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1

Analysis of vector wind change with respect to time for Cape Kennedy, Florida: Wind aloft profile change vs. time, phase 1  

NASA Technical Reports Server (NTRS)

Wind vector change with respect to time at Cape Kennedy, Florida, is examined according to the theory of multivariate normality. 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 fifteen 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, the joint distribution of wind component changes is bivariate normal, and the modulus of vector wind change is Rayleigh, has been 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 one to five hours, calculated from Jimsphere data, are presented.

Adelfang, S. I.

1977-01-01

2

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

3

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.

Eric Sokolowsky

2004-02-11

4

SSM/I and ECMWF Wind Vector Comparison  

NASA Technical Reports Server (NTRS)

Wentz was the first to convincingly show that satellite microwave radiometers have the potential to measure the oceanic wind vector. The most compelling evidence for this conclusion was the monthly wind vector maps derived solely from a statistical analysis of Special Sensor Microwave Imager (SSM/I) observations. In a qualitative sense, these maps clearly showed the general circulation over the world's oceans. In this report we take a closer look at the SSM/I monthly wind vector maps and compare them to European Center for Medium-Range Weather Forecasts (ECMWF) wind fields. This investigation leads both to an empirical comparison of SSM/I calculated wind vectors with ECMWF wind vectors, and to an examination of possible reasons that the SSM/I calculated wind vector direction would be inherently more reliable at some locations than others.

Wentz, Frank J.; Ashcroft, Peter D.

1996-01-01

5

The winds of change  

Technology Transfer Automated Retrieval System (TEKTRAN)

Wind-based power generation has been growing steadily in the United States and around the world, and this growth will continue—and accelerate—in the future, as the following background statistics demonstrate. The U.S. wind industry installed 8,358 megawatts (MW) of new wind generating capacity in 20...

6

Rapid Temporal Changes of Midtropospheric Winds  

NASA Technical Reports Server (NTRS)

The statistical distribution of the magnitude of the vector wind change over 0.25-, 1-, 2-. and 4-h periods based on data from October 1995 through March 1996 over central Florida is presented. The wind changes at altitudes from 6 to 17 km were measured using the Kennedy Space Center 50-MHz Doppler radar wind profiler. Quality controlled profiles were produced every 5 min for 112 gates, each representing 150 m in altitude. Gates 28 through 100 were selected for analysis because of their significance to ascending space launch vehicles. The distribution was found to be lognormal. The parameters of the lognormal distribution depend systematically on the time interval. This dependence is consistent with the behavior of structure functions in the f(exp 5/3) spectral regime. There is a small difference between the 1995 data and the 1996 data, which may represent a weak seasonal effect.

Merceret, Francis J.

1997-01-01

7

Space vector PWM control of dual inverter fed open-end winding induction motor drive  

Microsoft Academic Search

A space vector PWM technique is developed based on the combination of space vectors from dual inverters feeding the induction motor from both ends (open-end winding without neutral point). A total of 64 voltage space vector combinations are available for PWM voltage control of the inverter fed machine with open-end winding. A space phasor based PWM scheme is proposed with

E. G. Shivakumar; K. Gopakumar; S. K. Sinha; Andrei Pittet; V. T. Ranganathan

2001-01-01

8

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

9

Two-component horizontal wind vectors from the Raman-shifted Eye-safe Aerosol Lidar (REAL)  

NASA Astrophysics Data System (ADS)

Two-component horizontal wind vectors were calculated by applying a cross-correlation algorithm to square image blocks extracted from consecutive pairs of elastic backscatter lidar scans. The resulting vector components were compared with corresponding horizontal wind components from tower-mounted sonic anemometers located at the center of the image blocks at a range of 1.61 km. 180245 pairs of vectors derived from 75 days of field data collected between 19 March and 11 June 2007 were used in the analysis. Examples of time series comparisons from 4-h periods during light, strong, and changing wind conditions will be presented. The correlation between lidar-derived components and sonic anemometer components changes as a function of the mean backscatter signal-to-noise ratio (SNR) in the block area, maxima of the cross-correlation function (CCF), observed wind speed, and turbulent kinetic energy (TKE). The correlation between the lidar-derived velocity components and sonic anemometer wind components tends to be highest during light wind conditions with low TKE. Although the correlation of high frequency perturbations tends to be poor during windy and turbulent conditions, the technique is capable of sensing the mean flow. Examples of 2-dimensional, 2-component, flow fields will be presented. The NSF/NCAR REAL at California State University Chico. Streamlined flow field from 2-component vectors derived from 2 scans of the REAL and application of the cross-correlation technique. The area of the image spans 4 km by 4 km.

Mayor, S. D.

2012-12-01

10

Time changes in gradient and observed winds  

E-print Network

and the tangen- tial acceleration. It would be'nice to conclude that any differences between changes in the gradient wind and changes in the actual wind are due to the frictional force and/or tangential acceleration. However, Mantis (1968) points out...

Carlson, Ronald Dale

1972-01-01

11

Ocean Surface Vector Wind: Research Challenges and Operational Opportunities  

NASA Technical Reports Server (NTRS)

The atmosphere and ocean are joined together over seventy percent of Earth, with ocean surface vector wind (OSVW) stress one of the linkages. Satellite OSVW measurements provide estimates of wind divergence at the bottom of the atmosphere and wind stress curl at the top of the ocean; both variables are critical for weather and climate applications. As is common with satellite measurements, a multitude of OSVW data products exist for each currently operating satellite instrument. In 2012 the Joint Technical Commission on Oceanography and Marine Meteorology (JCOMM) launched an initiative to coordinate production of OSVW data products to maximize the impact and benefit of existing and future OSVW measurements in atmospheric and oceanic applications. This paper describes meteorological and oceanographic requirements for OSVW data products; provides an inventory of unique data products to illustrate that the challenge is not the production of individual data products, but the generation of harmonized datasets for analysis and synthesis of the ensemble of data products; and outlines a vision for JCOMM, in partnership with other international groups, to assemble an international network to share ideas, data, tools, strategies, and deliverables to improve utilization of satellite OSVW data products for research and operational applications.

Halpern, David

2012-01-01

12

Single-Vector Calibration of Wind-Tunnel Force Balances  

NASA Technical Reports Server (NTRS)

An improved method of calibrating a wind-tunnel force balance involves the use of a unique load application system integrated with formal experimental design methodology. The Single-Vector Force Balance Calibration System (SVS) overcomes the productivity and accuracy limitations of prior calibration methods. A force balance is a complex structural spring element instrumented with strain gauges for measuring three orthogonal components of aerodynamic force (normal, axial, and side force) and three orthogonal components of aerodynamic torque (rolling, pitching, and yawing moments). Force balances remain as the state-of-the-art instrument that provide these measurements on a scale model of an aircraft during wind tunnel testing. Ideally, each electrical channel of the balance would respond only to its respective component of load, and it would have no response to other components of load. This is not entirely possible even though balance designs are optimized to minimize these undesirable interaction effects. Ultimately, a calibration experiment is performed to obtain the necessary data to generate a mathematical model and determine the force measurement accuracy. In order to set the independent variables of applied load for the calibration 24 NASA Tech Briefs, October 2003 experiment, a high-precision mechanical system is required. Manual deadweight systems have been in use at Langley Research Center (LaRC) since the 1940s. These simple methodologies produce high confidence results, but the process is mechanically complex and labor-intensive, requiring three to four weeks to complete. Over the past decade, automated balance calibration systems have been developed. In general, these systems were designed to automate the tedious manual calibration process resulting in an even more complex system which deteriorates load application quality. The current calibration approach relies on a one-factor-at-a-time (OFAT) methodology, where each independent variable is incremented individually throughout its full-scale range, while all other variables are held at a constant magnitude. This OFAT approach has been widely accepted because of its inherent simplicity and intuitive appeal to the balance engineer. LaRC has been conducting research in a "modern design of experiments" (MDOE) approach to force balance calibration. Formal experimental design techniques provide an integrated view to the entire calibration process covering all three major aspects of an experiment; the design of the experiment, the execution of the experiment, and the statistical analyses of the data. In order to overcome the weaknesses in the available mechanical systems and to apply formal experimental techniques, a new mechanical system was required. The SVS enables the complete calibration of a six-component force balance with a series of single force vectors.

Parker, P. A.; DeLoach, R.

2003-01-01

13

A Novel Empirical Mode Decomposition With Support Vector Regression for Wind Speed Forecasting.  

PubMed

Wind energy is a clean and an abundant renewable energy source. Accurate wind speed forecasting is essential for power dispatch planning, unit commitment decision, maintenance scheduling, and regulation. However, wind is intermittent and wind speed is difficult to predict. This brief proposes a novel wind speed forecasting method by integrating empirical mode decomposition (EMD) and support vector regression (SVR) methods. The EMD is used to decompose the wind speed time series into several intrinsic mode functions (IMFs) and a residue. Subsequently, a vector combining one historical data from each IMF and the residue is generated to train the SVR. The proposed EMD-SVR model is evaluated with a wind speed data set. The proposed EMD-SVR model outperforms several recently reported methods with respect to accuracy or computational complexity. PMID:25222957

Ren, Ye; Suganthan, Ponnuthurai Nagaratnam; Srikanth, Narasimalu

2014-09-11

14

Climate Change: Potential Affect on Pesticide Application for Vector Control  

Technology Transfer Automated Retrieval System (TEKTRAN)

Global climate change has and will in the future contribute to the global burden of vector-borne disease by affecting the spatial and tempral distribution of disease. These changes in disease distributions are a direct result of altering the ecology of immature and adult habitats of insect vectors....

15

Short-Term Wind Power Prediction Using a Wavelet Support Vector Machine  

Microsoft Academic Search

This paper proposes a wavelet support vector machine (WSVM)-based model for short-term wind power prediction (WPP). A new wavelet kernel is proposed to improve the generalization ability of the support vector machine (SVM). The proposed kernel has such a general characteristic that some commonly used kernels are its special cases. Simulation studies are carried to validate the proposed model with

Jianwu Zeng; Wei Qiao

2012-01-01

16

Mode changing stability of wind turbine in an integrated wind turbine and rechargeable battery system  

Microsoft Academic Search

Power generated by wind turbines changes due to variation in wind speed that is independent of the load power. Rechargeable batteries could be used as a reserve power source to alleviate unbalance between the load power and power generated by wind turbines. A supervisory controller is proposed for an integrated wind turbine-battery system (wind turbine electrically connected to a rechargeable

Christine A. Mecklenborg; Dushyant Palejiya; John F. Hall; Dongmei Chen

2011-01-01

17

Measurement of oceanic wind vector using satellite microwave radiometers  

Microsoft Academic Search

The possibility of retrieving both wind speed and direction from microwave radiometer measurements of the ocean is studied using Special Sensor Microwave\\/Imager (SSM\\/I) measurements collocated with buoy reports from the National Data Buoy Center (NDBC). A physically based algorithm is used to retrieve the wind speed. The RMS difference between the SSM\\/I and buoy wind speed is 1.6 m\\/s for

Frank J. Wentz

1992-01-01

18

Vector Fields  

NSDL National Science Digital Library

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

Dray, Tevian

2006-01-01

19

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

20

Estimating daily wind speed under climate change  

Microsoft Academic Search

A semi-empirical downscaling approach is presented to estimate spatial and temporal statistical properties of local daily mean wind speed under global climate change. The present semi-empirical downscaling method consists of two elements. Since general circulation models (GCMs) are able to reproduce the features of the present atmospheric general circulation quite correctly, the first element represents the large-scale circulation of the

Istvan Bogardi; Istvan Matyasovzky

1996-01-01

21

Control strategies for enhanced power smoothing in wind energy systems using a flywheel driven by a vector-controlled induction machine  

Microsoft Academic Search

This paper presents a novel control strategy for power smoothing in wind energy applications, especially those feeding a stand-alone load. The system is based on a vector-controlled induction machine driving a flywheel and addresses the problem of regulating the DC-link system voltage against both input power surges\\/sags from a wind turbine or sudden changes in load demand. The control is

Roberto Cárdenas; Rubén Peña; Greg Asher; Jon Clare

2001-01-01

22

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

23

Sensorless vector control of induction machines for variable-speed wind energy applications  

Microsoft Academic Search

A sensorless vector-control strategy for an induction generator in a grid-connected wind energy conversion system is presented. The sensorless control system is based on a model reference adaptive system (MRAS) observer to estimate the rotational speed. In order to tune the MRAS observer and compensate for the parameter variation and uncertainties, a separate estimation of the speed is obtained from

Roberto Cárdenas; Rubén Peña

2004-01-01

24

Vector controlled induction machines for stand-alone wind energy applications  

Microsoft Academic Search

This paper describes the system and control structures for vector controlled induction generators used for variable speed, wind energy conversion (WEC) systems. The paper focuses on WEC systems feeding an isolated load or weak grid since for such systems the generated voltage and power flow must be regulated by the WEC system itself and the control structures are not trivial.

R. S. Pena; R. J. Cardenas; G. M. Asher; J. C. Clare

2000-01-01

25

A Vector Control for Grid-connected Wind Power Generation with Doubly Fed Induction Generator  

NASA Astrophysics Data System (ADS)

Recently, doubly fed induction generator (DFIG) and synchronous generator are mostly applied for wind power generation due to high efficiently for wind energy capture. An inverter system is required to control wind turbine speed and power factor in those generators. The inverter rating of the synchronous generator equals to generator rating. However, DFIG has the advantage that the inverter rating is about 25% to the generator rating. The paper describes a vector control of DFIG inter-connected to power line. The performance of proposed vector control is examined using power system simulation software PSCAD/EMTDC for the DFIG inter-connected to 6.6kv distribution line. The results show good dynamic responses and high accuracy to the stator active power control and the stator reactive power control.

Kai, Takaaki; Tanaka, Yuji; Kaneda, Hirotoshi; Kobayashi, Daichi; Tanaka, Akio

26

Integrating the ASCAT Observations into a Climate Data Record of Ocean Vector Winds  

NASA Astrophysics Data System (ADS)

Ocean surface vector winds have been continuously observed from space since 1991, starting with the ERS scatterometer, followed later by a series of other scatterometers. These measurements have been proved extremely useful for improving the skill of numerical weather forecasts. With a timeseries extending now to more than 20 years, these measurements can provide great insight into the climate variability of surface wind patterns. Integrating all the measurements from different sensors into a continuous and accurate timeseries suitable for climate analysis is however a challenging task. An essential requirement for this purpose is the consistency among wind retrievals from different sensors at all wind speed ranges. Here we present our methodology for creating a Climate Data Record of ocean vector winds. We first started with reprocessing the QuikSCAT wind measurements for the whole mission (1999-2009) by using a new Geophysical Model Function (GMF) specifically redeveloped for improving retrievals at high wind speeds. The new GMF Ku-2011 (Ricciardulli and Wentz, 2011) was developed using wind retrievals from the WindSat radiometer as calibration for the scatterometer backscatter ratio. WindSat wind speeds are believed to be accurate for winds up to at least 35 m/s (Meissner and Wentz, 2009). In order to continue the timeseries after the end of the QuikSCAT mission, we focused on developing a new GMF for the European scatterometer ASCAT, which started in 2007 and is planned to continue for several years. The motivation behind redeveloping the GMF, rather than using the operational one, is based on the necessity of a consistent methodology to reduce biases when combining QuikSCAT with ASCAT in a Climate Data Record. The new ASCAT GMF was developed calibrating the backscatter ratio to the wind speeds from the SSM/I and WindSat radiometers. A preliminary version of the RSS ASCAT winds has been recently produced. Here we will discuss the validation of these retrievals versus in situ observations and winds from other satellite missions. Particular emphasis will be on the comparison with the QuikSCAT retrievals during the overlapping period (2007-2009), in terms of overall consistency at all wind speed ranges and careful analysis of any regional bias. One important feature to keep in mind is the temporal gap in the local observing time of the two scatterometers (about 3-4 hours). This temporal gap can give raise to regional biases and diurnal aliasing in the merged timeseries if the diurnal cycle of ocean winds is not properly accounted for. An additional check for consistency and any potential temporal drift in the QuikSCAT and ASCAT timeseries is done by comparing them with the wind speed timeseries from the SSM/I and SSMIS radiometers. Once we ascertain the feasibility of merging QuikSCAT and ASCAT measurements with the required climate-quality accuracy, the Climate Data Record can be extended back in time to 1991 by using the same methodology for the European scatterometers ERS-1 and 2. This intercalibrated data set would then provide two decades of global ocean vector winds, suitable for climate research.

Ricciardulli, Lucrezia; Meissner, Thomas; Wentz, Frank

2013-04-01

27

[Vector transmitted diseases and climate changes in Europe].  

PubMed

The increase in temperatures recorded since the mid-nineteenth century is unprecedented in the history of mankind. The consequences of climate changes are numerous and can affect human health through direct (extreme events, natural disasters) or indirect (alteration of the ecosystem) mechanisms. Climate changes have repercussions on ecosystems, agriculture, social conditions, migration, conflicts and the transmission mode of infectious diseases. Vector-borne diseases are infections transmitted by the bite of infected arthropods such as mosquitoes, ticks, triatomines, sand flies and flies. Epidemiological cornerstones of vector-borne diseases are: the ecology and behaviour of the host, the ecology and behaviour of the vector, and the population's degree of immunity. Mosquito vectors related to human diseases mainly belong to the genus Culex, Aedes and Mansonia. Climate changes in Europe have increased the spread of new vectors, such as Aedes albopictus, and in some situations have made it possible to sustain the autochthonous transmission of some diseases (outbreak of Chukungunya virus in northern Italy in 2007, cases of dengue in the South of France and in Croatia). Despite the eradication of malaria from Europe, anopheline carriers are still present, and they may allow the transmission of the disease if the climatic conditions favour the development of the vectors and their contacts with plasmodium carriers. The tick Ixodes ricinus is a vector whose expansion has been documented both in latitude and in altitude in relation to the temperature increase; at the same time the related main viral and bacterial infections have increased. In northern Italy and Germany, the appearance of Leishmaniasis has been associated to climatic conditions that favour the development of the vector Phlebotomus papatasi and the maturation of the parasite within the vector, although the increase of cases of visceral leishmaniasis is also related to host immune factors, particularly immunodepression caused by the human immunodeficiency virus (HIV). Despite the importance of global warming in facilitating the transmission of certain infectious diseases, due consideration must be taken of the role played by other variables, such as the increase in international travel, migration and trade, with the risk of importing parasites and vectors with the goods. In addition, the control of certain infections was possible in the past through improvements in socio-economic conditions of affected populations. However, the reduction in resources allocated to health care has recently led to the re-emergence of diseases that were considered eradicated. PMID:25269959

Rossati, Antonella; Bargiacchi, Olivia; Kroumova, Vesselina; Garavelli, Pietro Luigi

2014-09-01

28

The influence of small-scale sea surface temperature gradients on surface vector winds and subsequent impacts on oceanic Ekman pumping  

NASA Astrophysics Data System (ADS)

Satellite observations have revealed a small-scale (< 1000 km) air--sea coupling in regions of strong sea surface temperature (SST) gradients (e.g., fronts, currents, eddies, and tropical instability waves), where the surface wind and wind stress are modified. Surface winds and wind stresses are persistently higher over the warm side of the SST front compared to the cool side, causing perturbations in the dynamically and thermodynamically curl and divergence fields. Capturing this small-scale SST--wind variability is important because it can significantly impact both local and remote (i.e., large scale) oceanic and atmospheric processes. The SST--wind relationship is not well represented in numerical weather prediction (NWP) and climate models, and the relative importance of the physical processes that are proposed to be responsible for this relationship is actively and vehemently debated. This study focuses on the physical mechanisms that are primarily responsible for the SST-induced changes in surface wind and wind stress, and on the physical implication on ocean forcing through Ekman pumping. The roles that SST-induced atmospheric baroclinicity and boundary-layer stability play in modifying the surface vector wind in regions of strong SST gradients are examined with an idealized model. Modeled changes in surface wind speed due to changes in atmospheric boundary-layer stability and baroclinicity are largely between -2.0 and 2.0 m s-1, which is consistent with past observational findings. The baroclinic-related changes in the surface vector wind are found to have a largely linear dependence on the SST gradient, whereas the stability-related changes are highly non-linear. The linearity of the baroclinic impacts matches that of the observed (satellite and in situ) SST--wind relationship. This result suggests that the baroclinic-related mechanism is the leading factor in driving the observed surface wind response to strong open ocean SST fronts on scales greater than 25 km. This study shows that the baroclinic-related changes in Ekman pumping are significant (first-order) over a seasonal (2003 winter season) time scale and that the small-scale impacts are quite important over larger spatial scales. These findings highlight the need to consider the small-scale SST--wind relationship even in coarser resolution model simulation, for which it may be feasible to parameterize because of the linear nature of the baroclinic-related effects.

Hughes, Paul J.

29

Angular Distribution of Solar Wind Magnetic Field Vector at 1 Au  

NASA Astrophysics Data System (ADS)

We study the angular distribution of the solar wind magnetic field vector at 1 AU and its solar cycle dependence using ACE observations. A total of twelve 27.27 day (the duration of a solar rotation) intervals during the solar maximum, the solar minimum, as well as the ascending and descending phases of solar cycle 23 are examined. For all selected intervals, we obtain the angular distribution function {{f}? }(? ), where ? is the angle between the instantaneous solar wind magnetic field vector and the average background magnetic field vector, and ? is the period length for the averaging. Our results show that in all periods {{f}? }(? ) has two populations, one at small angles and one at large angles. We suggest that the second population is due to the presence of current sheets in the solar wind. The solar-cycle dependence of {{f}? }(? ) and a ?-scaling property of the second population of {{f}? }(? ) are discussed. The ? scaling shows a clear dependence on the solar wind type. The implication of {{f}? }(? ) for particle acceleration at interplanetary shocks driven by coronal mass ejections, such as those in solar energetic particle events, is also discussed.

Xu, F.; Li, G.; Zhao, L.; Zhang, Y.; Khabarova, O.; Miao, B.; le Roux, J.

2015-03-01

30

Surface Wind Vector and Rain Rate Observation Capability of Future Hurricane Imaging Radiometer (HIRAD)  

NASA Technical Reports Server (NTRS)

The Hurricane Imaging Radiometer (HIRAD) is the next-generation Stepped Frequency Microwave Radiometer (SFMR), and it will offer the capability of simultaneous wide-swath observations of both extreme ocean surface wind vector and strong precipitation from either aircraft (including UAS) or satellite platforms. HIRAD will be a compact, lightweight, low-power instrument with no moving parts that will produce valid wind observations under hurricane conditions when existing microwave sensors (radiometers or scatterometers) are hindered by precipitation. The SFMR i s a proven aircraft remote sensing system for simultaneously observing extreme ocean surface wind speeds and rain rates, including those of major hurricane intensity. The proposed HIRAD instrument advances beyond the current nadir viewing SFMR to an equivalent wide-swath SFMR imager using passive microwave synthetic thinned aperture radiometer technology. The first version of the instrument will be a single polarization system for wind speed and rain rate, with a dual-polarization system to follow for wind vector capability. This sensor will operate over 4-7 GHz (C-band frequencies) where the required tropical cyclone remote sensing physics has been validated by both SFMR and WindSat radiometers. HIRAD incorporates a unique, technologically advanced array antenna and several other technologies successfully demonstrated by NASA s Instrument Incubator Program. A brassboard (laboratory) version of the instrument has been completed and successfully tested in a test chamber. Development of the aircraft instrument is underway, with flight testing planned for the fall of 2009. Preliminary Observing System Simulation Experiments (OSSEs) show that HIRAD will have a significant positive impact on surface wind analyses as either a new aircraft or satellite sensor. New off-nadir data collected in 2008 by SFMR that affirms the ability of this measurement technique to obtain wind speed data at non-zero incidence angle will be presented, as well as data from the brassboard instrument chamber tests.

Miller, Timothy; Atlas, Robert; Bailey, M. C.; Black, Peter; El-Nimri, Salem; Hood, Robbie; James, Mark; Johnson, James; Jones, Linwood; Ruf, Christopher; Uhlhorn, Eric

2009-01-01

31

Immunology, climate change and vector-borne diseases  

Microsoft Academic Search

Global climate change might expand the distribution of vector-borne pathogens in both time and space, thereby exposing host populations to longer transmission seasons, and immunologically naive populations to newly introduced pathogens. In the African highlands, where cool temperatures limit malaria parasite development, increases in temperature might enhance malaria transmission. St Louis encephalitis viral replication and the length of the transmission

Jonathan A Patz; William K Reisen

2001-01-01

32

Global climate change and vector-borne diseases  

USGS Publications Warehouse

Global warming will have different effects on different diseases because of the complex and idiosynchratic interactions between vectors, hosts, and pathogens that influence transmission dynamics of each pathogen. Human activities, including urbanization, rapid global travel, and vector management, have profound effects on disease transmission that can operate on more rapid time scales than does global climate change. The general concern about global warming encouraging the spread of tropical diseases is legitimate, but the effects vary among diseases, and the ecological implications are difficult to predict.

Ginsberg, H.S.

2002-01-01

33

Noise model based ?-support vector regression with its application to short-term wind speed forecasting.  

PubMed

Support vector regression (SVR) techniques are aimed at discovering a linear or nonlinear structure hidden in sample data. Most existing regression techniques take the assumption that the error distribution is Gaussian. However, it was observed that the noise in some real-world applications, such as wind power forecasting and direction of the arrival estimation problem, does not satisfy Gaussian distribution, but a beta distribution, Laplacian distribution, or other models. In these cases the current regression techniques are not optimal. According to the Bayesian approach, we derive a general loss function and develop a technique of the uniform model of ?-support vector regression for the general noise model (N-SVR). The Augmented Lagrange Multiplier method is introduced to solve N-SVR. Numerical experiments on artificial data sets, UCI data and short-term wind speed prediction are conducted. The results show the effectiveness of the proposed technique. PMID:24874183

Hu, Qinghua; Zhang, Shiguang; Xie, Zongxia; Mi, Jusheng; Wan, Jie

2014-09-01

34

A spaceborne LFM scatterometer for ocean surface wind vector measurement-a time domain approach  

Microsoft Academic Search

The limitations of the currently used continuous-wave-pulse (CW-pulse) spaceborne scatterometers for wind-vector retrieval are reviewed. The disadvantages due to purely time-domain or frequency-domain (Doppler filtering) approaches are described. To overcome the limitations of these methods, a modified scheme is proposed wherein the pulse transmitted is linearly frequency modulated (LFM) and the processing is carried out in the time domain. This

N. S. Pillai; A. M. Jha; TAPAN MISRA

1988-01-01

35

Effects of Changing Atmospheric Conditions on Wind Turbine Performance (Poster)  

SciTech Connect

Multi-megawatt, utility-scale wind turbines operate in turbulent and dynamic winds that impact turbine performance in ways that are gradually becoming better understood. This poster presents a study made using a turbulent flow field simulator (TurbSim) and a Turbine aeroelastic simulator (FAST) of the response of a generic 1.5 MW wind turbine to changing inflow. The turbine power output is found to be most sensitive to wind speed and turbulence intensity, but the relationship depends on the wind speed with respect to the turbine's rated wind speed. Shear is found to be poorly correlated to power. A machine learning method called 'regression trees' is used to create a simple model of turbine performance that could be used as part of the wind resource assessment process. This study has used simple flow fields and should be extended to more complex flows, and validated with field observations.

Clifton, A.

2012-12-01

36

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

37

Stator winding fault diagnosis in three-phase synchronous and asynchronous motors, by the extended Park's vector approach  

Microsoft Academic Search

This paper describes the use of the extended Park's vector approach (EPVA) for diagnosing the occurrence of stator winding faults in operating three-phase synchronous and asynchronous motors. The major theoretical principles related with the EPVA are presented and it is shown how stator winding faults can be effectively diagnosed by the use of this noninvasive approach. Experimental results, obtained in

Sérgio M. A. Cruz; A. J. Marques Cardoso

2001-01-01

38

Stator winding fault diagnosis in three-phase synchronous and asynchronous motors, by the extended Park's vector approach  

Microsoft Academic Search

This paper describes the use of the extended Park's vector approach (EPVA) for diagnosing the occurrence of stator winding faults in operating three-phase synchronous and asynchronous motors. The major theoretical principles related with the EPVA are presented and it is shown how stator winding faults can be effectively diagnosed by the use of this noninvasive approach. Experimental results, obtained in

S. M. A. Cruz; A. J. Marques Cardoso

2000-01-01

39

Wind shear detection using measurement of aircraft total energy change  

NASA Technical Reports Server (NTRS)

Encounters with wind shears are of concern and have caused major accidents, particularly during landing approaches. Changes in the longitudinal component of the wind affect the aircraft by changing its kinetic energy with respect to the air. It is shown that an instrument which will measure and display the rate of change of total energy of the aircraft with respect to the air will give a leading indication of wind shear problems. The concept is outlined and some instrumentation and display considerations are discussed.

Joppa, R. G.

1976-01-01

40

The vulnerability of wind power to climate change in Brazil  

Microsoft Academic Search

The availability and reliability of wind power depend a great deal on current and future climate conditions, which may vary in light of possible global climate change (GCC). Long-term energy planning, however, does not normally take possible future GCC into consideration, which may turn out to be a risky exercise. In the case of Brazil, the untapped wind power potential

André Frossard Pereira de Lucena; Alexandre Salem Szklo; Roberto Schaeffer; Ricardo Marques Dutra

2010-01-01

41

Immunology, climate change and vector-borne diseases.  

PubMed

Global climate change might expand the distribution of vector-borne pathogens in both time and space, thereby exposing host populations to longer transmission seasons, and immunologically naive populations to newly introduced pathogens. In the African highlands, where cool temperatures limit malaria parasite development, increases in temperature might enhance malaria transmission. St Louis encephalitis viral replication and the length of the transmission season depend upon ambient temperature. Warming temperatures in the American southwest might place at risk migratory, non-immune elderly persons that arrive in early fall to spend the winter. Warm temperatures might intensify or extend the transmission season for dengue fever. Immunologists should examine this interplay between human immunocompetence and vector-borne disease risks in a warmer world. PMID:11274908

Patz, J A; Reisen, W K

2001-04-01

42

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

43

Wave-vector dependence of magnetic-turbulence spectra in the solar wind.  

PubMed

Using four-point measurements of the Cluster spacecraft, the energy distribution was determined for magnetic field fluctuations in the solar wind directly in the three-dimensional wave-vector domain in the range |k|vector anisotropy is estimated with respect to directions parallel and perpendicular to the mean magnetic field, and the result suggests the dominance of quasi-two-dimensional turbulence toward smaller spatial scales. PMID:20482101

Narita, Y; Glassmeier, K-H; Sahraoui, F; Goldstein, M L

2010-04-30

44

Using support vector machines for anomalous change detonation  

SciTech Connect

We cast anomalous change detection as a binary classification problem, and use a support vector machine (SVM) to build a detector that does not depend on assumptions about the underlying data distribution. To speed up the computation, our SVM is implemented, in part, on a graphical processing unit. Results on real and simulated anomalous changes are used to compare performance to algorithms which effectively assume a Gaussian distribution. In this paper, we investigate the use of support vector machines (SVMs) with radial basis kernels for finding anomalous changes. Compared to typical applications of SVMs, we are operating in a regime of very low false alarm rate. This means that even for relatively large training sets, the data are quite meager in the regime of operational interest. This drives us to use larger training sets, which in turn places more of a computational burden on the SVM. We initially considered three different approaches to to address the need to work in the very low false alarm rate regime. The first is a standard SVM which is trained at one threshold (where more reliable estimates of false alarm rates are possible) and then re-thresholded for the low false alarm rate regime. The second uses the same thresholding approach, but employs a so-called least squares SVM; here a quadratic (instead of a hinge-based) loss function is employed, and for this model, there are good theoretical arguments in favor of adjusting the threshold in a straightforward manner. The third approach employs a weighted support vector machine, where the weights for the two types of errors (false alarm and missed detection) are automatically adjusted to achieve the desired false alarm rate. We have found in previous experiments (not shown here) that the first two types can in some cases work well, while in other cases they do not. This renders both approaches unreliable for automated change detection. By contrast, the third approach reliably produces good results, but at the cost of larger computational requirements caused by the need to estimate very small false alarm rates. To address these computational requirements, we employ a recently developed in-house solver for SVMs that is significantly faster than freely available standard solvers. But these computational issues are secondary to the larger question: do kernelized solutions provide better performance, in terms of detection rates and false alarm rates, than more traditional methods for change detection that effectively assume Gaussian data distributions? To this end, we will compare ROC curves obtained from the SVM with those from chronochrome, covariance equalization, and hyperbolic anomalous change detection.

Theiler, James P [Los Alamos National Laboratory; Steinwart, Ingo [UNIV STUTTGART; Llamocca, Daniel [UNM

2010-01-01

45

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

46

Assessment of NOAA Processed OceanSat-2 Scatterometer Ocean Surface Vector Wind Products  

NASA Astrophysics Data System (ADS)

The Indian Space Research Organization (ISRO) launched the Oceansat-2 satellite on 23 September 2009. Oceansat-2 carries a radar scatterometer instrument (OSCAT) capable of measuring ocean surface vector winds (OSVW) and an ocean color monitor (OCM), which will retrieve sea spectral reflectance. Oceansat-2 is ISRO's second in a series of satellites dedicated to ocean research. It will provide continuity to the services and applications of the Oceansat-1 OCM data along with additional data from a Ku-band pencil beam scatterometer. Oceansat-2 is a three-axis, body stabilized spacecraft placed into a near circular sun-synchronous orbit, at an altitude of 720 kilometers (km), with an equatorial crossing time of around 1200 hours. ISRO, the National Oceanic and Atmospheric Administration (NOAA), the National Aeronautics and Space Administration (NASA) and the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT) share the common goal of optimizing the quality and maximizing the utility of the Oceansat-2 data for the benefit of future global and regional scientific and operational applications. NOAA, NASA and EUMETSAT have been collaboratively working with ISRO on the assessment and analysis of OSCAT data to help facilitate continuation of QuikSCAT's decade-long Ku-band scatterometer data record. NOAA's interests are focused on the utilization of OSCAT data to support operational weather forecasting and warning in the marine environment. OSCAT has the potential to significantly mitigate the loss of NASA's QuikSCAT, which has negatively impacted NOAA's marine forecasting and warning services. Since March 2011 NOAA has been receiving near real time OSCAT measurements via EumetSat. NOAA has developed its own OSCAT wind processor. This processor produces ocean surface vector winds with resolution of 25km. Performance of NOAA OSCAT product will and its availability to larger user community will be presented and discussed.

Chang, P.; Jelenak, Z.; Soisuvarn, S.

2011-12-01

47

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

NASA Astrophysics Data System (ADS)

A 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

48

Climate change. Climate change and wind intensification in coastal upwelling ecosystems.  

PubMed

In 1990, Andrew Bakun proposed that increasing greenhouse gas concentrations would force intensification of upwelling-favorable winds in eastern boundary current systems that contribute substantial services to society. Because there is considerable disagreement about whether contemporary wind trends support Bakun's hypothesis, we performed a meta-analysis of the literature on upwelling-favorable wind intensification. The preponderance of published analyses suggests that winds have intensified in the California, Benguela, and Humboldt upwelling systems and weakened in the Iberian system over time scales ranging up to 60 years; wind change is equivocal in the Canary system. Stronger intensification signals are observed at higher latitudes, consistent with the warming pattern associated with climate change. Overall, reported changes in coastal winds, although subtle and spatially variable, support Bakun's hypothesis of upwelling intensification in eastern boundary current systems. PMID:24994651

Sydeman, W J; García-Reyes, M; Schoeman, D S; Rykaczewski, R R; Thompson, S A; Black, B A; Bograd, S J

2014-07-01

49

Large-scale winds in the southern North Sea region: the wind part of the KNMI’14 climate change scenarios  

NASA Astrophysics Data System (ADS)

The wind climate and its possible change in a warming world are important topics for many applications, among which are marine and coastal safety and wind energy generation. Therefore, wind is an important variable to investigate for climate change scenarios. In developing the wind part of the KNMI’14 climate change scenarios, output from several model categories have been analysed, ranging from global General Circulation Models via regional climate model (RCMs) to suitably re-sampled RCM output. The main conclusion is that global warming will not change the wind climate over the Netherlands and the North Sea beyond the large range of natural climate variability that has been experienced in the past.

Sterl, Andreas; Bakker, Alexander M. R.; van den Brink, Henk W.; Haarsma, Rein; Stepek, Andrew; Wijnant, Ine L.; de Winter, Renske C.

2015-03-01

50

Predicting the effect of climate change on African trypanosomiasis: integrating epidemiology with parasite and vector biology  

Microsoft Academic Search

Climate warming over the next century is expected to have a large impact on the interactions between pathogens and their animal and human hosts. Vector-borne diseases are particularly sensitive to warming because temperature changes can alter vector development rates, shift their geographical distribution and alter transmission dynamics. For this reason, African trypanosomiasis (sleeping sickness), a vector-borne disease of humans and

S. Moore; S. Shrestha; K. W. Tomlinson; H. Vuong

2012-01-01

51

Vectors  

NSDL National Science Digital Library

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

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

52

Methods of Recording Rapid Wind Changes  

NASA Technical Reports Server (NTRS)

The purpose of our research was to determine the rapid changes of air currents which impose varying stresses on the wings of airplanes. We attempted to express in figures the turbulence of the air, which perhaps plays some role in the behavior of airplanes in flight, as well as in the realization of certain methods of gliding flight. This is the reason which led us to conceive and develop the experimental equipment (hot-wire anemometer) described herein.

Magnan, A

1932-01-01

53

Changing winds cause melting of coastal Antarctic glaciers  

NASA Astrophysics Data System (ADS)

Anthropogenically induced changes in winds in the Southern Hemisphere are playing a key role in recent warming of subsurface waters around Antarctica, according to a new study by Spence et al. The warming water increases melting of coastal glaciers and thus could affect sea levels in the future.

Palus, Shannon

2014-11-01

54

Heat waves and wind storms in a changing climate  

Microsoft Academic Search

This work is a contribution to the European PRUDENCE project (Prediction of Regional scenarios and Uncertainties for Defining EuropeaN Climate change risks and Effects) by the University of Fribourg, Switzerland. Its objective is to assess changes in the frequency and intensity of extreme climatic events, in particular wind storms and heat\\/cold waves, from Regional Climate Model (RCM) control (1961-90) and

B. Koffi; S. Goyette; M. Beniston

2003-01-01

55

Secular Changes in Eta Carinae's Wind 1998-2011  

NASA Astrophysics Data System (ADS)

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; Davidson, Kris; Humphreys, Roberta M.; Ishibashi, Kazunori; Martin, John C.; Ruiz, María Teresa; Walter, Frederick M.

2012-05-01

56

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

57

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

58

Long-Term Changes in the Equatorial Pacific Trade Winds.  

NASA Astrophysics Data System (ADS)

Past work has shown that surface zonal equatorial wind stress, zonally integrated from one side of the Pacific to the other, is the key variable for estimating long-term El Niño behavior in the eastern Pacific. The long-term behavior of this key variable is difficult to determine directly because of the paucity of the equatorial wind observations and because of false trends in the wind data introduced by gradual changes in the methods of wind measurement. However, surface pressure data generally does not suffer from these false trends and theory suggests that this key wind variable is linearly related to the difference (p) of surface atmospheric pressure between the eastern and western equatorial Pacific. Detrended COADS pressure in the eastern and western equatorial Pacific and post 1960 detrended equatorial wind stress zonally averaged across the Pacific were used to verify this relationship. Pressure difference and zonally averaged equatorial zonal windstress () were highly correlated (r = 0.90) and the regression also showed that advection of zonal momentum contributes substantially to the momentum balance in the equatorial atmospheric boundary layer. Further, hindcasts of eastern equatorial Pacific sea surface temperature and sea level indicated that from p was more accurate than from winds even since 1960 when wind data were more plentiful. This suggests that the simple pressure difference p is an effective way to monitor both in the past and in the future.Using the p time series as a proxy for zonally integrated wind stress suggests that the equatorial trades strengthened during the early and mid-1930s, weakened from the late 1930s to late 1950s, strengthened during the 1960s, and weakened rapidly since. This pattern is qualitatively consistent with the long record of sea surface temperature measurements at Puerto Chicama (Peru). The more recent rapid weakening is consistent with trends in several physical variables reported previously by others. The long-term changes affect El Niño-La Niña intensity and contribute significantly to sea level rise on the western coast of the Americans. A proxy record of eastern Pacific sea surface temperature from coral suggests that such long-term (decade and longer) weakening and strengthening of the Pacific equatorial trades has occurred before major anthropogenic greenhouse gas release and at least back to 1600 AD.

Clarke, Allan J.; Lebedev, Anna

1996-05-01

59

Effect of wind turbine generator model and siting on wind power changes out of large WECS arrays  

NASA Technical Reports Server (NTRS)

Methods of reducing the WECS generation change through selection of the wind turbine model for each site, selection of an appropriate siting configuration, and wind array controls are discussed. An analysis of wind generation change from an echelon and a farm for passage of a thunderstorm is presented. Reduction of the wind generation change over ten minutes is shown to reduce the increase in spinning reserve, unloadable generation and load following requirements on unit commitment when significant WECS generation is present and the farm penetration constraint is satisfied. Controls on the blade pitch angle of all wind turbines in an array or a battery control are shown to reduce both the wind generation change out of an array and the effective farm penetration in anticipation of a storm so that the farm penetration constraint may be satisfied.

Schleuter, R. A.; Park, G. L.; Lotfalian, M.; Dorsey, J.; Shayanfar, H.

1981-01-01

60

Method for changing removable bearing for a wind turbine generator  

DOEpatents

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.

Bagepalli, Bharat Sampathkumaran (Niskayuna, NY); Jansen, Patrick Lee (Scotia, NY); Gadre, Aniruddha Dattatraya (Rexford, NY)

2008-04-22

61

The influence of virus-induced changes in plants on aphid vectors: insights from luteovirus pathosystems.  

PubMed

Plant virus infection can alter the suitability of host plants for their aphid vectors. Most reports indicate that virus-infected plants are superior hosts for vectors compared to virus-free plants with respect to vector growth rates, fecundity and longevity. Some aphid vectors respond preferentially to virus-infected plants compared to virus-free ones, while others avoid infected plants that are inferior hosts. Thus, it appears vectors can exploit changes in host plant quality associated with viral infection. Enhanced vector performance and preference for virus-infected plants might also be advantageous for viruses by promoting their spread and possibly enhancing their fitness. Our research has focused on two of the most important luteoviruses that infect wheat (Barley yellow dwarf virus), or potato (Potato leafroll virus), and their respective aphid vectors, the bird-cherry oat aphid, Rhopalosiphum padi, and the green peach aphid, Myzus persicae. The work has demonstrated that virus infection of host plants enhances the life history of vectors. Additionally, it has shown that virus infection alters the concentration and relative composition of volatile organic compounds in host plants, that apterae of each vector species settle preferentially on virus-infected plants, and that such responses are mediated by volatile organic compounds. The findings also indicate that plants respond heterogeneously to viral infection and as a result different plant parts change in attractiveness to vectors during infection and vector responses to virus-infected plants are dynamic. Such dynamic responses could enhance or reduce the probability of virus acquisition by individual aphids searching among plants. Finally, our work indicates that compared to non-viruliferous aphids, viruliferous ones are less or not responsive to virus-induced host plant volatiles. Changes in vector responsiveness to plants after vectors acquire virus could impact virus epidemiology by influencing virus spread. The potential implications of these findings for virus ecology and epidemiology are discussed. PMID:21549769

Bosque-Pérez, Nilsa A; Eigenbrode, Sanford D

2011-08-01

62

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, José E.; Saldaña, Azael; Carroll, C. Ronald

2012-01-01

63

Predicting the effect of climate change on African trypanosomiasis: integrating epidemiology with parasite and vector biology  

PubMed Central

Climate warming over the next century is expected to have a large impact on the interactions between pathogens and their animal and human hosts. Vector-borne diseases are particularly sensitive to warming because temperature changes can alter vector development rates, shift their geographical distribution and alter transmission dynamics. For this reason, African trypanosomiasis (sleeping sickness), a vector-borne disease of humans and animals, was recently identified as one of the 12 infectious diseases likely to spread owing to climate change. We combine a variety of direct effects of temperature on vector ecology, vector biology and vector–parasite interactions via a disease transmission model and extrapolate the potential compounding effects of projected warming on the epidemiology of African trypanosomiasis. The model predicts that epidemics can occur when mean temperatures are between 20.7°C and 26.1°C. Our model does not predict a large-range expansion, but rather a large shift of up to 60 per cent in the geographical extent of the range. The model also predicts that 46–77 million additional people may be at risk of exposure by 2090. Future research could expand our analysis to include other environmental factors that influence tsetse populations and disease transmission such as humidity, as well as changes to human, livestock and wildlife distributions. The modelling approach presented here provides a framework for using the climate-sensitive aspects of vector and pathogen biology to predict changes in disease prevalence and risk owing to climate change. PMID:22072451

Moore, Sean; Shrestha, Sourya; Tomlinson, Kyle W.; Vuong, Holly

2012-01-01

64

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

65

Model projected changes of extreme wind events in response to global warming  

Microsoft Academic Search

The changes in the frequency of occurrence of extreme wind storm events in response to anthropogenic global warming are explored using a multi-model ensemble of coupled climate model simulations. These changes, diagnosed using several different metrics based on the daily wind fields, indicate that the frequency of the most extreme wind events decreases over the tropics in association with the

G. Gastineau; B. J. Soden

2009-01-01

66

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; Moo-Llanes, David; Ramsey, Janine M.; Danis-Lozano, Rogelio; Peterson, A. Townsend

2014-01-01

67

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

68

About the correlation between solar micro bursts and the change of the solar wind parameters  

E-print Network

The Sun is the closest star to our planet and it is the most studied, perhaps, there exist too much procesess not-understood. One of the solar processes that have a direct interaction with the earth is the solar wind. The solar wind is defined as the plasma expulsed from the solar atmosphere, this wind was cataloged and is considered that have three components: - Passive solar wind: Is the constant component of the solar wind. - Supersonic and quasistady flux. - Sporadic supersonic flux. We present and brief explanation of the Parker's model of the solar wind and a correlation analysis between solar micro radio bursts and the change of the solar wind parameters.

Juan Carlos Martinez Oliveros; Daniel Ricardo Izquierdo P

2005-08-02

69

Simulating Population Genetics of Pathogen Vectors in Changing Landscapes: Guidelines and Application with Triatoma brasiliensis  

PubMed Central

Background Understanding the mechanisms that influence the population dynamics and spatial genetic structure of the vectors of pathogens infecting humans is a central issue in tropical epidemiology. In view of the rapid changes in the features of landscape pathogen vectors live in, this issue requires new methods that consider both natural and human systems and their interactions. In this context, individual-based model (IBM) simulations represent powerful yet poorly developed approaches to explore the response of pathogen vectors in heterogeneous social-ecological systems, especially when field experiments cannot be performed. Methodology/Principal Findings We first present guidelines for the use of a spatially explicit IBM, to simulate population genetics of pathogen vectors in changing landscapes. We then applied our model with Triatoma brasiliensis, originally restricted to sylvatic habitats and now found in peridomestic and domestic habitats, posing as the most important Trypanosoma cruzi vector in Northeastern Brazil. We focused on the effects of vector migration rate, maximum dispersal distance and attraction by domestic habitat on T. brasiliensis population dynamics and spatial genetic structure. Optimized for T. brasiliensis using field data pairwise fixation index (FST) from microsatellite loci, our simulations confirmed the importance of these three variables to understand vector genetic structure at the landscape level. We then ran prospective scenarios accounting for land-use change (deforestation and urbanization), which revealed that human-induced land-use change favored higher genetic diversity among sampling points. Conclusions/Significance Our work shows that mechanistic models may be useful tools to link observed patterns with processes involved in the population genetics of tropical pathogen vectors in heterogeneous social-ecological landscapes. Our hope is that our study may provide a testable and applicable modeling framework to a broad community of epidemiologists for formulating scenarios of landscape change consequences on vector dynamics, with potential implications for their surveillance and control. PMID:25102068

Rebaudo, Francois; Costa, Jane; Almeida, Carlos E.; Silvain, Jean-Francois; Harry, Myriam; Dangles, Olivier

2014-01-01

70

Impact to Space Shuttle Vehicle Trajectory on Day of Launch from change in Low Frequency Winds  

NASA Technical Reports Server (NTRS)

The National Aeronautics and Space Administration's (NASA) Space Shuttle utilizes atmospheric winds on day of launch to develop throttle and steering commands to best optimize vehicle performance while keeping structural loading on the vehicle within limits. The steering commands and resultant trajectory are influenced by both the high and low frequency component of the wind. However, the low frequency component has a greater effect on the ascent design. Change in the low frequency wind content from the time of trajectory design until launch can induce excessive loading on the vehicle. Wind change limits have been derived to protect from launching in an environment where these temporal changes occur. Process of developing wind change limits are discussed followed by an observational study of temporal wind change in low frequency wind profiles at the NASA's Kennedy Space Center area are presented.

Decker, Ryan K.; Puperi, Daniel; Leach, Richard

2007-01-01

71

RNA-seq analyses of blood-induced changes in gene expression in the mosquito vector species, Aedes aegypti  

Microsoft Academic Search

BACKGROUND: Hematophagy is a common trait of insect vectors of disease. Extensive genome-wide transcriptional changes occur in mosquitoes after blood meals, and these are related to digestive and reproductive processes, among others. Studies of these changes are expected to reveal molecular targets for novel vector control and pathogen transmission-blocking strategies. The mosquito Aedes aegypti (Diptera, Culicidae), a vector of Dengue

Mariangela Bonizzoni; W Augustine Dunn; Corey L Campbell; Ken E Olson; Michelle T Dimon; Osvaldo Marinotti; Anthony A James

2011-01-01

72

Performance evaluation of space vector modulation controlled inverter fed variable speed wind generator during permanent fault  

Microsoft Academic Search

This paper presents low voltage ride through (LVRT) characteristics analysis of variable speed wind turbine (VSWT) driving a permanent magnet synchronous generator (PMSG). The VSWT-PMSG is becoming very popular these days in wind power application. In some recent studies, the transient stability and LVRT characteristic of VSWT-PMSG has been reported using different types of symmetrical and unsymmetrical faults. However, this

S. M. Muyeen; J. Tamura

2010-01-01

73

Climate change effects on Chikungunya transmission in Europe: geospatial analysis of vector’s climatic suitability and virus’ temperature requirements  

PubMed Central

Background Chikungunya was, from the European perspective, considered to be a travel-related tropical mosquito-borne disease prior to the first European outbreak in Northern Italy in 2007. This was followed by cases of autochthonous transmission reported in South-eastern France in 2010. Both events occurred after the introduction, establishment and expansion of the Chikungunya-competent and highly invasive disease vector Aedes albopictus (Asian tiger mosquito) in Europe. In order to assess whether these outbreaks are indicative of the beginning of a trend or one-off events, there is a need to further examine the factors driving the potential transmission of Chikungunya in Europe. The climatic suitability, both now and in the future, is an essential starting point for such an analysis. Methods The climatic suitability for Chikungunya outbreaks was determined by using bioclimatic factors that influence, both vector and, pathogen. Climatic suitability for the European distribution of the vector Aedes albopictus was based upon previous correlative environmental niche models. Climatic risk classes were derived by combining climatic suitability for the vector with known temperature requirements for pathogen transmission, obtained from outbreak regions. In addition, the longest potential intra-annual season for Chikungunya transmission was estimated for regions with expected vector occurrences. In order to analyse spatio-temporal trends for risk exposure and season of transmission in Europe, climate change impacts are projected for three time-frames (2011–2040, 2041–2070 and 2071–2100) and two climate scenarios (A1B and B1) from the Intergovernmental Panel on Climate Change (IPCC). These climatic projections are based on regional climate model COSMO-CLM, which builds on the global model ECHAM5. Results European areas with current and future climatic suitability of Chikungunya transmission are identified. An increase in risk is projected for Western Europe (e.g. France and Benelux-States) in the first half of the 21st century and from mid-century onwards for central parts of Europe (e.g. Germany). Interestingly, the southernmost parts of Europe do not generally provide suitable conditions in these projections. Nevertheless, many Mediterranean regions will persist to be climatically suitable for transmission. Overall, the highest risk of transmission by the end of the 21st century was projected for France, Northern Italy and the Pannonian Basin (East-Central Europe). This general tendency is depicted in both, the A1B and B1 climate change scenarios. Conclusion In order to guide preparedness for further outbreaks, it is crucial to anticipate risk as to identify areas where specific public health measures, such as surveillance and vector control, can be implemented. However, public health practitioners need to be aware that climate is only one factor driving the transmission of vector-borne disease. PMID:24219507

2013-01-01

74

Vector Voyage!  

NSDL National Science Digital Library

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

Jeff White

2004-01-01

75

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

76

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.

77

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

78

Magnetotail Changes in Relation to the Solar Wind Magnetic Field and Magnetospheric Substorms  

Microsoft Academic Search

Substorm activity is known to be associated with changes in the solar wind parameters and the magnetotail configuration. In this paper we investigate whether the magnetotail changes occur only as a consequence of substorms or also as a direct consequence of changes in the solar wind paxameters. Using data from several satellites (Ogo 5, ATS 1, Imp 4, Explorer 33

MICHEL P. AUBRYAND; Robert L. McPherron

1971-01-01

79

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

80

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

E-print Network

'TER III CHAPTER IV CP. APTHR V CHAPTER VI CHAPTER VII INTRODUCTION. BACKGROUND. OBJECTIVFS. DATA. PROCEDURi. . . RESULTS COVi CLUSIOIiIS AND RHCORPIL'IJDATIONS. . . 16 1 Pi 19 21 39 REFERENCES. . . 42 APPHNDIX A DERIVAT10N OI' ELLISON... will be devoted to a survey and discussion of known vector regression techniques. Ellison (1954) developed regression equations for two vector sets. He pointed out that just as the interdependence of two scalar random variables, v and V, may be studied...

Zumwalt, James Tweed

1969-01-01

81

Confidence and sensitivity study of the OAFlux multisensor synthesis of the global ocean surface vector wind from 1987 onward  

NASA Astrophysics Data System (ADS)

This study presented an uncertainty assessment of the high-resolution global analysis of daily-mean ocean-surface vector winds (1987 onward) by the Objectively Analyzed air-sea Fluxes (OAFlux) project. The time series was synthesized from multiple satellite sensors using a variational approach to find a best fit to input data in a weighted least-squares cost function. The variational framework requires the a priori specification of the weights, or equivalently, the error covariances of input data, which are seldom known. Two key issues were investigated. The first issue examined the specification of the weights for the OAFlux synthesis. This was achieved by designing a set of weight-varying experiments and applying the criteria requiring that the chosen weights should make the best-fit of the cost function be optimal with regard to both input satellite observations and the independent wind time series measurements at 126 buoy locations. The weights thus determined represent an approximation to the error covariances, which inevitably contain a degree of uncertainty. Hence, the second issue addressed the sensitivity of the OAFlux synthesis to the uncertainty in the weight assignments. Weight perturbation experiments were conducted and ensemble statistics were used to estimate the sensitivity. The study showed that the leading sources of uncertainty for the weight selection are high winds (>15 ms-1) and heavy rain, which are the conditions that cause divergence in wind retrievals from different sensors. Future technical advancement made in wind retrieval algorithms would be key to further improvement of the multisensory synthesis in events of severe storms.

Yu, Lisan; Jin, Xiangze

2014-10-01

82

Full vector (3-D) inflow simulation in natural and wind farm environments using an expanded version of the SNLWIND (Veers) turbulence code  

SciTech Connect

We have recently expanded the numerical turbulence simulation (SNLWIND) developed by Veers [1] to include all three components of the turbulent wind vector. We have also configured the code to simulate the characteristics of turbulent wind fields upwind and downwind of a large wind farm, as well as over uniform, flat terrain. Veers's original method only simulates the longitudinal component of the wind in neutral flow. This paper overviews the development of spectral distribution, spatial coherence, and cross correlation models used to expired the SNLWIND code to include the three components of the turbulent wind over a range of atmospheric stabilities. These models are based on extensive measurements of the turbulence characteristics immediately upwind and downwind of a large wind farm in San Gorgonio Pass, California.

Kelley, N.D.

1992-11-01

83

Full vector (3-D) inflow simulation in natural and wind farm environments using an expanded version of the SNLWIND (Veers) turbulence code  

SciTech Connect

We have recently expanded the numerical turbulence simulation (SNLWIND) developed by Veers [1] to include all three components of the turbulent wind vector. We have also configured the code to simulate the characteristics of turbulent wind fields upwind and downwind of a large wind farm, as well as over uniform, flat terrain. Veers`s original method only simulates the longitudinal component of the wind in neutral flow. This paper overviews the development of spectral distribution, spatial coherence, and cross correlation models used to expired the SNLWIND code to include the three components of the turbulent wind over a range of atmospheric stabilities. These models are based on extensive measurements of the turbulence characteristics immediately upwind and downwind of a large wind farm in San Gorgonio Pass, California.

Kelley, N.D.

1992-11-01

84

Potential climate change impacts on the probability of wind damage in a south Swedish forest  

Microsoft Academic Search

We estimated how the possible changes in wind climate and state of the forest due to climate change may affect the probability\\u000a of exceeding critical wind speeds expected to cause wind damage within a forest management unit located in Southern Sweden.\\u000a The topography of the management unit was relatively gentle and the forests were dominated by Norway spruce (Picea abies

Kristina Blennow; Mikael Andersson; Johan Bergh; Ola Sallnäs; Erika Olofsson

2010-01-01

85

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

86

Possible Impacts of Climate Change on Wind Gust under Downscaled Future Climate Conditions over Ontario, Canada  

NASA Astrophysics Data System (ADS)

The overarching purpose of this study was to project changes in the occurrence frequency and magnitude of future wind gust events under downscaled future climate conditions over Ontario, Canada. Wind gust factors were employed to simulate hourly/daily wind gust based on hourly/daily wind speed. Regression-based downscaling methods were used to downscale future hourly/daily wind speed to each of the 14 selected cities in Ontario for eight GCM models with IPCC SRES A2 and B1 scenarios. The wind gust simulation models were then applied using downscaled future GCM wind speed data to project changes in occurrence frequency and intensity of the future hourly/daily wind gust events. Downscaling transfer functions and wind gust simulation models were validated using a cross-validation scheme and comparing data distributions and extreme-event frequencies derived from downscaled GCM control runs and observations over a comparative time period 1961-2000. The results showed that the models for all variables used in the study performed well. By comparing the current-past averaged conditions, the occurrence frequency and intensity of future wind gust events in the study area are projected to increase. The modeled results from this study found that the frequency and intensity of future wind gust events are projected to significantly increase under a changing climate in this century. This talk will introduce the research project and outline the modeling exercise and verification process. The major findings on future wind gust projections from the study will be summarized in the presentation as well. One of the major conclusions from the study is that the procedures used in the study are useful for climate change impact analysis on future wind gusts. The implication of the significant increases in future wind gust risks would be useful to be considered when revising engineering infrastructure design standards and developing adaptation strategies and policies.

Shouquan Cheng, Chad; Li, Guilong

2010-05-01

87

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

88

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

89

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

90

Recent tax law changes create new opportunities for leasing wind energy property  

SciTech Connect

Recent changes in tax law make leveraged lease transactions far more attractive on paper than they were before the changes. However, changes in the economy and the financial industry and other changes in law counterbalance the favorable tax law changes and make it uncertain whether lease transactions will be used to finance new wind facilities. (author)

Schutzer, George J.

2010-01-15

91

The impact of climate change on the U.S. wind energy resource  

SciTech Connect

The growing need for low-carbon emitting electricity sources has resulted in rapid growth in the wind power industry. The size and steadiness of the offshore wind resource has attracted growing investment in the planning of offshore wind turbine installations. Decisions about the location and character of wind farms should be made with an eye not only to present but also future wind resource, which may change as increasing carbon dioxide forces reductions in the poleward temperature gradient, and thus potentially in the mean tropospheric westerly winds. I propose to use the new North American Regional Climate Change Assessment Program climate projections to estimate the change of the wind power resource under various carbon dioxide loading scenarios and for a range of climate models. We will compare our assessment with both our assessment based on the IPCC AR4 model runs, to explore the extent to which improved model resolution changes the prediction for the wind power resource, and with present day estimates from reanalysis and scatterometer winds.

Daniel Kirk-Davidoff; Daniel Barrie

2013-03-19

92

Space-based surface wind vectors to aid understanding of air-sea interactions  

NASA Astrophysics Data System (ADS)

Our understanding and prediction of the large-scale air-sea interactions that are thought to significantly influence both the atmosphere and ocean can be improved by consistent oceanic surface wind data of high quality and high temporal and spatial resolution. Surface wind stress provides the most important forcing of the ocean circulation and the fluxes of heat, moisture, and momentum across the air-sea boundary are important factors in theories of El Nñio-Southern Oscillation (ENSO) and the 50-day oscillation. Unfortunately, an adequate observational data base to perform such studies has been lacking.In this paper, we describe a new and unique ocean surface wind data set derived by combining the Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave Imager (SSM/I) data with other conventional data, presenting both the methodology and some examples of the results. We are currently using these data in several studies, as discussed in the conclusion, and are preparing a more detailed description of the development and testing of our algorithms. These data are available through the National Aeronautics and Space Administration's Ocean Data System (NODS).

Atlas, R.; Bloom, S. C.; Hoffman, R. N.; Ardizzone, J. V.; Brin, G.

93

Assessment of changes of vector borne diseases with wetland characteristics using multivariate analysis.  

PubMed

Vector borne diseases are a threat to human health. Little attention has been paid to the prevention of these diseases. We attempted to identify the significant wetland characteristics associated with the spread of chikungunya, dengue fever and malaria in Kerala, a tropical region of South West India using multivariate analyses (hierarchical cluster analysis, factor analysis and multiple regression). High/medium turbid coastal lagoons and inland water-logged wetlands with aquatic vegetation have significant effect on the incidence of chikungunya while dengue influenced by high turbid coastal beaches and malaria by medium turbid coastal beaches. The high turbidity in water is due to the urban waste discharge namely sewage, sullage and garbage from the densely populated cities and towns. The large extent of wetland is low land area favours the occurrence of vector borne diseases. Hence the provision of pollution control measures at source including soil erosion control measures is vital. The identification of vulnerable zones favouring the vector borne diseases will help the authorities to control pollution especially from urban areas and prevent these vector borne diseases. Future research should cover land use cover changes, climatic factors, seasonal variations in weather and pollution factors favouring the occurrence of vector borne diseases. PMID:25412801

Sheela, A M; Sarun, S; Justus, J; Vineetha, P; Sheeja, R V

2015-04-01

94

Evidence that implicit assumptions of 'no evolution' of disease vectors in changing environments can be violated on a rapid timescale.  

PubMed

Projected impacts of climate change on vector-borne disease dynamics must consider many variables relevant to hosts, vectors and pathogens, including how altered environmental characteristics might affect the spatial distributions of vector species. However, many predictive models for vector distributions consider their habitat requirements to be fixed over relevant time-scales, when they may actually be capable of rapid evolutionary change and even adaptation. We examine the genetic signature of a spatial expansion by an invasive vector into locations with novel temperature conditions compared to its native range as a proxy for how existing vector populations may respond to temporally changing habitat. Specifically, we compare invasions into different climate ranges and characterize the importance of selection from the invaded habitat. We demonstrate that vector species can exhibit evolutionary responses (altered allelic frequencies) to a temperature gradient in as little as 7-10 years even in the presence of high gene flow, and further, that this response varies depending on the strength of selection. We interpret these findings in the context of climate change predictions for vector populations and emphasize the importance of incorporating vector evolution into models of future vector-borne disease dynamics. PMID:25688024

Egizi, Andrea; Fefferman, Nina H; Fonseca, Dina M

2015-04-01

95

Modeling and space vector control of a novel multilevel matrix converter for variable-speed wind power generators  

NASA Astrophysics Data System (ADS)

A novel multilevel matrix converter is developed to efficiently transfer energy between a three-phase variable-speed generator of a wind turbine and a three-phase ac utility network. Optimizing the energy transfer efficiency at light load is critical in variable-speed wind generators. Laboratory experiment suggests that converter efficiency at light load may be increased via soft-switching and multilevel switching techniques. The new converter includes the advantages of multilevel converters, such as reduced harmonic content, increased power handling capability without additional switching loss, and high efficiency at low machine voltages. It also features the characteristics of conventional matrix converters, such as space vector control and improved efficiency via auxiliary resonant commutation soft-switching techniques. Similar to a conventional matrix converter, the novel multilevel matrix converter uses a nine-switch matrix with four-quadrant switches to connect input phases at one side of the converter with output phases at the other side of the converter. However, the switches of the new converter are configured differently from those used in the conventional matrix converter. Each switch of the new converter is a cell that resembles a full-bridge inverter topology and can assume three voltage levels while used. Semiconductor devices in a switch cell are always clamped to a known constant do voltage of a capacitor. This is a typical characteristic of multilevel converters where device voltage stresses are reduced by clamping the main transistor voltages to low levels. With reduced voltage stresses, switching frequency can be increased to allow for reduced size of filter magnetics. Unlike conventional matrix converter, the multilevel matrix converter uses inductors on both input and output sides of the converter. This symmetry allows for both step up and step down operations. Each switch cell features double the power handling capability compared to the four-quadrant switches used in a conventional matrix converter. This increase in power handling capability is due to the doubling of the number of devices in a multilevel matrix converter switch cell. Scaling up the power handling capability is accomplished by cascading more than one switch cell per branch. Control of the new converter is achieved through space vector modulation in which three-phase ac voltages are transformed to the d-q reference frame and compared with a set of space vectors prior to modulation. Since it has 19683 different switching combinations, control can be difficult and complex. Nevertheless, the multilevel matrix converter has been modeled and controlled through simulation. Simulation results show the possibility of operating the converter to produce the desired voltage waveforms with universal input and output power factors and maintain constant capacitor voltages simultaneously. Also in this dissertation is the derivation of an analytical averaged equivalent circuit model of a PWM converter. This model reveals how dominant loss mechanisms vary with converter operating point. The model is based on the operational characteristics of power diodes and IGBTs. Laboratory experiments support the derived model and confirm that IGBT current tailing and diode reverse-recovery are indeed the most critical losses in a PWM converter. These losses are more significant at light load, hence reducing the energy capture capability of converters used in wind generation. The results suggest that multilevel conversion, which has been employed in the novel multilevel matrix converter, could improve the low-wind converter efficiency.

Al-Naseem, Osama Abdulrahman

96

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

E-print Network

ARCTIC VOL. 66, NO. 4 (DECEMBER 2013) P. 448­458 Changing Daily Wind Speeds on Alaska's North Slope-ecological conditions. Key words: Alaska, bowhead whale, caribou, wind speed, North Slope, social-ecological system collaborated with hunters from the coastal community of Wainwright, Alaska, to document their observations

97

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

E-print Network

18 IEEE power & energy magazine september/october 2010 R on the winds of change impact a much larger area than a coal or a gas power plant to pro- duce a given amount of energy. A wind power.937465 RENEWABLE ENERGY TECHNOL- ogies are being welcomed in many countries worldwide because of their minor

Dixon, Juan

98

Projecting Wind Energy Potential Under Climate Change with Ensemble of Climate Model Simulations  

NASA Astrophysics Data System (ADS)

Recent years have witnessed an increasing global concern over energy sustainability and security, triggered by a number of issues, such as (though not limited to): fossil fuel depletion, energy resource geopolitics, economic efficiency versus population growth debate, environmental concerns and climate change. Wind energy is a renewable and sustainable form of energy in which wind turbines convert the kinetic energy of wind into electrical energy. Global warming and differential surface heating may significantly impact the wind velocity and hence the wind energy potential. Sustainable design of wind mills requires understanding the impacts of climate change on wind energy potential, which we evaluate here with multiple General Circulation Models (GCMs). GCMs simulate the climate variables globally considering the greenhouse emission scenarios provided as Representation Concentration path ways (RCPs). Here we use new generation climate model outputs obtained from Coupled model Intercomparison Project 5(CMIP5). We first compute the wind energy potential with reanalysis data (NCEP/ NCAR), at a spatial resolution of 2.50, where the gridded data is fitted to Weibull distribution and with the Weibull parameters, the wind energy densities are computed at different grids. The same methodology is then used, to CMIP5 outputs (resultant of U-wind and V-wind) of MRI, CMCC, BCC, CanESM, and INMCM4 for historical runs. This is performed separately for four seasons globally, MAM, JJA, SON and DJF. We observe the muti-model average of wind energy density for historic period has significant bias with respect to that of reanalysis product. Here we develop a quantile based superensemble approach where GCM quantiles corresponding to selected CDF values are regressed to reanalysis data. It is observed that this regression approach takes care of both, bias in GCMs and combination of GCMs. With superensemble, we observe that the historical wind energy density resembles quite well with reanalysis/ observed output. We apply the same for future under RCP scenarios. We observe spatially and temporally varying global change of wind energy density. The underlying assumption is that the regression relationship will also hold good for future. The results highlight the needs to change the design standards of wind mills at different locations, considering climate change and at the same time the requirement of height modifications for existing mills to produce same energy in future.

Jain, A.; Shashikanth, K.; Ghosh, S.; Mukherjee, P. P.

2013-12-01

99

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

E-print Network

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

Haak, Hein

100

Wind  

NSDL National Science Digital Library

What part does the wind play in satisfying energy demands? This informational piece, part of a series about the future of energy, introduces students to wind as an energy source. Here students read about the history, uses, and efficiency of wind power. Information is also provided about benefits, limitations, and geographical considerations of wind power in the United States. Thought-provoking questions afford students chances to reflect on what they've read about the uses of wind power. Supplemental articles and information are available from a sidebar. Three energy-related web links are also provided. Copyright 2005 Eisenhower National Clearinghouse

Iowa Public Television. Explore More Project

2004-01-01

101

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

102

Changes in the Burgers Vector of Perfect Dislocation Loops without Contact with the External Dislocations  

Microsoft Academic Search

We report the observations of a new type of changing process in the Burgers vector of dislocations by in situ transmission electron microscopy. Small interstitial-type perfect dislocation loops in bcc iron with diameters less than approximately 50 nm are transformed from a 1\\/2 loop to another 1\\/2 one or an energetically unfavorable one; furthermore, a loop is transformed to a

K. Arakawa; M. Hatanaka; E. Kuramoto; K. Ono; H. Mori

2006-01-01

103

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

104

Operation of a Wind Turbine-Flywheel Energy Storage System under Conditions of Stochastic Change of Wind Energy  

PubMed Central

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

2014-01-01

105

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

106

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

107

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

108

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

109

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

110

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

111

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.

112

Correlated solar wind speed, density, and magnetic field changes at J. D. Richardson and C. Wang1  

E-print Network

Correlated solar wind speed, density, and magnetic field changes at Voyager 2 J. D. Richardson December 2003. [1] The character of the solar wind plasma data observed by Voyager 2 recently changed of the solar wind. The model reproduces the basic character (but not the details) of the observations

Richardson, John

113

A change vector analysis technique for monitoring land cover changes in Copsa Mica, Romania, in the period 1985-2011.  

PubMed

During the communist regime, Romania's planned economy focused exclusively on production neglecting the environment protection. The lack of less polluting production technologies and of environmental protection measures led to excessive pollution in certain industrialized areas. This is the case of the town of Copsa Mica in Sibiu County, which in 1987 was considered one of the most polluted towns in Europe. The present study assesses the change vector analysis (CVA) technique using a Landsat Thematic Mapper (TM) image time series to monitor land cover changes caused by carbon black and heavy metal pollution. CVA was applied to the tasseled cap greenness (TCG) and tasseled cap brightness (TCB) indices, as well as to the Normalized Difference Vegetation Index (NDVI) and bare soil index (BI). Various maps were generated for the periods 1985-1994, 1994-2003, 2003-2011, and 1985-2011, and threshold values were determined for the detection of land cover change/no change. The change direction and magnitude values were cross-tabulated and classified. The technique was assessed based on the change versus no-change error matrix. The results show that in the area of Copsa Mica, land cover changes occurred because of a considerable decrease in the area affected by carbon black and heavy metal pollution. The CVA technique proved efficient in monitoring the land cover changes caused by pollution and especially by carbon black pollution. Soil pollution by heavy metals is reflected in the bare soil surfaces present in the imagery. PMID:24861587

Vorovencii, Iosif

2014-09-01

114

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

115

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

116

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

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

Challenges in predicting climate and environmental effects on vector-borne disease episystems in a changing world.  

PubMed

Vector-borne pathogens cause enormous suffering to humans and animals. Many are expanding their range into new areas. Dengue, West Nile and Chikungunya have recently caused substantial human epidemics. Arthropod-borne animal diseases like Bluetongue, Rift Valley fever and African horse sickness pose substantial threats to livestock economies around the world. Climate change can impact the vector-borne disease epidemiology. Changes in climate will influence arthropod vectors, their life cycles and life histories, resulting in changes in both vector and pathogen distribution and changes in the ability of arthropods to transmit pathogens. Climate can affect the way pathogens interact with both the arthropod vector and the human or animal host. Predicting and mitigating the effects of future changes in the environment like climate change on the complex arthropod-pathogen-host epidemiological cycle requires understanding of a variety of complex mechanisms from the molecular to the population level. Although there has been substantial progress on many fronts the challenges to effectively understand and mitigate the impact of potential changes in the environment on vector-borne pathogens are formidable and at an early stage of development. The challenges will be explored using several arthropod-borne pathogen systems as illustration, and potential avenues to meet the challenges will be presented. PMID:20190119

Tabachnick, W J

2010-03-15

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

Robust Projections of Vertical Wind Shear Changes for the 21st Century  

NASA Astrophysics Data System (ADS)

We explore the changes in tropical vertical wind-shear projected for the 21^{st} Century in response to increased CO2, using a set of 21 climate model experiments performed for the IPCC-AR4. Many features of the shear changes are robust across the various models, in particular an increase on wind-shear in the tropical north Atlantic region. This region is the only one in the world exhibiting a robust increase in shear in the local summer season, the models show robust decreases in wind shear over much of the tropical oceans. The increase in Atlantic wind shear appears related to teleconnections from global-warming-induced reduction in the intensity of large-scale atmospheric circulation, which occurs preferentially in the zonally-asymmetric (i.e., Walker) component of the tropical Pacific circulation - i.e. "El Niño-like" atmospheric changes. Although the mechanisms behind the Pacific changes are distinct from those of El Niño (and are reproduced in both mixed-layer and full ocean dynamics coupled climate models), aspects of climate teleconnections resemble those associated with El Niño. The large-scale shears show a pronounced and robust weakening over the Indian and western tropical Pacific Oceans. The magnitude of the ensemble-mean changes is on the order of 0.5-1 m/s per degree warming, and the robust signals are evident in over 18 of the 21 models. In these models, the spatial structure in the changes to the frequency of extremes in tropical daily cyclonic vorticity show relation to the structure of the changes in wind shear. Effort should be undertaken to understand the extent to which these robust changes in large-scale wind shear may impact hurricane activity, and they should be considered in discussions of projected changes to hurricane intensity and frequency.

Vecchi, G. A.; Soden, B. J.

2006-12-01

121

DOE SBIR Phase II Final Technical Report - Assessing Climate Change Effects on Wind Energy  

SciTech Connect

Specialized Vertum Partners software tools were prototyped, tested and commercialized to allow wind energy stakeholders to assess the uncertainties of climate change on wind power production and distribution. This project resulted in three commercially proven products and a marketing tool. The first was a Weather Research and Forecasting Model (WRF) based resource evaluation system. The second was a web-based service providing global 10m wind data from multiple sources to wind industry subscription customers. The third product addressed the needs of our utility clients looking at climate change effects on electricity distribution. For this we collaborated on the Santa Ana Wildfire Threat Index (SAWTi), which was released publicly last quarter. Finally to promote these products and educate potential users we released “Gust or Bust”, a graphic-novel styled marketing publication.

Whiteman, Cameron; Capps, Scott

2014-11-05

122

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

123

Dynamics of Sylvatic Chagas Disease Vectors in Coastal Ecuador Is Driven by Changes in Land Cover  

PubMed Central

Background Chagas disease is a serious public health problem in Latin America where about ten million individuals show Trypanosoma cruzi infection. Despite significant success in controlling domiciliated triatomines, sylvatic populations frequently infest houses after insecticide treatment which hampers long term control prospects in vast geographical areas where vectorial transmission is endemic. As a key issue, the spatio-temporal dynamics of sylvatic populations is likely influenced by landscape yet evidence showing this effect is rare. The aim of this work is to examine the role of land cover changes in sylvatic triatomine ecology, based on an exhaustive field survey of pathogens, vectors, hosts, and microhabitat characteristics' dynamics. Methodology and Principal Findings The study was performed in agricultural landscapes of coastal Ecuador as a study model. Over one year, a spatially-randomized sampling design (490 collection points) allowed quantifying triatomine densities in natural, cultivated and domestic habitats. We also assessed infection of the bugs with trypanosomes, documented their microhabitats and potential hosts, and recorded changes in landscape characteristics. In total we collected 886 individuals, mainly represented by nymphal stages of one triatomine species Rhodnius ecuadoriensis. As main results, we found that 1) sylvatic triatomines had very high T. cruzi infection rates (71%) and 2) densities of T. cruzi-infected sylvatic triatomines varied predictably over time due to changes in land cover and occurrence of associated rodent hosts. Conclusion We propose a framework for identifying the factors affecting the yearly distribution of sylvatic T. cruzi vectors. Beyond providing key basic information for the control of human habitat colonization by sylvatic vector populations, our framework highlights the importance of both environmental and sociological factors in shaping the spatio-temporal population dynamics of triatomines. A better understanding of the dynamics of such socio-ecological systems is a crucial, yet poorly considered, issue for the long-term control of Chagas disease. PMID:24968118

Grijalva, Mario J.; Terán, David; Dangles, Olivier

2014-01-01

124

Changes in the abundance and distribution of upland breeding birds at an operational wind farm  

Microsoft Academic Search

Capsule No evidence for sustained declines in abundance or re?distribution of two key upland bird species on a wind farm site in the first three years of operation.Aims To describe changes in the abundance and distribution of birds on an upland wind farm during the first three years of operation.Methods Surveys to map the distribution of breeding birds were conducted

David J. T. Douglas; Paul E. Bellamy

2011-01-01

125

Changes in the Burgers Vector of Perfect Dislocation Loops without Contact with the External Dislocations  

SciTech Connect

We report the observations of a new type of changing process in the Burgers vector of dislocations by in situ transmission electron microscopy. Small interstitial-type perfect dislocation loops in bcc iron with diameters less than approximately 50 nm are transformed from a 1/2<111> loop to another 1/2<111> one or an energetically unfavorable <100> one; furthermore, a <100> loop is transformed to a 1/2<111> one. These transformations occurred on high-energy electron irradiation or simple heating without contact with external dislocations. The origin of these phenomena is discussed.

Arakawa, K.; Hatanaka, M.; Mori, H. [Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, 7-1, Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Kuramoto, E. [Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan); Ono, K. [Department of Material Science, Shimane University, 1060 Nishikawatsu, Matsue 690-8504 (Japan)

2006-03-31

126

Changes in the Burgers vector of perfect dislocation loops without contact with the external dislocations.  

PubMed

We report the observations of a new type of changing process in the Burgers vector of dislocations by in situ transmission electron microscopy. Small interstitial-type perfect dislocation loops in bcc iron with diameters less than approximately 50 nm are transformed from a 1/2<111> loop to another 1/2<111> one or an energetically unfavorable <100> one; furthermore, a <100> loop is transformed to a 1/2<111> one. These transformations occurred on high-energy electron irradiation or simple heating without contact with external dislocations. The origin of these phenomena is discussed. PMID:16605927

Arakawa, K; Hatanaka, M; Kuramoto, E; Ono, K; Mori, H

2006-03-31

127

Simulation comparison of a decoupled longitudinal control system and a velocity vector control wheel steering system during landings in wind shear  

NASA Technical Reports Server (NTRS)

A simulator comparison of the velocity vector control wheel steering (VCWS) system and a decoupled longitudinal control system is presented. The piloting task was to use the electronic attitude direction indicator (EADI) to capture and maintain a 3 degree glide slope in the presence of wind shear and to complete the landing using the perspective runway included on the EADI. The decoupled control system used constant prefilter and feedback gains to provide steady state decoupling of flight path angle, pitch angle, and forward velocity. The decoupled control system improved the pilots' ability to control airspeed and flight path angle during the final stages of an approach made in severe wind shear. The system also improved their ability to complete safe landings. The pilots preferred the decoupled control system in severe winds and, on a pilot rating scale, rated the approach and landing task with the decoupled control system as much as 3 to 4 increments better than use of the VCWS system.

Kimball, G., Jr.

1980-01-01

128

Interactions between fire, grazing and climate change at Wind Cave National Park, SD  

Microsoft Academic Search

Projected changes in global climate have important ramifications for the future of national parks and other reserves set aside to conserve ecological uniqueness. We explored potential implications of climatic changes on lifeform distribution and growth at Wind Cave National Park (WCNP), South Dakota, which lies on a climatically determined ecotone between grassland and forest. Fire, promoted by healthy grasslands, is

Dominique Bachelet; James M Lenihan; Christopher Daly; Ronald P Neilson

2000-01-01

129

A spatially interactive simulation of climate change, harvesting, wind, and tree species migration and  

E-print Network

A spatially interactive simulation of climate change, harvesting, wind, and tree species migration and projected changes to forest composition and biomass in northern Wisconsin, USA R O B E R T M . S C H E L L E R and D AV I D J . M L A D E N O F F Department of Forest Ecology and Management, University

Mladenoff, David

130

Limited change in dune mobility in response to a large decrease in wind power in semi-arid northern China since the 1970s  

USGS Publications Warehouse

The climatic controls on dune mobility, especially the relative importance of wind strength, remain incompletely understood. This is a key research problem in semi-arid northern China, both for interpreting past dune activity as evidence of paleoclimate and for predicting future environmental change. Potential eolian sand transport, which is approximately proportional to wind power above the threshold for sand entrainment, has decreased across much of northern China since the 1970s. Over the same period, effective moisture (ratio of precipitation to potential evapotranspiration) has not changed significantly. This "natural experiment" provides insight on the relative importance of wind power as a control on dune mobility in three dunefields of northern China (Mu Us, Otindag, and Horqin), although poorly understood and potentially large effects of human land use complicate interpretation. Dune forms in these three regions are consistent with sand transport vectors inferred from weather station data, suggesting that wind directions have remained stable and the stations adequately represent winds that shaped the dunes. The predicted effect of weaker winds since the 1970s would be dune stabilization, with lower sand transport rates allowing vegetation cover to expand. Large portions of all three dunefields remained stabilized by vegetation in the 1970s despite high wind power. Since the 1970s, trends in remotely sensed vegetation greenness and change in mobile dune area inferred from sequential Landsat images do indicate widespread dune stabilization in the eastern Mu Us region. On the other hand, expansion of active dunes took place farther west in the Mu Us dunefield and especially in the central Otindag dunefield, with little overall change in two parts of the Horqin dunes. Better ground truth is needed to validate the remote sensing analyses, but results presented here place limits on the relative importance of wind strength as a control on dune mobility in the study areas. High wind power alone does not completely destabilize these dunes. A large decrease in wind power either has little short-term effect on the dunes, or more likely its effect is sufficiently small that it is obscured by human impacts on dune stability in many parts of the study areas. ?? 2008 Elsevier B.V. All rights reserved.

Mason, J.A.; Swinehart, J.B.; Lu, H.; Miao, X.; Cha, P.; Zhou, Y.

2008-01-01

131

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

132

[Comment on ``Solar wind mechanism suggested for weather and climate change''] Weather and climate changes arising from solar wind effects on thunderstorm electrification  

Microsoft Academic Search

In ``Solar Wind Mechanism Suggested for Weather and Climate Change'' [Eos, August 9,1994], Brian A. Tinsley suggests that solar activity is modulating weather and climate through the effects it produces on the Earth's fair-weather electric field. This may well be true. It is questionable, however, whether the fair-weather electric field is strong enough to cause ice crystal formation in clouds

B. Vonnegut; C. B. Moore

1995-01-01

133

Past and future wind changes over the Southern Ocean  

NASA Astrophysics Data System (ADS)

Mid-latitude westerlies are a major component of the atmospheric circulation, and their response to climate change will determine changes in precipitation, storms, and ocean circulation and CO2 uptake. In this study, we analyse, mainly in terms of jet stream position, the behaviour of the southern westerlies for a future climate, obtained after stabilisation of the RCP4.5 scenario, as well as for the Last Glacial Maximum (LGM, 21 000 yr ago), which is the last past cold extreme with about opposite global temperature change from the future one. We use the models from the CMIP5-PMIP3 archive. The a priori guess would be that the behaviour of the westerly jet stream would be similar when examining its changes from LGM to pre-industrial (PI) con- ditions and from PI to RCP4.5, i.e. in both cases a poleward shift in response to global warming. While this is true for all models in the future case, the LGM shows instead little or inconsistent jet shifts, because of a strong cooling over Antarctica during the LGM. We show that the behavior of the jets in both cases can be quantitatively reproduced using two indices of temperature changes in the Tropics and the high latitudes.

Chavaillaz, Y.; Codron, F.; Kageyama, M.

2013-12-01

134

Evaluation of High-Resolution Ocean Surface Vector Winds Measured by QuikSCAT Scatterometer in Coastal Regions  

NASA Technical Reports Server (NTRS)

The SeaWinds scatterometer onboard QuikSCAT covers approximately 90% of the global ocean under clear and cloudy condition in 24 h, and the standard data product has 25-km spatial resolution. Such spatial resolution is not sufficient to resolve small-scale processes, especially in coastal oceans. Based on range-compressed normalized backscatter and a modified wind retrieval algorithm, a coastal wind dataset at 12.5-km resolution was produced. Even with larger error, the high-resolution winds, in medium to high strength, would still be useful over coastal ocean. Using measurements from moored buoys from the National Buoy Data Center, the high-resolution QuikSCAT wind data are found to have similar accuracy as standard data in the open ocean. The accuracy of both high- and standard-resolution winds, particularly in wind directions, is found to degrade near shore. The increase in error is likely caused by the inadequacy of the geophysical model function/ambiguity removal scheme in addressing coastal conditions and light winds situations. The modified algorithm helps to bring the directional accuracy of the high-resolution winds to the accuracy of the standard-resolution winds in near-shore regions, particularly in the nadir and far zones across the satellite track.

Tang, Wenqing; Liu, W. Timothy; Stiles, Bryan W.

2004-01-01

135

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

136

Age-related changes in the control of finger force vectors.  

PubMed

We explored changes in finger interaction in the process of healthy aging as a window into neural control strategies of natural movements. In particular, we quantified the amount of force produced by noninstructed fingers in different directions, the amount of force produced by the instructed finger orthogonally to the task direction, and the strength of multifinger synergies stabilizing the total force magnitude and direction during accurate force production. Healthy elderly participants performed accurate isometric force production tasks in five directions by individual fingers and by all four fingers acting together. Their data were compared with a dataset obtained in a similar earlier study of young subjects. Finger force vectors were measured using six-component force/torque sensors. Multifinger synergies were quantified using the framework of the uncontrolled manifold hypothesis. The elderly participants produced lower force magnitudes by noninstructed fingers and higher force magnitudes by instructed fingers in nontask directions. They showed strong synergies stabilizing the magnitude and direction of the total force vector. However, the synergy indexes were significantly lower than those observed in the earlier study of young subjects. The results are consistent with an earlier hypothesis of preferential weakening of intrinsic hand muscles with age. We interpret the findings as a shift in motor control from synergic to element-based, which may be causally linked to the documented progressive neuronal death at different levels of the neural axis. PMID:20829494

Kapur, Shweta; Zatsiorsky, Vladimir M; Latash, Mark L

2010-12-01

137

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

138

Assessing the impact of climate change on vector-borne viruses in the EU through the elicitation of expert opinion  

E-print Network

Assessing the impact of climate change on vector-borne viruses in the EU through the elicitation-borne viruses listed by the World Organization for Animal Health. It was predicted that climate change will increase the risk of incursions of African horse sickness virus (AHSV), Crimean-Congo haemorrhagic fever

Mottram, Nigel

139

Integrated data processing of remotely sensed and vector data for building change detection  

NASA Astrophysics Data System (ADS)

In recent years natural disasters have had an increasing impact leading to tremendous economic and human losses. Remote sensing technologies are being used more often for rapid detection and visualization of changes in the affected areas, providing essential information for damage assessment, planning and coordination of recovery activities. This study presents a GIS-based approach for the detection of damaged buildings. The methodology is based on the integrated analysis of vector data containing information about the original urban layout and remotely sensed images obtained after a catastrophic event. For the classification of building integrity a new `Detected Part of Contour' (DPC) feature was developed. The DPC feature defines a part of the building contour that can be detected in the related remotely sensed image. It reaches maximum value (100%) if the investigated building contour is intact. Next, several features based on the analysis of textural information of the remotely sensed image are considered. Finally, a binary classification of building conditions concludes the change detection analysis. The proposed method was applied to the 2010 earthquake in Qinghai (China). The results indicate that a GIS-based analysis can markedly improve the accuracy of change detection analysis. The proposed methodology has been developed solely within the Open Source Software environment (GRASS GIS, Python, Orange). The employment of Open Source Software provides the way for an innovative, flexible and costeffective implementation of change detection operations.

Sofina, N.; Ehlers, M.; Michel, U.

2012-10-01

140

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

141

Climate change influences on global distributions of dengue and chikungunya virus vectors.  

PubMed

Numerous recent studies have illuminated global distributions of human cases of dengue and other mosquito-transmitted diseases, yet the potential distributions of key vector species have not been incorporated integrally into those mapping efforts. Projections onto future conditions to illuminate potential distributional shifts in coming decades are similarly lacking, at least outside Europe. This study examined the global potential distributions of Aedes aegypti and Aedes albopictus in relation to climatic variation worldwide to develop ecological niche models that, in turn, allowed anticipation of possible changes in distributional patterns into the future. Results indicated complex global rearrangements of potential distributional areas, which-given the impressive dispersal abilities of these two species-are likely to translate into actual distributional shifts. This exercise also signalled a crucial priority: digitization and sharing of existing distributional data so that models of this sort can be developed more rigorously, as present availability of such data is fragmentary and woefully incomplete. PMID:25688023

Campbell, Lindsay P; Luther, Caylor; Moo-Llanes, David; Ramsey, Janine M; Danis-Lozano, Rogelio; Peterson, A Townsend

2015-04-01

142

Short Term Wind Forecasting for Sites with Abrupt Roughness and Thermal Changes  

NASA Astrophysics Data System (ADS)

With the increasing penetration of wind power to the electrical grid, the importance of short-term wind energy forecasting from hours to 2-3 days ahead has been recognized. Typically, the outputs of Numerical Weather Prediction (NWP) models are used to drive the forecasting system with forecast horizons of a few hours. We are studying the coupling of the local-scale models with North America regional NWP models such as GEM and NAM and nested meso-scale models for site specific wind and wind energy forecasting for wind farms near abrupt roughness and thermal changes. The goal is for real-time wind forecasts from 1 hour to 48 hours and comparison with field measurements at one or more sites in southern Ontario. Local, site specific, winds are affected on a local scale by a variety of factors. These include topography, on a range of scales, surface roughness and its spatial variation, surface temperatures or thermal properties and wakes behind surface mounted obstacles. On the meso-scale, effects such as sea or lake breezes and channelling effects are important factors. These local effects are generally not properly represented in meso-scale models, with a resolution of order 2-10 km. We will use various methods to simulate these local effects in our forecasting system. These include numerical vertical and horizontal interpolations and the use of models of flow in complex terrain. The results will be examined using the Mean Absolute Error and Root Mean Squared Error (RMSE). A decomposition of RMSE into amplitude and phase error will assist in identifying the forecasting errors and selecting MOS procedures for improving the forecasting. A comparison between the forecasted and measured wind speed at 80-m, the typical turbine hub height, shows encouraging results.

Liu, H.; Taylor, P. A.; Weng, W.; Salmon, J. R.

2008-12-01

143

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

144

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

145

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

146

Cytoplasmic pH dynamics in maize pulvinal cells induced by gravity vector changes  

NASA Technical Reports Server (NTRS)

In maize (Zea mays) and other grasses, changes in orientation of stems are perceived by pulvinal tissue, which responds to the stimulus by differential growth resulting in upward bending of the stem. The amyloplast-containing bundle sheath cells are the sites of gravity perception, although the initial steps of gravity perception and transmission remain unclear. In columella cells of Arabidopsis roots, we previously found that cytoplasmic pH (pH(c)) is a mediator in early gravitropic signaling (A.C. Scott, N.S. Allen [1999] Plant Physiol 121: 1291-1298). The question arises whether pH(c) has a more general role in signaling gravity vector changes. Using confocal ratiometric imaging and the fluorescent pH indicator carboxy seminaphtorhodafluor acetoxymethyl ester acetate, we measured pH(c) in the cells composing the maize pulvinus. When stem slices were gravistimulated and imaged on a horizontally mounted confocal microscope, pH(c) changes were only apparent within the bundle sheath cells, and not in the parenchyma cells. After turning, cytoplasmic acidification was observed at the sides of the cells, whereas the cytoplasm at the base of the cells where plastids slowly accumulated became more basic. These changes were most apparent in cells exhibiting net amyloplast sedimentation. Parenchyma cells and isolated bundle sheath cells did not show any gravity-induced pH(c) changes although all cell types responded to external stimuli in the predicted way: Propionic acid and auxin treatments induced acidification, whereas raising the external pH caused alkalinization. The results suggest that pH(c) has an important role in the early signaling pathways of maize stem gravitropism.

Johannes, E.; Collings, D. A.; Rink, J. C.; Allen, N. S.; Brown, C. S. (Principal Investigator)

2001-01-01

147

[Impact of changes in the environment on vector-transmitted diseases].  

PubMed

We have defined the relationship between infectious diseases and environmental conditions and considered the development of this relationship to its current situation, where human intervention is occurring more often and is becoming more aggressive. The increase in the transport of freight and passengers by air has allowed parasite vectors to spread quickly and easily over large distances. Every country can now be reached from any other country within a couple of days. Usually, foreign species are unable to establish themselves and to persist in the new environment; but the recent arrival of Aedes albopictus in Albania, Italy and the Americas is a cause for concern. Demographic pressure has increased the need for land and the exploitation of new areas leads to large changes in the vegetation. The classic example of this man-made damage is the destruction of tropical forest in Western Africa, but the destruction of herbaceous vegetation, such as papyrus, in East Africa, could also have serious epidemiological consequences. Streams and rivers have been managed for power production and irrigation. The use of dams, both large and small, and the culture of rice in paddy-fields produces large expanses of water which are suitable breeding grounds for mosquitoes and snails, the vectors of human diseases such as malaria and schistosomiasis in sub-Saharan Africa. They are, however, of lesser importance in Asia and the Americas. Urbanization imposes a set of very similar structures on a specific rural environment. The effect of these two factors on each other determines the pathologies associated with each town. The suburban area is a specific environment where both urban and rural diseases occur and are made worse by poor hygiene conditions (waste, sewage, etc.). However, not all man-made changes to the environment cause a deterioration in public health. Urban and agricultural development projects must consider these issues and should use medical and environmental studies to avoid causing epidemic-prone conditions or spreading endemic diseases. Currently, most studies are limited to listing the specific diseases in the target area and very few attempt to assess the possible consequences of changing the environment. Forecasting the consequences of changes in environmental management is of great importance, but it requires the development of multi-disciplinary teams in the field who must be involved in the planning and implementation of the projects. PMID:9410453

Mouchet, J; Carnevale, P

1997-01-01

148

Climate Change, Vector-borne Disease and Interdisciplinary Research: Social Science Perspectives on an Environment and Health Controversy  

Microsoft Academic Search

Over the last two decades, the science of climate change’s theoretical impacts on vector-borne disease has generated controversy\\u000a related to its methodological validity and relevance to disease control policy. Critical social science analysis, drawing\\u000a on science and technology studies and the sociology of social movements, demonstrates consistency between this controversy\\u000a and the theory that climate change is serving as a

Ben W. Brisbois; S. Harris Ali

149

SeaWinds Scatterometer Wind Vector Retrievals Within Hurricanes Using AMSR and NEXRAD to Perform Corrections for Precipitation Effects: Comparison of AMSR and NEXRAD Retrievals of Rain  

NASA Technical Reports Server (NTRS)

The opportunity provided by satellite scatterometers to measure ocean surface winds in strong storms and hurricanes is diminished by the errors in the received backscatter (SIGMA-0) caused by the attenuation, scattering and surface roughening produced by heavy rain. Providing a good rain correction is a very challenging problem, particularly at Ku band (13.4 GHz) where rain effects are strong. Corrections to the scatterometer measurements of ocean surface winds can be pursued with either of two different methods: empirical or physical modeling. The latter method is employed in this study because of the availability of near simultaneous and collocated measurements provided by the MIDORI-II suite of instruments. The AMSR was designed to measure atmospheric water-related parameters on a spatial scale comparable to the SeaWinds scatterometer. These quantities can be converted into volumetric attenuation and scattering at the Ku-band frequency of SeaWinds. Optimal estimates of the volume backscatter and attenuation require a knowledge of the three dimensional distribution of reflectivity on a scale comparable to that of the precipitation. Studies selected near the US coastline enable the much higher resolution NEXRAD reflectivity measurements evaluate the AMSR estimates. We are also conducting research into the effects of different beam geometries and nonuniform beamfilling of precipitation within the field-of-view of the AMSR and the scatterometer. Furthermore, both AMSR and NEXRAD estimates of atmospheric correction can be used to produce corrected SIGMA-0s, which are then input to the JPL wind retrieval algorithm.

Weissman, David E.; Hristova-Veleva, Svetla; Callahan, Philip

2006-01-01

150

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

PubMed

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 forest damage results from tornadoes in the south-east and mid-west, while downbursts are the most important type of wind disturbance in the Great Lakes area. Downbursts vary widely in size, but large ones can damage thousands of hectares, while tornadoes are much smaller, seldom affecting more than several hundred hectares. Tornadoes cause the most severe wind disturbances. Site characteristics such as physiography, soil moisture, and soil depth; stand characteristics like density and canopy roughness; and tree characteristics such as size, species, rooting depth, and wood strength, are the factors most recognized as influencing damage patterns. The consequences of wind damage to forests, such as change in environmental conditions, density, size structure, species composition, and successional status, occur on both immediate (hours-to-days) and long-term (months-to-decades) time scales. Most wind disturbances result in the post-disturbance vegetation being comprised of surviving canopy trees, and varying amounts of sprouts, released understory stems, and new seedlings. Stand size structure is usually reduced, and successional status of a forest is often advanced. Diversity can be either increased or decreased, depending on the measure of abundance used to calculate diversity. Because tornadoes and downbursts are in part products of thermodynamic climatic circumstances, they may be affected by anticipated changes in climatic conditions as the 21st century progresses. However, the current understanding of tornado and downburst formation from supercell storms is very incomplete, and climate-change model predictions sufficiently coarse, that predictions of changes in frequency, size, intensity, or timing of these extreme events must be regarded as highly uncertain. Moreover, retrospective approaches that employ tree demography and dendrochronology require prohibitively large sample sizes to resolve details of the relationship between climate fluctuations and characteristics of these storms. To improve predictions of changes in the climatology of these storms, we need improved understanding of the genesis of tornadoes and downbursts within thunderstorms, and greater resolution in global climate models. To improve coping strategies, forest scientists can contribute by giving more attention to how various silvicultural actions influence stand and tree vulnerability. Finally, increased focus on the dynamics of forest recovery and regrowth may suggest management actions that can facilitate desired objectives after one of these unpredictable wind disturbances. PMID:11087033

Peterson, C J

2000-11-15

151

ERS-1 scatterometer calibration and validation activities at ECMWF. B: From radar backscatter characteristics to wind vector solutions  

NASA Technical Reports Server (NTRS)

Calibration and validation activities for the ERS-1 scatterometer were carried out at ECMWF (European Center for Medium range Weather Forecast) complementary to the 'Haltenbanken' field campaign off the coast of Norway. At a Numerical Weather Prediction (NWP) center a wealth of verifying data is available both in time and space. This data is used to redefine the wind retrieval procedure given the instrumental characteristics. It was found that a maximum likelihood estimation procedure to obtain the coefficients of a reformulated sigma deg to wind relationship should use radar measurements in logarithmic rather than physical space, and use winds as the wind components rather than wind speed and direction. Doing this, a much more accurate transfer function than the one currently operated by ESA was derived. Sigma deg measurement space shows no signature of a separation in an upwind solution cone and a downwind solution cone. As such signature was anticipated in ESA's wind direction ambiguity removal algorithm, reconsideration of the procedure is necessary. Despite the fact that revisions have to be made in the process of wind retrieval; a grid potential is shown for scatterometry in meteorology and climatology.

Stoffelen, AD; Anderson, David L. T.; Woiceshyn, Peter M.

1992-01-01

152

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.

2012-08-03

153

Zoom in at African country level: potential climate induced changes in areas of suitability for survival of malaria vectors  

PubMed Central

Background Predicting anopheles vectors’ population densities and boundary shifts is crucial in preparing for malaria risks and unanticipated outbreaks. Although shifts in the distribution and boundaries of the major malaria vectors (Anopheles gambiae s.s. and An. arabiensis) across Africa have been predicted, quantified areas of absolute change in zone of suitability for their survival have not been defined. In this study, we have quantified areas of absolute change conducive for the establishment and survival of these vectors, per African country, under two climate change scenarios and based on our findings, highlight practical measures for effective malaria control in the face of changing climatic patterns. Methods We developed a model using CLIMEX simulation platform to estimate the potential geographical distribution and seasonal abundance of these malaria vectors in relation to climatic factors (temperature, rainfall and relative humidity). The model yielded an eco-climatic index (EI) describing the total favourable geographical locations for the species. The EI values were classified and exported to a GIS package. Using ArcGIS, the EI shape points were clipped to the extent of Africa and then converted to a raster layer using Inverse Distance Weighted (IDW) interpolation method. Generated maps were then transformed into polygon-based geo-referenced data set and their areas computed and expressed in square kilometers (km2). Results Five classes of EI were derived indicating the level of survivorship of these malaria vectors. The proportion of areas increasing or decreasing in level of survival of these malaria vectors will be more pronounced in eastern and southern African countries than those in western Africa. Angola, Ethiopia, Kenya, Mozambique, Tanzania, South Africa and Zambia appear most likely to be affected in terms of absolute change of malaria vectors suitability zones under the selected climate change scenarios. Conclusion The potential shifts of these malaria vectors have implications for human exposure to malaria, as recrudescence of the disease is likely to be recorded in several new areas and regions. Therefore, the need to develop, compile and share malaria preventive measures, which can be adapted to different climatic scenarios, remains crucial. PMID:24885061

2014-01-01

154

Assessing the impact of climate change on vector-borne viruses in the EU through the elicitation of expert opinion  

Microsoft Academic Search

SUMMARY Expert opinion was elicited to undertake a qualitative risk assessment to estimate the current and future risks to the European Union (EU) from five vector-borne viruses listed by the World Organization for Animal Health. It was predicted that climate change will increase the risk of incursions of African horse sickness virus (AHSV), Crimean-Congo haemorrhagic fever virus (CCHFV) and Rift

A. B R O UW; V. R AMNIAL; L. KELLY; R. K O S M ID

155

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.

156

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

157

A multi-model ensemble approach for assessment of climate change impact on surface winds in France  

Microsoft Academic Search

Statistical downscaling of 14 coupled atmosphere-ocean general circulation models (AOGCM) is presented to assess potential\\u000a changes of the 10 m wind speeds in France. First, a statistical downscaling method is introduced to estimate daily mean 10 m\\u000a wind speed at specific sites using general circulation model output. Daily 850 hPa wind field has been selected as the large\\u000a scale circulation predictor. The method

Julien Najac; Julien Boé; Laurent Terray

2009-01-01

158

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

159

Climate change, vector-borne disease and interdisciplinary research: social science perspectives on an environment and health controversy.  

PubMed

Over the last two decades, the science of climate change's theoretical impacts on vector-borne disease has generated controversy related to its methodological validity and relevance to disease control policy. Critical social science analysis, drawing on science and technology studies and the sociology of social movements, demonstrates consistency between this controversy and the theory that climate change is serving as a collective action frame for some health researchers. Within this frame, vector-borne disease data are interpreted as a symptom of climate change, with the need for further interdisiplinary research put forth as the logical and necessary next step. Reaction to this tendency on the part of a handful of vector-borne disease specialists exhibits characteristics of academic boundary work aimed at preserving the integrity of existing disciplinary boundaries. Possible reasons for this conflict include the leadership role for health professionals and disciplines in the envisioned interdiscipline, and disagreements over the appropriate scale of interventions to control vector-borne diseases. Analysis of the competing frames in this controversy also allows identification of excluded voices and themes, such as international political economic explanations for the health problems in question. A logical conclusion of this analysis, therefore, is the need for critical reflection on environment and health research and policy to achieve integration with considerations of global health equity. PMID:21125310

Brisbois, Ben W; Ali, S Harris

2010-12-01

160

Improving the textural characterization of trabecular bone structure to quantify its changes: the locally adapted scaling vector method  

NASA Astrophysics Data System (ADS)

We extend the recently introduced scaling vector method (SVM) to improve the textural characterization of oriented trabecular bone structures in the context of osteoporosis. Using the concept of scaling vectors one obtains non-linear structural information from data sets, which can account for global anisotropies. In this work we present a method which allows us to determine the local directionalities in images by using scaling vectors. Thus it becomes possible to better account for local anisotropies and to implement this knowledge in the calculation of the scaling properties of the image. By applying this adaptive technique, a refined quantification of the image structure is possible: we test and evaluate our new method using realistic two-dimensional simulations of bone structures, which model the effect of osteoblasts and osteoclasts on the local change of relative bone density. The partial differential equations involved in the model are solved numerically using cellular automata (CA). Different realizations with slightly varying control parameters are considered. Our results show that even small changes in the trabecular structures, which are induced by variation of a control parameters of the system, become discernible by applying the locally adapted scaling vector method. The results are superior to those obtained by isotropic and/or bulk measures. These findings may be especially important for monitoring the treatment of patients, where the early recognition of (drug-induced) changes in the trabecular structure is crucial.

Raeth, Christoph W.; Mueller, Dirk; Boehm, Holger F.; Rummeny, Ernst J.; Link, Thomas M.; Monetti, Roberto

2005-04-01

161

A parametric study of the behavior of the angular momentum vector during spin rate changes of rigid-body spacecraft  

NASA Astrophysics Data System (ADS)

During a spin-up or spin-down maneuver of a spinning spacecraft, it is usual to have not only a constant body-fixed torque about the desired spin axis, but also small undesired constant torques about the transverse axes. This causes the orientation of the angular momentum vector to change in inertial space. Since an analytic solution is available for the angular momentum vector as a function of time, this behavior can be studied for large variations of the dynamic parameters, such as the initial spin rate, the inertial properties and the torques. As an example, the spin-up and spin-down maneuvers of the Galileo spacecraft was studied and as a result, very simple heuristic solutions were discovered which provide very good approximations to the parametric behavior of the angular momentum vector orientation.

Longuski, J. M.; Kia, T.

1984-06-01

162

Climate variability and change in the United States: potential impacts on vector- and rodent-borne diseases.  

PubMed Central

Diseases such as plague, typhus, malaria, yellow fever, and dengue fever, transmitted between humans by blood-feeding arthropods, were once common in the United States. Many of these diseases are no longer present, mainly because of changes in land use, agricultural methods, residential patterns, human behavior, and vector control. However, diseases that may be transmitted to humans from wild birds or mammals (zoonoses) continue to circulate in nature in many parts of the country. Most vector-borne diseases exhibit a distinct seasonal pattern, which clearly suggests that they are weather sensitive. Rainfall, temperature, and other weather variables affect in many ways both the vectors and the pathogens they transmit. For example, high temperatures can increase or reduce survival rate, depending on the vector, its behavior, ecology, and many other factors. Thus, the probability of transmission may or may not be increased by higher temperatures. The tremendous growth in international travel increases the risk of importation of vector-borne diseases, some of which can be transmitted locally under suitable circumstances at the right time of the year. But demographic and sociologic factors also play a critical role in determining disease incidence, and it is unlikely that these diseases will cause major epidemics in the United States if the public health infrastructure is maintained and improved. PMID:11359689

Gubler, D J; Reiter, P; Ebi, K L; Yap, W; Nasci, R; Patz, J A

2001-01-01

163

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

PubMed

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

2011-03-01

164

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

165

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

166

Spatial Orientation and Balance Control Changes Induced by Altered Gravito-Inertial Force Vectors  

NASA Technical Reports Server (NTRS)

Seventeen healthy and eight vestibular deficient subjects were exposed to an interaural centripetal acceleration of 1 G (resultant 45 deg roll tilt of 1.4 G) on a 0.8 meter radius centrifuge for a period of 90 minutes in the dark. The subjects sat with head fixed upright, except every 4 of 10 minutes when instructed to rotate their head so that their nose and eyes pointed towards a visual point switched on every 3 to 5 seconds at random places (within +/- 30 deg) in the Earth horizontal plane. Motion sickness caused some subjects to limit their head movements during significant portions of the 90 minute period, and led three normal subjects to stop the test earlier. Eye movements, including directed saccades for subjective Earth- and head-referenced planes, were recorded before, during, and immediately after centrifugation using electro-oculography. Postural stability measurements were made before and within ten minutes after centrifugation. In normal subjects, postural sway and multisegment body kinematics were gathered during an eyes-closed head movement cadence (sway-referenced support platform), and in response to translational/rotational platform perturbations. A significant increase in postural sway, segmental motion amplitude and hip frequency was observed after centrifugation. This effect was short-lived, with a recovery time of several postural test trials. There were also asymmetries in the direction of post-centrifugation center of sway and head tilt which depended on the subject's orientation during the centrifugation adaptation period (left ear or right ear out). To delineate the effect of the magnitude of the gravito-inertial vector versus its direction during the adaptive centrifugation period, we tilted eight normal subjects in the roll axis at a 45 deg angle in the dark for 90 minutes without rotational motion. Their postural responses did not change following the period of tilt. Based on verbal reports, normal subjects overestimated roll-tilt during 90 minutes of both tilt and centrifugation stimuli. Subjective estimates of head-horizontal, provided by directed saccades, revealed significant errors after approximately 30 minutes that tended to increase only in the group who underwent centrifugation. Immediately after centrifugation, subjects reported feeling tilted on average 10 degrees in the opposite direction, which was in agreement with the direction of their earth-directed saccades. In vestibular deficient (VD) subjects, postural sway was measured using a sway-referenced or earth-fixed support surface, and with or without a head movement sequence. 'Me protocol was selected for each patient during baseline testing, and corresponded to the most challenging condition in which the patient was able to maintain balance with eyes closed. Bilaterally VD subjects showed no postural decrement after centrifugation, while unilateral VD subjects had varying degrees of decrement. Unilateral VD subjects were tested twice; they underwent centrifugation both with right ear out and left ear out. Their post-centrifuation center of sway shifted at right angles depending on the centrifuge GIF orientation. Bilateral VD subjects bad shifts as well, but no consistent directional trend. VD subjects underestimated roll-tilt during centrifugation, These results suggest that orientation of the gravito-inertial vector and its magnitude arc both used by the central nervous system for calibration of multiple orientation systems. A change in the background gravito-inertial force (otolith input) can rapidly initiate postural and perceptual adaptation in several sensorimotor systems, independent of a structured visual surround.

Kaufman, Galen D.; Wood, Scott J.; Gianna, Claire C.; Black, F. Owen; Paloski, William H.; Dawson, David L. (Technical Monitor)

1999-01-01

167

Response of the bird cherry-oat aphid ( Rhopalosiphum padi) to climate change in relation to its pest status, vectoring potential and function in a crop–vector–virus pathosystem  

Microsoft Academic Search

Global climate change threatens world food production via direct effects on plant growth and alterations to pest and pathogen prevalence and distribution. Complex relationships between host plant, pest, pathogen and environment create uncertainty particularly involving vector-borne diseases. We attempt to improve the understanding of the effects of climate change via a detailed review of one crop–vector–pathogen system.The bird cherry-oat aphid,

K. J. Finlay; J. E. Luck

168

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

169

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

170

Oceanography. Centennial changes in North Pacific anoxia linked to tropical trade winds.  

PubMed

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 (?(15)N) from multiple sediment cores. Increasing ?(15)N since ~1990 records an expansion of anoxia, consistent with observed O2 trends. However, this was preceded by a longer declining ?(15)N 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. PMID:25104384

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

2014-08-01

171

Low-speed wind-tunnel tests of a large scale blended arrow advanced supersonic transport model having variable cycle engines and vectoring exhaust nozzles  

NASA Technical Reports Server (NTRS)

A low-speed wind-tunnel investigation was conducted in a full-scale tunnel to determine the performance and static stability and control characteristics of a large-scale model of a blended-arrow advanced supersonic transport configuration incorporating variable-cycle engines and vectoring exhaust nozzles. Configuration variables tested included: (1) engine mode (cruise or low-speed), (2) engine exit nozzle deflection, (3) leading-edge flap geometry, and (4) trailing-edge flap deflection. Test variables included values of C sub micron from 0 to 0.38, values of angle of attack from -10 degrees to 30 degrees, values of angle of sideslip, from -5 degrees to 5 degrees, and values of Reynolds number, from 3.5 million to 6.8 million.

Parlett, L. P.; Shivers, J. P.

1976-01-01

172

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

173

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

174

Navigational Vectors  

NSDL National Science Digital Library

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

2008-12-10

175

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

SciTech Connect

The observations obtained during the IMS from the IGS magnetometer chain extending from Cambridge, England, to Tromso, Norway were 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. 24 refs., 3 figs.

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

1993-01-08

176

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

NASA Technical Reports Server (NTRS)

Surface features related to the wind are observed in data from the Mars Pathfinder lander and 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 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, and a second wind pattern oriented approx. 90 degrees to the first. This latter wind could be from the W-NW or from the E-SE and was responsible for cutting the ventifacts and modifying the crater rims. 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, in which the original surface formed by sedimentary processes from Tiu and Ares Vallis events has been modified by repeated burial and exhumation.

Greeley, R.; Kraft, M. D.; Kuzmin, R. O.; Bridges, N. T.

1999-01-01

177

Wind Disturbance Produced Changes in Tree Species Assemblage in the Peruvian Amazon  

NASA Astrophysics Data System (ADS)

Wind disturbance has been a frequently overlooked abiotic cause of mass tree mortality in the Amazon basin. In the Peruvian Amazon these wind disturbances are produced by meteorological events such as convective systems. Downbursts for example produce short term descendent wind speeds that can be in excess of 30 m s-1. These are capable of producing tree blowdowns which have been reported to be as large as 33 km2 in the Amazon basin. We used the chronosequence of Landsat Satellite imagery to find and locate where these blowdowns have occurred in the Loreto region of the Peruvian Amazon. Spectral Mixture Analysis was used to estimate the proportion landcover of green vegetation, non-photosynthetic vegetation (NPV), soil and shade in each pixel. The change in NPV was calculated by subtracting the NPV signal in the Landsat image prior to the blowdown occurrence, from the image following the disturbance. Our prior research has established a linear relationship between tree mortality and change in NPV. It is hypothesized that these mass tree mortality events result in changes in the tree species assemblage of affected forests. Here we present preliminary tree species assemblage data from two sites in the Peruvian Amazon near Iquitos, Peru. The site (ALP) at the Allpahuayo Mishana reserve (3.945 S, 73.455 W) is 30 km south of Iquitos, Peru, and hosts the remnants of a 50 ha blowdown that occurred in either 1992 or 1993. Another site (NAPO) on the Napo river about 60 km north of Iquitos, is the location of an approximately 300 ha blowdown that occurred in 1998. At each site, a 3000 m x 10 m transect encompassing non disturbed and disturbed areas was installed, and trees greater than 10 cm diameter at breast height were measured for diameter, height and were identified to the species. Stem density of trees with diameter at breast height > 10 cm, and tree height appear to be similar both inside and outside the blowdown affected areas of the forests at both sites. At the ALP and NAPO sites the most dramatic change in the tree species assemblage has been a three and an eleven fold increase in the pioneer tree family, Cecropiaceae, respectively. This preliminary data suggests that wind disturbance is capable of producing large shifts in the tree species assemblage of affected Amazon forests.

Rifai, S. W.; Chambers, J. Q.; Negron Juarez, R. I.; Ramirez, F.; Tello, R.; Alegria Muñoz, W.

2010-12-01

178

Detection and Monitoring of Spatio-temporal Change in the Distribution of Mosquito Vector Populations  

Technology Transfer Automated Retrieval System (TEKTRAN)

Mosquitoes transmit blood-borne disease agents that cause morbidity and mortality in human and animal populations. Preemption of epidemics/epizootics of mosquito-borne disease is predicated on the timely and effective application of vector control. Such timing is decided on the basis of adult mosq...

179

Assessment of change in hydration in women during pregnancy and postpartum with bioelectrical impedance vectors  

Technology Transfer Automated Retrieval System (TEKTRAN)

Increases in total body water (TBW) are typical of late-stage pregnancy. Because excessive TBW expansion or contraction can lead to adverse outcomes, a safe non-invasive method for routine assessment of TBW would be useful clinically. Impedance vectors are derived from resistance (R) and reactance...

180

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

181

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

182

Global Climate Change and Its Potential Impact on Disease Transmission by Salinity-Tolerant Mosquito Vectors in Coastal Zones  

PubMed Central

Global climate change can potentially increase the transmission of mosquito vector-borne diseases such as malaria, lymphatic filariasis, and dengue in many parts of the world. These predictions are based on the effects of changing temperature, rainfall, and humidity on mosquito breeding and survival, the more rapid development of ingested pathogens in mosquitoes and the more frequent blood feeds at moderately higher ambient temperatures. An expansion of saline and brackish water bodies (water with <0.5?ppt or parts per thousand, 0.5–30?ppt and >30?ppt salt are termed fresh, brackish, and saline respectively) will also take place as a result of global warming causing a rise in sea levels in coastal zones. Its possible impact on the transmission of mosquito-borne diseases has, however, not been adequately appreciated. The relevant impacts of global climate change on the transmission of mosquito-borne diseases in coastal zones are discussed with reference to the Ross–McDonald equation and modeling studies. Evidence is presented to show that an expansion of brackish water bodies in coastal zones can increase the densities of salinity-tolerant mosquitoes like Anopheles sundaicus and Culex sitiens, and lead to the adaptation of fresh water mosquito vectors like Anopheles culicifacies, Anopheles stephensi, Aedes aegypti, and Aedes albopictus to salinity. Rising sea levels may therefore act synergistically with global climate change to increase the transmission of mosquito-borne diseases in coastal zones. Greater attention therefore needs to be devoted to monitoring disease incidence and preimaginal development of vector mosquitoes in artificial and natural coastal brackish/saline habitats. It is important that national and international health agencies are aware of the increased risk of mosquito-borne diseases in coastal zones and develop preventive and mitigating strategies. Application of appropriate counter measures can greatly reduce the potential for increased coastal transmission of mosquito-borne diseases consequent to climate change and a rise in sea levels. It is proposed that the Jaffna peninsula in Sri Lanka may be a useful case study for the impact of rising sea levels on mosquito vectors in tropical coasts. PMID:22723781

Ramasamy, Ranjan; Surendran, Sinnathamby Noble

2012-01-01

183

Do changes in the size of mud flocs affect the acoustic backscatter values recorded by a Vector ADV?  

NASA Astrophysics Data System (ADS)

A series of experiments were conducted to examine the effect of mud floc growth on the acoustic back-scatter signal recorded by a Nortek Vector acoustic Doppler velocimeter (ADV). Several studies have shown that calibration equations can be developed to link the backscatter strength with average suspended sediment concentration (SSC) when the sediment particle size distribution remains constant. However, when mud is present, the process of flocculation can alter the suspended particle size distribution. Past studies have shown that it is still unclear as to the degree of dependence of the calibration equation on changes in floc size. Part of the ambiguity lies in the fact that flocs can be porous and rather loosely packed and therefore will not scatter sound waves as a solid particle would. In addition, direct, detailed measurements of floc size have not accompanied experiments examining the dependence of ADV backscatter and suspended sediment concentration. In this set of experiments, direct measurement of the floc size distribution is made with time in a mixing chamber using a floc camera system. A Vector ADV and an OBS are also placed within the tank to measure acoustic backscatter and SSC as the flocs change size with time; concentration in the experiments ranges from 15 to 90 mg/l. Results showed that the growth of mud flocs did influence the SNR recorded by the Vector ADV, and that the sensitivity of the SNR signal to changes in floc size was higher for flocs with diameters less than ?80 ?m (it kr=1 at a diameter of 80 ?m). The response of SNR to changes in floc size and SSC was modeled with a modified sonar equation. If properly calibrated, the model was able to capture the functional behavior of SNR with changes in floc size and concentration. Values of the calibration coefficients showed that while changes in floc diameter up to about 80 ?m did alter the SNR, the change was less than what would be expected from a similar change in the size of solid scatterers.

Rouhnia, Mohamad; Keyvani, Ali; Strom, Kyle

2014-08-01

184

Solar cycle changes in the geo-effectiveness of small-scale solar wind turbulence measured by Wind and ACE at 1 AU  

NASA Astrophysics Data System (ADS)

Multi-scale structure of the solar wind in the ecliptic at 1 AU undergoes significant evolution with the phase of the solar cycle. Wind spacecraft measurements during 1995 to 1998 and ACE spacecraft measurements during 1997 to 2005 were used to characterise the evolution of small-scale (~1 min to 2 h) fluctuations in the solar wind speed vsw, magnetic energy density B2, and solar wind ? parameter, in the context of large-scale (~1 day to years) variations. The large-scale variation in ? most resembled large-scale variations in B2. The probability density of large fluctuations in ? and B2 both had strong minima during 1995, a familiar signature of solar minimum. Generalized Structure Function (GSF) analysis was used to estimate inertial range scaling exponents aGSF and their evolution throughout 1995 to 2005. For the entire data set, the weighted average scaling exponent for small-scale fluctuations in vsw was aGSF=0.284±0.001, a value characteristic of intermittent MHD turbulence (>1/4), whereas the scaling exponents for corresponding fluctuations in B2 and ? were aGSF=0.395±0.001 and 0.334±0.001, respectively. These values are between the range expected for Gaussian fluctuations (1/2) and Kolmogorov turbulence (1/3). However, the scaling exponent for ? changed from a Gaussian-Kolmogorov value of 0.373±0.005 during 1997 (end of solar minimum) to an MHD turbulence value of 0.247±0.004 during 2003 (recurrent fast streams). Changes in the characteristics of solar wind turbulence may be reproducible from one solar cycle to the next.

Parkinson, M. L.; Healey, R. C.; Dyson, P. L.

2007-06-01

185

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

186

Modeling flow over roughness changes and applications to wind energy for sites on the Great Lakes (Invited)  

NASA Astrophysics Data System (ADS)

The wind energy resource offshore is not well understood in the Great Lakes area. This is unfortunate as potential offshore wind farm sites are attracting great interest. In an effort to improve our knowledge of the offshore resource, data are now being collected in specific locations. Preferred Great Lakes wind farm sites are in relatively shallow water reasonably close to shore. Airflow over these sites will often be within a transition zone as air flows from a rough land surface to a smoother lake surface. There will also often be changes in the thermal stratification of the air column within this Internal Boundary Layer (IBL). For long fetches and heights of order 100m we can formulate and solve the Reynolds averaged Navier-Stokes equations. We make boundary-layer approximations for pressure and assume that along-wind diffusion is minimal. Effects of gentle terrain can be added separately. Results suggest that relatively long fetches of order 100 km are required before winds at 100m fully adjust to the smoother lake surface. Over Lakes Erie and Ontario winds are frequently from the 180-270 degree quadrant and this suggests that the wind resource should be better in the northern (Canadian) half of these lakes. We illustrate this with energy density plots for locations near lakes Erie and Ontario.

Taylor, P. A.; Salmon, J.; Weng, W.

2010-12-01

187

Monitoring vegetation dynamics by coupling linear trend analysis with change vector analysis: a case study in the Xilingol steppe in northern China  

Microsoft Academic Search

Timely and accurate monitoring of grassland vegetation dynamics is essential for sustainable grassland management in China. We coupled linear trend analysis (LTA) with change vector analysis (CVA) to improve the effectiveness of grassland monitoring. LTA was used to detect continuous inter-annual vegetation trends to identify significant change trend regions (SCTRs) in location and significant change trend periods (SCTPs) in time.

Yuanyuan Zhao; Chunyang He; Qiaofeng Zhang

2012-01-01

188

Monitoring vegetation dynamics by coupling linear trend analysis with change vector analysis: a case study in the Xilingol steppe in northern China  

Microsoft Academic Search

Timely and accurate monitoring of grassland vegetation dynamics is essential for sustainable grassland management in China. We coupled linear trend analysis (LTA) with change vector analysis (CVA) to improve the effectiveness of grassland monitoring. LTA was used to detect continuous inter-annual vegetation trends to identify significant change trend regions (SCTRs) in location and significant change trend periods (SCTPs) in time.

Yuanyuan Zhao; Chunyang He; Qiaofeng Zhang

2011-01-01

189

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

190

Observational Evidence of Changing Photospheric Vector Magnetic Fields Associated with Solar Flares  

E-print Network

. 2002; Wang et al. 2002, 2004a; Yurchyshyn et al. 2004; Wang 2006), white-light (WL) structure changes, substantial changes are found in the longitudinal magnetic fields associated with decaying penumbrae and darkened umbrae at the flaring PIL (Liu et al. 2005) suggesting that changes of the sunspot WL structure

191

Potential effects of climate change on distribution and activity of insect vectors of grapevine pathogens  

Microsoft Academic Search

The impact of changing climatic conditions on viticulture is currently mainly discussed with respect to alterations in grape physiology, adaptation of cultivars and cultural practice. However, pests and diseases of grapevine are influenced by changing climate, too. They are affected either directly through impacts on their life history and epidemiology or indirectly by changes of grapevine physiology and phenology. This

Élisabeth BOUDON-PADIEU; Michael MAIXNER

192

Incidence of Vector-borne Disease and Climate Change: A Study in Semi-arid Algeria  

NASA Astrophysics Data System (ADS)

Leishmaniases are among the most important emerging and resurging vector-borne diseases, second only to malaria in terms of the number of affected people. Leishmaniases are endemic in 88 countries worldwide and threaten about 350 million people (WHO, 2007). Since the first reported case of zoonotic cutaneous leishmaniasis (ZCL) in Saida, Algeria in 1991, 1,275 cases have been recorded (Makhlouf & Houti, 2010) with the vast majority of study-area cases (99%) reported between the years of 2000 and 2009. An investigation of potential climatic indicators for the apparent shift in disease prevalence was conducted by comparing anomalies in the climate data specific to the local pathogen cycle. It was determined that long term climate trends have resulted in conditions that promote the prevalence of ZCL. Increased precipitation have resulted in greater vegetation and promoted host and vector population growth through a trophic cascade. Increased minimum temperatures have lengthened the annual duration of sandfly activity. Short term variations in maximum temperatures, however show a correlation with disease suppression in the subsequent years. These findings indicate a potential to forecast the risk of ZCL infection through models of the trophic cascade and sandfly population growth.

Blakey, T.; Bounoua, L.

2012-12-01

193

Impact of climate change upon vector born diseases in Europe and Africa using ENSEMBLES Regional Climate Models  

NASA Astrophysics Data System (ADS)

Climate variability is an important component in determining the incidence of a number of diseases with significant human/animal health and socioeconomic impacts. The most important diseases affecting health are vector-borne, such as malaria, Rift Valley Fever and including those that are tick borne, with over 3 billion of the world population at risk. Malaria alone is responsible for at least one million deaths annually, with 80% of malaria deaths occurring in sub-Saharan Africa. The climate has a large impact upon the incidence of vector-borne diseases; directly via the development rates and survival of both the pathogen and the vector, and indirectly through changes in the environmental conditions. A large ensemble of regional climate model simulations has been produced within the ENSEMBLES project framework for both the European and African continent. This work will present recent progress in human and animal disease modelling, based on high resolution climate observations and regional climate simulations. Preliminary results will be given as an illustration, including the impact of climate change upon bluetongue (disease affecting the cattle) over Europe and upon malaria and Rift Valley Fever over Africa. Malaria scenarios based on RCM ensemble simulations have been produced for West Africa. These simulations have been carried out using the Liverpool Malaria Model. Future projections highlight that the malaria incidence decreases at the northern edge of the Sahel and that the epidemic belt is shifted southward in autumn. This could lead to significant public health problems in the future as the demography is expected to dramatically rise over Africa for the 21st century.

Caminade, Cyril; Morse, Andy

2010-05-01

194

Changes in fluxes of heat, H2O, CO2 caused by a large wind farm  

Technology Transfer Automated Retrieval System (TEKTRAN)

The Crop Wind Energy Experiment (CWEX) provides a platform to investigate the effect of wind turbines and large wind farms on surface fluxes of momentum, heat, moisture and carbon dioxide (CO2). In 2010 and 2011, eddy covariance flux stations were installed between two lines of turbines at the south...

195

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

E-print Network

for grid integration of wind power on European level. Description (max. 400 words) Within the European and the electricity market. In order to cope with the fluctuations in the wind power production, other units frequent operation of the power plants in less efficient part-load operation. Hence, large-scale wind power

196

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 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. Analyzing changes in a changing climate implies that several uncertainties need to be taken into account. First, there is the uncertainty in climate experiments, which represents the possible development of the emission of greenhouse gases. Second, there is uncertainty between the climate models that are used to analyze the effect of different climate experiments. The third uncertainty is the natural variability of the climate. When this system variability is large, small trends will be difficult to detect. The natural variability results in statistical uncertainty, especially for events with high return values. We addressed the first two types of uncertainties for extreme wind conditions in the North Sea using 12 CMIP5 GCMs. To evaluate the differences between the climate experiments, two climate experiments (rcp4.5 and rcp8.5) from 2050-2100 are compared with historical runs, running from 1950-2000. Rcp4.5 is considered to be a middle climate experiment and rcp8.5 represents high-end climate scenarios. The projections of the 12 GCMs for a given scenario illustrate model uncertainty. We focus on the North Sea basin, because changes in wind conditions could have a large impact on safety of the densely populated North Sea coast, an area that has already a high exposure to flooding. Our results show that, consistent with ERA-Interim results, the annual maximum wind speed in the historical run demonstrates large interannual variability. For the North Sea, the annual maximum wind speed is not projected to change in either rcp4.5 or rcp8.5. In fact, the differences in the 12 GCMs are larger than the difference between the three experiments. Furthermore, our results show that, the variation in direction of annual maximum wind speed is large and this precludes a firm statement on climate-change induced changes in these directions. Nonetheless, most models indicate a decrease in annual maximum wind speed from south-eastern directions and an increase from south-western and western directions. This might be caused by a poleward shift of the storm track. The amount of wind from north-west and north-north-west, wind directions that are responsible for the development of extreme storm surges in the southern part of the North Sea, are not projected to change. However, North Sea coasts that have the longest fetch for western direction, e.g. the German Bight, may encounter more often high storm surge levels and extreme waves when the annual maximum wind will indeed be more often from western direction.

de Winter, R.; Ruessink, G.; Sterl, A.

2012-12-01

197

Climate, environmental and socio-economic change: weighing up the balance in vector-borne disease transmission.  

PubMed

Arguably one of the most important effects of climate change is the potential impact on human health. While this is likely to take many forms, the implications for future transmission of vector-borne diseases (VBDs), given their ongoing contribution to global disease burden, are both extremely important and highly uncertain. In part, this is owing not only to data limitations and methodological challenges when integrating climate-driven VBD models and climate change projections, but also, perhaps most crucially, to the multitude of epidemiological, ecological and socio-economic factors that drive VBD transmission, and this complexity has generated considerable debate over the past 10-15 years. In this review, we seek to elucidate current knowledge around this topic, identify key themes and uncertainties, evaluate ongoing challenges and open research questions and, crucially, offer some solutions for the field. Although many of these challenges are ubiquitous across multiple VBDs, more specific issues also arise in different vector-pathogen systems. PMID:25688012

Parham, Paul E; Waldock, Joanna; Christophides, George K; Hemming, Deborah; Agusto, Folashade; Evans, Katherine J; Fefferman, Nina; Gaff, Holly; Gumel, Abba; LaDeau, Shannon; Lenhart, Suzanne; Mickens, Ronald E; Naumova, Elena N; Ostfeld, Richard S; Ready, Paul D; Thomas, Matthew B; Velasco-Hernandez, Jorge; Michael, Edwin

2015-04-01

198

Potential impacts of climate change on the ecology of dengue and its mosquito vector the Asian tiger mosquito (Aedes albopictus)  

NASA Astrophysics Data System (ADS)

Shifts in temperature and precipitation patterns caused by global climate change may have profound impacts on the ecology of certain infectious diseases. We examine the potential impacts of climate change on the transmission and maintenance dynamics of dengue, a resurging mosquito-vectored infectious disease. In particular, we project changes in dengue season length for three cities: Atlanta, GA; Chicago, IL and Lubbock, TX. These cities are located on the edges of the range of the Asian tiger mosquito within the United States of America and were chosen as test cases. We use a disease model that explicitly incorporates mosquito population dynamics and high-resolution climate projections. Based on projected changes under the Special Report on Emissions Scenarios (SRES) A1fi (higher) and B1 (lower) emission scenarios as simulated by four global climate models, we found that the projected warming shortened mosquito lifespan, which in turn decreased the potential dengue season. These results illustrate the difficulty in predicting how climate change may alter complex systems.

Erickson, R. A.; Hayhoe, K.; Presley, S. M.; Allen, L. J. S.; Long, K. R.; Cox, S. B.

2012-09-01

199

Ligand-induced conformational change of a protein reproduced by a linear combination of displacement vectors obtained from normal mode analysis.  

PubMed

The conformational change of a protein upon ligand binding was examined by normal mode analysis (NMA) based on an elastic-network model (ENM) for a full-atom system using dihedral angles as independent variables. Specifically, we investigated the extent to which conformational change vectors of atoms from an apo form to a holo form of a protein can be represented by a linear combination of the displacement vectors of atoms in the apo form calculated for the lowest-frequency m normal modes (m=1, 2,…, 20). In this analysis, the latter vectors were best fitted to the former ones by the least-squares method. Twenty-two paired proteins in the holo and apo forms, including three dimer pairs, were examined. The results showed that, in most cases, the conformational change vectors were reproduced well by a linear combination of the displacement vectors of a small number of low-frequency normal modes. The conformational change around an active site was reproduced as well as the entire conformational change, except for some proteins that only undergo significant conformational changes around active sites. The weighting factors for 20 normal modes optimized by the least-squares fitting characterize the conformational changes upon ligand binding for these proteins. The conformational changes sampled around the apo form of a protein by the linear combination of the displacement vectors obtained by ENM-based NMA may help solve the flexible-docking problem of a protein with another molecule because the results presented herein suggest that they have a relatively high probability of being involved in an actual conformational change. PMID:21807453

Wako, Hiroshi; Endo, Shigeru

2011-12-01

200

A Simplified Morphing Blade for Horizontal Axis Wind Turbines  

E-print Network

salinas@hotmail.com The aim of designing wind turbine blades is to improve the power capture ability speed vr Relative wind speed vre Reference wind speed vci Cut-in wind speed vco Cut-out wind speed Produced Power of wind turbine rotor x Vector of the decision variables p Vector of the design parameters r

Boyer, Edmond

201

THE ABRUPT CHANGES IN THE PHOTOSPHERIC MAGNETIC AND LORENTZ FORCE VECTORS DURING SIX MAJOR NEUTRAL-LINE FLARES  

SciTech Connect

We analyze the spatial and temporal variations of the abrupt photospheric magnetic changes associated with six major flares using 12 minute, 0.''5 pixel{sup -1} vector magnetograms from NASA's Helioseismic and Magnetic Imager instrument on the Solar Dynamics Observatory satellite. The six major flares occurred near the main magnetic neutral lines of four active regions, NOAA 11158, 11166, 11283, and 11429. During all six flares the neutral-line field vectors became stronger and more horizontal, in each case almost entirely due to strengthening of the horizontal field components parallel to the neutral line. In all six cases the neutral-line pre-flare fields were more vertical than the reference potential fields, and collapsed abruptly and permanently closer to potential-field tilt angles during every flare, implying that the relaxation of magnetic stress associated with non-potential tilt angles plays a major role during major flares. The shear angle with respect to the reference potential field did not show such a pattern, demonstrating that flare processes do not generally relieve magnetic stresses associated with photospheric magnetic shear. The horizontal fields became significantly and permanently more aligned with the neutral line during the four largest flares, suggesting that the collapsing field is on average more aligned with the neutral line than the pre-flare neutral-line field. The vertical Lorentz force had a large, abrupt, permanent downward change during each of the flares, consistent with loop collapse. The horizontal Lorentz force changes acted mostly parallel to the neutral line in opposite directions on each side, a signature of the fields contracting during the flare, pulling the two sides of the neutral line toward each other. The greater effect of the flares on field tilt than on shear may be explained by photospheric line-tying.

Petrie, G. J. D. [National Solar Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States)

2012-11-01

202

The Abrupt Changes in the Photospheric Magnetic and Lorentz Force Vectors during Six Major Neutral-line Flares  

NASA Astrophysics Data System (ADS)

We analyze the spatial and temporal variations of the abrupt photospheric magnetic changes associated with six major flares using 12 minute, 0farcs5 pixel-1 vector magnetograms from NASA's Helioseismic and Magnetic Imager instrument on the Solar Dynamics Observatory satellite. The six major flares occurred near the main magnetic neutral lines of four active regions, NOAA 11158, 11166, 11283, and 11429. During all six flares the neutral-line field vectors became stronger and more horizontal, in each case almost entirely due to strengthening of the horizontal field components parallel to the neutral line. In all six cases the neutral-line pre-flare fields were more vertical than the reference potential fields, and collapsed abruptly and permanently closer to potential-field tilt angles during every flare, implying that the relaxation of magnetic stress associated with non-potential tilt angles plays a major role during major flares. The shear angle with respect to the reference potential field did not show such a pattern, demonstrating that flare processes do not generally relieve magnetic stresses associated with photospheric magnetic shear. The horizontal fields became significantly and permanently more aligned with the neutral line during the four largest flares, suggesting that the collapsing field is on average more aligned with the neutral line than the pre-flare neutral-line field. The vertical Lorentz force had a large, abrupt, permanent downward change during each of the flares, consistent with loop collapse. The horizontal Lorentz force changes acted mostly parallel to the neutral line in opposite directions on each side, a signature of the fields contracting during the flare, pulling the two sides of the neutral line toward each other. The greater effect of the flares on field tilt than on shear may be explained by photospheric line-tying.

Petrie, G. J. D.

2012-11-01

203

Kinetic Monte Carlo studies of the effects of Burgers vector changes on the reaction kinetics of one-dimensionally gliding interstitial clusters  

Microsoft Academic Search

Kinetic Monte Carlo simulations of one-dimensionally diffusing interstitial clusters (dislocation loops) are used to gain insight into their role in microstructure evolution under irradiation. The simulations investigate the changes in reaction kinetics of these defects as a function of changes in the Burgers vector and variation in the size and density of randomly or periodically distributed sinks. In this paper

Howard L. Heinisch; Bachu N. Singh; Stanislav I. Golubov

2000-01-01

204

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

205

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

206

Reconstructing Holocene changes in the Southern Hemisphere westerly winds: Integrating modern processes and paleoclimate data from New Zealand's southern fjords  

NASA Astrophysics Data System (ADS)

The Southern Hemisphere westerly winds are an important component of the global carbon cycle due to their influence on Southern Ocean CO2 flux. In addition, the winds influence mid-latitude storm tracks, thereby controlling moisture balance over much of New Zealand's South Island and other Southern Hemisphere regions. Fiordland, New Zealand is an ideal locale to investigate Holocene changes in westerly wind behavior: It sits at the northern margin of the wind field maximum, is sensitive to latitudinal and strength fluctuations of the winds, and is the location of numerous fjord sub-basins with high sedimentation rates (up to 3 mm/yr). Due to the strong positive relationship between wind speed and regional rainfall, reconstructions of past precipitation and fjord circulation can inform us of past westerly wind behavior. These processes can be observed through changes in the rate of organic carbon delivery from land: When precipitation is high, more terrestrial organic carbon is delivered to the fjords, while low precipitation shifts the balance toward accumulation of marine organic carbon. An important first step towards reconstructing past westerly wind variability is to characterize the distribution and cycling of carbon throughout different depositional settings in the fjords to determine the optimal location for the development of paleoclimate records. Here, we present a geochemical characterization of surface sediments and the water column throughout the region and apply this understanding to sediment cores. During three field seasons in 2012 and 2013, we collected surface sediments, particulate organic matter, and piston cores from 10 different fjords spanning 44-46° S. Our results suggest that organic carbon in the fjord basins largely follows a two-end-member mixing model, drawing from marine and terrestrial end-member sources. We see consistent down-fjord trends in carbon and nitrogen concentrations and isotopes measured from surface sediments and particulate organic matter. Terrestrial organic carbon dominates toward the head of each fjord and marine organic content increases moving toward the mouth, and the consistency of this relationship allows us to compare downcore results from different basins. We will apply our modern-process framework to several cores that span the last 4,000 years and discuss the implications for late Holocene westerly wind variability in this understudied but important region.

Hinojosa, J.; Moy, C. M.; Wilson, G. S.; Stirling, C. H.

2013-12-01

207

Late-glacial to holocene changes in winds, upwelling, and seasonal production of the northern California current system  

USGS Publications Warehouse

A core 120 km off the coast of southern Oregon was examined for changes in lithology, diatoms, and pollen over the past 30,000 yr. Primary production during the late Pleistocene was about half that of the Holocene. Evidence from diatoms and pollen indicates that summer upwelling was much weaker, implying an absence of strong northerly winds. Early Pliocene diatoms found throughout the late Pleistocene section were probably derived from diatomites east of the Cascades and provide evidence for strong easterly winds over a dry continental interior. The findings verify predictions of a climate model based on glacial maximum conditions. There is no compelling evidence for a climatic reversal corresponding to the European Younger Dryas chron. During the early Holocene (9000-7000 yr B.P.) there may have been years when winds were insufficiently strong to support upwelling, so that warm stratified waters lay closer to the coast. ?? 1992.

Sancetta, C.; Lyle, M.; Heusser, L.; Zahn, R.; Bradbury, J.P.

1992-01-01

208

Population Genetics of Two Key Mosquito Vectors of Rift Valley Fever Virus Reveals New Insights into the Changing Disease Outbreak Patterns in Kenya  

PubMed Central

Rift Valley fever (RVF) outbreaks in Kenya have increased in frequency and range to include northeastern Kenya where viruses are increasingly being isolated from known (Aedes mcintoshi) and newly-associated (Ae. ochraceus) vectors. The factors contributing to these changing outbreak patterns are unclear and the population genetic structure of key vectors and/or specific virus-vector associations, in particular, are under-studied. By conducting mitochondrial and nuclear DNA analyses on >220 Kenyan specimens of Ae. mcintoshi and Ae. ochraceus, we uncovered high levels of vector complexity which may partly explain the disease outbreak pattern. Results indicate that Ae. mcintoshi consists of a species complex with one of the member species being unique to the newly-established RVF outbreak-prone northeastern region of Kenya, whereas Ae. ochraceus is a homogeneous population that appears to be undergoing expansion. Characterization of specimens from a RVF-prone site in Senegal, where Ae. ochraceus is a primary vector, revealed direct genetic links between the two Ae. ochraceus populations from both countries. Our data strongly suggest that unlike Ae. mcintoshi, Ae. ochraceus appears to be a relatively recent, single 'introduction' into Kenya. These results, together with increasing isolations from this vector, indicate that Ae. ochraceus will likely be of greater epidemiological importance in future RVF outbreaks in Kenya. Furthermore, the overall vector complexity calls into question the feasibility of mosquito population control approaches reliant on genetic modification. PMID:25474018

Tchouassi, David P.; Bastos, Armanda D. S.; Sole, Catherine L.; Diallo, Mawlouth; Lutomiah, Joel; Mutisya, James; Mulwa, Francis; Borgemeister, Christian; Sang, Rosemary; Torto, Baldwyn

2014-01-01

209

Population genetics of two key mosquito vectors of rift valley Fever virus reveals new insights into the changing disease outbreak patterns in kenya.  

PubMed

Rift Valley fever (RVF) outbreaks in Kenya have increased in frequency and range to include northeastern Kenya where viruses are increasingly being isolated from known (Aedes mcintoshi) and newly-associated (Ae. ochraceus) vectors. The factors contributing to these changing outbreak patterns are unclear and the population genetic structure of key vectors and/or specific virus-vector associations, in particular, are under-studied. By conducting mitochondrial and nuclear DNA analyses on >220 Kenyan specimens of Ae. mcintoshi and Ae. ochraceus, we uncovered high levels of vector complexity which may partly explain the disease outbreak pattern. Results indicate that Ae. mcintoshi consists of a species complex with one of the member species being unique to the newly-established RVF outbreak-prone northeastern region of Kenya, whereas Ae. ochraceus is a homogeneous population that appears to be undergoing expansion. Characterization of specimens from a RVF-prone site in Senegal, where Ae. ochraceus is a primary vector, revealed direct genetic links between the two Ae. ochraceus populations from both countries. Our data strongly suggest that unlike Ae. mcintoshi, Ae. ochraceus appears to be a relatively recent, single 'introduction' into Kenya. These results, together with increasing isolations from this vector, indicate that Ae. ochraceus will likely be of greater epidemiological importance in future RVF outbreaks in Kenya. Furthermore, the overall vector complexity calls into question the feasibility of mosquito population control approaches reliant on genetic modification. PMID:25474018

Tchouassi, David P; Bastos, Armanda D S; Sole, Catherine L; Diallo, Mawlouth; Lutomiah, Joel; Mutisya, James; Mulwa, Francis; Borgemeister, Christian; Sang, Rosemary; Torto, Baldwyn

2014-12-01

210

Statistical-dynamical downscaling for wind energy potentials: Evaluation and applications to decadal hindcasts and climate change projections  

NASA Astrophysics Data System (ADS)

A statistical-dynamical downscaling (SDD) approach for the regionalisation of wind energy output (Eout) over Europe with special focus on Germany is proposed. SDD uses an extended circulation weather type (CWT) analysis on global daily MSLP fields with the central point being located over Germany. 77 weather classes based on the associated circulation weather type and the intensity of the geostrophic flow are identified. Representatives of these classes are dynamical downscaled with the regional climate model COSMO-CLM. By using weather class frequencies of different datasets the simulated representatives are recombined to probability density functions (PDFs) of near-surface wind speed and finally to Eout of a sample wind turbine for present and future climate. This is performed for reanalysis, decadal hindcasts and long-term future projections. For evaluation purposes results of SDD are compared to wind observations and to simulated Eout of purely dynamical downscaling (DD) methods. For the present climate SDD is able to simulate realistic PDFs of 10m-wind speed for most stations in Germany. The resulting spatial Eout patterns are similar to DD simulated Eout. In terms of decadal hindcasts results of SDD are similar to DD simulated Eout over Germany, Poland, Czech Republic, and Benelux, for which high correlations between annual Eout timeseries of SDD and DD are detected for selected hindcasts. Lower correlation is found for other European countries. It is demonstrated that SDD can be used to downscale the full ensemble of the MPI-ESM decadal prediction system. Long-term climate change projections in SRES scenarios of ECHAM5/MPI-OM as obtained by SDD agree well to results of other studies using DD methods, with increasing Eout over Northern Europe and a negative trend over Southern Europe. Despite some biases it is concluded that SDD is an adequate tool to assess regional wind energy changes in large model ensembles.

Pinto, Joaquim G.; Reyers, Mark; Mömken, Julia

2014-05-01

211

Influence on the hydrodynamic performance of a variable vector propeller of different rules of pitch angle change  

NASA Astrophysics Data System (ADS)

To design a more effective blade pitch adjustment mechanism, research was done on changes to the hydrodynamic characteristics of VVPs (Variable Vector Propeller) caused by different rules for changing pitch angle. A mathematical method for predicting the hydrodynamic characteristics of a VVP under unsteady conditions is presented based on the panel method. Mathematical models for evaluation based on potential flow theory and the Green theorem are also presented. The hydrodynamic characteristics are numerically predicted. To avoid gaps between panels, hyperboloidal quadrilateral panels were used. The pressure Kutta condition on the trailing edge of the VVP blade was satisfied by the Newton-Raphson iterative procedure. The influence coefficients of the panels were calculated by Morino’s analytical formulations to improve numerical calculation speed, and the method developed by Yanagizawa was used to eliminate the point singularity on derivation calculus while determining the velocities on propeller surfaces. The calculation results show that it’s best for the hydrodynamic characteristics of the VVP that pitch angle changes follow the sine rule.

Chang, Xin; Zou, Jing-Xiang; Huang, Sheng; Guo, Chun-Yu

2007-12-01

212

Solar wind disturbance changes between L1 and Earth's magnetosphere: Modeled series at L1 and real events  

NASA Astrophysics Data System (ADS)

While modeling the solar wind interaction with the Earth's magnetic dipole, most of the existing MHD codes set initial boundary conditions at ~35 Earth radii upstream. These modeling results are often compared with measurements taken by various spacecraft located at the Lagrangian L1 point and flown within the Earth's magnetosphere at high and low orbits, and the ground-based observations. At the same time, a number of experimental magnetospheric and space weather models utilize the L1 observations as input parameters. These discrepancies in the outer boundary conditions may cause misinterpretation of the MHD & experimental modeling results and real observations across various domains. Although numerous techniques were developed for processing the solar wind plasma over ~200 Re between L1 and Earth (from simple ballistics to minimum-variance methods), none of these techniques help when the slower and faster plasma packets intersperse, causing various SW and IMF discontinuities heavily interact with each other on their way to Earth. In this study, we attempted to understand through the MHD modeling how the pulsing (i.e., slowing/accelerating) solar wind flow changes along the way from L1 to Earth, and compare these modeling results with a few real events measured by the ACE-WIND spacecraft pair during the intervals of minimal spacecraft transverse separation. Our results might help in better understanding how the L1 solar wind data should be used in the current techniques for space weather specification and forecasting.

Papitashvili, V.; Kabin, K.

2008-12-01

213

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

E-print Network

This EMGT 835 project is a wind energy business plan for Midwest Engineering, an engineering and construction company active in the energy sector. This plan was created to develop a roadmap for the company to increase its market share in wind...

Jacobson, Ryan J.

2007-12-14

214

Modelling the reorientation of sea-ice faults as the wind changes direction  

E-print Network

, tensile and shear deformation. A constant wind-stress gradient is applied until the initially frozen ice of their length by a particular fraction, the ice pack deformation is neglected and the wind stress is rotated and others (2004) used a discrete-element model to study sea-ice fracture due to different imposed patterns

Feltham, Daniel

215

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

216

Wind-driven changes in Southern Ocean residual circulation, ocean carbon reservoirs and atmospheric CO2  

E-print Network

shift shoals dense isopycnals that out- crop in the Southern Ocean and reduces the biogenic car- bon CO2: stronger or northward-shifted wes- terly winds in the Southern Hemisphere result in increased atmo- spheric pCO2 by *20 latm; weaker or southward-shifted winds lead to the opposing result

Williams, Ric

217

The trophic responses of two different rodent-vector-plague systems to climate change.  

PubMed

Plague, the causative agent of three devastating pandemics in history, is currently a re-emerging disease, probably due to climate change and other anthropogenic changes. Without understanding the response of plague systems to anthropogenic or climate changes in their trophic web, it is unfeasible to effectively predict years with high risks of plague outbreak, hampering our ability for effective prevention and control of the disease. Here, by using surveillance data, we apply structural equation modelling to reveal the drivers of plague prevalence in two very different rodent systems: those of the solitary Daurian ground squirrel and the social Mongolian gerbil. We show that plague prevalence in the Daurian ground squirrel is not detectably related to its trophic web, and that therefore surveillance efforts should focus on detecting plague directly in this ecosystem. On the other hand, plague in the Mongolian gerbil is strongly embedded in a complex, yet understandable trophic web of climate, vegetation, and rodent and flea densities, making the ecosystem suitable for more sophisticated low-cost surveillance practices, such as remote sensing. As for the trophic webs of the two rodent species, we find that increased vegetation is positively associated with higher temperatures and precipitation for both ecosystems. We furthermore find a positive association between vegetation and ground squirrel density, yet a negative association between vegetation and gerbil density. Our study thus shows how past surveillance records can be used to design and improve existing plague prevention and control measures, by tailoring them to individual plague foci. Such measures are indeed highly needed under present conditions with prevailing climate change. PMID:25540277

Xu, Lei; Schmid, Boris V; Liu, Jun; Si, Xiaoyan; Stenseth, Nils Chr; Zhang, Zhibin

2015-02-01

218

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

219

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

220

Relative Velocity and Vectors  

NSDL National Science Digital Library

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

Weaver, David

221

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

222

Time-course changes in left ventricular myocardial deformation in STZ-induced rabbits on velocity vector imaging  

PubMed Central

Objectives To clarify the time-course changes in left ventricular myocardial deformation using velocity vector imaging and to provide insights into our understanding of the cardiac pathophysiology in diabetes mellitus. Methods Thirty New Zealand white rabbits were randomly divided into either the control group (n?=?10) or the diabetes mellitus (DM) group (induced with STZ, n?=?20). For the myocardial deformation studies, echocardiography and syngo-vector velocity imaging (VVI) were performed at baseline and after 2, 4, 8, and 12 weeks in all of the rabbits. The left ventricular (LV) global longitudinal and circumferential strain and strain rate were measured. For histomorphological study of the heart structure, 2 of the STZ-induced rabbits were killed at 2, 4, 8, and 12 weeks. Routine hematoxylin and eosin staining was performed. Results At 2 weeks, the global longitudinal strain (GLS), systolic strain rate (GLSRs), and diastolic strain rate (GLSRd) were significantly lower in the DM group compared with the control group (-18.16% versus -24.00%, -1.86 s-1 versus -2.49 s-1, 1.93 s-1 versus 2.42 s-1, respectively, P?

2014-01-01

223

The Impacts of Land Use Change on Malaria Vector Abundance in a Water-Limited Highland Region of Ethiopia  

NASA Astrophysics Data System (ADS)

Changes in land use and climate are expected to alter risk of malaria transmission in areas where rainfall limits vector abundance. We use a coupled hydrology-entomology model to investigate the effects of land use change on hydrological processes impacting mosquito abundance in a highland village of Ethiopia. Land use affects partitioning of rainfall into infiltration and runoff that reaches small-scale topographic depressions, which constitute the primary breeding habitat of Anopheles arabiensis mosquitoes. A physically-based hydrology model isolates hydrological mechanisms by which land use impacts pool formation and persistence, and an agent-based entomology model evaluates the response of mosquito populations. This approach reproduced observed interannual variability in mosquito abundance between the 2009 and 2010 wet seasons. Several scenarios of land cover were then evaluated using the calibrated, field-validated model. Model results show variation in pool persistence and depth, as well as in mosquito abundance, due to land use changes alone. The model showed particular sensitivity to surface roughness, but also to root zone uptake. Scenarios in which land use was modified from agriculture to forest generally resulted in lowest mosquito abundance predictions; classification of the entire domain as rainforest produced a 34% decrease in abundance compared to 2010 results. This study also showed that in addition to vegetation type, spatial proximity of land use change to habitat locations has an impact on mosquito abundance. This modeling approach can be applied to assess impacts of climate and land use conditions that fall outside of the range of previously observed variability.

Stryker, J.; Bomblies, A.

2012-12-01

224

Climate change and vector-borne diseases: what are the implications for public health research and policy?  

PubMed

Vector-borne diseases continue to contribute significantly to the global burden of disease, and cause epidemics that disrupt health security and cause wider socioeconomic impacts around the world. All are sensitive in different ways to weather and climate conditions, so that the ongoing trends of increasing temperature and more variable weather threaten to undermine recent global progress against these diseases. Here, we review the current state of the global public health effort to address this challenge, and outline related initiatives by the World Health Organization (WHO) and its partners. Much of the debate to date has centred on attribution of past changes in disease rates to climate change, and the use of scenario-based models to project future changes in risk for specific diseases. While these can give useful indications, the unavoidable uncertainty in such analyses, and contingency on other socioeconomic and public health determinants in the past or future, limit their utility as decision-support tools. For operational health agencies, the most pressing need is the strengthening of current disease control efforts to bring down current disease rates and manage short-term climate risks, which will, in turn, increase resilience to long-term climate change. The WHO and partner agencies are working through a range of programmes to (i) ensure political support and financial investment in preventive and curative interventions to bring down current disease burdens; (ii) promote a comprehensive approach to climate risk management; (iii) support applied research, through definition of global and regional research agendas, and targeted research initiatives on priority diseases and population groups. PMID:25688013

Campbell-Lendrum, Diarmid; Manga, Lucien; Bagayoko, Magaran; Sommerfeld, Johannes

2015-04-01

225

Transient and Steady-State Simulation Study of Decoupled d-q Vector Control in PWM Converter of Variable Speed Wind Turbines  

Microsoft Academic Search

Variable-speed wind turbines are attractive to the high performance and are commonly used by the wind turbine industry today. They are based on variable-speed operation with pitch control using either a direct driven synchronous generator (without gearbox) or a doubly-fed induction generator. For both, there is an AC\\/DC\\/AC PWM converter that is used for wind turbine control and grid interface.

Shuhui LiandTimothy; T. A. Haskew

2007-01-01

226

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

227

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

228

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

E-print Network

1 Abstract--A bi-objective optimization model of power and power changes generated by a wind theory is introduced. Data-mining algorithms were used to identify the model of power generation from prediction, power ramp rate, data mining, wind turbine operation strategy, generator torque, blade pitch

Kusiak, Andrew

229

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

230

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

231

Winds of change: How will windstorms and forest harvesting affect C cycling in northern MN under different climate scenarios?  

NASA Astrophysics Data System (ADS)

Forest managers struggle to manage timber resources while integrating the complex interactions that exist among disturbances with the novel conditions produced by a changing climate. To help forest managers better integrate climate change and disturbance projections into their forest management plans, we are using a forest landscape disturbance and succession model (LANDIS-II, Century extension) to project carbon sequestration in northern Minnesota under multiple climate change, management and disturbance scenarios. The model was calibrated and validated using empirical estimates of aboveground productivity and net ecosystem exchange. Our simulations suggest that windstorms will decrease tree biomass and soil organic matter and will increase dead C, resulting in an overall decrease in total C and C sink strength under the GFDL A1FI climate scenario. However the direct effects of climate change on C via altered production and heterotrophic respiration were larger than the impacts of wind. In contrast, forest harvesting will remain the dominant determinant of C dynamics under A1FI, even under management scenarios of more selective logging and longer rotation periods. Recovery from historic (late 1800s and early 1900s) disturbance - clearcut logging and wildfire - remain an important, though declining, driver of long-term C dynamics. Our research results will inform regional planning efforts and help forest managers evaluate the relative importance of disturbances (e.g. wind) and forest harvesting under a changing climate.

Lucash, M. S.; Scheller, R. M.; Gustafson, E.; Sturtevant, B.

2013-12-01

232

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

Fernández, María Soledad; Santini, María Soledad; Cavia, Regino; Sandoval, Adolfo Enrique; Pérez, Adriana Alicia; Acardi, Soraya; Salomón, Oscar Daniel

2013-01-01

233

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

234

A `low-level' explanation for the recent large warming trend over the western Antarctic Peninsula involving blocked winds and changes in  

E-print Network

involving blocked winds and changes in zonal circulation A. Orr,1 D. Cresswell,1 G. J. Marshall,2 J. C. R. Cresswell, G. J. Marshall, J. C. R. Hunt, J. Sommeria, C. G. Wang, and M. Light (2004), A `low

Hunt, Julian

235

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

236

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

237

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

PubMed

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

2013-09-01

238

Analysis of Unit-Level Changes in Operations with Increased SPP Wind from EPRI/LCG Balancing Study  

SciTech Connect

Wind power development in the United States is outpacing previous estimates for many regions, particularly those with good wind resources. The pace of wind power deployment may soon outstrip regional capabilities to provide transmission and integration services to achieve the most economic power system operation. Conversely, regions such as the Southeastern United States do not have good wind resources and will have difficulty meeting proposed federal Renewable Portfolio Standards with local supply. There is a growing need to explore innovative solutions for collaborating between regions to achieve the least cost solution for meeting such a renewable energy mandate. The Department of Energy funded the project 'Integrating Midwest Wind Energy into Southeast Electricity Markets' to be led by EPRI in coordination with the main authorities for the regions: SPP, Entergy, TVA, Southern Company and OPC. EPRI utilized several subcontractors for the project including LCG, the developers of the model UPLAN. The study aims to evaluate the operating cost benefits of coordination of scheduling and balancing for Southwest Power Pool (SPP) wind transfers to Southeastern Electric Reliability Council (SERC) Balancing Authorities (BAs). The primary objective of this project is to analyze the benefits of regional cooperation for integrating mid-western wind energy into southeast electricity markets. Scenarios were defined, modeled and investigated to address production variability and uncertainty and the associated balancing of large quantities of wind power in SPP and delivery to energy markets in the southern regions of the SERC. DOE funded Oak Ridge National Laboratory to provide additional support to the project, including a review of results and any side analysis that may provide additional insight. This report is a unit-by-unit analysis of changes in operations due to the different scenarios used in the overall study. It focuses on the change in capacity factors and the number of start-ups required for each unit since those criteria summarize key aspects of plant operations, how often are they called upon and how much do they operate. The primary analysis of the overall project is based on security-constrained unit commitment (SCUC) and economic dispatch (SCED) simulations of the SPP-SERC regions as modeled for the year 2022. The SCUC/SCED models utilized for the project were developed through extensive consultation with the project utility partners, to ensure the various regions and operational practices are represented as best as possible in the model. SPP, Entergy, Oglethorpe Power Company (OPC), Southern Company, and the Tennessee Valley Authority (TVA) actively participated in the project providing input data for the models and review of simulation results and conclusions. While other SERC utility systems are modeled, the listed SERC utilities were explicitly included as active participants in the project due to the size of their load and relative proximity to SPP for importing wind energy.

Hadley, Stanton W [ORNL

2012-01-01

239

Impacts of the Changing Seasonality of Wind-driven Mixing on the Arctic System  

NASA Astrophysics Data System (ADS)

The Arctic Ocean has been traditionally described as an ocean with low variability and weak turbulence levels. Many years of observations from ice camps and ice-based instruments have shown that the sea-ice cover effectively isolates the water column from direct wind forcing and damps the existing motions, resulting in relativily small upper ocean variability. Under the ice, direct and indirect estimates across the Arctic basins confirmed that turbulent vertical mixing does not play a significant role in the general distribution of oceanic properties and for the evolution of Arctic water masses. However, as the sea-ice cover continues to decreases in the summer, the Arctic Ocean is now subject to more direct wind forcing which generate large inertial motions in the surface mixed layer and in water column. During ice-free periods, wind-driven inertial motions and mixing are important both on the shelves and over the deep basins. Wind forcing is responsible for deepening the mixed layer - as in lower latitudes, and for enhanced mixing throughout the water column. We discuss some potential impacts of this enhanced mixing on Arctic ecosystem and heat/freshwater balances.

Rainville, L.; Woodgate, R. A.; Overland, J. E.; Mahadevan, A.; Matrai, P. A.; Wang, M.

2011-12-01

240

The changing wind structure of the WR/LBV star in HD 5980  

NASA Astrophysics Data System (ADS)

HD 5980 is an extraordinary system of massive stars that is located in the Small Magellanic Cloud. It contains an eclipsing binary {P=19.3 d} consisting of a luminous blue variable {LBV} and its Wolf-Rayet {WR} companion. The LBV underwent a major eruptive event in 1994 during which its bolometric luminosity increased by a factor of 5 and it is currently approaching its minimum state of activity. The primary objective of this proposal is to determine the wind velocity and mass-loss rate of the LBV in its current state. With these observations and our earlier observations and analyses, HD 5980 offers the unprecedented opportunity of deriving all the fundamental parameters of an LBV system throughout its activity cycle, parameters which are required in order to constrain the sources of the instabilities that lead to the eruptive phenomena. To accomplish these goals, we request 2 HST orbits to observe HD 5980 with STIS in order to obtain one set of FUV MAMA and CCD spectra at the eclipse, when the LBV occults its WR companion.The study of HD 5980 and the UV spectrum that we propose to acquire are relevant to a broad range of problems including wind-wind collision phenomena, the formation of circumstellar structures powered by stellar winds and the evolution of supernova progenitors.

Koenigsberger, Gloria

2013-10-01

241

A Marine Radar Wind Sensor  

Microsoft Academic Search

A new method for retrieving the wind vector from radar-image sequences is presented. This method, called WiRAR, uses a marine X-band radar to analyze the backscatter of the ocean surface in space and time with respect to surface winds. Wind direction is found using wind-induced streaks, which are very well aligned with the mean surface wind direction and have a

Heiko Dankert; Jochen Horstmann

2007-01-01

242

First US-China Joint Ground Based Fabry-Perot Interferometer Observations of Longitudinal Variations in the Thermospheric Winds due to Geomagnetic Latitude Changes  

NASA Astrophysics Data System (ADS)

For the first time, three Fabry-Perot interferometers from US (Boulder, 40N, 115W, 49N MLAT) and China (Xinglong, 40N,115E, 34N, MLAT; Kelan, 39N, 112E, 33N MLAT) were used to examine the longitudinal variations in the thermospheric winds due to the geomagnetic latitude differences between the American and Asian sectors. Two cases studies were made. During a case of quiet geomagnetic condition, the meridional winds were very similar at the US and Chinese stations. The meridional winds at Boulder reached most equatorward wind after midnight, whereas in China, the largest equatorward winds are found near midnight. The Boulder zonal winds turned westward earlier in the morning hours and had larger diurnal variations because of its higher magnetic latitude. During the case of moderated active geomagnetic condition, the meridional winds were still similar in the two continents. Boulder zonal winds had much large diurnal variation compared to the geomagnetically quiet condition. NCAR TIEGCM simulations show a very good agreement with observation for the meridional winds. The simulated zonal winds have noticeable differences with observation but the general tendencies in longitudinal variations are correct. The model output shows the ion drift is not directly responsible for the longitudinal variations in the winds. The pressure gradient has more direct effect on the longitudinal changes in the winds. The simulation results also show larger diurnal variations at higher geomagnetic latitudes due to the influence of the auroral oval heating. No nonmigrating tide effects were seen in the two cases both near the fall equinox in Oct 2012.

Wu, Qian; Wang, Jing-Song; Xu, Jiyao; Yuan, Wei; Li, Tao; Zhang, Xiaoxin; Huang, C.

243

Kinetic Monte Carlo studies of the effects of Burgers Vector Changes on the Reaction Kinetics of One-Dimensionally Gliding Interstitial Clusters  

SciTech Connect

Kinetic Monte Carlo simulations of one-dimensionally diffusing interstitial clusters (dislocation loops) are used to gain insight into their role in microstructure evolution under irradiation. The simulations investigate the changes in reaction kinetics of these defects as a function of changes in the Burgers vector and variation in the size and density of randomly or periodically distributed sinks. In this paper we report on several kinetic Monte Carlo studies intended to elucidate the effects of mixed 1-D/3-D migration relative to pure 3-D and pure 1-D migration. We have investigated the effects of variation of the average distance traveled between Burgers vector changes (L) on the absorption of individual defects into absorbers of varying size and varying concentration, as well as the effects of variatioin in (L) on the time dependence of absorption of a collection of defects into an array of absorbers. Significant effects of Burgers vector changes on the reaction kinetics of the diffusing interstitial clusters are clearly demonstrated. Even when (L) is larger relative to the size and spacing of microstructural features, significant effects of mixed 1-D/3-D migration on reaction kinetics are evident.

Heinisch, Howard L.; Singh, Bachu N.; Golubov, Stanislav I.

2000-01-01

244

The influence of changes in wind patterns on the areal extension of surface cyanobacterial blooms in a large shallow lake in China.  

PubMed

It has been hypothesized that climate change will induce the areal extension of cyanobacterial blooms. However, this hypothesis lacks field-based observation. In the present study both long-term historical data and short-term field measurement were used to identify the importance of changes in wind patterns on the cyanobacterial bloom in Lake Taihu (China), a large, shallow, eutrophic lake located in a subtropical zone. The cyanobacterial bloom mainly composed of Microcystis spp. recurred frequently throughout the year. The regression analysis of multi-year satellite image data extracted by the Floating Algae Index revealed that both the annual mean monthly maximum cyanobacterial bloom area (MMCBA) increased year by year from 2000 to 2011, while the contemporaneous cyanobacterial biomass showed no significant change. However, the correlation analysis shows that MMCBA was negatively correlated with wind speed. Our short-term field measurements indicated that the influence of wind on surface cyanobacterial blooms is that the Chlorophyll-a (Chla) concentration is fully mixing throughout the water column when the wind speed exceed 7ms(-1). At lower wind speeds, there was vertical stratification of Chla with high surface concentrations and an increase in bloom area. The regression analysis of wind speed indicates that the climate has changed over the last decade. Lake Taihu has become increasingly calm, with the decrease of strong wind frequency between 2000 and 2011, corresponding to the increase in the MMCBA over time. Therefore, we conclude that changes in wind patterns related to climate change have favored the increase of cyanobacterial blooms in Lake Taihu. PMID:25747360

Wu, Tingfeng; Qin, Boqiang; Brookes, Justin D; Shi, Kun; Zhu, Guangwei; Zhu, Mengyuan; Yan, Wenming; Wang, Zhen

2015-06-15

245

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

246

Response of the Earth's Magnetosphere to Changes in the Solar Wind  

NASA Technical Reports Server (NTRS)

The solar wind couples to the magnetosphere via dynamic pressure and electric field. Pressure establishes the size and shape of the system, while the electric field transfers energy, mass, and momentum to the magnetosphere. When the interplanetary magnetic field (IMF) is antiparallel to the dayside magnetic field, magnetic reconnection connects the IMF to the dipole field. Solar wind transport of the newly opened field lines to the nightside creates an internal convection system. These open field lines must ultimately be closed by reconnection on the nightside. For many decades, it was thought that a magnetospheric substorm was the process for accomplishing this and that all magnetic activity was a consequence of substorms. It is now recognized that there are a variety of modes of response of the magnetosphere to the solar wind. In this paper, we briefly describe these modes and the conditions under which they occur. They include substorms, pseudo-breakups, poleward boundary intensifications (PBI), steady magnetospheric convection (SMC), sawtooth injection events, magnetic storms, high-intensity long-duration continuous AE activities (HILDCAAs), and storm-time activations. There are numerous explanations for these different phenomena, some of which do not involve magnetic reconnection. However, we speculate that it is possible to interpret each mode in terms of differences in the way magnetic reconnection occurs on the nightside.

McPherron, Robert L.; Weygand, James M.; Hsu, Tung-Shin

2007-01-01

247

Ionospheric traveling convection vortices observed near the polar cleft: A triggered response to sudden changes in the solar wind  

SciTech Connect

Analysis of 20-second resolution magnetometer data from an array of temporary stations operated around Soendre Stroemfjord, Greenland during the summer of 1986 shows the signatures of localized ionospheric traveling convection vortices. An example of an isolated event of this kind observed near 08 local time is presented in detail. This event consists of a twin vortex pattern of convection consistent with the presence of two field-aligned current filaments separated by about 600 km in the east-west direction. This system of current is observed to move westward (tailward) past the array of stations at about 4 km/sec. The event is associated with relative quiet time ionospheric convection and occurs during an interval of northward IMF. It is, however, associated with a large fluctuation in both the Z and Y components of the IMF and with a large sudden decrease in the solar wind number density. The propagation of the system is inconsistent with existing models of FTE current systems, but nevertheless appears to be related to a readjustment of the magnetopause boundary to a sudden change in the solar wind dynamic pressure and/or to a change in reconnection brought about by a sudden reorientation of the IMF. copyright American Geophysical Union 1988

Friis-Christensen, E.; McHenry, M.A.; Clauer, C.R.; Vennerstroem, S.

1988-03-01

248

Ionospheric traveling convection vortices observed near the polar cleft - A triggered response to sudden changes in the solar wind  

NASA Technical Reports Server (NTRS)

Analysis of 20-second resolution magnetometer data from an array of temporary stations operated around Sondre Stromfjord, Greenland, during the summer of 1986 shows the signatures of localized ionospheric traveling convection vortices. An example of an isolated event of this kind observed near 08 local time is presented in detail. This event consists of a twin vortex pattern of convection consistent with the presence of two field-aligned current filaments separated by about 600 km in the east-west direction. This system of currents is observed to move westward (tailward) past the array of stations at about 4 km/sec. The event is associated with relative quiet time ionospheric convection and occurs during an interval of northward IMF. It is, however, associated with a large fluctuation in both the Z and Y components of the IMF and with a large sudden decrease in the solar wind number density. The propagation of the system is inconsistent with existing models of FTE current systems, but nevertheless appears to be related to a readjustment of the magnetopause boundary to a sudden change in the solar wind dynamic pressure and/or to a change in reconnection brought about by a sudden reorientation of the IMF.

Friis-Christensen, E.; Vennerstrom, S.; Mchenry, M. A.; Clauer, C. R.

1988-01-01

249

The impact of climate change on the geographical distribution of two vectors of Chagas disease: implications for the force of infection.  

PubMed

Chagas disease, caused by the parasite Trypanosoma cruzi, is the most important vector-borne disease in Latin America. The vectors are insects belonging to the Triatominae (Hemiptera, Reduviidae), and are widely distributed in the Americas. Here, we assess the implications of climatic projections for 2050 on the geographical footprint of two of the main Chagas disease vectors: Rhodnius prolixus (tropical species) and Triatoma infestans (temperate species). We estimated the epidemiological implications of current to future transitions in the climatic niche in terms of changes in the force of infection (FOI) on the rural population of two countries: Venezuela (tropical) and Argentina (temperate). The climatic projections for 2050 showed heterogeneous impact on the climatic niches of both vector species, with a decreasing trend of suitability of areas that are currently at high-to-moderate transmission risk. Consequently, climatic projections affected differently the FOI for Chagas disease in Venezuela and Argentina. Despite the heterogeneous results, our main conclusions point out a decreasing trend in the number of new cases of Tr. cruzi human infections per year between current and future conditions using a climatic niche approach. PMID:25688019

Medone, Paula; Ceccarelli, Soledad; Parham, Paul E; Figuera, Andreína; Rabinovich, Jorge E

2015-04-01

250

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

251

Lentivirus vector-mediated mitofusin-2 overexpression in rat ovary changes endocrine function and promotes follicular development in vivo.  

PubMed

The aim of the present study was to evaluate the expression and effect of rat mitofusin-2 (rMfn2) in the ovaries and other organs in rats. Rat models were developed by the intraovarian microinjection of an rMfn2-overexpressing lentiviral vector. Lenti-green fluorescent protein (GFP)-rMfn2 was microinjected into rat ovaries at a dosage of 2×10(6) tuberculin units virosome (n=25) and lenti-GFP was microinjected as a control (n=25). The expression of rMfn2 in the ovaries and other tissues was observed by fluorescence microscopy on days 7, 15, 30, 45 and 60 after the microinjection (n=5/day from each group). The serum levels of estradiol (E2), progesterone (P), follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were determined by radioimmunoassay. Western blotting was used for the quantitative analysis of the expression of rMfn2 and the progesterone receptor (PR), estradiol receptor (ER), luteinizing hormone receptor (LHR) and follicle-stimulating hormone receptor (FSHR). The expression of rMfn2 was detected on day 7 after infection, increased with time and was maintained efficiently until day 60. In addition, rMfn2 was highly expressed in the fallopian tubes, uterus, cardiac muscle, liver and kidney, but expressed at a low level in adipose tissue. The serum levels of E2 and P in the model group were significantly increased compared with those in the control group, whereas the FSH and LH levels showed no significant difference between groups. The expression levels of the ER and PR in the model group were higher than those in the control group; however, no significant difference was observed between groups for the expression levels of LHR and FSHR. These findings suggest that the intraovarian microinjection of lenti-GFP-rMfn2 resulted in a significant time-dependent overexpression of rMfn2 in various organs, and that rMfn2 overexpression in rat ovaries changed the endocrine function and promoted follicular development. PMID:25120590

Hu, Xiaojing; Lei, Xiubing; Wang, Jidong; Pan, Hongjuan; Li, Cong; Yao, Zhenwei

2014-09-01

252

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

NASA Astrophysics Data System (ADS)

The 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

253

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

254

Impact of land use change on wind erosion and dust emission: scenarios from the central US  

Technology Transfer Automated Retrieval System (TEKTRAN)

There will be significant changes in land cover and land use throughout the central United States in the coming years, particularly as a result of climate change, changes in US rangeland/farm policy, and increasing exploitation of land-intensive sustainable energy sources. The purpose of this study ...

255

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.

National Weather Service

2012-12-18

256

A Wind and Rain Backscatter Model Derived From AMSR and SeaWinds Data  

Microsoft Academic Search

The SeaWinds scatterometer was originally designed to measure wind vectors over the ocean by exploiting the relationship between wind-induced surface roughening and the normalized radar backscatter cross section. Rain can degrade scatterometer wind estimation; however, the simultaneous wind\\/rain (SWR) algorithm was developed to enable SeaWinds to simultaneously retrieve wind and rain rate data. This algorithm is based on colocating data

Seth N. Nielsen; David G. Long

2009-01-01

257

Thermal and Pressure Characterization of a Wind Tunnel Force Balance Using the Single Vector System. Experimental Design and Analysis Approach to Model Pressure and Temperature Effects in Hypersonic Wind Tunnel Research  

NASA Technical Reports Server (NTRS)

Wind tunnel research at NASA Langley Research Center s 31-inch Mach 10 hypersonic facility utilized a 5-component force balance, which provided a pressurized flow-thru capability to the test article. The goal of the research was to determine the interaction effects between the free-stream flow and the exit flow from the reaction control system on the Mars Science Laboratory aeroshell during planetary entry. In the wind tunnel, the balance was exposed to aerodynamic forces and moments, steady-state and transient thermal gradients, and various internal balance cavity pressures. Historically, these effects on force measurement accuracy have not been fully characterized due to limitations in the calibration apparatus. A statistically designed experiment was developed to adequately characterize the behavior of the balance over the expected wind tunnel operating ranges (forces/moments, temperatures, and pressures). The experimental design was based on a Taylor-series expansion in the seven factors for the mathematical models. Model inversion was required to calculate the aerodynamic forces and moments as a function of the strain-gage readings. Details regarding transducer on-board compensation techniques, experimental design development, mathematical modeling, and wind tunnel data reduction are included in this paper.

Lynn, Keith C.; Commo, Sean A.; Johnson, Thomas H.; Parker, Peter A,

2011-01-01

258

Virus-mediated chemical changes in rice plants impact the relationship between non-vector planthopper Nilaparvata lugens Stål and its egg parasitoid Anagrus nilaparvatae Pang et Wang.  

PubMed

In order to clarify the impacts of southern rice black-streaked dwarf virus (SRBSDV) infection on rice plants, rice planthoppers and natural enemies, differences in nutrients and volatile secondary metabolites between infected and healthy rice plants were examined. Furthermore, the impacts of virus-mediated changes in plants on the population growth of non-vector brown planthopper (BPH), Nilaparvata lugens, and the selectivity and parasitic capability of planthopper egg parasitoid Anagrus nilaparvatae were studied. The results showed that rice plants had no significant changes in amino acid and soluble sugar contents after SRBSDV infection, and SRBSDV-infected plants had no significant effect on population growth of non-vector BPH. A. nilaparvatae preferred BPH eggs both in infected and healthy rice plants, and tended to parasitize eggs on infected plants, but it had no significant preference for infected plants or healthy plants. GC-MS analysis showed that tridecylic aldehyde occurred only in rice plants infected with SRBSDV, whereas octanal, undecane, methyl salicylate and hexadecane occurred only in healthy rice plants. However, in tests of behavioral responses to these five volatile substances using a Y-tube olfactometer, A. nilaparvatae did not show obvious selectivity between single volatile substances at different concentrations and liquid paraffin in the control group. The parasitic capability of A. nilaparvatae did not differ between SRBSDV-infected plants and healthy plant seedlings. The results suggested that SRBSDV-infected plants have no significant impacts on the non-vector planthopper and its egg parasitoid, A. nilaparvatae. PMID:25141278

He, Xiaochan; Xu, Hongxing; Gao, Guanchun; Zhou, Xiaojun; Zheng, Xusong; Sun, Yujian; Yang, Yajun; Tian, Junce; Lu, Zhongxian

2014-01-01

259

Virus-Mediated Chemical Changes in Rice Plants Impact the Relationship between Non-Vector Planthopper Nilaparvata lugens Stål and Its Egg Parasitoid Anagrus nilaparvatae Pang et Wang  

PubMed Central

In order to clarify the impacts of southern rice black-streaked dwarf virus (SRBSDV) infection on rice plants, rice planthoppers and natural enemies, differences in nutrients and volatile secondary metabolites between infected and healthy rice plants were examined. Furthermore, the impacts of virus-mediated changes in plants on the population growth of non-vector brown planthopper (BPH), Nilaparvata lugens, and the selectivity and parasitic capability of planthopper egg parasitoid Anagrus nilaparvatae were studied. The results showed that rice plants had no significant changes in amino acid and soluble sugar contents after SRBSDV infection, and SRBSDV-infected plants had no significant effect on population growth of non-vector BPH. A. nilaparvatae preferred BPH eggs both in infected and healthy rice plants, and tended to parasitize eggs on infected plants, but it had no significant preference for infected plants or healthy plants. GC-MS analysis showed that tridecylic aldehyde occurred only in rice plants infected with SRBSDV, whereas octanal, undecane, methyl salicylate and hexadecane occurred only in healthy rice plants. However, in tests of behavioral responses to these five volatile substances using a Y-tube olfactometer, A. nilaparvatae did not show obvious selectivity between single volatile substances at different concentrations and liquid paraffin in the control group. The parasitic capability of A. nilaparvatae did not differ between SRBSDV-infected plants and healthy plant seedlings. The results suggested that SRBSDV-infected plants have no significant impacts on the non-vector planthopper and its egg parasitoid, A. nilaparvatae. PMID:25141278

Gao, Guanchun; Zhou, Xiaojun; Zheng, Xusong; Sun, Yujian; Yang, Yajun; Tian, Junce; Lu, Zhongxian

2014-01-01

260

Decades-long changes of the interstellar wind through our solar system.  

PubMed

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. PMID:24009386

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

261

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

262

A Spatio-temporal Description of the Abrupt Changes in the Photospheric Magnetic and Lorentz-Force Vectors During the 15 February 2011 X2.2 Flare  

NASA Astrophysics Data System (ADS)

The active region NOAA 11158 produced the first X-class flare of Solar Cycle 24, an X2.2 flare at 01:44 UT on 15 February 2011. The Helioseismic and Magnetic Imager (HMI) instrument on the Solar Dynamics Observatory (SDO) satellite produces 12-minute, 0.5'' pixel-1 vector magnetograms. Here we analyze a series of these data covering a 12-hour interval centered at the time of this flare. We describe the spatial distributions of the photospheric magnetic changes associated with the flare, including the abrupt changes in the field vector, vertical electric current and Lorentz-force vector acting on the solar interior. We also describe these parameters' temporal evolution. The abrupt magnetic changes were concentrated near the neutral line and in two neighboring sunspots. Near the neutral line, the field vectors became stronger and more horizontal during the flare and the shear increased. This was due to an increase in strength of the horizontal field components near the neutral line, most significant in the horizontal component parallel to the neutral line but the perpendicular component also increased in strength. The vertical component did not show a significant, permanent overall change at the neutral line. The increase in field strength at the neutral line was accompanied by a compensating decrease in field strength in the surrounding volume. In the two sunspots near the neutral line the integrated azimuthal field abruptly decreased during the flare but this change was permanent in only one of the spots. There was a large, abrupt, downward vertical Lorentz-force change acting on the solar interior during the flare, consistent with results of past analyses and recent theoretical work. The horizontal Lorentz force acted in opposite directions along each side of neutral line, with the two sunspots at each end subject to abrupt torsional forces relaxing their magnetic twist. These shearing forces were consistent with a contraction of field and decrease of shear near the neutral line, whereas the field itself became more sheared as a result of the field collapsing towards the neutral line from the surrounding volume. The Lorentz forces acting on the atmospheric volume above the photosphere were equal and opposite.

Petrie, G. J. D.

2013-10-01

263

Short-Term Wind Power Forecasts using Doppler Lidar  

NASA Astrophysics Data System (ADS)

With a ground-based Doppler lidar on the upwind side of a wind farm in the Tehachapi Pass of California, radial wind velocity measurements were collected for repeating sector sweeps, scanning up to 10 kilometers away. This region consisted of complex terrain, with the scans made between mountains. The dataset was utilized for techniques being studied for short-term forecasting of wind power by correlating changes in energy content and of turbulence intensity by tracking spatial variance, in the wind ahead of a wind farm. A ramp event was also captured and its propagation was tracked. Orthogonal horizontal wind vectors were retrieved from the radial velocity using a sector Velocity Azimuth Display method. Streamlines were plotted to determine the potential sites for a correlation of upstream wind speed with wind speed at downstream locations near the wind farm. A "virtual wind turbine" was "placed" in locations along the streamline by using the time-series velocity data at the location as the input to a modeled wind turbine, to determine the extractable energy content at that location. The relationship between this time-dependent energy content upstream and near the wind farm was studied. By correlating the energy content with each upstream location based on a time shift estimated according to advection at the mean wind speed, several fits were evaluated. A prediction of the downstream energy content was produced by shifting the power output in time and applying the best-fit function. This method made predictions of the power near the wind farm several minutes in advance. Predictions were also made up to an hour in advance for a large ramp event. The Magnitude Absolute Error and Standard Deviation are presented for the predictions based on each selected upstream location.

Magerman, Beth

264

The winds of change: students' comfort level in different learning environments  

Microsoft Academic Search

The information technology workforce now more than ever requires graduates to be ready to 'produce' the instant they 'hit the ground'. The core discipline knowledge and skills haven't changed dramatically over the years, but the 'soft skills' have changed and have become more important than ever. Undergraduate information technology degree must prepare graduates for the workforce, and not just transmit

Kathy Lynch; Selby Markham

2003-01-01

265

Coherent Doppler Lidar for Boundary Layer Studies and Wind Energy  

NASA Astrophysics Data System (ADS)

This thesis outlines the development of a vector retrieval technique, based on data assimilation, for a coherent Doppler LIDAR (Light Detection and Ranging). A detailed analysis of the Optimal Interpolation (OI) technique for vector retrieval is presented. Through several modifications to the OI technique, it is shown that the modified technique results in significant improvement in velocity retrieval accuracy. These modifications include changes to innovation covariance portioning, covariance binning, and analysis increment calculation. It is observed that the modified technique is able to make retrievals with better accuracy, preserves local information better, and compares well with tower measurements. In order to study the error of representativeness and vector retrieval error, a lidar simulator was constructed. Using the lidar simulator a thorough sensitivity analysis of the lidar measurement process and vector retrieval is carried out. The error of representativeness as a function of scales of motion and sensitivity of vector retrieval to look angle is quantified. Using the modified OI technique, study of nocturnal flow in Owens' Valley, CA was carried out to identify and understand uncharacteristic events on the night of March 27th 2006. Observations from 1030 UTC to 1230 UTC (0230 hr local time to 0430 hr local time) on March 27 2006 are presented. Lidar observations show complex and uncharacteristic flows such as sudden bursts of westerly cross-valley wind mixing with the dominant up-valley wind. Model results from Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS RTM) and other in-situ instrumentations are used to corroborate and complement these observations. The modified OI technique is used to identify uncharacteristic and extreme flow events at a wind development site. Estimates of turbulence and shear from this technique are compared to tower measurements. A formulation for equivalent wind speed in the presence of variations in wind speed and direction, combined with shear is developed and used to determine wind energy content in presence of turbulence.

Choukulkar, Aditya

266

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

267

Vectorized Monte Carlo  

SciTech Connect

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

Brown, F.B.

1981-01-01

268

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

269

The Winds of Change: Thomas Kuhn and the Revolution in the Teaching of Writing.  

ERIC Educational Resources Information Center

Uses Thomas Kuhn's hypothesis on paradigm shifts--changes in a discipline from established models to newer ones--to examine the developing shift in writing instruction from the product-oriented to the process-oriented model. (RL)

Hairston, Maxine

1982-01-01

270

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

271

Changes in the Observing System Contributing To Perceived Changes in Large Scale Circulation  

NASA Astrophysics Data System (ADS)

Ocean surface wind observations have transitioned from purely in situ systems to satellite dominated systems. Reanalyses treat satellite winds as physically identical to in situ winds (albeit with different error characteristics). However, there are systematic differences between satellite and in situ winds. Prior work has shown that this wind observing system change causes trends in latent heat flux that are consistent with trends in analyses, both in spatial pattern and magnitude. These physical differences have also been confirmed in comparisons of research vessel and scatterometer winds (May and Bourassa, 2011), and have been shown to be quite large on weather time scales (Kara et al. 2007). For the published example for 0Z on January 1, 2005, the change in wind shear (U10 - Usfc) was modified by from -15% to +10%, and the monthly average was changed by from -10% to +5%. The differences do to waves and currents are examined herein. The vector differences in seasonal averages are determined from the modern data record, and used to infer systematic changes from the purely in situ system to a satellite-based system. These differences are examined in terms of biases to long term changes in Walker circulation and Hadley circulation. While the changes in wind speed are small compared to the wind speed, they are substantial in comparison to long term trends.

Bourassa, M. A.

2012-12-01

272

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

273

Charm changing weak hadronic decays of triplet (C=1) baryons emitting axial-vector mesons including factorizable and pole contributions  

SciTech Connect

We investigate the weak nonleptonic decays of {lambda}{sub c}{sup +}, {xi}{sub c}{sup +}, and {xi}{sub c}{sup 0} into the octet baryons (J{sup P}=1/2{sup +}) and axial-vector mesons (J{sup P}=1{sup +}) employing the factorization scheme for W-emission diagrams and the pole model for W-exchange contributions. Determining the baryon-baryon transition form factors in the nonrelativistic quark model and incorporating the constraints of heavy quark symmetry, we predict their branching ratios and asymmetry parameters.

Sharma, Arvind; Verma, R. C. [Department of Physics, College of Engineering and Management, Kapurthala-144601 (India); Department of Physics, Punjabi University, Patiala-147002 (India)

2009-11-01

274

The National assessment of shoreline shange—A GIS compilation of vector shorelines and associated shoreline change data for the Pacific Northwest coast  

USGS Publications Warehouse

Sandy ocean beaches are a popular recreational destination and are often surrounded by communities that consist of valuable real estate. Development along sandy coastal areas 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. Investigators with the U.S. Geological Survey's National Assessment of Shoreline Change Project have compiled a comprehensive database of digital vector shorelines and rates of shoreline change for the Pacific Northwest coast including the states of Washington and Oregon. No widely accepted standard for analyzing shoreline change currently exists. Current measurement and methods for calculating rates of change 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 that is consistent from coast to coast for measuring changes in shoreline position. 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 the Pacific Northwest coast that contains a discussion of the data presented here is available and cited in the Geospatial Data section of this report.

Kratzmann, Meredith; Himmelstoss, Emily A.; Ruggiero, Peter; Thieler, E. Robert; Reid, David

2013-01-01

275

Changes in the High-Latitude Topside Ionospheric Vertical Electron-Density Profiles in Response to Solar-Wind Perturbations During Large Magnetic Storms  

NASA Technical Reports Server (NTRS)

The latest results from an investigation to establish links between solar-wind and topside-ionospheric parameters will be presented including a case where high-latitude topside electron-density Ne(h) profiles indicated dramatic rapid changes in the scale height during the main phase of a large magnetic storm (Dst < -200 nT). These scale-height changes suggest a large heat input to the topside ionosphere at this time. The topside profiles were derived from ISIS-1 digital ionograms obtained from the NASA Space Physics Data Facility (SPDF) Coordinated Data Analysis Web (CDA Web). Solar-wind data obtained from the NASA OMNIWeb database indicated that the magnetic storm was due to a magnetic cloud. This event is one of several large magnetic storms being investigated during the interval from 1965 to 1984 when both solar-wind and digital topside ionograms, from either Alouette-2, ISIS-1, or ISIS-2, are potentially available.

Benson, Robert F.; Fainberg, Joseph; Osherovich, Vladimir; Truhlik, Vladimir; Wang, Yongli; Arbacher, Becca

2011-01-01

276

Winds of Change: Latinos in the Heartland and the Nation. JSRI Statistical Brief No. 5.  

ERIC Educational Resources Information Center

This statistical brief provides a follow-up assessment of the changing demographic and economic landscape of the Midwest between 1980 and 1990. Latino population growth in the Midwest during the 1980s was modest, but since the region's other groups experienced minimal or negative growth, Latino growth accounted for over half the Midwest's total…

Aponte, Robert; Siles, Marcelo E.

277

The Winds of Change in Russian Higher Education: Is the East Moving West?  

ERIC Educational Resources Information Center

In the last 30 years, major changes have taken place in the public sector worldwide under the rubric of New Public Management [NPM]. The education sector is perhaps one of the key areas drawing an intense interest and discussion in the wake of NPM. The Russian State seems to be no longer an exception to this global trend. In line with this, the…

Timoshenko, Konstantin

2011-01-01

278

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

279

Rice stripe virus affects the viability of its vector offspring by changing developmental gene expression in embryos  

PubMed Central

Plant viruses may affect the viability and development process of their herbivore vectors. Small brown planthopper (SBPH) is main vector of Rice stripe virus (RSV), which causes serious rice stripe disease. Here, we reported the effects of RSV on SBPH offspring by crossing experiments between viruliferous and non-viruliferous strains. The life parameters of offspring from different cross combinations were compared. The hatchability of F1 progeny from viruliferous parents decreased significantly, and viruliferous rate was completely controlled by viruliferous maternal parent. To better elucidate the underlying biological mechanisms, the morphology of eggs, viral propagation and distribution in the eggs and expression profile of embryonic development genes were investigated. The results indicated that RSV replicated and accumulated in SBPH eggs resulting in developmental stunt or delay of partial eggs; in addition, RSV was only able to infect ovum but not sperm. According to the expression profile, expression of 13 developmental genes was regulated in the eggs from viruliferous parents, in which two important regulatory genes (Ls-Dorsal and Ls-CPO) were most significantly down-regulated. In general, RSV exerts an adverse effect on SBPH, which is unfavourable for the expansion of viruliferous populations. The viewpoint is also supported by systematic monitoring of SBPH viruliferous rate. PMID:25601039

Li, Shuo; Wang, Shijuan; Wang, Xi; Li, Xiaoli; Zi, Jinyan; Ge, Shangshu; Cheng, Zhaobang; Zhou, Tong; Ji, Yinghua; Deng, Jinhua; Wong, Sek-Man; Zhou, Yijun

2015-01-01

280

Rice stripe virus affects the viability of its vector offspring by changing developmental gene expression in embryos.  

PubMed

Plant viruses may affect the viability and development process of their herbivore vectors. Small brown planthopper (SBPH) is main vector of Rice stripe virus (RSV), which causes serious rice stripe disease. Here, we reported the effects of RSV on SBPH offspring by crossing experiments between viruliferous and non-viruliferous strains. The life parameters of offspring from different cross combinations were compared. The hatchability of F1 progeny from viruliferous parents decreased significantly, and viruliferous rate was completely controlled by viruliferous maternal parent. To better elucidate the underlying biological mechanisms, the morphology of eggs, viral propagation and distribution in the eggs and expression profile of embryonic development genes were investigated. The results indicated that RSV replicated and accumulated in SBPH eggs resulting in developmental stunt or delay of partial eggs; in addition, RSV was only able to infect ovum but not sperm. According to the expression profile, expression of 13 developmental genes was regulated in the eggs from viruliferous parents, in which two important regulatory genes (Ls-Dorsal and Ls-CPO) were most significantly down-regulated. In general, RSV exerts an adverse effect on SBPH, which is unfavourable for the expansion of viruliferous populations. The viewpoint is also supported by systematic monitoring of SBPH viruliferous rate. PMID:25601039

Li, Shuo; Wang, Shijuan; Wang, Xi; Li, Xiaoli; Zi, Jinyan; Ge, Shangshu; Cheng, Zhaobang; Zhou, Tong; Ji, Yinghua; Deng, Jinhua; Wong, Sek-Man; Zhou, Yijun

2015-01-01

281

Direct active and reactive power control of DFIG for wind energy generation  

Microsoft Academic Search

This paper presents a new direct power control (DPC) strategy for a doubly fed induction generator (DFIG)-based wind energy generation system. The strategy is based on the direct control of stator active and reactive power by selecting appropriate voltage vectors on the rotor side. It is found that the initial rotor flux has no impact on the changes of the

Lie Xu; Phillip Cartwright

2006-01-01

282

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

283

Titan’s Rotation Reveals an Internal Ocean and Changing Zonal Winds  

NASA Astrophysics Data System (ADS)

Cassini radar observations of Saturn’s moon Titan over several years show that its rotational period is changing and is different from its orbital period. The present-day rotation period difference from synchronous spin leads to a shift of ~0.36° per year in apparent longitude and is consistent with seasonal exchange of angular momentum between the surface and Titan’s dense superrotating atmosphere, but only if Titan’s crust is decoupled from the core by an internal water ocean like that on Europa.

Lorenz, Ralph D.; Stiles, Bryan W.; Kirk, Randolph L.; Allison, Michael D.; Persi del Marmo, Paolo; Iess, Luciano; Lunine, Jonathan I.; Ostro, Steven J.; Hensley, Scott

2008-03-01

284

How do cosmic rays change their energy in the solar wind?  

NASA Technical Reports Server (NTRS)

The diffusion-convection (modulation) equation is derived directly from the Boltzmann equation on the basis of a minimum number of assumptions concerning the scattering process, among which are: (1) that the scattered particles undergo no energy change, and (2) that isotropy is an equilibrium state. It is noted that, in the event that the background plasma contains a magnetic field and the flow speeds of the plasma and scattering centers are different, additional terms arise that will modify the equations. If, moreover, the scatterers have individual motions relative to their average flow, the second-order Fermi acceleration term will appear.

Jones, F. C.

1983-01-01

285

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

286

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. It’s 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

287

Vector quantization  

Microsoft Academic Search

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

Robert M. Gray

1984-01-01

288

A Marine-Radar Wind Sensor  

Microsoft Academic Search

A method, called WiRAR, is developed to measure the wind vector using a marine X-band radar as sensor. WiRAR extracts local wind directions from wind induced streaks, which are visible in radar images at scales above 50 m. It is shown that the streaks are very well aligned with the mean surface wind directions. Wind speeds are derived with WiRAR

Heiko Dankert; Jochen Horstmann

2006-01-01

289

Winds of change: growing demands for transparency in the relationship between doctors and the pharmaceutical industry.  

PubMed

The relationship between medicine and the pharmaceutical industry in the United States is undergoing rapid and momentous change; US Senator Grassley has alleged inadequate disclosure of earnings from industry and lack of acknowledgement of conflicts of interest by leading academics. This article is based on the premise that it is not the relationship per se that is the problem, but rather how that relationship is enacted. The influential 2008 report of the Association of American Medical Colleges (AAMC) has provided detailed recommendations on appropriate interactions between academic physicians and industry (eg, proscribing receipt of gifts including travel support, and proscribing speaking at industry-sponsored educational programs). Contrary to expectations, there has been widespread acceptance of such guidelines. In Australia, details of all industry-sponsored educational events are now listed on the Medicines Australia website. Australian doctors have no alternative but to drastically improve the transparency of their interactions with industry, both in terms of the remuneration received and disclosure of potential conflicts of interest. Australian universities should seriously consider developing recommendations similar to those of the AAMC. PMID:19740050

Mitchell, Philip B

2009-09-01

290

Impact of environmental changes and human-related factors on the potential malaria vector, Anopheles labranchiae (Diptera: Culicidae), in Maremma, Central Italy.  

PubMed

The Maremma Plain (central Italy) was hyper-endemic for malaria until the mid-20th century, when a national campaign for malaria elimination drastically reduced the presence of the main vector Anopheles labranchiae Falleroni. However, the introduction of rice cultivation over 30 yr ago has led to an increase in the An. labranchiae population and concern over possible malaria reemergence. We studied the impact of anthropogenic environmental changes on the abundance and distribution of An. labranchiae in Maremma, focusing on rice fields, the main breeding sites. Adults and larvae were collected in three main areas with diverse ecological characteristics. Data were collected on human activity, land use, and seasonal climatic and demographic variations. We also interviewed residents and tourists regarding their knowledge of malaria. Our findings showed that the most important environmental changes have occurred along the coast; An. labranchiae foci are present throughout the area, with massive reproduction strictly related to rice cultivation in coastal areas. Although the abundance of this species has drastically decreased over the past 30 yr, it remains high and, together with climatic conditions and the potential introduction of gametocyte carriers, it may represent a threat for the occurrence of autochthonous malaria cases. Our findings suggest the need for the continuous monitoring of An. labranchiae in the study area. In addition to entomological surveillance, more detailed knowledge of human-induced environmental changes is needed, so as to have a more complete database that can be used for vector-control plans and for properly managing emergencies related to autochthonous introduced cases. PMID:22897043

Boccolini, D; Toma, L; Di Luca, M; Severini, F; Cocchi, M; Bella, A; Massa, A; Mancini Barbieri, F; Bongiorno, G; Angeli, L; Pontuale, G; Raffaelli, I; Fausto, A M; Tamburro, A; Romi, R

2012-07-01

291

Wind farm and solar park effects on plant-soil carbon cycling: uncertain impacts of changes in ground-level microclimate.  

PubMed

Global energy demand is increasing as greenhouse gas driven climate change progresses, making renewable energy sources critical to future sustainable power provision. Land-based wind and solar electricity generation technologies are rapidly expanding, yet our understanding of their operational effects on biological carbon cycling in hosting ecosystems is limited. Wind turbines and photovoltaic panels can significantly change local ground-level climate by a magnitude that could affect the fundamental plant-soil processes that govern carbon dynamics. We believe that understanding the possible effects of changes in ground-level microclimates on these phenomena is crucial to reducing uncertainty of the true renewable energy carbon cost and to maximize beneficial effects. In this Opinions article, we examine the potential for the microclimatic effects of these land-based renewable energy sources to alter plant-soil carbon cycling, hypothesize likely effects and identify critical knowledge gaps for future carbon research. PMID:24132939

Armstrong, Alona; Waldron, Susan; Whitaker, Jeanette; Ostle, Nicholas J

2014-06-01

292

Wind farm and solar park effects on plant–soil carbon cycling: uncertain impacts of changes in ground-level microclimate  

PubMed Central

Global energy demand is increasing as greenhouse gas driven climate change progresses, making renewable energy sources critical to future sustainable power provision. Land-based wind and solar electricity generation technologies are rapidly expanding, yet our understanding of their operational effects on biological carbon cycling in hosting ecosystems is limited. Wind turbines and photovoltaic panels can significantly change local ground-level climate by a magnitude that could affect the fundamental plant–soil processes that govern carbon dynamics. We believe that understanding the possible effects of changes in ground-level microclimates on these phenomena is crucial to reducing uncertainty of the true renewable energy carbon cost and to maximize beneficial effects. In this Opinions article, we examine the potential for the microclimatic effects of these land-based renewable energy sources to alter plant–soil carbon cycling, hypothesize likely effects and identify critical knowledge gaps for future carbon research. PMID:24132939

Armstrong, Alona; Waldron, Susan; Whitaker, Jeanette; Ostle, Nicholas J

2014-01-01

293

Spatial modelling of the potential temperature-dependent transmission of vector-associated diseases in the face of climate change: main results and recommendations from a pilot study in Lower Saxony (Germany)  

Microsoft Academic Search

The sustained climate change is going to modify the geographic distribution, the seasonal transmission gate and the intensity\\u000a of the transmission of vector-borne diseases such as malaria or the bluetongue disease. These diseases occur nowadays at higher\\u000a latitudes or altitudes. A further rise in ambient temperature and rainfall will extend the duration of the season in which\\u000a mosquito vectors are

Winfried Schröder; Gunther Schmidt

2008-01-01

294

The Pollination of Trimenia moorei (Trimeniaceae): Floral Volatiles, Insect/Wind Pollen Vectors and Stigmatic Self?incompatibility in a Basal Angiosperm  

PubMed Central

Trimenia moorei (Oliv.) Philipson is an andromonoecious liane with >0·40 of the total flower buds maturing as bisexual flowers. Male and bisexual flowers are strongly scented with pollen, anther sacs and receptacle scars testing positively for volatile emissions. Scent analyses detect over 20 components. The major fatty acid derivative is 8?heptadecene, and 2?phenylethanol dominates the benzenoids. While hover?flies in the genera Melangyna and Triglyphus contact the stigma with their probosces, the stigma secretes no free?flowing, edible fluids. Copious pollen is the only edible reward consumed by hover?flies (Syprhidae), sawflies (Pergidae) and bees in the families Apidae, Colletidae and Halictidae. All these insects carried pollen of T. moorei on their heads, legs and thoraces and female bees in the genera Apis, Exoneura, Leioproctus and Lasioglossum stored pollen on their hind legs. Pollen traps also indicate that pollen is shed directly into the air, permitting wind pollination. When bisexual flower buds are bagged (isolated from insect foragers) on the liane then subjected to a series of hand?pollination experiments after perianth segments open, the structural analyses of pollen–carpel interactions indicate that T. moorei has a trichome?rich dry?type stigma with an early?acting self?incompatibility (SI) system. Bicellular pollen grains deposited on stigmas belonging to the same plant germinate but fail to penetrate intercellular spaces, while grains deposited following cross?pollination reach the ovule within 24 h. Fluorescence analyses of 76 carpels collected at random from unbagged (open?pollinated) flowers on five plants indicates that at least 64 % of carpels are cross?pollinated in situ. Trimenia moorei is the first species within the ANITA group, and second within reilictual?basal angiosperm lineages, to exhibit stigmatic SI in combination with dry?type stigma and bicellular pollen, a condition once considered to be atypical for angiosperms as a whole but now known to be present in numerous taxa. PMID:12930730

BERNHARDT, PETER; SAGE, TAMMY; WESTON, PETER; AZUMA, HIROSHI; LAM, MATHEW; THIEN, LEONARD B.; BRUHL, JEREMY

2003-01-01

295

Optimization of satellite coverage in observing cause and effect changes in the ionosphere, magnetosphere, and solar wind. Master's thesis  

SciTech Connect

Disturbances in the ionosphere sometimes cause adverse effects to communications systems, power grids, etc. on the earth. Currently, very little, if any, lead time is given to warn of an impending problem. If a forecast could be made of ionospheric occurrences, some lead time may be given to appropriate agencies and equipment may be saved. Most changes that occur in the ionosphere are a result of interaction of energy, currents, etc. between the magnetosphere and/or solar wind. Before a forecast can be made, however, improvement of ionospheric models currently in use need to be made. The models currently depict features in various regions of the ionosphere but not always where these features are actually observed. So an improvement to the model is needed to create an accurate baseline condition, or in other words an accurate depiction of the current ionosphere. Models could be improved by inputting real-time data from the ionosphere into the model. This data would come from satellites and/or ground-based stations.

Loveless, M.J.

1993-06-01

296

A piecewise linear model for detecting climatic trends and their structural changes with application to mesosphere/lower thermosphere winds over Collm, Germany  

NASA Astrophysics Data System (ADS)

A piecewise linear model is developed to detect climatic trends and their structural changes in time series with a priori unknown number and positions of breakpoints (BPs). The departure (i.e., the initial noise term) of trends from time series is allowed to be interpreted by the first- and second-order autoregressive models. The goodness of fit of candidate models, if the residuals are accepted as normally distributed white noise, is evaluated using the Schwarz Bayesian Information Criterion (BIC). The uncertainties of all trend parameters are estimated using the Monte-Carlo method. The model is applied to the mesosphere and lower thermosphere (MLT) winds obtained at Collm, Germany, during 1960-2007. A persistent increase after ˜1980 of the zonal prevailing wind is observed in all seasons and hence in the zonal annual mean based on the primary models. Trends of the meridional prevailing wind are different for different seasons. Several major trend BPs are identified in the annual mean zonal and meridional winds according to BIC. However, in view of the large wind variability before the late 1970s, alternative models are considered. This provides four additional minor breaks. In some cases, the initial noise must be further interpreted by autoregressive models, suggesting that other unidentified factors may also play a role.

Liu, R. Q.; Jacobi, Ch.; Hoffmann, P.; Stober, G.; Merzlyakov, E. G.

2010-11-01

297

Implications of global change and climate variability for vector-borne diseases: generic approaches to impact assessments.  

PubMed

Global change is pervasive and occurring at a dramatic rate. It involves changes in land use, vegetation cover, species translocations and even the climate of the planet. The consequences for the biosphere are uncertain. Past research emphasis has been on the science of climate change as the major driver of policy. The present priority in the global-change community is to define the likely nature and extent of those impacts on biodiversity and the functioning of ecosystems. In addition, increasing consideration is now being given to adaptation measures. The way in which that is being initiated is to develop adaptation measures to respond to medium-term climate variability in the form of altered El Nino and similar cycles, and changes in the frequency of extreme events. Given the large number of stakeholders in agriculture, human health and environment, there is a need for great efficiencies if the scientific community is going to be able to respond in a meaningful way with foreseeable resources. The plethora of problems means that generic approaches are needed. The present situation, with parasitologists each doing their own thing in terms of developing and using software tools, is like the tower of Babel. Parasitologists need common tools and languages to facilitate communication and collaboration. Advances in computing, with object-oriented programming languages and seamless exchange of information between different packages and platforms, are providing some exciting opportunities to overcome these problems. PMID:9673872

Sutherst, R W

1998-06-01

298

Hot gas ingestion test results of a two-poster vectored thrust concept with flow visualization in the NASA Lewis 9- x 15-foot low speed wind tunnel  

NASA Technical Reports Server (NTRS)

A 9.2 percent scale Short Takeoff and Vertical Landing (STOVL) hot gas ingestion model was designed and built by McDonnell Douglas Corporation (MCAIR) and tested in the Lewis Research Center 9 x 15 foot Low Speed Wind Tunnel (LSWT). Hot gas ingestion, the entrainment of heated engine exhaust into the inlet flow field, is a key development issure for advanced short takeoff and vertical landing aircraft. Flow visualization from the Phase 1 test program, which evaluated the hot ingestion phenomena and control techniques, is covered. The Phase 2 test program evaluated the hot gas ingestion phenomena at higher temperatures and used a laser sheet to investigate the flow field. Hot gas ingestion levels were measured for the several forward nozzle splay configurations and with flow control/life improvement devices (LIDs) which reduced the hot gas ingestion. The model support system had four degrees of freedom - pitch, roll, yaw, and vertical height variation. The model support system also provided heated high-pressure air for nozzle flow and a suction system exhaust for inlet flow. The test was conducted at full scale nozzle pressure ratios and inlet Mach numbers. Test and data analysis results from Phase 2 and flow visualization from both Phase 1 and 2 are documented. A description of the model and facility modifications is also provided. Headwind velocity was varied from 10 to 23 kn. Results are presented over a range of nozzle pressure ratios at a 10 kn headwind velocity. The Phase 2 program was conducted at exhaust nozzle temperatures up to 1460 R and utilized a sheet laser system for flow visualization of the model flow field in and out of ground effects. The results reported are for nozzle exhaust temperatures up to 1160 R. These results will contain the compressor face pressure and temperature distortions, the total pressure recovery, the inlet temperature rise, and the environmental effects of the hot gas. The environmental effects include the ground plane contours, the model airframe heating, and the location of the ground flow separation.

Johns, Albert L.; Neiner, George; Bencic, Timothy J.; Flood, Joseph D.; Amuedo, Kurt C.; Strock, Thomas W.

1990-01-01

299

Three-Dimensional Wind Profiling of Offshore Wind Energy Areas With Airborne Doppler Lidar  

NASA Technical Reports Server (NTRS)

A technique has been developed for imaging the wind field over offshore areas being considered for wind farming. This is accomplished with an eye-safe 2-micrometer wavelength coherent Doppler lidar installed in an aircraft. By raster scanning the aircraft over the wind energy area (WEA), a three-dimensional map of the wind vector can be made. This technique was evaluated in 11 flights over the Virginia and Maryland offshore WEAs. Heights above the ocean surface planned for wind turbines are shown to be within the marine boundary layer, and the wind vector is seen to show variation across the geographical area of interest at turbine heights.

Koch, Grady J.; Beyon, Jeffrey Y.; Cowen, Larry J.; Kavaya, Michael J.; Grant, Michael S.

2014-01-01

300

Three-dimensional wind profiling of offshore wind energy areas with airborne Doppler lidar  

NASA Astrophysics Data System (ADS)

A technique has been developed for imaging the wind field over offshore areas being considered for wind farming. This is accomplished with an eye-safe 2-?m wavelength coherent Doppler lidar installed in an aircraft. By raster scanning the aircraft over the wind energy area (WEA), a three-dimensional map of the wind vector can be made. This technique was evaluated in 11 flights over the Virginia and Maryland offshore WEAs. Heights above the ocean surface planned for wind turbines are shown to be within the marine boundary layer, and the wind vector is seen to show variation across the geographical area of interest at turbine heights.

Koch, Grady J.; Beyon, Jeffrey Y.; Cowen, Larry J.; Kavaya, Michael J.; Grant, Michael S.

2014-01-01

301

Cloning vector  

DOEpatents

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

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

1994-01-01

302

Cloning vector  

DOEpatents

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

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

1994-12-27

303

Changes in water and wind resources across the central and northeastern U.S. 2060-2010 in 24 km WRF downscale climate simulations  

NASA Astrophysics Data System (ADS)

GCM ensembles for the IPCC AR4 indicate that by 2060 water and wind resources will change appreciably over the central and northeastern U.S. In order to investigate these possible changes on a scale relevant for agriculture and offshore wind-power planners, we produced 24 km downscale simulations using the Weather Research and Forecasting (WRF) model. Our simulations span the years 2006-2010 and 2056-2060 with boundary conditions supplied by CCSM4 (IPCC emissions scenario RCP 8.5). By calculating the difference between the simulated time periods we find: 1) ~10% decrease in total annual precipitation across the southern half of the Ogallala aquifer in the central U.S., and ~10% increase across the northeastern states; and 2) Minimal change in annual-average 10-meter wind strength across the study areas, but with significant changes seasonal values. Interrogation of the simulation results is ongoing, and a complete synthesis will be presented at the annual meeting.

Birkel, S. D.; Maasch, K. A.; Oglesby, R. J.; Fulginiti, L.; Trindade, F.; Hays, C.

2012-12-01

304

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

305

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

306

Molecular and macromolecular alterations of recombinant adenoviral vectors do not resolve changes in hepatic drug metabolism during infection  

Microsoft Academic Search

In this report we test the hypothesis that long-term virus-induced alterations in CYP occur from changes initiated by the virus that may not be related to the immune response. Enzyme activity, protein expression and mRNA of CYP3A2, a correlate of human CYP3A4, and CYP2C11, responsive to inflammatory mediators, were assessed 0.25, 1, 4, and 14 days after administration of several

Shellie M. Callahan; Piyanuch Wonganan; Maria A. Croyle

2008-01-01

307

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

Microsoft Academic Search

We used an Ixodes scapularis population model to investigate potential northward spread of the tick associated with climate change. Annual degree-days O0 8C 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

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

2005-01-01

308

Wind speed forecasting for wind energy applications  

NASA Astrophysics Data System (ADS)

With more wind energy being integrated into our grid systems, forecasting wind energy has become a necessity for all market participants. Recognizing the market demands, a physical approach to site-specific hub-height wind speed forecasting system has been developed. This system is driven by the outputs from the Canadian Global Environmental Multiscale (GEM) model. A simple interpolation approach benchmarks the forecasting accuracy inherited from GEM. Local, site specific winds are affected on a local scale by a variety of factors including representation of the land surface and local boundary-layer process over heterogeneous terrain which have been a continuing challenge in NWP models like GEM with typical horizontal resolution of order 15-km. In order to resolve these small scale effects, a wind energy industry standard model, WAsP, is coupled with GEM to improve the forecast. Coupling the WAsP model with GEM improves the overall forecasts, but remains unsatisfactory for forecasting winds with abrupt surface condition changes. Subsequently in this study, a new coupler that uses a 2-D RANS model of boundary-layer flow over surface condition changes with improved physics has been developed to further improve the forecasts when winds coming from a water surface to land experience abrupt changes in surface conditions. It has been demonstrated that using vertically averaged wind speeds to represent geostrophic winds for input into the micro-scale models could reduce forecast errors. The hub-height wind speed forecasts could be further improved using a linear MOS approach. The forecasting system has been evaluated, using a wind energy standard evaluation matrix, against data from an 80-m mast located near the north shore of Lake Erie. Coupling with GEM-LAM and a power conversion model using a theoretical power curve have also been investigated. For hub-height wind speeds GEM appears to perform better with a 15-Ian grid than the high resolution GEM-2.5Ian version at the validation site.

Liu, Hong

309

Effects of sea state on offshore wind resourcing in Florida  

NASA Astrophysics Data System (ADS)

Offshore resource assessment relies on estimating wind speeds at turbine hub height using observations typically made at substantially lower height. The methods used to adjust from observed wind speeds to hub height can impact resource estimation. The importance of directional sea state is examined, both as seasonal averages and as a function of the diurnal cycle. A General Electric 3.6 MW offshore turbine is used as a model for a power production. Including sea state increases or decreases seasonally averaged power production by roughly 1%, which is found to be an economically significant change. These changes occur because the sea state modifies the wind shear (vector wind difference between the buoy height and the moving surface) and therefore the extrapolation from the observation to hub height is affected. These seemingly small differences in capacity can alter profits by millions of dollars depending upon the size of the farm and fluctuations in price per kWh throughout the year. A 2% change in capacity factor can lead to a 10 million dollar difference from total kWh produced from a wind farm of 100 3.6MW turbines. These economic impacts can be a deciding factor in determining whether a resource is viable for development. Modification of power output due to sea states are shown for seasonal and diurnal time scales. Three regions are examined herein: West Florida, East Florida, and Nantucket Sound. The average capacity after sea state is included suggests areas around Florida could provide substantial amounts of wind power throughout three-fourths of the calendar year. At certain times of day winter average produced capacity factors in West Florida can be up to 45% more than in summer when sea state is included. Nantucket Sound capacity factors are calculated for comparison to a region near a planned United States offshore wind farm. This study provides evidence to suggest including sea state in offshore wind resource assessment causes economically significant differences for offshore wind power siting.

Collier, Cristina

310

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

311

Satellite-derived sea surface height and sea surface wind data fusion for spilled oil tracking  

NASA Astrophysics Data System (ADS)

Data fusion is defined as a framework with the purpose of obtaining information of 'greater quality'. Within the framework tools are expressed for the alliance of data originating from different sources. The exact definition of 'greater quality' is stated in this context as more reliable prediction for the trajectory of spilled oil from two different microwave sensor data, namely ERS-2 altimeter and ADEOS/NSCAT scatterometer data. An example is presented in the case of trajectory of bow section and associated oil upwelling from the sunken tanker Nakhodka occurred from January to June in 1997 in Japan Sea. Spill distance is defined as a horizontal distance from the oil upwelling point to the location of sunken Nakhodka and a spill direction is defined as an angle made by the geographic north and the line corresponding to the spill distance. Geostrophic current vectors are derived from ERS-2 altimeter and wind-induced current vectors are derived from ADEOS/NSCAT scatterometer data. These two different satellite-derived vectors are 'fused' together in the surface current model to estimate and evaluate the trajectory of bow section and associated oil upwelling from the sunken tanker Nakhodka. Result of comparison between the estimated and the observed trajectory of bow section indicates that the estimated trajectory is agreed well with the observed one in the first half of drift period, while in the latter half of drift period the estimated trajectory is not agreed well with the observed one, which may be attributable to changes of wind directions within 24 hours from the satellite overpasses. Moreover the comparison between spill vector and 'fused' surface current vector shows the good correspondence in terms of direction when in situ wind accelerates the surface current vector, while the comparison between the twos shows the bad correspondence when the temporal changes of wind vector occurs.

Kozai, K.

312

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

313

Reciprocal Vectors  

NASA Astrophysics Data System (ADS)

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

Vogt, Joachim; Paschmann, Gotz; Chanteur, Gérard

314

An oilspill trajectory analysis model with a variable wind deflection angle  

USGS Publications Warehouse

The oilspill trajectory movement algorithm consists of a vector sum of the surface drift component due to wind and the surface current component. In the U.S. Geological Survey oilspill trajectory analysis model, the surface drift component is assumed to be 3.5% of the wind speed and is rotated 20 degrees clockwise to account for Coriolis effects in the Northern Hemisphere. Field and laboratory data suggest, however, that the deflection angle of the surface drift current can be highly variable. An empirical formula, based on field observations and theoretical arguments relating wind speed to deflection angle, was used to calculate a new deflection angle at each time step in the model. Comparisons of oilspill contact probabilities to coastal areas calculated for constant and variable deflection angles showed that the model is insensitive to this changing angle at low wind speeds. At high wind speeds, some statistically significant differences in contact probabilities did appear. ?? 1982.

Samuels, W.B.; Huang, N.E.; Amstutz, D.E.

1982-01-01

315

The interacting winds of Eta Carinae: Observed forbidden line changes and the Forbidden Blue(-Shifted) Crab  

NASA Astrophysics Data System (ADS)

The massive binary, Eta Carinae (EC), produces such massive winds that strong forbidden line emission of singly- and doubly-ionized iron traces wind-wind interactions from the current cycle plus fossil interactions from one, two and three 5.54-year cycles ago.With an eccentricity of >0.9, the >90 solar mass primary (EC-A) and >30 solar mass secondary (EC-B) approach to within 1.5 AU during periastron and recede to nearly 30 AU across apastron. The wind-wind structures move outward driven by the 420 km/s primary wind interacting with the ~3000 km/s secondary wind yielding partially-accelerated compressed primary wind shells that are excited by mid-UV from EC-A and in limited lines of sight, FUV from EC-B.These structures are spectroscopically and spatially resolved by HST's Space Telescope Imaging Spectrograph. At critical binary phases, we have mapped the central 2'x2' region in the light of [Fe III] and [Fe II] with spatial resolution of 0.12' and velocity resolution of 40 km/s.1) The bulk of forbidden emission originates from the large cavity northwest of EC and is due to ionization of massive ejecta from the 1840s and 1890s eruptions. The brightest clumps are the Weigelt Blobs C and D, but there are additionally multiple, fainter emission clumps. Weigelt B appears to have faded.2) Three concentric, red-shifted [FeII] arcs expand at ~470 km/s excited by mid-UV of EC-A.3) The structure of primarily blue-shifted [Fe III] emission resembles a Maryland Blue Crab. The claws appear at the early stages of the high-excitation recovery from the periastron passage, expand at radial velocities exceeding the primary wind terminal velocity, 420 km/s and fade as the binary system approaches periastron with the primary wind enveloping the FUV radiation from EC-B.4) All [Fe III] emission faded by late June 2014 and disappeared by August 2, 2014, the beginning of periastron passage.Comparisons to HST/STIS observations between 1998 to 2004.3 indicate long-term fading of [Fe II]. Likewise, Na D emission has faded. 3D hydro/radiative models suggest a small decrease (< factor of 2) in primary mass loss rate to be the cause.

Gull, Theodore R.; Madura, Thomas; Corcoran, Michael F.; Teodoro, Mairan; Richardson, Noel; Hamaguchi, Kenji; Groh, Jose H.; Hillier, Desmond John; Damineli, Augusto; Weigelt, Gerd

2015-01-01

316

Harnessing Wind  

NSDL National Science Digital Library

Students are introduced to the ways that engineers study and harness the wind. They learn about the different kinds of winds and how to measure wind direction. In addition, they learn how air pressure creates winds and how engineers design and test wind turbines to harness renewable wind energy.

2014-09-18

317

Vector carpets  

SciTech Connect

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

Dovey, D.

1995-03-22

318

Aerodynamics of thrust vectoring  

NASA Technical Reports Server (NTRS)

Thrust vectoring as a means to enhance maneuverability and aerodynamic performane of a tactical aircraft is discussed. This concept usually involves the installation of a multifunction nozzle. With the nozzle, the engine thrust can be changed in direction without changing the attitude of the aircraft. Change in the direction of thrust induces a significant change in the aerodynamic forces on the aircraft. Therefore, this device can be used for lift-augmenting as well as stability and control purposes. When the thrust is deflected in the longitudinal direction, the lift force and the pitching stability can be manipulated, while the yawing stability can be controlled by directing the thrust in the lateral direction.

Tseng, J. B.; Lan, C. Edward

1989-01-01

319

Winds of Change: The Physics of Accretion, Ejection, and X-ray Variability in GRS1915+105  

NASA Astrophysics Data System (ADS)

In the last twenty years, even as multiwavelength observations of black hole X-ray binaries have led to major advances, the microquasar GRS 1915+105 has continually challenged our understanding of the physics of accretion and ejection. With its relativistic jets, ionized winds, and myriad states of rapid, extreme variability, this remarkable black hole has been alternately seen as the black sheep of X-ray binaries and a Rosetta stone for black hole astrophysics. In this talk, I will present our efforts to use a decade of high-resolution X-ray spectroscopy of GRS 1915+105 to shed light on the processes that regulate its erratic behavior. I will highlight in particular the role of accretion disk winds on time scales ranging from seconds to years. Drawing on recent results, I will discuss the broader implications of these massive winds for the physics of inflows and outflows around black holes.

Neilsen, Joseph

2013-04-01

320

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.

321

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.

2014-09-14

322

Pipeline vectorization  

Microsoft Academic Search

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

Markus Weinhardt; Wayne Luk

2001-01-01

323

Inertial response from wind turbines  

NASA Astrophysics Data System (ADS)

Wind power is an essential part of the strategy to address challenges facing the energy sector. Operation of the electricity network in 2020 will require higher levels of response and reserve from generation. The provision of inertial response from wind turbines was investigated. A model was developed for the simulation of frequency on the mainland UK system, including a simplified model for a synchronous generator to represent Full Power Converter turbines. Two different methods of inertia response, the step method and the inertia coupling method, were modelled and introduced into the turbine torque speed control. Simulations illustrated the effects on primary frequency control for a high penetration of wind turbines. Results are shown for different demand levels with generation losses of 1320GW and 1800GW. A comparison of the inertia functions is included and the effect of wind speed and the constant speed region of the maximum power extraction curve. For the scenarios modelled only a small change in turbine output was required for inertia response (0.02p.u). Without inertia response a large increase in synchronous plant response was needed. A test rig was constructed consisting of a Full Power Converter bridge and a synchronous generator driven by a dc machine. Power converters were designed and constructed by the candidate. Vector control of both the generator converter and grid converter was implemented on a dedicated control platform. The inertia coupling function was implemented and a test frequency deviation injected to represent a load generation imbalance. Results compared closely to those from the model and demonstrated the capability to closely couple turbine speed to system frequency with adjustment of the response via a filter if desired. The experimental work confirmed the adequacy of the simplified generator model and further confirmed the possibility of using inertia response. The inertia coupling function was considered suitable for use for the UK system.

Moore, Ian F.

324

DSCOVR High Time Resolution Solar Wind Measurements  

NASA Technical Reports Server (NTRS)

The Deep Space Climate Observatory (DSCOVR), previously known as Triana, spacecraft is expected to be launched in late 2014. It will carry a fluxgate magnetometer, Faraday Cup solar wind detector and a top-hat electron electrostatic analyzer. The Faraday Cup will provide an unprecedented 10 vectors/sec time resolution measurement of the solar wind proton and alpha reduced distribution functions. Coupled with the 40 vector/sec vector magnetometer measurements, the identification of specific wave modes in the solar wind will be possible for the first time. The science objectives and data products of the mission will be discussed.

Szabo, Adam

2012-01-01

325

DSCOVR High Time Resolution Solar Wind Measurements  

NASA Astrophysics Data System (ADS)

The Deep Space Climate Observatory (DSCOVR), previously known as Triana, spacecraft is expected to be launched in late 2014. It will carry a fluxgate magnetometer, Faraday Cup solar wind detector and a top-hat electron electrostatic analyzer. The Faraday Cup will provide an unprecedented 10 vectors/sec time resolution measurement of the solar wind proton and alpha reduced distribution functions. Coupled with the 40 vector/sec vector magnetometer measurements, the identification of specific wave modes in the solar wind will be possible for the first time. The science objectives and data products of the mission will be discussed.

Szabo, A.

2012-12-01

326

Wind-Tunnel Investigations on a Changed Mustang Profile with Nose Flap Force and Pressure-Distribution Measurements  

NASA Technical Reports Server (NTRS)

Measurements are described which were taken in the large wind tunnel of the AVA on a rectangular wing "Mustang 2" with nose flap of a chord of 10 percent. Besides force measurements the results of pressure-distribution measurements are given and compared with those on the same profile "without" nose flap.

Krueger, W.

1947-01-01

327

Comparison of dayside and nightside reconnection changes resulting from a sudden enhancement in solar wind dynamic pressure  

NASA Astrophysics Data System (ADS)

Magnetic reconnection at the dayside magnetopause is the main process by which mass, energy, and momentum from the solar wind enter the terrestrial magnetosphere. Magnetic reconnection at the nightside energizes magnetotail plasma and closes the lobe open flux, thus completing the cycle that initiates and sustains magnetospheric convection. Understanding the drivers of reconnection and convection in the magnetosphere is one of the primary goals of magnetospheric physics. It has long been recognized that the Interplanetary Magnetic Field (IMF) is the most influential factor in initiation of reconnection and convection in the magnetosphere. Recent evidence has shown that the solar wind dynamic pressure plays also an important role in enhancing both dayside and nightside reconnection, and driving enhanced ionospheric convection. Super Dual Auroral Radar Network (SuperDARN) observations show that solar wind pressure fronts induce significantly enhanced ionospheric convection in the dayside ionosphere. In parallel, Defense Meteorological Satellite Program (DMSP) precipitating particle measurements and POLAR Ultra-Violet Imager (UVI) images have demonstrated that sudden solar wind pressure increases also significantly affect the size of the polar cap. The polar cap is observed to shrink after an increase in solar wind pressure, especially on the nightside, suggesting an enhancement of magnetotail reconnection. MHD models of the interaction of the magnetosphere with solar wind pressure fronts have managed to reproduce the enhancement of dayside reconnection, but have failed so far to account for the observed closing of the polar cap on the nightside and the suggested magnetotail reconnection increase. We use SuperDARN observations of ionospheric convection within both the dayside and nightside polar ionosphere, including near the magnetic separatrix, to evaluate the relative strengths of the observed dayside and nightside reconnection enhancements after an abrupt increase in solar wind dynamic pressure. We show that enhancements of both dayside and nightside convection occur after an increase in pressure, suggesting an increased reconnection rate on both sides of the ionosphere. We discuss these results in terms of a competition between dayside and nightside reconnection in the determination of the size of the polar cap and possibly their effect on the transpolar potential.

Boudouridis, A.; Zesta, E.; Lyons, L. R.; Ruohoniemi, J. M.; Lummerzheim, D.; Anderson, P. C.

2007-12-01

328

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, Mônica; Moreno, Marta; Conn, Jan E.; Gamboa, Dionicia; Abeles, Shira; Vinetz, Joseph M.; Ferreira, Marcelo U.

2012-01-01

329

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

330

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

331

Wind tunnel study on wind and turbulence intensity profiles in wind turbine wake  

NASA Astrophysics Data System (ADS)

In recent years, there has been a rapid development of the wind farms in Japan. It becomes very important to investigate the wind turbine arrangement in wind farm, in order that the wake of one wind turbine does not to interfere with the flow in other wind turbines. In such a case, in order to achieve the highest possible efficiency from the wind, and to install as many as possible wind turbines within a limited area, it becomes a necessity to study the mutual interference of the wake developed by wind turbines. However, there is no report related to the effect of the turbulence intensity of the external flow on the wake behind a wind turbine generated in the wind tunnel. In this paper, the measurement results of the averaged wind profile and turbulence intensity profile in the wake in the wind tunnel are shown when the turbulence intensity of the external wind was changed. The wind tunnel experiment is performed with 500mm-diameter two-bladed horizontal axis wind turbine and the wind velocity in wake is measured by an I-type hot wire probe. As a result, it is clarified that high turbulence intensities enable to the entrainment of the main flow and the wake and to recover quickly the velocity in the wake.

Maeda, Takao; Kamada, Yasunari; Murata, Junsuke; Yonekura, Sayaka; Ito, Takafumi; Okawa, Atsushi; Kogaki, Tetsuya

2011-06-01

332

Seasonal changes in estuarine dissolved organic matter due to variable flushing time and wind-driven mixing events  

NASA Astrophysics Data System (ADS)

This study examined the seasonality of dissolved organic matter (DOM) sources and transformations within the Neuse River estuary (NRE) in eastern North Carolina between March 2010 and February 2011. During this time, monthly surface and bottom water samples were collected along the longitudinal axis of the NRE, ranging from freshwater to mesohaline segments. The monthly mean of all surface and bottom measurements made on collected samples was used to clarify larger physical mixing controls in the estuary as a whole. By comparing monthly mean trends in DOM and chromophoric dissolved organic matter (CDOM) properties in surface and bottom waters during varying hydrological conditions, we found that DOM and CDOM quality in the NRE is controlled by a combination of discharge, wind speed, and wind direction. The quality of DOM was assessed using C:N ratios, specific ultraviolet absorption at 254 nm (SUVA254), the absorption spectral slope ratio (SR), and the humification (HIX) and biological (BIX) indices from fluorescence. The NRE reflects allochthonous sources when discharge and flushing time are elevated at which times SUVA254 and HIX increased relative to base flow. During periods of reduced discharge and long flushing times in the estuary, extensive autochthonous production modifies the quality of the DOM pool in the NRE. This was evidenced by falling C:N values, and higher BIX and SR values. Lastly, a combination of increased wind speed and shifts in wind direction resulted in benthic resuspension events of degraded, planktonic OM. Thus, the mean DOM characteristics in this shallow micro-tidal estuary can be rapidly altered during episodic mixing events on timescales of a few weeks.

Dixon, Jennifer L.; Osburn, Christopher L.; Paerl, Hans W.; Peierls, Benjamin L.

2014-12-01

333

Emotional tone of ontario newspaper articles on the health effects of industrial wind turbines before and after policy change.  

PubMed

Newspapers are often a primary source of health information for the public about emerging technologies. Information in newspapers can amplify or attenuate readers' perceptions of health risk depending on how it is presented. Five geographically distinct wind energy installations in Ontario, Canada were identified, and newspapers published in their surrounding communities were systematically searched for articles on health effects from industrial wind turbines from May 2007 to April 2011. The authors retrieved 421 articles from 13 community, 2 provincial, and 2 national newspapers. To measure the emotional tone of the articles, the authors used a list of negative and positive words, informed from previous studies as well as from a random sample of newspaper articles included in this study. The majority of newspaper articles (64.6%, n = 272) emphasized negative rather than positive/neutral tone, with community newspapers publishing a higher proportion of negative articles than provincial or national newspapers, ?(2)(2) = 15.1, p < .001. Articles were more likely to be negative when published 2 years after compared with 2 years before provincial legislation to reduce dependence on fossil fuels (the Green Energy Act), ?(2)(3) = 9.7, p < .05. Repeated public exposure to negative newspaper content may heighten readers' health risk perceptions about wind energy. PMID:25806896

Deignan, Benjamin; Hoffman-Goetz, Laurie

2015-05-01

334

Changes in Sea-Level Pressure over South Korea Associated with High-Speed Solar Wind Events  

E-print Network

We explore a possibility that the daily sea-level pressure (SLP) over South Korea responds to the high-speed solar wind event. This is of interest in two aspects: First, if there is a statistical association this can be another piece of evidence showing that various meteorological observables indeed respond to variations in the interplanetary environment. Second, this can be a very crucial observational constraint since most models proposed so far are expected to preferentially work in higher latitude regions than the low latitude region studied here. We have examined daily solar wind speed ${\\rm V}$, daily SLP difference ${\\rm \\Delta SLP}$, and daily ${\\rm \\log(BV^{2})}$ using the superposed epoch analysis in which the key date is set such that the daily solar wind speed exceeds 800 ${\\rm kms^{-1}}$. We find that the daily ${\\rm \\Delta SLP}$ averaged out of 12 events reaches its peak at day +1 and gradually decreases back to its normal level. The amount of positive deviation of ${\\rm \\Delta SLP}$ is +2.5 hPa...

Cho, Il-Hyun; Marubashi, Katsuhide; Kim, Yeon-Han; Park, Young-Deuk; Chang, Heon-Young

2011-01-01

335

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

336

WIND-DRIVEN RAINSPLASH EROSION  

Technology Transfer Automated Retrieval System (TEKTRAN)

In wind-driven rains, variations in raindrop trajectory and frequency are highly expected due to the changes in the angle of raindrop incidence. This paper presents experimental data obtained on the effects of horizontal wind velocity on physical raindrop impact and rainsplash detachment. In a wind ...

337

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

338

Reproductive allocation in plants as affected by elevated carbon dioxide and other environmental changes: a synthesis using meta-analysis and graphical vector analysis.  

PubMed

Reproduction is an important life history trait that strongly affects dynamics of plant populations. Although it has been well documented that elevated carbon dioxide (CO2) in the atmosphere greatly enhances biomass production in plants, the overall effect of elevated CO2 on reproductive allocation (RA), i.e., the proportion of biomass allocated to reproductive structures, is little understood. We combined meta-analysis with graphical vector analysis to examine the overall effect of elevated CO2 on RA and how other environmental factors, such as low nutrients, drought and elevated atmospheric ozone (O3), interacted with elevated CO2 in affecting RA in herbaceous plants. Averaged across all species of different functional groups and environmental conditions, elevated CO2 had little effect on RA (-0.9 %). RA in plants of different reproductive strategies and functional groups, however, differed in response to elevated CO2. For example, RA in iteroparous wild species decreased by 8 %, while RA in iteroparous crops increased significantly (+14 %) at elevated CO2. RA was unaffected by CO2 in plants grown with no stress or in low-nutrient soils. RA decreased at elevated CO2 and elevated O3, but increased in response to elevated CO2 in drought-stressed plants, suggesting that elevated CO2 could ameliorate the adverse effect of drought on crop production to some extent. Our results demonstrate that elevated CO2 and other global environmental changes have the potential to greatly alter plant community composition through differential effects on RA of different plant species and thus affect the dynamics of natural and agricultural ecosystems in the future. PMID:25537120

Wang, Xianzhong; Taub, Daniel R; Jablonski, Leanne M

2015-04-01

339

Quantifying the respective contribution of wind stress and diabatic forcing to decadal temperature changes and regional sea level trends over 1993-2010 based on ECCO solutions  

NASA Astrophysics Data System (ADS)

Since 1993 and based on satellite altimetry data, sea level trends display a large regional variability. Some regions experience a sea level rise (e.g., the west tropical Pacific Ocean, the subpolar north Atlantic Ocean...) whereas other regions experience a drop (e.g., the east tropical Pacific Ocean, golf of Alaska...). Those sea level trends appear to be steric in nature. Moreover, steric changes appear to be mainly thermosteric, although halosteric effects can reduce or enhance thermosteric changes in some specific regions (Stammer et al., 2013). Understanding and quantifying the processes involved in regional sea level changes are important tasks to better constrain and ascertain the physical processes involved in regional sea level changes and then, to improve predictions to anticipate potential impacts. In this study, we analyze the ocean heat content change and its origin by analyzing Estimating the Circulation and Climate of the Ocean estimates (ECCO, Wunsch et al., 2009). We run numerical experiments to estimate and quantify the respective contribution of each atmospheric forcing (e.g., wind stress and diabatic forcing) to heat content change and regional sea level trends.

Llovel, W.; Fukumori, I.; Wang, O.

2013-12-01

340

SEERISK concept: Dealing with climate change related hazards in southeast Europe: A common methodology for risk assessment and mapping focusing on floods, drought, winds, heat wave and wildfire.  

NASA Astrophysics Data System (ADS)

Southeast Europe is a region that suffers often from natural hazards and has experienced significant losses in the recent past due to extreme weather conditions and their side-effects (cold and heat waves, extreme precipitation leading to floods / flash floods, thunderstorms, extreme winds, drought and wildfires). SEERISK ("Joint Disaster Management Risk Assessment and Preparedness in the Danube macro-region") is a European funded SEE (Southeast Europe) project that aims at the harmonisation and consistency among risk assessment practices undertaken by the partner countries at various levels regarding climate change related disasters. A common methodology for risk assessment has been developed that offers alternatives in order to tackle the problem of limited data. The methodology proposes alternative steps for hazard and vulnerability assessment that, according to the data availability, range from detailed modelling to expert judgement. In the present study the common methodology has been adapted for five hazard types (floods, drought, winds, heat wave and wildfire) that are expected to be affected by climate change in the future and are relevant for the specific study areas. The last step will be the application of the methodology in six different case studies in Hungary, Romania, Bosnia, Bulgaria, Slovakia and Serbia followed by field exercises.

Papathoma-Koehle, Maria; Promper, Catrin; Glade, Thomas

2014-05-01

341

Heat transfer phase change paint test (OH-42) of a Rockwell International SSV orbiter in the NASA/LRC Mach 8 variable density wind tunnel  

NASA Technical Reports Server (NTRS)

Phase change paint tests of a Rockwell International .00593-scale space shuttle orbiter were conducted in the Langley Research Center's Variable Density Wind Tunnel. The test objectives were to determine the effects of various wing/underbody configurations on the aerodynamic heating rates and boundary layer transition during simulated entry conditions. Several models were constructed. Each varied from the other in either wing cuff radius, airfoil thickness, or wing-fuselage underbody blending. Two ventral fins were glued to the fuselage underside of one model to test the interference heating effects. Simulated Mach 8 entry data were obtained for each configuration at angles of attack ranging from 25 to 40 deg, and a Reynolds number variation of one million to eight million. Elevon, bodyflap, and rudder flare deflections were tested. Oil flow visualization and Schlieren photographs were obtained to aid in reducing the phase change paint data as well as to observe the flow patterns peculiar to each configuration.

Jones, R.; Creel, T. R., Jr.; Lawing, P.; Quan, M.; Dye, W.; Cummings, J.; Gorowitz, H.; Craig, C.; Rich, G.

1973-01-01

342

Results of phase change paint tests of 0.040 scale 50% forebody models (82-0) of the space shuttle orbiter in the AEDC VKF B hypersonic wind tunnel (OH75)  

NASA Technical Reports Server (NTRS)

Post-test information and data are presented from phase change paint, aerodynamic heating wind tunnel tests of a Rockwell International space shuttle orbiter forebody model. These tests were conducted in the Arnold Engineering and Development Center von Karman Facility Tunnel B Hypersonic Wind Tunnel. The purpose of these tests was to determine the effect of simulated orbiter protuberances and penetrations (including RCS nozzles) on aerodynamic heating rates during simulated entry conditions.

Dye, W. H.

1976-01-01

343

Wild Wind  

NSDL National Science Digital Library

Students learn the difference between global, prevailing and local winds. They make wind vanes out of paper, straws and soda bottles and use them to measure wind direction over time. They analyze their data to draw conclusions about the local prevailing winds.

2014-09-18

344

Meteorology (Wind)  

Atmospheric Science Data Center

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

345

Hanford Site peak gust wind speeds  

SciTech Connect

Peak gust wind data collected at the Hanford Site since 1945 are analyzed to estimate maximum wind speeds for use in structural design. The results are compared with design wind speeds proposed for the Hanford Site. These comparisons indicate that design wind speeds contained in a January 1998 advisory changing DOE-STD-1020-94 are excessive for the Hanford Site and that the design wind speeds in effect prior to the changes are still appropriate for the Hanford Site.

Ramsdell, J.V.

1998-09-29

346

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

347

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.

348

Developing and Testing Wind Velocity Retrieval Algorithms for Doppler Wind Lidar  

NASA Astrophysics Data System (ADS)

A 3-dimensional wind lidar is being evaluated at the National Wind Technology Center (NWTC) for its applications in wind energy. The focus of the work described here is to develop algorithms that can increase data availability and accuracy in estimating wind velocity from the line of sight (los) velocity (Vlos) from Plan Position Indicator (PPI) scans. The common algorithm (AL0) starts by removing Vlos estimates that have low signal-to-noise ratio (SNR). Then, assuming a horizontally homogeneous wind field and zero vertical wind speed (w), the wind velocity is estimated by application of ordinary least square (OLS) fitting, and the results are averaged to produce the 10-minute mean wind velocity (scalar averaging) at each range-gate position. This approach has uncertainties because: (1) SNR is robust but conservative for quality control and use of any SNR threshold may result in exclusion of valid Vlos values causing low data availability. (2) While 10-minute mean w = 0 is typically valid, assuming zero w for each individual Vlos field may introduce biases. (3) The variance of Vlos changes with azimuth angle as it is the projection of the variance of the wind vector on the los. This violates the equal variance assumption in OLS fitting. The two new algorithms are developed to increase data availability and the accuracy of 10-minute mean wind velocities. Both algorithms assume that the wind velocity is normally distributed and use the maximum likelihood estimator for which the variance of Vlos changes with azimuth angle. The first algorithm (AL1) uses the 10-minute mean Vlos to estimate the 10-minute mean wind velocity. In comparison to scalar averaging, AL1 can reduce the variation in Vlos and the assumption of w = 0 is more likely to be valid. To increase data availability, Vlos with low SNR is retained if its difference from the mean is smaller than three times the standard deviation of Vlos. The second algorithm (AL2) uses the median of Vlos over 10 minutes (as opposed to the mean value as in AL1). For a normal distribution, the sample median is a robust estimate of the mean and is insensitive to outliers (e.g. incorrect measurements associated with low SNR). Thus, using the sample median allows for the use of Vlos with very low SNR and eventually increase data availability for AL2. A preliminary analysis of lidar data collected during February 15 to 26, 2013 shows that AL2 out-performs AL0 and AL1 when the resulting wind speed estimates are compared with independent data from a sonic anemometer (Table 1). Work is underway to test the performance of the three algorithms using a dataset of several months collected during spring/summer 2013 at NWTC, and the errors/uncertainties of each approach will be quantified in terms of their relationships with atmospheric conditions, such as wind shear and atmospheric stability, using the data from instrumentation deployed on the NWTC meteorological towers.Table 1 Summary of performance of the three lidar wind retrieval algorithms

Wang, H.; Barthelmie, R. J.; Clifton, A.; Capaldo, N.; Pryor, S. C.

2013-12-01

349

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

350

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

351

Solar wind eddies and the heliospheric current sheet  

NASA Technical Reports Server (NTRS)

Ulysses has collected data between 1 and 5 AU during, and just following solar maximum, when the heliospheric current sheet (HCS) can be thought of as reaching its maximum tilt and being subject to the maximum amount of turbulence in the solar wind. The Ulysses solar wind plasma instrument measures the vector velocity and can be used to estimate the flow speed and direction in turbulent 'eddies' in the solar wind that are a fraction of an astronomical unit in size and last (have either a turnover or dynamical interaction time of) several hours to more than a day. Here, in a simple exercise, these solar wind eddies at the HCS are characterized using Ulysses data. This character is then used to define a model flow field with eddies that is imposed on an ideal HCS to estimate how the HCS will be deformed by the flow. This model inherently results in the complexity of the HCS increasing with heliocentric distance, but the result is a measure of the degree to which the observed change in complexity is a measure of the importance of solar wind flows in deforming the HCS. By comparison with randomly selected intervals not located on the HCS, it appears that eddies on the HCS are similar to those elsewhere at this time during the solar cycle, as is the resultant deformation of the interplanetary magnetic field (IMF). The IMF deformation is analogous to what is often termed the 'random walk' of interplanetary magnetic field lines.

Suess, S. T.; Mccomas, D. J.; Bame, S. J.; Goldstein, B. E.

1995-01-01

352

Wind measurements for non-uniform wind fields from spaceborne scatterometers  

NASA Technical Reports Server (NTRS)

Radar backscattering coefficient measurements by spaceborne scatterometers are presently simulated for the case of nonuniform wind fields, by means of a detailed numerical integration of the radar equation. The winds thus estimated are then compared with a nominal field which is defined as the average wind vector over the wind cell. The simulation results obtained for the NASA scatterometer are presented for cases of random wind fields whose spectra are consistent with the Seasat scatterometer sea surface wind spectrum. When the nonuniformity is small, system noise dominates the wind error; wind error degradation is therefore small for both perfect and imperfect coregistration cases. When it is relatively large, however, the wind error degradation persistently increases for both perfect and imperfect coregistrations.

Chi, Chong-Yung; Li, Fuk K.

1987-01-01

353

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

354

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

355

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

356

Extreme Wind Velocity Measurement System  

NASA Technical Reports Server (NTRS)

A wind velocity measurement system employs two different principles of physics to measure wind speed: (1) the aerodynamic force imparted to a low profile, rigidly mounted cylindrical rod, and (2) the vibrating frequency of the rod as vortices are shed from the rod's cylindrical surface. A set of strain gages is used as a common sensor for both measurements, and these provide force measurements imparted by the wind on the rod. The signals generated by the strain gages are fed to processing circuitry that calculates the wind speed and direction from the signals. The force measurement is proportional to the square of the wind speed. Since it is a vector quantity, it can also be used to derive wind direction. The vortex shedding frequency is a scalar quantity and is linearly proportional to wind speed. This frequency can be calculated by analyzing the force measurements generated by the strain gages over time. Both of the wind velocity calculations can be advantageously used by the processing circuitry to generate an accurate wind velocity reading.

Zysko, Jan A. (Inventor); Starr, Stanley O. (Inventor)

2002-01-01

357

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

358

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

359

The Solar Wind  

NASA Technical Reports Server (NTRS)

The first evidence of the solar wind was provided through observations of comet tail deflections by L. Biermann in 1951. A cometary ion tail is oriented along the difference between the cometary and solar wind velocities, whereas the dust tail is in the antisunward direction; the ion tail directions demonstrated the existence of an outflow of ionized gas from the Sun (the solar wind) and allowed estimates of solar wind speed. Spacecraft observations have now established that at 1 AU the solar wind has a typical ion number density of about 7 /cc and is composed by number of about 95% protons and 5% Helium, with other minor ions also present. The solar wind as observed at 1 AU in the ecliptic has speeds typically in the range 300-700 km/ s. At such speeds ions travel from the Sun to 1 AU in from 2.5 to 6 days. The impact of the solar wind on planets with magnetic fields (Earth, Jupiter, Saturn, Uranus, Neptune) causes phenomena such as magnetospheres, aurorae, and geomagnetic storms, whereas at objects lacking magnetospheres (Mars, Venus, comets), atmospheric neutrals undergo charge exchange and are picked up by the solar wind flow. The solar wind also shields the Earth from low energy cosmic rays, and is responsible for the existence of the anomalous component of the cosmic rays a low energy component that is created locally rather than in the galaxy. Presented here is a brief introduction to the solar wind and a description of some current topics of research. Solar wind properties vary a great deal due to the changing magnetic structure on the Sun.

Goldstein, B. E.

1998-01-01

360

Vectors: Tip to Tail  

NSDL National Science Digital Library

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

Sharon Linamen

2012-07-23

361

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

362

Wind Turbine  

USGS Multimedia Gallery

The species of bats that are most susceptible to wind turbines all roost in trees throughout the year, leading some scientists to speculate that they may be visually mistaking wind turbines for trees in which to roost....

363

Wind Energy  

NSDL National Science Digital Library

Students learn about wind energy by making a pinwheel to model a wind turbine. Just like engineers, they decide where and how their turbine works best by testing it in different areas of the playground.

2014-09-18

364

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.

National Weather Service

2012-07-24

365

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.

366

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.

2011-08-20

367

Efficient transfer of base changes from a vector to the rice genome by homologous recombination: involvement of heteroduplex formation and mismatch correction  

Microsoft Academic Search

Gene targeting refers to the alteration of a specific DNA sequence in an endogenous gene at its original locus in the genome by homologous recombination. Through a gene-targeting procedure with positive- negative selection, we previously reported the generation of fertile transgenic rice plants with a positive marker inserted into the Adh2 gene by using an Agrobacterium-mediated transformation vector containing the

Yasuyo Johzuka-Hisatomi; Rie Terada; Shigeru Iida

2008-01-01

368

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

369

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

Microsoft Academic Search

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

D. T. Patten; S. D. Smith

1980-01-01

370

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

371

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

372

Balance of Forces with the Wind (title provided or enhanced by cataloger)  

NSDL National Science Digital Library

This applet tests the balance of the frictional, pressure gradient, and Coriolis forces with the wind. The applet displays vectors for these forces and the wind as the latitude, friction (drag), and pressure gradient are adjusted.

Steve Ackerman

373

Long-Term Wind Power Variability  

SciTech Connect

The National Renewable Energy Laboratory started collecting wind power data from large commercial wind power plants (WPPs) in southwest Minnesota with dedicated dataloggers and communication links in the spring of 2000. Over the years, additional WPPs in other areas were added to and removed from the data collection effort. The longest data stream of actual wind plant output is more than 10 years. The resulting data have been used to analyze wind power fluctuations, frequency distribution of changes, the effects of spatial diversity, and wind power ancillary services. This report uses the multi-year wind power data to examine long-term wind power variability.

Wan, Y. H.

2012-01-01

374

(^-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

375

Wind Turbines Adaptation to the Variability of the Wind Field  

NASA Astrophysics Data System (ADS)

WIND TURBINES ADAPTATION TO THE VARIABILITY OF THE WIND FIELD The subject of our scientific research is wind power turbines (WPT) with the horizontal axis which were now common in the world. Efficient wind turbines work is largely determined by non-stationarity of the wind field, expressed in its gustiness, the presence of vertical and horizontal shifts of wind speed and direction. At critical values of the wind parameters WPT has aerodynamic and mechanical overload, leading to breakdowns, premature wear and reduce the life of the wind turbine. To prevent accidents at the peak values of wind speed it is used the regulatory system of windwheels. WPT control systems provide a process orientation of the wind turbine rotor axis in the line of the mean wind. Wind turbines are also equipped with braking device used to protect against breakdowns when a significant increase in the wind. In general, all these methods of regulation are not always effective. Thus, in practice there may be situations when the wind speed is many times greater than the stated limit. For example, if there are microbursts in the atmospheric boundary layer, low-level wind shears caused by its gust front, storms, etc. It is required for a wind power turbine adaptation to intensive short-term wind impulses and considerable vertical wind shifts that the data about them shall be obtained ahead of time. To do this it is necessary to have the information on the real structure of the wind field in the area of the blade sweep for the minimum range against the wind that is determined by the mean speed and the system action time. The implementation of acoustic and laser traditional wind sounding systems is limited by ambient acoustic noise, by heavy rain, snowfall and by fog. There are free of these disadvantages the inclined radioacoustic sounding (IRASS) technique which works for a system of remote detection and control of wind gusts. IRASS technique is realized as low-potential Doppler pulse radar including combined RF-acoustic antenna installed coaxially with the gondola of the wind power turbine. The work of the technique is synchronized with rotation of blades to eliminate their shielding action. Dangerous in terms of dynamic strength is the wind load pulse, the rise time which is comparable with the period of the natural frequency of the wind turbine elements (blade, tower, rotor, etc.). The amplitude decay of resonant vibrations at critical values of the speed of rotation can be realized through the use of mechanical elastic supports with nonlinear artificial dampers. They have a high coefficient of resistance, but may cause self-excited oscillations. We propose the way to deal with raised vibration of wind turbine elements at the expense of short-term increase of damping in the range of critical rotary axis speeds or during impulsive effects of wind loadings (wind gusts). This is possible through the use of non-linear electromagnetic dampers or active magnetic bearings. Their feature is the possibility of varying the mechanical stiffness and damping properties by changing the electrical parameters of electromagnets. The controlling of these parameters is carried out by the control system (CS) with the information feedback on the spatial-temporal structure of the wind field obtained from IRASS. In the composition of the CS can also be included the rotational speed sensor of the WPT rotor. This approach to the adaptation of wind turbines will allow to reduce vibration and to perform early compensation of the load on their components, which arise under the wind gusts. In addition, corrections about the wind field obtained with IRASS, would increase the mean power of WPT.

Ulianov, Yuriy; Martynenko, Gennadii; Misaylov, Vitaliy; Soliannikova, Iuliia

2010-05-01

376

Tropical Winds in the Stratosphere from HRDI (1991-1996)  

NSDL National Science Digital Library

The High Resolution Doppler Interferometer (HRDI) measures winds in both the stratosphere and mesosphere. The tropical winds in the stratosphere undergo a slow two year variation called the quasibianunual oscillation. This oscillation controls mixing throughout the stratosphere and HRDI has given us much detail on wind changes associated with this oscillation. The animation indicates the line of zero wind speed in the zonal tropical winds, the height at which the winds change from eastward to westward.

Greg Shirah

1999-04-09

377

Wind Power: Creating a Wind Generator  

NSDL National Science Digital Library

This lesson challenges groups of learners to design and construct a wind generator with the most electrical output. The lesson focuses on the engineering design process and how it is used to identify a question (solve a problem), develop a design or change a design, test that design, observe and collect data, analyze that data, and finally, form a conclusion that can inform another round of design. In this activity, learners attempt to maximize the voltage obtained from a wind-driven turbine by conducting several experimental designs.

Demetrius Lutz

2012-01-01

378

Emerging Vector-Borne Diseases – Incidence through Vectors  

PubMed Central

Vector-borne diseases use to be a major public health concern only in tropical and subtropical areas, but today they are an emerging threat for the continental and developed countries also. Nowadays, in intercontinental countries, there is a struggle with emerging diseases, which have found their way to appear through vectors. Vector-borne zoonotic diseases occur when vectors, animal hosts, climate conditions, pathogens, and susceptible human population exist at the same time, at the same place. Global climate change is predicted to lead to an increase in vector-borne infectious diseases and disease outbreaks. It could affect the range and population of pathogens, host and vectors, transmission season, etc. Reliable surveillance for diseases that are most likely to emerge is required. Canine vector-borne diseases represent a complex group of diseases including anaplasmosis, babesiosis, bartonellosis, borreliosis, dirofilariosis, ehrlichiosis, and leishmaniosis. Some of these diseases cause serious clinical symptoms in dogs and some of them have a zoonotic potential with an effect to public health. It is expected from veterinarians in coordination with medical doctors to play a fundamental role at primarily prevention and then treatment of vector-borne diseases in dogs. The One Health concept has to be integrated into the struggle against emerging diseases. During a 4-year period, from 2009 to 2013, a total number of 551 dog samples were analyzed for vector-borne diseases (borreliosis, babesiosis, ehrlichiosis, anaplasmosis, dirofilariosis, and leishmaniasis) in routine laboratory work. The analysis was done by serological tests – ELISA for borreliosis, dirofilariosis, and leishmaniasis, modified Knott test for dirofilariosis, and blood smear for babesiosis, ehrlichiosis, and anaplasmosis. This number of samples represented 75% of total number of samples that were sent for analysis for different diseases in dogs. Annually, on average more then half of the samples brought to the laboratory to analysis for different infectious diseases are analyzed for vector-borne diseases. In the region of Vojvodina (northern part of Serbia), the following vector-borne infectious diseases have been found in dogs so far borreliosis, babesiosis, dirofilariosis, leishmaniasis, and anaplasmosis. PMID:25520951

Savi?, Sara; Vidi?, Branka; Grgi?, Zivoslav; Potkonjak, Aleksandar; Spasojevic, Ljubica

2014-01-01

379

AN ANALYSIS OF SEAWINDS SIMULTANEOUS WIND/RAIN RETRIEVAL IN SEVERE WEATHER EVENTS  

E-print Network

backscatter to a geophysical model function. However, SeaWinds measurements are also sensitive to rain both wind vectors and rain rates for a given ocean area. Instantaneous results of simultaneous wind/rain con- struction of a model to simulate variability in the SeaWinds rain estimates. The model is used

Long, David G.

380

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

381

Vector-Borne Diseases  

NSDL National Science Digital Library

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

Harvey Artsob

382

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

383

Automated mesoscale winds determined from satellite imagery  

NASA Technical Reports Server (NTRS)

A new automated technique for extracting mesoscale fields from GOES visible/infrared satellite imagery was developed. Quality control parameters were defined to allow objective editing of the wind fields. The system can produce equivalent or superior cloud wind estimates compared to the time consuming manual methods used on various interactive meteorological processing systems. Analysis of automated mesoscale cloud wind for a test case yields an estimated random error value one meter per second and produces both regional and mesoscale vector wind field structure and divergence patterns that are consistent in time and highly correlated with subsequent severe thunderstorm development.

1987-01-01

384

Vector Interpolative Logic  

E-print Network

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

Dragan Radojevi?; Zvonko Mari?

385

Vector Lane Threading  

Microsoft Academic Search

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

Suzanne Rivoire; Rebecca Schultz; Tomofumi Okuda; Christos Kozyrakis

2006-01-01

386

A Multithreaded Vector Coprocessor  

Microsoft Academic Search

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

Bernard Goossens

1997-01-01

387

Wind/Hybrid Electricity Applications  

SciTech Connect

Wind energy is widely recognized as the most efficient and cost effective form of new renewable energy available in the Midwest. New utility-scale wind farms (arrays of large turbines in high wind areas producing sufficient energy to serve thousands of homes) rival the cost of building new conventional forms of combustion energy plants, gas, diesel and coal power plants. Wind energy is not subject to the inflationary cost of fossil fuels. Wind energy can also be very attractive to residential and commercial electric customers in high wind areas who would like to be more self-sufficient for their energy needs. And wind energy is friendly to the environment at a time when there is increasing concern about pollution and climate change. However, wind energy is an intermittent source of power. Most wind turbines start producing small amounts of electricity at about 8-10 mph (4 meters per second) of wind speed. The turbine does not reach its rated output until the wind reaches about 26-28 mph (12 m/s). So what do you do for power when the output of the wind turbine is not sufficient to meet the demand for energy? This paper will discuss wind hybrid technology options that mix wind with other power sources and storage devices to help solve this problem. This will be done on a variety of scales on the impact of wind energy on the utility system as a whole, and on the commercial and small-scale residential applications. The average cost and cost-benefit of each application along with references to manufacturers will be given. Emerging technologies that promise to shape the future of renewable energy will be explored as well.

McDaniel, Lori

2001-03-31

388

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

389

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.

390

Wind Generator  

NSDL National Science Digital Library

Windmills have been used for hundreds of years to collect energy from the wind in order to pump water, grind grain, and more recently generate electricity. There are many possible designs for the blades of a wind generator and engineers are always trying new ones. Design and test your own wind generator, then try to improve it by running a small electric motor connected to a voltage sensor.

The Concord Consortium

2012-05-21

391

Seasonal Changes in Estuarine Dissolved Organic Matter Due to Variations in Discharge, Flushing Times and Wind-driven Mixing Events  

NASA Astrophysics Data System (ADS)

Estuaries are highly productive habitats that transport and transform organic matter (OM), experience large changes in ionic composition and act as a transition zone between terrestrial and marine environments (Paerl et al. 1998; Markager et al. 2011; Osburn et al. 2012). OM source and matrix effects (such as salinity and pH) influence the chemical structure of DOM in estuaries and therefore affect its bioavailability, photo-reactivity, and its overall fate in these systems (Jaffe et al. 2004; Boyd et al. 2010; Pace et al. 2012; Osburn et al. 2012; Cawley et al. 2013). Within estuaries, dissolved organic matter (DOM) is a heterogeneous mixture of aromatic and aliphatic compounds, and its composition in aquatic systems varies spatially and temporally with source (Bauer and Bianchi 2011). However, the main source of DOM in estuaries, rivers and other aquatic systems, originates from vascular plant detritus, soil humus, older fossil (i.e., petrogenic) organic carbon, black carbon, marine OM and in situ production (Hedges 2002; Houghton 2007; Bauer and Bianchi 2011). Chromophoric dissolved organic matter (CDOM), the light absorbing fraction of DOM, can be characterized using optical methods such as absorption and fluorescence spectroscopy (e.g. Coble, 1996; Stedmon and Markager, 2003). By analyzing the spatial and temporal variability of DOM and CDOM within estuaries, information pertaining to OM source and fate across the freshwater-marine continuum can be obtained. These methods offer an inexpensive, non-destructive means for obtaining sensitive measurements of a diverse group of organic compounds. By using this technology to analyze the spatial and temporal variability of CDOM within estuaries, information pertaining to OM source and fate across the freshwater-marine continuum can be obtained (Fellman et al. 2011; Osburn et al. 2012; Murphy et al. 2014). Chemical biomarkers are also routinely used to identify DOM sources in coastal waters. Examples are carbon stable isotopes (Bauer, 2002) and lignin (e.g., Benner and Opsahl, 2001; Harvey and Mannino, 2001). Marine DOM derived from phytoplankton typically has carbon stable isotope (delta13C) values that range from --20 to --22‰, while terrestrial DOM derived from C3 land plants typically have delta13C values that range from --26 to --28‰ (Bauer, 2002). Lignin is an important component of vascular plants, thus making it a unique geochemical biomarker, which can be used to trace the fate of terrestrial DOM in coastal seawater (e.g., Hernes and Benner, 2003; Walker et al. 2009; Osburn and Stedmon, 2011). Further, the ratios of the different phenolic compounds derived from the oxidation of lignin can be used to distinguish between plant sources (e.g. angiosperm vs. gymnosperm, or woody vs. non-woody tissue) and the extent of exposure to degradation (Hedges et al. 1988). The highly productive, eutrophic waters of the Neuse River Estuary (NRE), in eastern North Carolina, USA, serve as a transition zone for terrigenous DOM between the head of the Neuse River and Pamlico Sound. Previous studies have determined that the NRE is dominated by inputs from riverine discharge, yet very clear shifts in DOM quality are apparent as discharge varied (Paerl et al. 1998; Osburn et al. 2012). Furthermore, flushing times within the NRE will aid in determining whether DOM is primarily autochthonous or allochthonous and if it is processed internally or transported downstream to the Pamlico Sound (Paerl et al. 1998; Mari et al. 2007, Peierls et al. 2012). Therefore, the main sources of DOM and its composition can change throughout an estuary depending on the hydrodynamic conditions. For example, increases in flushing time may allow for the accumulation of autochthonous DOM because of (1) planktonic communities within the water column having more time to utilize nutrients within the system, resulting in phytoplankton blooms and (2) lower inputs of allochthonous OM from the NRE's watershed (Dixon et al. accepted). Therefore, the main sources of DOM and its composition can change throughout an est

Dixon, Jennifer Louise

392

Storminess variation at Skagen, northern Denmark since AD 1860: Relations to climate change and implications for coastal dunes  

NASA Astrophysics Data System (ADS)

Systematic observations of wind speed and direction have been collected at Skagen Fyr (Skagen Lighthouse), northern Denmark from December 1860 to August 2012. Wind speed and wind direction are analyzed based on two data sets given in Beaufort and m/s respectively and based on these data storminess variation is analyzed. Changes in wind climate during this time interval cover the final phase of the relatively cold Little Ice Age and the following warming since the late 19th century. Since the end of the Little Ice Age the wind pattern has clearly changed in terms of both strength and direction. Between 1860 and 1875 storminess (wind events exceeding Beaufort 8) is extremely high, but since then storminess decreases. Around 1870 the annual drift potential (DP) is also extremely high and reaches up to 9600 vector units (VU); since 1980 DP levels are below 3000 VU and decreasing. Resultant drift direction (RDD) is towards the east or east-north-east until about 1960 when it steadily becomes more and more northerly. Most storms occur during autumn and early winter. Summers are less stormy but characterized by unidirectional winds. Since the end of the Little Ice Age most inland parabolic dunes on Skagen Odde have undergone a general stabilization. This shift in dune dynamics is primarily related to continued dune management, but the change in wind climate including an overall decrease in storminess (including a marked decrease in summer storminess) and an increase in southerly and south-westerly winds probably contribute to dune stabilization.

Clemmensen, Lars B.; Hansen, Kristian W. T.; Kroon, Aart

2014-12-01

393

VisibleWind: wind profile measurements at low altitude  

NASA Astrophysics Data System (ADS)

VisibleWindTM is developing an inexpensive rapid response system, for accurately characterizing wind shear and small scale wind phenomena in the boundary layer and for prospecting suitable locations for wind power turbines. The ValidWind system can also collect reliable "ground truth" for other remote wind sensors. The system employs small (0.25 m dia.) lightweight balloons and a tracker consisting of an Impulse 200 XL laser rangefinder coupled to a PC for automated data recording. Experiments on balloon trajectories demonstrate that the laser detection of range (+/- 0.5 m), together with measured azimuth and altitude, is an inexpensive, convenient, and capable alternative to other wind tracking methods. The maximum detection range has been increased to 2200 meters using micro-corner-cube retroreflector tape on balloons. Low power LEDs enable nighttime tracking. To avoid large balloon gyrations about the mean trajectory, we use balloons having low ascent rates and subcritical Reynolds numbers. Trajectory points are typically recorded every 4 - 7 seconds. Atmospheric features observed under conditions of inversions or "light and variable winds" include abrupt onsets of shear at altitudes of 100-250 m, velocity changes of order 1-3 m/s within layers of 10-20 m thickness, and veering of the wind direction by 180 degrees or more as altitude increases from 300 to 500 m. We have previously reported comparisons of balloon-based wind profiles with the output of a co-located sodar. Even with the Impulse rangefinder, our system still requires a "man in the loop" to track the balloon. A future system enhancement will automate balloon tracking, so that laser returns are obtained automatically at 1 Hz. While balloon measurements of large-scale, high altitude wind profiles are well known, this novel measurement system provides high-resolution, real-time characterization of the fluctuating local wind fields at the bottom of the boundary layer where wind power turbines and other remote wind sensors must operate.

Wilkerson, Tom; Bradford, Bill; Marchant, Alan; Apedaile, Tom; Wright, Cordell

2009-09-01

394

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

395

2008 WIND TECHNOLOGIES MARKET REPORT  

Microsoft Academic Search

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

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

2009-01-01

396

Wind turbine rotor control system  

Microsoft Academic Search

In a pitch control system for a wind turbine, a mechanical control system changes pitch angle of the rotor blades collectively in response to blade pitch moment. The control system is designed to be used with a downwind constant speed two-bladed horizontal axis teetering hub wind turbine. Pitch placement controls torque for a synchronous alternator connected to the electrical power

C. Coleman; H. D. Currin

1984-01-01

397

Solar wind stagnation near comets  

Microsoft Academic Search

The nature of the solar wind flow near comets is examined analytically in this paper. In particular, typical values for the stagnation pressure and magnetic barrier strength are estimated, taking into account magnetic field line tension and change-exchange cooling of the mass-loaded solar wind. A knowledge of the strength of the magnetic barrier is required in order to determine the

A. A. Galeev; T. E. Cravens; T. I. Gombosi

1985-01-01

398

Stage-specific binding of Leishmania donovani to the sand fly vector midgut is regulated by conformational changes in the abundant surface lipophosphoglycan.  

PubMed

The life cycle of Leishmania parasites within the sand fly vector includes the development of extracellular promastigotes from a noninfective, procyclic stage into an infective, metacyclic stage that is uniquely adapted for transmission by the fly and survival in the vertebrate host. These adaptations were explored in the context of the structure and function of the abundant surface lipophosphoglycan (LPG) on Leishmania donovani promastigotes. During metacyclogenesis, the salient structural feature of L. donovani LPG is conserved, involving expression of a phosphoglycan chain made up of unsubstituted disaccharide-phosphate repeats. Two important developmental modifications were also observed. First, the size of the molecule is substantially increased because of a twofold increase in the number of phosphorylated disaccharide repeat units expressed. Second, there is a concomitant decrease in the presentation of terminally exposed sugars. This later property was indicated by the reduced accessibility of terminal galactose residues to galactose oxidase and the loss of binding by the lectins, peanut agglutinin, and concanavalin A, to metacyclic LPG in vivo and in vitro. The loss of lectin binding was not due to downregulation of the capping oligosaccharides as the same beta-linked galactose or alpha-linked mannose-terminating oligosaccharides were present in both procyclic and metacyclic promastigotes. The capping sugars on procyclic LPG were found to mediate procyclic attachment to the sand fly midgut, whereas these same sugars on metacyclic LPG failed to mediate metacyclic binding. And whereas intact metacyclic LPG did not inhibit procyclic attachment, depolymerized LPG inhibited as well as procyclic LPG, demonstrating that the ligands are normally buried. The masking of the terminal sugars is attributed to folding and clustering of the extended phosphoglycan chains, which form densely distributed particulate structures visible on fracture-flip preparations of the metacyclic surface. The exposure and subsequent masking of the terminal capping sugars explains the stage specificity of promastigote attachment to and release from the vector midgut, which are key events in the development of transmissible infections in the fly. PMID:7836922

Sacks, D L; Pimenta, P F; McConville, M J; Schneider, P; Turco, S J

1995-02-01

399

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

400

Methods and apparatus for reducing peak wind turbine loads  

DOEpatents

A method for reducing peak loads of wind turbines in a changing wind environment includes measuring or estimating an instantaneous wind speed and direction at the wind turbine and determining a yaw error of the wind turbine relative to the measured instantaneous wind direction. The method further includes comparing the yaw error to a yaw error trigger that has different values at different wind speeds and shutting down the wind turbine when the yaw error exceeds the yaw error trigger corresponding to the measured or estimated instantaneous wind speed.

Moroz, Emilian Mieczyslaw

2007-02-13

401

Wind energy.  

PubMed

From its rebirth in the early 1980s, the rate of development of wind energy has been dramatic. Today, other than hydropower, it is the most important of the renewable sources of power. The UK Government and the EU Commission have adopted targets for renewable energy generation of 10 and 12% of consumption, respectively. Much of this, by necessity, must be met by wind energy. The US Department of Energy has set a goal of 6% of electricity supply from wind energy by 2020. For this potential to be fully realized, several aspects, related to public acceptance, and technical issues, related to the expected increase in penetration on the electricity network and the current drive towards larger wind turbines, need to be resolved. Nevertheless, these challenges will be met and wind energy will, very likely, become increasingly important over the next two decades. An overview of the technology is presented. PMID:17272245

Leithead, W E

2007-04-15

402

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