on Distributed Wind Power is provided on page 4. Much of the data included in this report were compiled by Berkeley Lab, and come from a variety of sources, including the American Wind Energy Association (AWEA), the Energy Information Administration (EIA), and the Federal Energy Regulatory Commission (FERC). The Appendix provides a summary of the many data sources used in the report. Data on 2008 wind capacity additions in the United States are based on information provided by AWEA; some minor adjustments to those data may be expected. In other cases, the data shown here represent only a sample of actual wind projects installed in the United States; furthermore, the data vary in quality. As such, emphasis should be placed on overall trends, rather than on individual data points. Finally, each section of this document focuses on historical market information, with an emphasis on 2008; with the exception of the final section, the report does not seek to forecast future trends.

Wiser, Ryan H.; Bolinger, Mark; Barbose, G.; Mills, A.; Rosa, A.; Porter, K.; Fink, S.; Tegen, S.; Musial, W.; Oteri, F.; Heimiller, D.; Rberts, B.; Belyeu, K.; Stimmel, R.

2009-07-15

398

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

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

399

Wind tunnel investigation on wind turbine wakes and wind farms  

NASA Astrophysics Data System (ADS)

The interaction between atmospheric boundary layer and wind farms leads to flow modifications, which need to be deeply characterized in order to relate them to wind farm performance. The wake flow produced from a wind farm is the result of a strong interaction between multiple turbine wakes, so that the wind farm configuration turns out to be one of the dominant features to enhance power production. For the present work a wind tunnel investigation was carried out with hot-wire anemometry and velocity measurements performed with multi-hole pressure probes. The tested wind farms consist of miniature three-bladed wind turbine models. Preliminarily, the wake flow generated from a single wind turbine is surveyed, which is characterized by a strong velocity defect lying in proximity of the wind turbine hub height. The wake gradually recovers by moving downstream; the characteristics of the incoming boundary layer and wind turbulence intensity can strongly affect the wake recovery, and thus performance of following wind turbines. An increased turbulence level is typically detected downstream of each wind turbine for heights comparable to the wind turbine blade top-tip. These wake flow fluctuations produce increased fatigue loads on the following wind turbines within a wind farm, which could represent a significant hazard for real wind turbines. Dynamics of vorticity structures present in wind turbine wakes are also investigated; particular attention is paid to the downstream evolution of the tip helicoidal vortices and to oscillations of the hub vortex. The effect of wind farm layout on power production is deeply investigated. Particular emphasis is placed on studying how the flow adjusts as it moves inside the wind farm and can affect the power production. Aligned and staggered wind farm configurations are analysed, also with varying separation distances in the streamwise and spanwise directions. The present experimental results are being used to test and guide the development of improved parameterizations of wind turbines in high-resolution numerical models, such as large-eddy simulations (LES).

Iungo, G. V.; Coëffé, J.; Porté-Agel, F.

2012-04-01

400

Vector wave propagation method.  

PubMed

In this paper, we extend the scalar wave propagation method (WPM) to vector fields. The WPM [Appl. Opt.32, 4984 (1993)] was introduced in order to overcome the major limitations of the beam propagation method (BPM). With the WPM, the range of application can be extended from the simulation of waveguides to simulation of other optical elements like lenses, prisms and gratings. In that reference it was demonstrated that the wave propagation scheme provides valid results for propagation angles up to 85 degrees and that it is not limited to small index variations in the axis of propagation. Here, we extend the WPM to three-dimensional vectorial fields (VWPMs) by considering the polarization dependent Fresnel coefficients for transmission in each propagation step. The continuity of the electric field is maintained in all three dimensions by an enhanced propagation vector and the transfer matrix. We verify the validity of the method by transmission through a prism and by comparison with the focal distribution from vectorial Debye theory. Furthermore, a two-dimensional grating is simulated and compared with the results from three-dimensional RCWA. Especially for 3D problems, the runtime of the VWPM exhibits special advantage over the RCWA. PMID:20360813

Fertig, M; Brenner, K-H

2010-04-01

401

Gap Winds  

NSDL National Science Digital Library

This module provides a basic understanding of why gap winds occur, their typical structures, and how gap wind strength and extent are controlled by larger-scale, or synoptic, conditions. You will learn about a number of important gap flows in coastal regions around the world, with special attention given to comprehensively documented gap wind cases in the Strait of Juan de Fuca and the Columbia River Gorge. Basic techniques for evaluating and predicting gap flows are presented. The module reviews the capabilities and limitations of the current generation of mesoscale models in producing realistic gap winds. By the end of this module, you should have sufficient background to diagnose and forecast gap flows around the world, and to use this knowledge to understand their implications for operational decisions. Other features in this module include a concise summary for quick reference and a final exam to test your knowledge. Like other modules in the Mesoscale Meteorology Primer, this module comes with audio narration, rich graphics, and a companion print version.

Comet

2003-03-20

402

Measuring surface wind direction by monostatic HF ground-wave radar at the eastern China Sea  

Microsoft Academic Search

The extraction of full wind vectors from data obtained by single-site (monostatic) high-frequency ground-wave radar (HFGWR) is an ongoing challenge because of the inherent directional ambiguities. Here, a new algorithm for resolving the ambiguity of wind direction from monostatic data is presented. The true wind direction is determined by minimizing the sum of the difference among three wind directions derived

Weimin Huang; Eric Gill; Shicai Wu; Biyang Wen; Zijie Yang; Jiechang Hou

2004-01-01

403

Pattern forced geophysical vector field segmentation based on Clifford FFT  

NASA Astrophysics Data System (ADS)

Vector field segmentation is gaining increasing importance in geophysics research. Existing vector field segmentation methods usually can only handle the statistical characteristics of the original data. It is hard to integrate the patterns forced by certain geophysical phenomena. In this paper, a template matching method is firstly constructed on the foundation of the Clifford Fourier Transformation (CFT). The geometric meanings of both inner and outer components can provide more attractive information about the similarities between original vector field and template data. A composed similarity field is constructed based on the coefficients fields. After that, a modified spatial consistency preserving K-Means cluster algorithm is proposed. This algorithm is applied to the similarity fields to extract the template forced spatial distribution pattern. The complete algorithm for the overall processing is given and the experiments of ENSO forced global ocean surface wind segmentation are configured to test our method. The results suggest that the pattern forced segmentation can extract more latent information that cannot be directly measured from the original data. And the spatial distribution of ENSO influence on the surface wind field is clearly given in the segmentation result. All the above suggest that the method we proposed provides powerful and new thoughts and tools for geophysical vector field data analysis.

Yuan, Linwang; Yu, Zhaoyuan; Luo, Wen; Yi, Lin; Hu, Yong

2013-10-01

404

Three-Dimensional Venturi Sensor for Measuring Extreme Winds  

NASA Technical Reports Server (NTRS)

A three-dimensional (3D) Venturi sensor is being developed as a compact, rugged means of measuring wind vectors having magnitudes of as much as 300 mph (134 m/s). This sensor also incorporates auxiliary sensors for measuring temperature from -40 to +120 F (-40 to +49 C), relative humidity from 0 to 100 percent, and atmospheric pressure from 846 to 1,084 millibar (85 to 108 kPa). Conventional cup-and-vane anemometers are highly susceptible to damage by both high wind forces and debris, due to their moving parts and large profiles. In addition, they exhibit slow recovery times contributing to an inaccurately high average-speed reading. Ultrasonic and hot-wire anemometers overcome some of the disadvantages of the cup and-vane anemometers, but they have other disadvantageous features, including limited dynamic range and susceptibility to errors caused by external acoustic noise and rain. In contrast, the novel 3D Venturi sensor is less vulnerable to wind damage because of its smaller profile and ruggedness. Since the sensor has no moving parts, it provides increased reliability and lower maintenance costs. It has faster response and recovery times to changing wind conditions than traditional systems. In addition, it offers wide dynamic range and is expected to be relatively insensitive to rain and acoustic energy. The Venturi effect in this sensor is achieved by the mirrored double-inflection curve, which is then rotated 360 to create the desired detection surfaces. The curve is optimized to provide a good balance of pressure difference between sensor ports and overall maximum fluid velocity while in the shape. Four posts are used to separate the two shapes, and their size and location were chosen to minimize effects on the pressure measurements. The 3D Venturi sensor has smart software algorithms to map the wind pressure exerted on the surfaces of the design. Using Bernoulli's equation, the speed of the wind is calculated from the differences among the pressure readings at the various ports. The direction of the wind is calculated from the spatial distribution and magnitude of the pressure readings. All of the pressure port sizes and locations have been optimized to minimize measurement errors and to reside in areas demonstrating a stable pressure reading proportional to the velocity range.

Zysko, Jan A.; Perotti, Jose M.; Amis, Christopher; Randazzo, John; Blalock, Norman; Eckhoff, Anthony

2003-01-01

405

Bridging the Vector Calculus Gap  

NSDL National Science Digital Library

This paper was written collaboratively by a physicist and a mathematician to raise awareness about the "vector calculus gap" and offer realistic solutions to bridge the gap. The authors define the vector calculus gap as a disparity between the way mathematicians and physical scientists think about vectors, which they argue results in performance difficulties for students of physics and engineering. In this paper, they advocate emphasizing geometric reasoning over algebraic computation when introducing vectors. In addition, their proposed instructional method uses differentials to bridge the vector calculus gap. Included are sample group activities and tips for incorporating these ideas in the classroom. SEE RELATED ITEMS BELOW for a link to the authors' full web site on Bridging the Vector Calculus Gap.

Dray, Tevian; Manogue, Corinne A.

2008-12-23

406

Measuring Winds With Pulsed C-Band Radar  

NASA Technical Reports Server (NTRS)

Research has begun on use of pulsed C-band radar in multistatic configuration to measure winds in absence of clouds. Experimental system based on principle of multistatic radar. Multiple receivers track on same point in sky to measure winds from different angles, obtaining complete wind vector at that point. Includes one radar station that both transmits and receives and one or more other stations receiving only. Advantage of multistatic configuration greatly reduces effects of ground clutter on receive-only stations. Objective of effort to develop capability to use wind-measurement data to predict, as early and accurately as possible, formation of local thunderstorms-with lead times of several hours.

Lennon, Carl; Wesenberg, Richard; Britt, Thomas O.; Brooks, Michael; Edwards, Deloris; Franklin, Chris; Kiriazes, John; Kitayama, Brad; Medina, Jim

1989-01-01

407

2008 Wind Technologies Market Report  

SciTech Connect

The U.S. wind industry experienced a banner year in 2008, once again surpassing even optimistic growth projections from years past. At the same time, the past year has been one of upheaval, with the global financial crisis impacting near-term growth prospects for the wind industry, and with significant federal policy changes enacted to push the industry toward continued aggressive expansion. This report examines key trends.

Wiser, R.; Bolinger, M.

2009-07-01

408

3-D Vector Field Simulation  

NSDL National Science Digital Library

This simulation illustrates a wide range of 3D vector fields, including spherical, radial, and linear. The fields can be displayed as vectors, particle trajectories, equipotentials, and other options. The number of particles, vectors, or streamlines, and the field strength are adjustable. Directions and source code are also included. This is an extension of a 3D Electric and Magnetic Field viewer from the same author.

Falstad, Paul

2004-07-13

409

Adenoviral vectors for gene therapy  

Microsoft Academic Search

Vectors based on human adenovirus serotypes 2 (Ad2) and 5 (Ad5) of species C possess a number of features that have favored\\u000a their widespread employment for gene delivery both in?vitro and in?vivo. However, the use of recombinant Ad2- and Ad5-based\\u000a vectors for gene therapy also suffers from a number of disadvantages. These vectors possess the tropism of the parental viruses,

Joanne T. Douglas

2007-01-01