WorldWideScience

Sample records for wind number density

  1. Number density structures in the inner heliosphere

    Science.gov (United States)

    Stansby, D.; Horbury, T. S.

    2018-06-01

    Aims: The origins and generation mechanisms of the slow solar wind are still unclear. Part of the slow solar wind is populated by number density structures, discrete patches of increased number density that are frozen in to and move with the bulk solar wind. In this paper we aimed to provide the first in-situ statistical study of number density structures in the inner heliosphere. Methods: We reprocessed in-situ ion distribution functions measured by Helios in the inner heliosphere to provide a new reliable set of proton plasma moments for the entire mission. From this new data set we looked for number density structures measured within 0.5 AU of the Sun and studied their properties. Results: We identified 140 discrete areas of enhanced number density. The structures occurred exclusively in the slow solar wind and spanned a wide range of length scales from 50 Mm to 2000 Mm, which includes smaller scales than have been previously observed. They were also consistently denser and hotter that the surrounding plasma, but had lower magnetic field strengths, and therefore remained in pressure balance. Conclusions: Our observations show that these structures are present in the slow solar wind at a wide range of scales, some of which are too small to be detected by remote sensing instruments. These structures are rare, accounting for only 1% of the slow solar wind measured by Helios, and are not a significant contribution to the mass flux of the solar wind.

  2. Wind power statistics and an evaluation of wind energy density

    Energy Technology Data Exchange (ETDEWEB)

    Jamil, M.; Parsa, S.; Majidi, M. [Materials and Energy Research Centre, Tehran (Iran, Islamic Republic of)

    1995-11-01

    In this paper the statistical data of fifty days` wind speed measurements at the MERC- solar site are used to find out the wind energy density and other wind characteristics with the help of the Weibull probability distribution function. It is emphasized that the Weibull and Rayleigh probability functions are useful tools for wind energy density estimation but are not quite appropriate for properly fitting the actual wind data of low mean speed, short-time records. One has to use either the actual wind data (histogram) or look for a better fit by other models of the probability function. (Author)

  3. Winding around the winding number in topology, geometry, and analysis

    CERN Document Server

    Roe, John

    2015-01-01

    The winding number is one of the most basic invariants in topology. It measures the number of times a moving point P goes around a fixed point Q, provided that P travels on a path that never goes through Q and that the final position of P is the same as its starting position. This simple idea has far-reaching applications. The reader of this book will learn how the winding number can help us show that every polynomial equation has a root (the fundamental theorem of algebra), guarantee a fair division of three objects in space by a single planar cut (the ham sandwich theorem), explain why ever

  4. Gauge transformations with fractional winding numbers

    International Nuclear Information System (INIS)

    Abouelsaood, A.

    1996-01-01

    The role which gauge transformations of noninteger winding numbers might play in non-Abelian gauge theories is studied. The phase factor acquired by the semiclassical physical states in an arbitrary background gauge field when they undergo a gauge transformation of an arbitrary real winding number is calculated in the path integral formalism assuming that a θFF term added to the Lagrangian plays the same role as in the case of integer winding numbers. Requiring that these states provide a representation of the group of open-quote open-quote large close-quote close-quote gauge transformations, a condition on the allowed backgrounds is obtained. It is shown that this representability condition is only satisfied in the monopole sector of a spontaneously broken gauge theory, but not in the vacuum sector of an unbroken or a spontaneously broken non-Abelian gauge theory. It is further shown that the recent proof of the vanishing of the θ parameter when gauge transformations of arbitrary fractional winding numbers are allowed breaks down in precisely those cases where the representability condition is obeyed because certain gauge transformations needed for the proof, and whose existence is assumed, are either spontaneously broken or cannot be globally defined as a result of a topological obstruction. copyright 1996 The American Physical Society

  5. The number density of a charged relic

    International Nuclear Information System (INIS)

    Berger, C.F.; Kraml, S.; Palorini, F.

    2008-07-01

    We investigate scenarios in which a charged, long-lived scalar particle decouples from the primordial plasma in the Early Universe. We compute the number density at time of freeze-out considering both the cases of abelian and non-abelian interactions and including the effect of Sommerfeld enhancement at low initial velocity. We also discuss as extreme case the maximal cross section that fulfils the unitarity bound. We then compare these number densities to the exotic nuclei searches for stable relics and to the BBN bounds on unstable relics and draw conclusions for the cases of a stau or stop NLSP in supersymmetric models with a gravitino or axino LSP. (orig.)

  6. The number density of a charged relic

    Energy Technology Data Exchange (ETDEWEB)

    Berger, C.F. [Massachusetts Institute of Technology, Cambridge, MA (United States). Center for Theoretical Physics]|[California Univ., Santa Barbara, CA (United States). Kavli Inst. for Theoretical Physics; Covi, L. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Kraml, S. [CNRS/IN2P3, Grenoble (France). Lab. de Physique Subatomique et de Cosmologie; Palorini, F. [Lyon Univ., UCBL, CNRS/IN2P3, Villeurbanne (France). IPN de Lyon

    2008-07-15

    We investigate scenarios in which a charged, long-lived scalar particle decouples from the primordial plasma in the Early Universe. We compute the number density at time of freeze-out considering both the cases of abelian and non-abelian interactions and including the effect of Sommerfeld enhancement at low initial velocity. We also discuss as extreme case the maximal cross section that fulfils the unitarity bound. We then compare these number densities to the exotic nuclei searches for stable relics and to the BBN bounds on unstable relics and draw conclusions for the cases of a stau or stop NLSP in supersymmetric models with a gravitino or axino LSP. (orig.)

  7. Effect of pole number and slot number on performance of dual rotor permanent magnet wind power generator using ferrite magnets

    Directory of Open Access Journals (Sweden)

    Peifeng Xu

    2017-05-01

    Full Text Available Dual rotor permanent magnet (DRPM wind power generator using ferrite magnets has the advantages of low cost, high efficiency, and high torque density. How to further improve the performance and reduce the cost of the machine by proper choice of pole number and slot number is an important problem to be solved when performing preliminarily design a DRPM wind generator. This paper presents a comprehensive performance comparison of a DRPM wind generator using ferrite magnets with different slot and pole number combinations. The main winding factors are calculated by means of the star of slots. Under the same machine volume and ferrite consumption, the flux linkage, back-electromotive force (EMF, cogging torque, output torque, torque pulsation, and losses are investigated and compared using finite element analysis (FEA. The results show that the slot and pole number combinations have an important impact on the generator properties.

  8. High Power Density Power Electronic Converters for Large Wind Turbines

    DEFF Research Database (Denmark)

    Senturk, Osman Selcuk

    . For these VSCs, high power density is required due to limited turbine nacelle space. Also, high reliability is required since maintenance cost of these remotely located wind turbines is quite high and these turbines operate under harsh operating conditions. In order to select a high power density and reliability......In large wind turbines (in MW and multi-MW ranges), which are extensively utilized in wind power plants, full-scale medium voltage (MV) multi-level (ML) voltage source converters (VSCs) are being more preferably employed nowadays for interfacing these wind turbines with electricity grids...... VSC solution for wind turbines, first, the VSC topology and the switch technology to be employed should be specified such that the highest possible power density and reliability are to be attained. Then, this qualitative approach should be complemented with the power density and reliability...

  9. A joint probability density function of wind speed and direction for wind energy analysis

    International Nuclear Information System (INIS)

    Carta, Jose A.; Ramirez, Penelope; Bueno, Celia

    2008-01-01

    A very flexible joint probability density function of wind speed and direction is presented in this paper for use in wind energy analysis. A method that enables angular-linear distributions to be obtained with specified marginal distributions has been used for this purpose. For the marginal distribution of wind speed we use a singly truncated from below Normal-Weibull mixture distribution. The marginal distribution of wind direction comprises a finite mixture of von Mises distributions. The proposed model is applied in this paper to wind direction and wind speed hourly data recorded at several weather stations located in the Canary Islands (Spain). The suitability of the distributions is judged from the coefficient of determination R 2 . The conclusions reached are that the joint distribution proposed in this paper: (a) can represent unimodal, bimodal and bitangential wind speed frequency distributions, (b) takes into account the frequency of null winds, (c) represents the wind direction regimes in zones with several modes or prevailing wind directions, (d) takes into account the correlation between wind speeds and its directions. It can therefore be used in several tasks involved in the evaluation process of the wind resources available at a potential site. We also conclude that, in the case of the Canary Islands, the proposed model provides better fits in all the cases analysed than those obtained with the models used in the specialised literature on wind energy

  10. Wind Characteristics and an Evaluation of Wind Power Density at Three Sites in Egypt

    International Nuclear Information System (INIS)

    Etman, S.M.

    2008-01-01

    This paper presents the results of the analysis of wind speed data for one calendar year (2005) at three stations (El-Tor, El-Nonzha, and El-Notron) in Egypt along with the wind energy potential of each site. The wind power density at 25 m height was obtained by extrapolation of data at 10 m using a Power-law expression. The frequency distribution of observed hourly wind speeds occurring at each station is examined, particularly for wind speeds greater than or equal to 3 and 5 m/s (cut-in wind speeds for most wind turbines). The study reveals that the wind turbine can be operated at the sites El-Tor, El-Nouzha, and El-Notron with an annual availability factor of about 89.9 %, 76.2 %, and 67.9 % if the cut-in wind speed is 3 m/s and 67.2 %,51.8 %, and 17.1 % if the cut-in wind speed is 5 m/s, respectively. The total available wind power density ( kWh/m 2 /yr) Was estimated at the selected sites; El-Tor, El-Nouzha and El-Notron and was found to be: 3838.4, 825.5 and 284 kWh/m 2 /yr for case 3m/s and 2276.2, 489,5 and 71 kWh/m 2 /yr for case 5 m/s, respectively

  11. Wind farm density and harvested power in very large wind farms: A low-order model

    Science.gov (United States)

    Cortina, G.; Sharma, V.; Calaf, M.

    2017-07-01

    In this work we create new understanding of wind turbine wakes recovery process as a function of wind farm density using large-eddy simulations of an atmospheric boundary layer diurnal cycle. Simulations are forced with a constant geostrophic wind and a time varying surface temperature extracted from a selected period of the Cooperative Atmospheric Surface Exchange Study field experiment. Wind turbines are represented using the actuator disk model with rotation and yaw alignment. A control volume analysis around each turbine has been used to evaluate wind turbine wake recovery and corresponding harvested power. Results confirm the existence of two dominant recovery mechanisms, advection and flux of mean kinetic energy, which are modulated by the background thermal stratification. For the low-density arrangements advection dominates, while for the highly loaded wind farms the mean kinetic energy recovers through fluxes of mean kinetic energy. For those cases in between, a smooth balance of both mechanisms exists. From the results, a low-order model for the wind farms' harvested power as a function of thermal stratification and wind farm density has been developed, which has the potential to be used as an order-of-magnitude assessment tool.

  12. Induction Motor with Switchable Number of Poles and Toroidal Winding

    Directory of Open Access Journals (Sweden)

    MUNTEANU, A.

    2011-05-01

    Full Text Available This paper presents a study of an induction motor provided with toroidal stator winding. The ring-type coils offer a higher versatility in obtaining a different number of pole pairs by means of delta/star and series/parallel connections respectively. As consequence, the developed torque can vary within large limits and the motor can be utilized for applications that require, for example, high load torque values for a short time. The study involves experimental tests and FEM simulation for an induction machine with three configurations of pole pairs. The conclusions attest the superiority of the toroidal winding for certain applications such as electric vehicles or lifting machines.

  13. Manifestation of solar activity in solar wind particle flux density

    International Nuclear Information System (INIS)

    Kovalenko, V.A.

    1988-01-01

    An analysis has been made of the origin of long-term variations in flux density of solar wind particles (nv) for different velocity regimes. The study revealed a relationship of these variations to the area of the polar coronal holes (CH). It is shown that within the framework of the model under development, the main longterm variations of nv are a result of the latitude redistribution of the solar wind mass flux in the heliosphere and are due to changes in the large-scale geometry of the solar plasma flow in the corona. A study has been made of the variations of nv for high speed solar wind streams. It is found that nv in high speed streams which are formed in CH, decreases from minimum to maximum solar activity. The analysis indicates that this decrease is attributable to the magnetic field strength increase in coronal holes. It has been found that periods of rapid global changes of background magnetic fields on the Sun are accompanied by a reconfiguration of coronal magnetic fields, rapid changes in the length of quiescent filaments, and by an increase in the density of the particle flux of a high speed solar wind. It has been established that these periods precede the formation of CH, corresponding to the increase in solar wind velocity near the Earth and to enhancement of the level of geomagnetic disturbance. (author)

  14. The winding number of three complexes in SU(3)

    International Nuclear Information System (INIS)

    Lasher, G.

    1989-01-01

    The Phillip-Stone algorithm for the topological charge of a lattice gauge field requires the computation of the winding number of certain 3-complexes in the space of the group. The extension of the computational procedure for the SU(2) gauge group to SU(3) requires an understanding of the SU(3) geometry. An important issue is the behavior of a 3-cell in SU(3) as it approaches a critical configuration, i.e., one at which the cell is a discontinuous function of its vertices. A measure of the proximity of a cell to criticality is found and a method for computing its contribution to the winding number is recommended. (orig.)

  15. Solar wind structure suggested by bimodal correlations of solar wind speed and density between the spacecraft SOHO and Wind

    Science.gov (United States)

    Ogilvie, K. W.; Coplan, M. A.; Roberts, D. A.; Ipavich, F.

    2007-08-01

    We calculate the cross-spacecraft maximum lagged-cross-correlation coefficients for 2-hour intervals of solar wind speed and density measurements made by the plasma instruments on the Solar and Heliospheric Observatory (SOHO) and Wind spacecraft over the period from 1996, the minimum of solar cycle 23, through the end of 2005. During this period, SOHO was located at L1, about 200 R E upstream from the Earth, while Wind spent most of the time in the interplanetary medium at distances of more than 100 R E from the Earth. Yearly histograms of the maximum, time-lagged correlation coefficients for both the speed and density are bimodal in shape, suggesting the existence of two distinct solar wind regimes. The larger correlation coefficients we suggest are due to structured solar wind, including discontinuities and shocks, while the smaller are likely due to Alfvénic turbulence. While further work will be required to firmly establish the physical nature of the two populations, the results of the analysis are consistent with a solar wind that consists of turbulence from quiet regions of the Sun interspersed with highly filamentary structures largely convected from regions in the inner solar corona. The bimodal appearance of the distributions is less evident in the solar wind speed than in the density correlations, consistent with the observation that the filamentary structures are convected with nearly constant speed by the time they reach 1 AU. We also find that at solar minimum the fits for the density correlations have smaller high-correlation components than at solar maximum. We interpret this as due to the presence of more relatively uniform Alfvénic regions at solar minimum than at solar maximum.

  16. The redshift number density evolution of Mg II absorption systems

    International Nuclear Information System (INIS)

    Chen Zhi-Fu

    2013-01-01

    We make use of the recent large sample of 17 042 Mg II absorption systems from Quider et al. to analyze the evolution of the redshift number density. Regardless of the strength of the absorption line, we find that the evolution of the redshift number density can be clearly distinguished into three different phases. In the intermediate redshift epoch (0.6 ≲ z ≲ 1.6), the evolution of the redshift number density is consistent with the non-evolution curve, however, the non-evolution curve over-predicts the values of the redshift number density in the early (z ≲ 0.6) and late (z ≳ 1.6) epochs. Based on the invariant cross-section of the absorber, the lack of evolution in the redshift number density compared to the non-evolution curve implies the galaxy number density does not evolve during the middle epoch. The flat evolution of the redshift number density tends to correspond to a shallow evolution in the galaxy merger rate during the late epoch, and the steep decrease of the redshift number density might be ascribed to the small mass of halos during the early epoch.

  17. Precision Electron Density Measurements in the SSX MHD Wind Tunnel

    Science.gov (United States)

    Suen-Lewis, Emma M.; Barbano, Luke J.; Shrock, Jaron E.; Kaur, Manjit; Schaffner, David A.; Brown, Michael R.

    2017-10-01

    We characterize fluctuations of the line averaged electron density of Taylor states produced by the magnetized coaxial plasma gun of the SSX device using a 632.8 nm HeNe laser interferometer. The analysis method uses the electron density dependence of the refractive index of the plasma to determine the electron density of the Taylor states. Typical magnetic field and density values in the SSX device approach about B ≅ 0.3 T and n = 0 . 4 ×1016 cm-3 . Analysis is improved from previous density measurement methods by developing a post-processing method to remove relative phase error between interferometer outputs and to account for approximately linear phase drift due to low-frequency mechanical vibrations of the interferometer. Precision density measurements coupled with local measurements of the magnetic field will allow us to characterize the wave composition of SSX plasma via density vs. magnetic field correlation analysis, and compare the wave composition of SSX plasma with that of the solar wind. Preliminary results indicate that density and magnetic field appear negatively correlated. Work supported by DOE ARPA-E ALPHA program.

  18. Strong coupling QCD at finite baryon-number density

    International Nuclear Information System (INIS)

    Karsch, F.; Muetter, K.H.

    1989-01-01

    We present a new representation of the partition function for strong-coupling QCD which is suitable also for finite baryon-number-density simulations. This enables us to study the phase structure in the canonical formulation (with fixed baryon number B) as well as the grand canonical one (with fixed chemical potential μ). We find a clear signal for a first-order chiral phase transition at μ c a=0.63. The critical baryon-number density n c a 3 =0.045 is only slightly higher than the density of nuclear matter. (orig.)

  19. Power spectral density analysis of wind-shear turbulence for related flight simulations. M.S. Thesis

    Science.gov (United States)

    Laituri, Tony R.

    1988-01-01

    Meteorological phenomena known as microbursts can produce abrupt changes in wind direction and/or speed over a very short distance in the atmosphere. These changes in flow characteristics have been labelled wind shear. Because of its adverse effects on aerodynamic lift, wind shear poses its most immediate threat to flight operations at low altitudes. The number of recent commercial aircraft accidents attributed to wind shear has necessitated a better understanding of how energy is transferred to an aircraft from wind-shear turbulence. Isotropic turbulence here serves as the basis of comparison for the anisotropic turbulence which exists in the low-altitude wind shear. The related question of how isotropic turbulence scales in a wind shear is addressed from the perspective of power spectral density (psd). The role of the psd in related Monte Carlo simulations is also considered.

  20. MATERIAL COMPOSITIONS AND NUMBER DENSITIES FOR NEUTRONICS CALCULATIONS

    International Nuclear Information System (INIS)

    D. A. Thomas

    1996-01-01

    The purpose of this analysis is to calculate the number densities and isotopic weight percentages of the standard materials to be used in the neutronics (criticality and radiation shielding) evaluations by the Waste Package Development Department. The objective of this analysis is to provide material number density information which can be referenced by future neutronics design analyses, such as for those supporting the Conceptual Design Report

  1. Number theory an introduction via the density of primes

    CERN Document Server

    Fine, Benjamin

    2016-01-01

    Now in its second edition, this textbook provides an introduction and overview of number theory based on the density and properties of the prime numbers. This unique approach offers both a firm background in the standard material of number theory, as well as an overview of the entire discipline. All of the essential topics are covered, such as the fundamental theorem of arithmetic, theory of congruences, quadratic reciprocity, arithmetic functions, and the distribution of primes. New in this edition are coverage of p-adic numbers, Hensel's lemma, multiple zeta-values, and elliptic curve methods in primality testing. Key topics and features include: A solid introduction to analytic number theory, including full proofs of Dirichlet's Theorem and the Prime Number Theorem Concise treatment of algebraic number theory, including a complete presentation of primes, prime factorizations in algebraic number fields, and unique factorization of ideals Discussion of the AKS algorithm, which shows that primality testing is...

  2. Characteristics of Solar Wind Density Depletions During Solar Cycles 23 and 24

    Directory of Open Access Journals (Sweden)

    Keunchan Park

    2017-06-01

    Full Text Available Solar wind density depletions are phenomena that solar wind density is rapidly decreased and keep the state. They are generally believed to be caused by the interplanetary (IP shocks. However, there are other cases that are hardly associated with IP shocks. We set up a hypothesis for this phenomenon and analyze this study. We have collected the solar wind parameters such as density, speed and interplanetary magnetic field (IMF data related to the solar wind density depletion events during the period from 1996 to 2013 that are obtained with the advanced composition explorer (ACE and the Wind satellite. We also calculate two pressures (magnetic, dynamic and analyze the relation with density depletion. As a result, we found total 53 events and the most these phenomena’s sources caused by IP shock are interplanetary coronal mass ejection (ICME. We also found that solar wind density depletions are scarcely related with IP shock’s parameters. The solar wind density is correlated with solar wind dynamic pressure within density depletion. However, the solar wind density has an little anti-correlation with IMF strength during all events of solar wind density depletion, regardless of the presence of IP shocks. Additionally, In 47 events of IP shocks, we find 6 events that show a feature of blast wave. The quantities of IP shocks are weaker than blast wave from the Sun, they are declined in a short time after increasing rapidly. We thus argue that IMF strength or dynamic pressure are an important factor in understanding the nature of solar wind density depletion. Since IMF strength and solar wind speed varies with solar cycle, we will also investigate the characteristics of solar wind density depletion events in different phases of solar cycle as an additional clue to their physical nature.

  3. Frozen density embedding with non-integer subsystems' particle numbers.

    Science.gov (United States)

    Fabiano, Eduardo; Laricchia, Savio; Della Sala, Fabio

    2014-03-21

    We extend the frozen density embedding theory to non-integer subsystems' particles numbers. Different features of this formulation are discussed, with special concern for approximate embedding calculations. In particular, we highlight the relation between the non-integer particle-number partition scheme and the resulting embedding errors. Finally, we provide a discussion of the implications of the present theory for the derivative discontinuity issue and the calculation of chemical reactivity descriptors.

  4. Effective atomic number, electron density and kerma of gamma ...

    Indian Academy of Sciences (India)

    Abstract. An attempt has been made to estimate the effective atomic number, electron density (0.001 to 105 MeV) and kerma (0.001 to 20 MeV) of gamma radiation for a wide range of oxides of ... The lanthanide oxides find remarkable applications in the field of medicine, biology, nuclear engineering and space technology.

  5. Optimal Pole Number and Winding Designs for Low Speed–High Torque Synchronous Reluctance Machines

    Directory of Open Access Journals (Sweden)

    Gurutz Artetxe

    2018-01-01

    Full Text Available This paper studies the feasibility of using synchronous reluctance machines (SynRM for low speed–high torque applications. The challenge lies in obtaining low torque ripple values, high power factor, and, especially, high torque density values, comparable to those of permanent magnet synchronous machines (PMSMs, but without resorting to use permanent magnets. A design and calculation procedure based on multistatic finite element analysis is developed and experimentally validated via a 200 Nm, 160 rpm prototype SynRM. After that, machine designs with different rotor pole and stator slot number combinations are studied, together with different winding types: integral-slot distributed-windings (ISDW, fractional-slot distributed-windings (FSDW and fractional-slot concentrated-windings (FSCW. Some design criteria for low-speed SynRM are drawn from the results of the study. Finally, a performance comparison between a PMSM and a SynRM is performed for the same application and the conclusions of the study are summarized.

  6. Winding numbers in homotopy theory from integers to reals

    International Nuclear Information System (INIS)

    Mekhfi, M.

    1993-07-01

    In Homotopy Theory (HT) we define paths on a given topological space. Closed paths prove to be construction elements of a group (the fundamental group) Π 1 and carry charges, the winding numbers. The charges are integers as they indicate how many times closed paths encircle a given hole (or set of holes). Open paths as they are defined in (HT) do not possess any groups structure and as such they are less useful in topology. In the present paper we enlarge the concept of a path in such a way that both types of paths do possess a group structure. In this broad sense we have two fundamental groups the Π i = Z group and the SO(2) group of rotations but the latter has the global property that there is no periodicity in the rotation angle. There is also two charge operators W and W λ whose eigenvalues are either integers or reals depending respectively on the paths being closed or open. Also the SO(2) group and the real charge operator W λ are not independently defined but directly related respectively to the Π i group and to the integer charge operator W. Thus well defined links can be established between seemingly different groups and charges. (author). 3 refs, 1 fig

  7. Effective atomic number and electron density of marble concrete

    International Nuclear Information System (INIS)

    Akkurt, I.; El-Khayatt, A.M.

    2013-01-01

    The effective atomic numbers (Z eff ) and effective electron density (N e ) of different type concrete have been measured and the results were compared with the calculation obtained using the mass attenuation coefficients (μ/ρ) obtained via XCOM in the photon energy range of 1 keV-100 GeV. Six different concrete in where marble has been used in the rate of 0, 5, 10, 15, 20, 25 %, has been used in the study. (author)

  8. Multi-objective random search algorithm for simultaneously optimizing wind farm layout and number of turbines

    DEFF Research Database (Denmark)

    Feng, Ju; Shen, Wen Zhong; Xu, Chang

    2016-01-01

    A new algorithm for multi-objective wind farm layout optimization is presented. It formulates the wind turbine locations as continuous variables and is capable of optimizing the number of turbines and their locations in the wind farm simultaneously. Two objectives are considered. One is to maximi...

  9. Substorm-related thermospheric density and wind disturbances derived from CHAMP observations

    Directory of Open Access Journals (Sweden)

    P. Ritter

    2010-06-01

    Full Text Available The input of energy and momentum from the magnetosphere is most efficiently coupled into the high latitude ionosphere-thermosphere. The phenomenon we are focusing on here is the magnetospheric substorm. This paper presents substorm related observations of the thermosphere derived from the CHAMP satellite. With its sensitive accelerometer the satellite can measure the air density and zonal winds. Based on a large number of substorm events the average high and low latitude thermospheric response to substorm onsets was deduced. During magnetic substorms the thermospheric density is enhanced first at high latitudes. Then the disturbance travels at an average speed of 650 m/s to lower latitudes, and 3–4 h later the bulge reaches the equator on the night side. Under the influence of the Coriolis force the travelling atmospheric disturbance (TAD is deflected westward. In accordance with present-day atmospheric models the disturbance zonal wind velocities during substorms are close to zero near the equator before midnight and attain moderate westward velocities after midnight. In general, the wind system is only weakly perturbed (Δvy<20 m/s by substorms.

  10. Effective atomic numbers and electron density of dosimetric material

    Directory of Open Access Journals (Sweden)

    Kaginelli S

    2009-01-01

    Full Text Available A novel method for determination of mass attenuation coefficient of x-rays employing NaI (Tl detector system and radioactive sources is described.in this paper. A rigid geometry arrangement and gating of the spectrometer at FWHM position and selection of absorber foils are all done following detailed investigation, to minimize the effect of small angle scattering and multiple scattering on the mass attenuation coefficient, m/r, value. Firstly, for standardization purposes the mass attenuation coefficients of elemental foils such as Aluminum, Copper, Molybdenum, Tantalum and Lead are measured and then, this method is utilized for dosimetric interested material (sulfates. The experimental mass attenuation coefficient values are compared with the theoretical values to find good agreement between the theory and experiment within one to two per cent. The effective atomic numbers of the biological substitute material are calculated by sum rule and from the graph. The electron density of dosimetric material is calculated using the effective atomic number. The study has discussed in detail the attenuation coefficient, effective atomic number and electron density of dosimetric material/biological substitutes.

  11. Atmospheric air density analysis with Meteo-40S wind monitoring system

    Directory of Open Access Journals (Sweden)

    Zahariea Dănuţ

    2017-01-01

    Full Text Available In order to estimate the wind potential of wind turbine sites, the wind resource maps can be used for mean annual wind speed, wind speed frequency distribution and mean annual wind power density determination. The general evaluation of the wind resource and the wind turbine ratings are based on the standard air density measured at sea level and at 15°C, ρs=1.225 kg/m3. Based on the experimental data obtained for a continental climate specific location, this study will present the relative error between the standard air density and the density of the dry and the moist air. Considering a cold day, for example on Friday 10th February 2017, on 1-second measurement rate and 10-minute measuring interval starting at 16:20, the mean relative errors obtained are 10.4145% for dry air, and 10.3634% for moist air. Based on these results, a correction for temperature, atmospheric air pressure and relative humidity should be always considered for wind resource assessment, as well as for the predicting the wind turbines performance.

  12. Power-Production Diagnostic Tools for Low-Density Wind Farms with Applications to Wake Steering

    Science.gov (United States)

    Takle, E. S.; Herzmann, D.; Rajewski, D. A.; Lundquist, J. K.; Rhodes, M. E.

    2016-12-01

    Hansen (2011) provided guidelines for wind farm wake analysis with applications to "high density" wind farms (where average distance between turbines is less than ten times rotor diameter). For "low-density" (average distance greater than fifteen times rotor diameter) wind farms, or sections of wind farms we demonstrate simpler sorting and visualization tools that reveal wake interactions and opportunities for wind farm power prediction and wake steering. SCADA data from a segment of a large mid-continent wind farm, together with surface flux measurements and lidar data are subjected to analysis and visualization of wake interactions. A time-history animated visualization of a plan view of power level of individual turbines provides a quick analysis of wake interaction dynamics. Yaw-based sectoral histograms of enhancement/decline of wind speed and power from wind farm reference levels reveals angular width of wake interactions and identifies the turbine(s) responsible for the power reduction. Concurrent surface flux measurements within the wind farm allowed us to evaluate stability influence on wake loss. A one-season climatology is used to identify high-priority candidates for wake steering based on estimated power recovery. Typical clearing prices on the day-ahead market are used to estimate the added value of wake steering. Current research is exploring options for identifying candidate locations for wind farm "build-in" in existing low-density wind farms.

  13. Fractional winding numbers and the U(1) problem

    International Nuclear Information System (INIS)

    Rothe, K.D.; Swieca, J.A.; Pontificia Univ. Catolica do Rio de Janeiro

    1980-06-01

    The effective Lagrangian description of gauge theories with spontaneous mass generation is simulated by considering the chiral Gross-Neveu model embedded in a two-dimensional U(1) gauge theory. It is shown that in this hybrid model the non-vanishing expectation value of psi psi is due to the contribution of instanton configurations with fractional winding. (Author) [pt

  14. Experimental investigation on performance of crossflow wind turbine as effect of blades number

    Science.gov (United States)

    Kurniawati, Diniar Mungil; Tjahjana, Dominicus Danardono Dwi Prija; Santoso, Budi

    2018-02-01

    Urban living is one of the areas with large electrical power consumption that requires a power supply that is more than rural areas. The number of multi-storey buildings such as offices, hotels and several other buildings that caused electricity power consumption in urban living is very high. Therefore, energy alternative is needed to replace the electricity power consumption from government. One of the utilization of renewable energy in accordance with these conditions is the installation of wind turbines. One type of wind turbine that is now widely studied is a crossflow wind turbines. Crossflow wind turbine is one of vertical axis wind turbine which has good self starting at low wind speed condition. Therefore, the turbine design parameter is necessary to know in order to improve turbine performance. One of wind turbine performance parameter is blades number. The main purpose of this research to investigate the effect of blades number on crossflow wind turbine performance. The design of turbine was 0.4 × 0.4 m2 tested by experimental method with configuration on three kinds of blades number were 8,16 and 20. The turbine investigated at low wind speed on 2 - 5 m/s. The result showed that best performance on 16 blade number.

  15. Small numbers are sensed directly, high numbers constructed from size and density.

    Science.gov (United States)

    Zimmermann, Eckart

    2018-04-01

    Two theories compete to explain how we estimate the numerosity of visual object sets. The first suggests that the apparent numerosity is derived from an analysis of more low-level features like size and density of the set. The second theory suggests that numbers are sensed directly. Consistent with the latter claim is the existence of neurons in parietal cortex which are specialized for processing the numerosity of elements in the visual scene. However, recent evidence suggests that only low numbers can be sensed directly whereas the perception of high numbers is supported by the analysis of low-level features. Processing of low and high numbers, being located at different levels of the neural hierarchy should involve different receptive field sizes. Here, I tested this idea with visual adaptation. I measured the spatial spread of number adaptation for low and high numerosities. A focused adaptation spread of high numerosities suggested the involvement of early neural levels where receptive fields are comparably small and the broad spread for low numerosities was consistent with processing of number neurons which have larger receptive fields. These results provide evidence for the claim that different mechanism exist generating the perception of visual numerosity. Whereas low numbers are sensed directly as a primary visual attribute, the estimation of high numbers however likely depends on the area size over which the objects are spread. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Podocyte number and density changes during early human life.

    Science.gov (United States)

    Kikuchi, Masao; Wickman, Larysa; Rabah, Raja; Wiggins, Roger C

    2017-05-01

    Podocyte depletion, which drives progressive glomerulosclerosis in glomerular diseases, is caused by a reduction in podocyte number, size or function in the context of increasing glomerular volume. Kidneys obtained at autopsy from premature and mature infants who died in the first year of life (n = 24) were used to measure podometric parameters for comparison with previously reported data from older kidneys. Glomerular volume increased 4.6-fold from 0.13 ± 0.07 μm 3 x10 6 in the pre-capillary loop stage, through 0.35 μm 3 x10 6 at the capillary loop, to 0.60 μm 3 x10 6 at the mature glomerular stage. Podocyte number per glomerulus increased from 326 ± 154 per glomerulus at the pre-capillary loop stage to 584 ± 131 per glomerulus at the capillary loop stage of glomerular development to reach a value of 589 ± 166 per glomerulus in mature glomeruli. Thus, the major podocyte number increase occurs in the early stages of glomerular development, in contradistinction to glomerular volume increase, which continues after birth in association with body growth. As glomeruli continue to enlarge, podocyte density (number per volume) rapidly decreases, requiring a parallel rapid increase in podocyte size that allows podocyte foot processes to maintain complete coverage of the filtration surface area. Hypertrophic stresses on the glomerulus and podocyte during development and early rapid growth periods of life are therefore likely to play significant roles in determining how and when defects in podocyte structure and function due to genetic variants become clinically manifest. Therapeutic strategies aimed at minimizing mismatch between these factors may prove clinically useful.

  17. Constraining the cosmic radiation density due to lepton number

    International Nuclear Information System (INIS)

    Mangano, Gianpiero; Miele, Gennaro; Pastor, Sergio; Pisanti, Ofelia; Sarikas, Srdjan

    2013-01-01

    The cosmic energy density in the form of radiation before and during Big Bang Nucleosynthesis is typically parameterized in terms of the effective number of neutrinos N eff , and it is a key parameters in cosmological models slightly more general than the successful minimal ΛCDM scenario. This quantity, in case of no extra degrees of freedom, depends upon the chemical potential and the temperature characterizing the three active neutrino distributions, as well as by their possible non-thermal features. We summarize here the results of a recent analysis to determine the BBN bound on N eff from primordial neutrino–antineutrino asymmetries, with a careful treatment of the dynamics of neutrino oscillations, and considering quite a wide range for the total lepton number in the neutrino sector, η ν =η ν e +η ν μ +η ν τ and the initial electron neutrino asymmetry η ν e in . Comparing these results with the forthcoming measurement of N eff by the Planck satellite will give insight on the nature of the radiation content of the universe

  18. Determination of the number of Vertical Axis Wind Turbine blades based on power spectrum

    Directory of Open Access Journals (Sweden)

    Fedak Waldemar

    2017-01-01

    Full Text Available Technology of wind exploitation has been applied widely all over the world and has already reached the level in which manufacturers want to maximize the yield with the minimum investment outlays. The main objective of this paper is the determination of the optimal number of blades in the Cup-Bladed Vertical Axis Wind Turbine. Optimizing the size of the Vertical Axis Wind Turbine allows the reduction of costs. The maximum power of the rotor is selected as the performance target. The optimum number of Vertical Axis Wind Turbine blades evaluation is based on analysis of a single blade simulation and its superposition for the whole rotor. The simulation of working blade was done in MatLab environment. Power spectrum graphs were prepared and compared throughout superposition of individual blades in the Vertical Axis Wind Turbine rotor. The major result of this research is the Vertical Axis Wind Turbine power characteristic. On the basis of the analysis of the power spectra, optimum number of the blades was specified for the analysed rotor. Power spectrum analysis of wind turbine enabled the specification of the optimal number of blades, and can be used regarding investment outlays and power output of the Vertical Axis Wind Turbine.

  19. Determination of the number of Vertical Axis Wind Turbine blades based on power spectrum

    Science.gov (United States)

    Fedak, Waldemar; Anweiler, Stanisław; Gancarski, Wojciech; Ulbrich, Roman

    2017-10-01

    Technology of wind exploitation has been applied widely all over the world and has already reached the level in which manufacturers want to maximize the yield with the minimum investment outlays. The main objective of this paper is the determination of the optimal number of blades in the Cup-Bladed Vertical Axis Wind Turbine. Optimizing the size of the Vertical Axis Wind Turbine allows the reduction of costs. The maximum power of the rotor is selected as the performance target. The optimum number of Vertical Axis Wind Turbine blades evaluation is based on analysis of a single blade simulation and its superposition for the whole rotor. The simulation of working blade was done in MatLab environment. Power spectrum graphs were prepared and compared throughout superposition of individual blades in the Vertical Axis Wind Turbine rotor. The major result of this research is the Vertical Axis Wind Turbine power characteristic. On the basis of the analysis of the power spectra, optimum number of the blades was specified for the analysed rotor. Power spectrum analysis of wind turbine enabled the specification of the optimal number of blades, and can be used regarding investment outlays and power output of the Vertical Axis Wind Turbine.

  20. Optimized chord and twist angle distributions of wind turbine blade considering Reynolds number effects

    Energy Technology Data Exchange (ETDEWEB)

    Wang, L.; Tang, X. [Univ. of Central Lancashire. Engineering and Physical Sciences, Preston (United Kingdom); Liu, X. [Univ. of Cumbria. Sustainable Engineering, Workington (United Kingdom)

    2012-07-01

    The aerodynamic performance of a wind turbine depends very much on its blade geometric design, typically based on the blade element momentum (BEM) theory, which divides the blade into several blade elements. In current blade design practices based on Schmitz rotor design theory, the blade geometric parameters including chord and twist angle distributions are determined based on airfoil aerodynamic data at a specific Reynolds number. However, rotating wind turbine blade elements operate at different Reynolds numbers due to variable wind speed and different blade span locations. Therefore, the blade design through Schmitz rotor theory at a specific Reynolds number does not necessarily provide the best power performance under operational conditions. This paper aims to provide an optimal blade design strategy for horizontal-axis wind turbines operating at different Reynolds numbers. A fixed-pitch variable-speed (FPVS) wind turbine with S809 airfoil is chosen as a case study and a Matlab program which considers Reynolds number effects is developed to determine the optimized chord and twist angle distributions of the blade. The performance of the optimized blade is compared with that of the preliminary blade which is designed based on Schmitz rotor design theory at a specific Reynolds number. The results demonstrate that the proposed blade design optimization strategy can improve the power performance of the wind turbine. This approach can be further developed for any practice of horizontal axis wind turbine blade design. (Author)

  1. A comparison of shock-cloud and wind-cloud interactions: effect of increased cloud density contrast on cloud evolution

    Science.gov (United States)

    Goldsmith, K. J. A.; Pittard, J. M.

    2018-05-01

    The similarities, or otherwise, of a shock or wind interacting with a cloud of density contrast χ = 10 were explored in a previous paper. Here, we investigate such interactions with clouds of higher density contrast. We compare the adiabatic hydrodynamic interaction of a Mach 10 shock with a spherical cloud of χ = 103 with that of a cloud embedded in a wind with identical parameters to the post-shock flow. We find that initially there are only minor morphological differences between the shock-cloud and wind-cloud interactions, compared to when χ = 10. However, once the transmitted shock exits the cloud, the development of a turbulent wake and fragmentation of the cloud differs between the two simulations. On increasing the wind Mach number, we note the development of a thin, smooth tail of cloud material, which is then disrupted by the fragmentation of the cloud core and subsequent `mass-loading' of the flow. We find that the normalized cloud mixing time (tmix) is shorter at higher χ. However, a strong Mach number dependence on tmix and the normalized cloud drag time, t_{drag}^' }, is not observed. Mach-number-dependent values of tmix and t_{drag}^' } from comparable shock-cloud interactions converge towards the Mach-number-independent time-scales of the wind-cloud simulations. We find that high χ clouds can be accelerated up to 80-90 per cent of the wind velocity and travel large distances before being significantly mixed. However, complete mixing is not achieved in our simulations and at late times the flow remains perturbed.

  2. Assessing different parameters estimation methods of Weibull distribution to compute wind power density

    International Nuclear Information System (INIS)

    Mohammadi, Kasra; Alavi, Omid; Mostafaeipour, Ali; Goudarzi, Navid; Jalilvand, Mahdi

    2016-01-01

    Highlights: • Effectiveness of six numerical methods is evaluated to determine wind power density. • More appropriate method for computing the daily wind power density is estimated. • Four windy stations located in the south part of Alberta, Canada namely is investigated. • The more appropriate parameters estimation method was not identical among all examined stations. - Abstract: In this study, the effectiveness of six numerical methods is evaluated to determine the shape (k) and scale (c) parameters of Weibull distribution function for the purpose of calculating the wind power density. The selected methods are graphical method (GP), empirical method of Justus (EMJ), empirical method of Lysen (EML), energy pattern factor method (EPF), maximum likelihood method (ML) and modified maximum likelihood method (MML). The purpose of this study is to identify the more appropriate method for computing the wind power density in four stations distributed in Alberta province of Canada namely Edmonton City Center Awos, Grande Prairie A, Lethbridge A and Waterton Park Gate. To provide a complete analysis, the evaluations are performed on both daily and monthly scales. The results indicate that the precision of computed wind power density values change when different parameters estimation methods are used to determine the k and c parameters. Four methods of EMJ, EML, EPF and ML present very favorable efficiency while the GP method shows weak ability for all stations. However, it is found that the more effective method is not similar among stations owing to the difference in the wind characteristics.

  3. Assessment of wind speed and wind power through three stations in Egypt, including air density variation and analysis results with rough set theory

    International Nuclear Information System (INIS)

    Essa, K.S.M.; Embaby, M.; Marrouf, A.A.; Koza, A.M.; Abd El-Monsef, M.E.

    2007-01-01

    It is well known that the wind energy potential is proportional to both air density and the third power of the wind speed average over a suitable time period. The wind speed and air density have random variables depending on both time and location. The main objective of this work is to derive the most general wind energy potential of the wind formulation putting into consideration the time variable in both wind speed and air density. The correction factor is derived explicitly in terms of the cross-correlation and the coefficients of variation.The application is performed for environmental and wind speed measurements at the Cairo Airport, Kosseir and Hurguada, Egypt. Comparisons are made between Weibull, Rayleigh, and actual data distributions of wind speed and wind power of one year 2005. A Weibull distribution is the best match to the actual probability distribution of wind speed data for most stations. The maximum wind energy potential was 373 W/m 2 in June at Hurguada (Red Sea coast) where the annual mean value was 207 W/m 2 . By Using Rough Set Theory, We Find That the Wind Power Depends on the Wind Speed with greater than air density

  4. The small amplitude of density turbulence in the inner solar wind

    Directory of Open Access Journals (Sweden)

    S. R. Spangler

    2003-01-01

    Full Text Available Very Long Baseline Interferometer (VLBI observations were made of radio sources close to the Sun, whose lines of sight pass through the inner solar wind (impact parameters 16-26 RE. Power spectra were analyzed of the interferometer phase fluctuations due to the solar wind plasma. These power spectra provide information on the level of plasma density fluctuations on spatial scales of roughly one hundred to several thousand kilometers. By specifying an outer scale to the turbulence spectrum, we can estimate the root-mean-square (rms amplitude of the density fluctuations. The data indicate that the rms fluctuation in density is only about 10% of the mean density. This value is low, and consistent with extrapolated estimates from more distant parts of the solar wind. Physical speculations based on this result are presented.

  5. Relative Density of Backfilled Soil Material around Monopiles for Offshore Wind Turbines

    DEFF Research Database (Denmark)

    Sørensen, Søren Peder Hyldal; Ibsen, Lars Bo; Frigaard, Peter

    2012-01-01

    The relative density of backfilled soil material around offshore monopiles is assessed through experimental testing in the Large Wave Channel (GWK) of the Coastal Research Centre (FZK) in Hannover. The relative density of the backfill material was found to vary between 65 and 80 %. The dependency...... of the relative density of backfill on the maximum pile bending moment is assessed through three-dimensional numerical modeling of a monopile foundation located at the offshore wind farm at Horns Reef, Denmark....

  6. Influence of Reynolds Number on Multi-Objective Aerodynamic Design of a Wind Turbine Blade.

    Science.gov (United States)

    Ge, Mingwei; Fang, Le; Tian, De

    2015-01-01

    At present, the radius of wind turbine rotors ranges from several meters to one hundred meters, or even more, which extends Reynolds number of the airfoil profile from the order of 105 to 107. Taking the blade for 3MW wind turbines as an example, the influence of Reynolds number on the aerodynamic design of a wind turbine blade is studied. To make the study more general, two kinds of multi-objective optimization are involved: one is based on the maximum power coefficient (CPopt) and the ultimate load, and the other is based on the ultimate load and the annual energy production (AEP). It is found that under the same configuration, the optimal design has a larger CPopt or AEP (CPopt//AEP) for the same ultimate load, or a smaller load for the same CPopt//AEP at higher Reynolds number. At a certain tip-speed ratio or ultimate load, the blade operating at higher Reynolds number should have a larger chord length and twist angle for the maximum Cpopt//AEP. If a wind turbine blade is designed by using an airfoil database with a mismatched Reynolds number from the actual one, both the load and Cpopt//AEP will be incorrectly estimated to some extent. In some cases, the assessment error attributed to Reynolds number is quite significant, which may bring unexpected risks to the earnings and safety of a wind power project.

  7. Influence of Reynolds Number on Multi-Objective Aerodynamic Design of a Wind Turbine Blade

    Science.gov (United States)

    Ge, Mingwei; Fang, Le; Tian, De

    2015-01-01

    At present, the radius of wind turbine rotors ranges from several meters to one hundred meters, or even more, which extends Reynolds number of the airfoil profile from the order of 105 to 107. Taking the blade for 3MW wind turbines as an example, the influence of Reynolds number on the aerodynamic design of a wind turbine blade is studied. To make the study more general, two kinds of multi-objective optimization are involved: one is based on the maximum power coefficient (C Popt) and the ultimate load, and the other is based on the ultimate load and the annual energy production (AEP). It is found that under the same configuration, the optimal design has a larger C Popt or AEP (C Popt//AEP) for the same ultimate load, or a smaller load for the same C Popt//AEP at higher Reynolds number. At a certain tip-speed ratio or ultimate load, the blade operating at higher Reynolds number should have a larger chord length and twist angle for the maximum C popt//AEP. If a wind turbine blade is designed by using an airfoil database with a mismatched Reynolds number from the actual one, both the load and C popt//AEP will be incorrectly estimated to some extent. In some cases, the assessment error attributed to Reynolds number is quite significant, which may bring unexpected risks to the earnings and safety of a wind power project. PMID:26528815

  8. Design of wind turbines for non-standard air density

    DEFF Research Database (Denmark)

    Soraperra, Giusepe

    2005-01-01

    -standard density is intrinsically different, it is impossible to reach the standard rated power at the standard rated speed. Three scenarios are possible (i) to keep the standard rated speed of the turbine by changing the size of the electric generator; (ii) to change the rated speed of the turbine by adopting...... a different pitch angel setting; (iii) adoption of extendeders to the blades can also help in restraining the standard rated power at the standard rated speed for p less than pst. The power curves for the three turbine configurations, each in three different air density conformations, have been calculated...

  9. Computerized system for building 'the rose' of the winds and defining the velocity and the average density of the wind power for a given place

    International Nuclear Information System (INIS)

    Valkov, I.; Dekova, I.; Arnaudov, A.; Kostadinov, A.

    2002-01-01

    This paper considers the structure and the working principle of a computerized system for building 'the rose' of the winds. The behaviour of the system has been experimentally investigated and on the basis of the received data 'the rose' of the winds has been built, a diagram of the average wind velocity at a predefined step in the course of time has been made, and the average density of the wind power has been quantitatively defined. The proposed system enables possibilities for creating a data base of wind parameters, their processing and graphical visualizing of the received results. The system allows to improve the work of devices of wild's wind gauge type. (authors)

  10. Tidal signatures of the thermospheric mass density and zonal wind at midlatitude: CHAMP and GRACE observations

    Directory of Open Access Journals (Sweden)

    C. Xiong

    2015-02-01

    Full Text Available By using the accelerometer measurements from CHAMP and GRACE satellites, the tidal signatures of the thermospheric mass density and zonal wind at midlatitudes have been analyzed in this study. The results show that the mass density and zonal wind at southern midlatitudes are dominated by a longitudinal wave-1 pattern. The most prominent tidal components in mass density and zonal wind are the diurnal tides D0 and DW2 and the semidiurnal tides SW1 and SW3. This is consistent with the tidal signatures in the F region electron density at midlatitudes as reported by Xiong and Lühr (2014. These same tidal components are observed both in the thermospheric and ionospheric quantities, supporting a mechanism that the non-migrating tides in the upper atmosphere are excited in situ by ion–neutral interactions at midlatitudes, consistent with the modeling results of Jones Jr. et al. (2013. We regard the thermospheric dynamics as the main driver for the electron density tidal structures. An example is the in-phase variation of D0 between electron density and mass density in both hemispheres. Further research including coupled atmospheric models is probably needed for explaining the similarities and differences between thermospheric and ionospheric tidal signals at midlatitudes.

  11. THz limb sounder (TLS) for lower thermospheric wind, oxygen density, and temperature

    Science.gov (United States)

    Wu, Dong L.; Yee, Jeng-Hwa; Schlecht, Erich; Mehdi, Imran; Siles, Jose; Drouin, Brian J.

    2016-07-01

    Neutral winds are one of the most critical measurements in the lower thermosphere and E region ionosphere (LTEI) for understanding complex electrodynamic processes and ion-neutral interactions. We are developing a high-sensitivity, low-power, noncryogenic 2.06 THz Schottky receiver to measure wind profiles at 100-140 km. The new technique, THz limb sounder (TLS), aims to measure LTEI winds by resolving the wind-induced Doppler shift of 2.06 THz atomic oxygen (OI) emissions. As a transition between fine structure levels in the ground electronic state, the OI emission is in local thermodynamic equilibrium (LTE) at altitudes up to 350 km. This LTE property, together with day-and-night capability and small line-of-sight gradient, makes the OI limb sounding a very attractive technique for neutral wind observations. In addition to the wind measurement, TLS can also retrieve [OI] density and neutral temperature in the LTEI region. TLS leverages rapid advances in THz receiver technologies including subharmonically pumped (SHP) mixers and Schottky-diode-based power multipliers. Current SHP Schottky receivers have produced good sensitivity for THz frequencies at ambient environment temperatures (120-150 K), which are achievable through passively cooling in spaceflight. As an emerging technique, TLS can fill the critical data gaps in the LTEI neutral wind observations to enable detailed studies on the coupling and dynamo processes between charged and neutral molecules.

  12. Evolution of the Sunspot Number and Solar Wind B Time Series

    Science.gov (United States)

    Cliver, Edward W.; Herbst, Konstantin

    2018-03-01

    The past two decades have witnessed significant changes in our knowledge of long-term solar and solar wind activity. The sunspot number time series (1700-present) developed by Rudolf Wolf during the second half of the 19th century was revised and extended by the group sunspot number series (1610-1995) of Hoyt and Schatten during the 1990s. The group sunspot number is significantly lower than the Wolf series before ˜1885. An effort from 2011-2015 to understand and remove differences between these two series via a series of workshops had the unintended consequence of prompting several alternative constructions of the sunspot number. Thus it has been necessary to expand and extend the sunspot number reconciliation process. On the solar wind side, after a decade of controversy, an ISSI International Team used geomagnetic and sunspot data to obtain a high-confidence time series of the solar wind magnetic field strength (B) from 1750-present that can be compared with two independent long-term (> ˜600 year) series of annual B-values based on cosmogenic nuclides. In this paper, we trace the twists and turns leading to our current understanding of long-term solar and solar wind activity.

  13. Radial evolution of the intermittency of density fluctuations in the fast solar wind

    International Nuclear Information System (INIS)

    Bruno, R.; D'Amicis, R.; Telloni, D.; Primavera, L.; Sorriso-Valvo, L.; Carbone, V.; Malara, F.; Veltri, P.; Pietropaolo, E.

    2014-01-01

    We study the radial evolution of the intermittency of density fluctuations in the fast solar wind. The study is performed by analyzing the plasma density measurements provided by Helios 2 in the inner heliosphere between 0.3 and 0.9 AU. The analysis is carried out by means of a complete set of diagnostic tools, including the flatness factor at different timescales to estimate intermittency, the Kolmogorov-Smirnov test to estimate the degree of intermittency, and the Fourier transform to estimate the power spectral densities of these fluctuations. Density fluctuations within the fast wind are rather intermittent and their level of intermittency, together with the amplitude of intermittent events, decreases with the distance from the Sun, at odds with the intermittency of both magnetic field and all other plasma parameters. Furthermore, the intermittent events are strongly correlated, exhibiting temporal clustering. This indicates that the mechanism underlying their generation departs from a time-varying Poisson process. A remarkable, qualitative similarity with the behavior of plasma density fluctuations obtained from a numerical study of the nonlinear evolution of parametric instability in the solar wind supports the idea that this mechanism has an important role in governing density fluctuations in the inner heliosphere.

  14. A comment on "bats killed in large numbers at United States wind energy facilities"

    Science.gov (United States)

    Huso, Manuela M.P.; Dalthorp, Dan

    2014-01-01

    Widespread reports of bat fatalities caused by wind turbines have raised concerns about the impacts of wind power development. Reliable estimates of the total number killed and the potential effects on populations are needed, but it is crucial that they be based on sound data. In a recent BioScience article, Hayes (2013) estimated that over 600,000 bats were killed at wind turbines in the United States in 2012. The scientific errors in the analysis are numerous, with the two most serious being that the included sites constituted a convenience sample, not a representative sample, and that the individual site estimates are derived from such different methodologies that they are inherently not comparable. This estimate is almost certainly inaccurate, but whether the actual number is much smaller, much larger, or about the same is uncertain. An accurate estimate of total bat fatality is not currently possible, given the shortcomings of the available data.

  15. Satellite accelerometer measurements of neutral density and winds during geomagnetic storms

    Science.gov (United States)

    Marcos, F. A.; Forbes, J. M.

    1986-01-01

    A new thermospheric wind measurement technique is reported which is based on a Satellite Electrostatic Triaxial Accelerometer (SETA) system capable of accurately measuring accelerations in the satellite's in-track, cross-track and radial directions. Data obtained during two time periods are presented. The first data set describes cross-track winds measured between 170 and 210 km during a 5-day period (25 to 29 March 1979) of mostly high geomagnetic activity. In the second data set, cross-track winds and neutral densities from SETA and exospheric temperatures from the Millstone Hill incoherent scatter radar are examined during an isolated magnetic substorm occurring on 21 March 1979. A polar thermospheric wind circulation consisting of a two cell horizontal convection pattern is reflected in both sets of cross-track acceleration measurements. The density response is highly asymmetric with respect to its day/night behavior. Latitude structures of the density response at successive times following the substorm peak suggest the equatorward propagation of a disturbance with a phase speed between 300 and 600 m/s. A deep depression in the density at high latitudes (less than 70 deg) is evident in conjunction with this phenomenon. The more efficient propagation of the disturbance to lower latitudes during the night is probably due to the midnight surge effect.

  16. Increased Mach Number Capability for the NASA Glenn 10x10 Supersonic Wind Tunnel

    Science.gov (United States)

    Slater, J. W.; Saunders, J. D.

    2015-01-01

    Computational simulations and wind tunnel testing were conducted to explore the operation of the Abe Silverstein Supersonic Wind Tunnel at the NASA Glenn Research Center at test section Mach numbers above the current limit of Mach 3.5. An increased Mach number would enhance the capability for testing of supersonic and hypersonic propulsion systems. The focus of the explorations was on understanding the flow within the second throat of the tunnel, which is downstream of the test section and is where the supersonic flow decelerates to subsonic flow. Methods of computational fluid dynamics (CFD) were applied to provide details of the shock boundary layer structure and to estimate losses in total pressure. The CFD simulations indicated that the tunnel could be operated up to Mach 4.0 if the minimum width of the second throat was made smaller than that used for previous operation of the tunnel. Wind tunnel testing was able to confirm such operation of the tunnel at Mach 3.6 and 3.7 before a hydraulic failure caused a stop to the testing. CFD simulations performed after the wind tunnel testing showed good agreement with test data consisting of static pressures along the ceiling of the second throat. The CFD analyses showed increased shockwave boundary layer interactions, which was also observed as increased unsteadiness of dynamic pressures collected in the wind tunnel testing.

  17. The first Donaldson invariant as the winding number of a Nicolai map

    International Nuclear Information System (INIS)

    Mansfield, P.

    1988-01-01

    The authors show that the first Donaldson invariant expressed by Witten as the partition function of a relativistic quantum field theory can be interpreted as the winding number of the stochastic map introduced by Nicolai in the context of supersymmetric Yang-Mills theories

  18. Atmospheric pressure, density, temperature and wind variations between 50 and 200 km

    Science.gov (United States)

    Justus, C. G.; Woodrum, A.

    1972-01-01

    Data on atmospheric pressure, density, temperature and winds between 50 and 200 km were collected from sources including Meteorological Rocket Network data, ROBIN falling sphere data, grenade release and pitot tube data, meteor winds, chemical release winds, satellite data, and others. These data were analyzed by a daily difference method and results on the distribution statistics, magnitude, and spatial structure of the irregular atmospheric variations are presented. Time structures of the irregular variations were determined by the analysis of residuals from harmonic analysis of time series data. The observed height variations of irregular winds and densities are found to be in accord with a theoretical relation between these two quantities. The latitude variations (at 50 - 60 km height) show an increasing trend with latitude. A possible explanation of the unusually large irregular wind magnitudes of the White Sands MRN data is given in terms of mountain wave generation by the Sierra Nevada range about 1000 km west of White Sands. An analytical method is developed which, based on an analogy of the irregular motion field with axisymmetric turbulence, allows measured or model correlation or structure functions to be used to evaluate the effective frequency spectra of scalar and vector quantities of a spacecraft moving at any speed and at any trajectory elevation angle.

  19. A study of density modulation index in the inner heliospheric solar wind during solar cycle 23

    International Nuclear Information System (INIS)

    Bisoi, Susanta Kumar; Janardhan, P.; Ingale, M.; Subramanian, P.; Ananthakrishnan, S.; Tokumaru, M.; Fujiki, K.

    2014-01-01

    The ratio of the rms electron density fluctuations to the background density in the solar wind (density modulation index, ε N ≡ ΔN/N) is of vital importance for understanding several problems in heliospheric physics related to solar wind turbulence. In this paper, we have investigated the behavior of ε N in the inner heliosphere from 0.26 to 0.82 AU. The density fluctuations ΔN have been deduced using extensive ground-based observations of interplanetary scintillation at 327 MHz, which probe spatial scales of a few hundred kilometers. The background densities (N) have been derived using near-Earth observations from the Advanced Composition Explorer. Our analysis reveals that 0.001 ≲ ε N ≲ 0.02 and does not vary appreciably with heliocentric distance. We also find that ε N declines by 8% from 1998 to 2008. We discuss the impact of these findings on problems ranging from our understanding of Forbush decreases to the behavior of the solar wind dynamic pressure over the recent peculiar solar minimum at the end of cycle 23.

  20. Three-dimensional density and compressible magnetic structure in solar wind turbulence

    Science.gov (United States)

    Roberts, Owen W.; Narita, Yasuhito; Escoubet, C.-Philippe

    2018-03-01

    The three-dimensional structure of both compressible and incompressible components of turbulence is investigated at proton characteristic scales in the solar wind. Measurements of the three-dimensional structure are typically difficult, since the majority of measurements are performed by a single spacecraft. However, the Cluster mission consisting of four spacecraft in a tetrahedral formation allows for a fully three-dimensional investigation of turbulence. Incompressible turbulence is investigated by using the three vector components of the magnetic field. Meanwhile compressible turbulence is investigated by considering the magnitude of the magnetic field as a proxy for the compressible fluctuations and electron density data deduced from spacecraft potential. Application of the multi-point signal resonator technique to intervals of fast and slow wind shows that both compressible and incompressible turbulence are anisotropic with respect to the mean magnetic field direction P⟂ ≫ P∥ and are sensitive to the value of the plasma beta (β; ratio of thermal to magnetic pressure) and the wind type. Moreover, the incompressible fluctuations of the fast and slow solar wind are revealed to be different with enhancements along the background magnetic field direction present in the fast wind intervals. The differences in the fast and slow wind and the implications for the presence of different wave modes in the plasma are discussed.

  1. The role of meridional density differences for a wind-driven overturning circulation

    Energy Technology Data Exchange (ETDEWEB)

    Schewe, J.; Levermann, A. [Potsdam Institute for Climate Impact Research, Earth System Analysis, Potsdam (Germany); Potsdam University, Physics Institute, Potsdam (Germany)

    2010-03-15

    Experiments with the coupled climate model CLIMBER-3{alpha}, which contains an oceanic general circulation model, show deep upwelling in the Southern Ocean to be proportional to the surface wind stress in the latitudinal band of Drake Passage. At the same time, the distribution of the Southern Ocean upwelling onto the oceanic basins is controlled by buoyancy distribution; the inflow into each basin being proportional to the respective meridional density difference. We observe approximately the same constant of proportionality for all basins, and demonstrate that it can be directly related to the flow geometry. For increased wind stress in the Southern Ocean, the overturning increases both in the Atlantic and the Indo-Pacific basin. For strongly reduced wind stress, the circulation enters a regime where Atlantic overturning is maintained through Pacific upwelling, in order to satisfy the transports set by the density differences. Previous results on surface buoyancy and wind stress forcing, obtained with different models, are reproduced within one model in order to distill a consistent picture. We propose that both Southern Ocean upwelling and meridional density differences set up a system of conditions that determine the global meridional overturning circulation. (orig.)

  2. Number density measurements on analytical discharge systems: application of ''hook'' spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Majidi, V.; Hsu, W.; Coleman, D.M.

    1988-01-01

    Various methods for determining atomic, ionic and electron number densities are reviewed. Time- and spatially-resolved number densities of sodium atoms in the post discharge environment of a high voltage spark are then quantitatively determined using the anomalous dispersion hook method. Number densities are calculated from hook separation near the Na D-lines. Lateral profiles are subsequently transformed to the radial domain using a derivative free Abel inversion process. Advantages, limitations, and practical ramification of the hook method are discussed.

  3. Number density measurements on analytical discharge systems: application of ''hook'' spectroscopy

    International Nuclear Information System (INIS)

    Majidi, V.; Hsu, W.; Coleman, D.M.

    1988-01-01

    Various methods for determining atomic, ionic and electron number densities are reviewed. Time- and spatially-resolved number densities of sodium atoms in the post discharge environment of a high voltage spark are then quantitatively determined using the anomalous dispersion hook method. Number densities are calculated from hook separation near the Na D-lines. Lateral profiles are subsequently transformed to the radial domain using a derivative free Abel inversion process. Advantages, limitations, and practical ramification of the hook method are discussed. (author)

  4. Turbulence, raindrops and the l{sup 1/2} number density law

    Energy Technology Data Exchange (ETDEWEB)

    Lovejoy, S [Department of Physics, McGill University, 3600 University street, Montreal, Quebec, H3A 2T8 (Canada); Schertzer, D [Universite Paris-Est, ENPC/CEREVE, 77455 Marne-la-Vallee Cedex 2 (France)], E-mail: lovejoy@physics.mcgill.ca

    2008-07-15

    Using a unique data set of three-dimensional drop positions and masses (the HYDROP experiment), we show that the distribution of liquid water in rain displays a sharp transition between large scales which follow a passive scalar-like Corrsin-Obukhov (k{sup -5/3}) spectrum and a small-scale statistically homogeneous white noise regime. We argue that the transition scale l{sub c} is the critical scale where the mean Stokes number (= drop inertial time/turbulent eddy time) St{sub l} is unity. For five storms, we found l{sub c} in the range 45-75 cm with the corresponding dissipation scale St{sub {eta}} in the range 200-300. Since the mean interdrop distance was significantly smaller ({approx} 10 cm) than l{sub c} we infer that rain consists of 'patches' whose mean liquid water content is determined by turbulence with each patch being statistically homogeneous. For l>l{sub c}, we have St{sub l}<1 and due to the observed statistical homogeneity for lwind velocities at coarse grained resolution l{sub c}. From this, we derive equations for the number and mass densities (n and {rho}) and their variance fluxes ({psi} and {chi}). By showing that {chi} is dissipated at small scales (with l{sub {rho}}{sub ,diss}{approx}l{sub c}) and {psi} over a wide range, we conclude that {rho} should indeed follow Corrsin-Obukhov k{sup -5/3} spectra but that n should instead follow a k{sup -2} spectrum corresponding to fluctuations scaling as {delta}{rho}{approx}l{sup 1/3} and {delta}n{approx}l{sup 1/2}. While the Corrsin-Obukhov law has never been observed in rain before, its discovery is perhaps not surprising; in contrast the {delta}n{approx}l{sup 1/2} number density law is quite new. The key difference between the {delta}{rho}, {delta}n laws is the fact that the microphysics (coalescence, breakup) conserves drop mass, but not numbers of particles. This implies that the timescale for the transfer of the

  5. How Planting Density Affects Number and Yield of Potato Minitubers in a Commercial Glasshouse Production System

    NARCIS (Netherlands)

    Veeken, van der A.J.H.; Lommen, W.J.M.

    2009-01-01

    Commercial potato minituber production systems aim at high tuber numbers per plant. This study investigated by which mechanisms planting density (25.0, 62.5 and 145.8 plants/m2) of in vitro derived plantlets affected minituber yield and minituber number per plantlet. Lowering planting density

  6. SPENT NUCLEAR FUEL NUMBER DENSITIES FOR MULTI-PURPOSE CANISTER CRITICALITY CALCULATIONS

    International Nuclear Information System (INIS)

    D. A. Thomas

    1996-01-01

    The purpose of this analysis is to calculate the number densities for spent nuclear fuel (SNF) to be used in criticality evaluations of the Multi-Purpose Canister (MPC) waste packages. The objective of this analysis is to provide material number density information which will be referenced by future MPC criticality design analyses, such as for those supporting the Conceptual Design Report

  7. Geometrical meaning of winding number and its characterization of topological phases in one-dimensional chiral non-Hermitian systems

    Science.gov (United States)

    Yin, Chuanhao; Jiang, Hui; Li, Linhu; Lü, Rong; Chen, Shu

    2018-05-01

    We unveil the geometrical meaning of winding number and utilize it to characterize the topological phases in one-dimensional chiral non-Hermitian systems. While chiral symmetry ensures the winding number of Hermitian systems are integers, it can take half integers for non-Hermitian systems. We give a geometrical interpretation of the half integers by demonstrating that the winding number ν of a non-Hermitian system is equal to half of the summation of two winding numbers ν1 and ν2 associated with two exceptional points, respectively. The winding numbers ν1 and ν2 represent the times of the real part of the Hamiltonian in momentum space encircling the exceptional points and can only take integers. We further find that the difference of ν1 and ν2 is related to the second winding number or energy vorticity. By applying our scheme to a non-Hermitian Su-Schrieffer-Heeger model and an extended version of it, we show that the topologically different phases can be well characterized by winding numbers. Furthermore, we demonstrate that the existence of left and right zero-mode edge states is closely related to the winding number ν1 and ν2.

  8. Spacecraft radio scattering observations of the power spectrum of electron density fluctuations in the solar wind

    International Nuclear Information System (INIS)

    Woo, R.; Armstrong, J.W.

    1979-01-01

    Solar wind electron density power spectra in the solar equatorial region are inferred from observations of phase scintillations and spectral broadening made with the Viking, Helios, and Pioneer spacecraft. The heliocentric distance range covered is 2--215 R/sub S/, and for some observations close to the sun the spectra extend to fluctuation frequencies as high as 100 Hz. For heliocentric distances > or approx. =20 R/sub S/ the equivalent spacecraft-measured one-dimensional density spectrym V/sub n/e is well modeled by a single power law (f/sup -alpha/) in the frequency range 10 -4 -5 x 10 -2 Hz. The mean spectral index α is 1.65, very close to the Kolmogorov value of 5/3. Under the assumption of constant solar wind speed, V/sub n/e varies as R/sup -3.45/, where R is heliocentric distance. Within 20 R/sub S/, V/sub n/e can still be modeled by a single power law over the frequency range 10 -3 -10 1 Hz, but the spectral index becomes smaller, αapprox.1.1. The flattening of the density spectrum with 20 R/sub S/ is presumably associated with energy deposition in the near-sun region and acceleration of the solar wind

  9. An Optimal Number-Dependent Preventive Maintenance Strategy for Offshore Wind Turbine Blades Considering Logistics

    Directory of Open Access Journals (Sweden)

    Mahmood Shafiee

    2013-01-01

    Full Text Available In offshore wind turbines, the blades are among the most critical and expensive components that suffer from different types of damage due to the harsh maritime environment and high load. The blade damages can be categorized into two types: the minor damage, which only causes a loss in wind capture without resulting in any turbine stoppage, and the major (catastrophic damage, which stops the wind turbine and can only be corrected by replacement. In this paper, we propose an optimal number-dependent preventive maintenance (NDPM strategy, in which a maintenance team is transported with an ordinary or expedited lead time to the offshore platform at the occurrence of the Nth minor damage or the first major damage, whichever comes first. The long-run expected cost of the maintenance strategy is derived, and the necessary conditions for an optimal solution are obtained. Finally, the proposed model is tested on real data collected from an offshore wind farm database. Also, a sensitivity analysis is conducted in order to evaluate the effect of changes in the model parameters on the optimal solution.

  10. Hydroxyl layer: trend of number density and intra-annual variability

    Science.gov (United States)

    Sonnemann, G. R.; Hartogh, P.; Berger, U.; Grygalashvyly, M.

    2015-06-01

    The layer of vibrationally excited hydroxyl (OH*) near the mesopause in Earth's atmosphere is widely used to derive the temperature at this height and to observe dynamical processes such as gravity waves. The concentration of OH* is controlled by the product of atomic hydrogen, with ozone creating a layer of enhanced concentration in the mesopause region. However, the basic influences on the OH* layer are atomic oxygen and temperature. The long-term monitoring of this layer provides information on a changing atmosphere. It is important to know which proportion of a trend results from anthropogenic impacts on the atmosphere and which proportion reflects natural variations. In a previous paper (Grygalashvyly et al., 2014), the trend of the height of the layer and the trend in temperature were investigated particularly in midlatitudes on the basis of our coupled dynamic and chemical transport model LIMA (Leibniz Institute Middle Atmosphere). In this paper we consider the trend for the number density between the years 1961 and 2009 and analyze the reason of the trends on a global scale. Further, we consider intra-annual variations. Temperature and wind have the strongest impacts on the trend. Surprisingly, the increase in greenhouse gases (GHGs) has no clear influence on the chemistry of OH*. The main reason for this lies in the fact that, in the production term of OH*, if atomic hydrogen increases due to increasing humidity of the middle atmosphere by methane oxidation, ozone decreases. The maximum of the OH* layer is found in the mesopause region and is very variable. The mesopause region is a very intricate domain marked by changeable dynamics and strong gradients of all chemically active minor constituents determining the OH* chemistry. The OH* concentration responds, in part, very sensitively to small changes in these parameters. The cause for this behavior is given by nonlinear reactions of the photochemical system being a nonlinear enforced chemical oscillator

  11. Hydroxyl layer: trend of number density and intra-annual variability

    Directory of Open Access Journals (Sweden)

    G. R. Sonnemann

    2015-06-01

    Full Text Available The layer of vibrationally excited hydroxyl (OH* near the mesopause in Earth's atmosphere is widely used to derive the temperature at this height and to observe dynamical processes such as gravity waves. The concentration of OH* is controlled by the product of atomic hydrogen, with ozone creating a layer of enhanced concentration in the mesopause region. However, the basic influences on the OH* layer are atomic oxygen and temperature. The long-term monitoring of this layer provides information on a changing atmosphere. It is important to know which proportion of a trend results from anthropogenic impacts on the atmosphere and which proportion reflects natural variations. In a previous paper (Grygalashvyly et al., 2014, the trend of the height of the layer and the trend in temperature were investigated particularly in midlatitudes on the basis of our coupled dynamic and chemical transport model LIMA (Leibniz Institute Middle Atmosphere. In this paper we consider the trend for the number density between the years 1961 and 2009 and analyze the reason of the trends on a global scale. Further, we consider intra-annual variations. Temperature and wind have the strongest impacts on the trend. Surprisingly, the increase in greenhouse gases (GHGs has no clear influence on the chemistry of OH*. The main reason for this lies in the fact that, in the production term of OH*, if atomic hydrogen increases due to increasing humidity of the middle atmosphere by methane oxidation, ozone decreases. The maximum of the OH* layer is found in the mesopause region and is very variable. The mesopause region is a very intricate domain marked by changeable dynamics and strong gradients of all chemically active minor constituents determining the OH* chemistry. The OH* concentration responds, in part, very sensitively to small changes in these parameters. The cause for this behavior is given by nonlinear reactions of the photochemical system being a nonlinear enforced

  12. A new estimation method for nuclide number densities in equilibrium cycle

    International Nuclear Information System (INIS)

    Seino, Takeshi; Sekimoto, Hiroshi; Ando, Yoshihira.

    1997-01-01

    A new method is proposed for estimating nuclide number densities of LWR equilibrium cycle by multi-recycling calculation. Conventionally, it is necessary to spend a large computation time for attaining the ultimate equilibrium state. Hence, the cycle in nearly constant fuel composition has been considered as an equilibrium state which can be achieved by a few of recycling calculations on a simulated cycle operation under a specific fuel core design. The present method uses steady state fuel nuclide number densities as the initial guess for multi-recycling burnup calculation obtained by a continuously fuel supplied core model. The number densities are modified to be the initial number densities for nuclides of a batch supplied fuel. It was found that the calculated number densities could attain to more precise equilibrium state than that of a conventional multi-recycling calculation with a small number of recyclings. In particular, the present method could give the ultimate equilibrium number densities of the nuclides with the higher mass number than 245 Cm and 244 Pu which were not able to attain to the ultimate equilibrium state within a reasonable number of iterations using a conventional method. (author)

  13. Interplanetary Type III Bursts and Electron Density Fluctuations in the Solar Wind

    Science.gov (United States)

    Krupar, V.; Maksimovic, M.; Kontar, E. P.; Zaslavsky, A.; Santolik, O.; Soucek, J.; Kruparova, O.; Eastwood, J. P.; Szabo, A.

    2018-04-01

    Type III bursts are generated by fast electron beams originated from magnetic reconnection sites of solar flares. As propagation of radio waves in the interplanetary medium is strongly affected by random electron density fluctuations, type III bursts provide us with a unique diagnostic tool for solar wind remote plasma measurements. Here, we performed a statistical survey of 152 simple and isolated type III bursts observed by the twin-spacecraft Solar TErrestrial RElations Observatory mission. We investigated their time–frequency profiles in order to retrieve decay times as a function of frequency. Next, we performed Monte Carlo simulations to study the role of scattering due to random electron density fluctuations on time–frequency profiles of radio emissions generated in the interplanetary medium. For simplification, we assumed the presence of isotropic electron density fluctuations described by a power law with the Kolmogorov spectral index. Decay times obtained from observations and simulations were compared. We found that the characteristic exponential decay profile of type III bursts can be explained by the scattering of the fundamental component between the source and the observer despite restrictive assumptions included in the Monte Carlo simulation algorithm. Our results suggest that relative electron density fluctuations /{n}{{e}} in the solar wind are 0.06–0.07 over wide range of heliospheric distances.

  14. Hybrid PV/wind system with quinary asymmetric inverter without increasing DC-link number

    Directory of Open Access Journals (Sweden)

    Aida Baghbany Oskouei

    2016-06-01

    Full Text Available This paper suggests quinary asymmetric inverter with coupled inductors and transformer, and uses it in hybrid system including photovoltaic (PV and wind. This inverter produces twenty-five-level voltage in addition to merits of multilevel inverter, has only one DC source. Then, it is adequate for hybrid systems, which prevents increasing DC-link and makes control of system easy. Proposed structure also provides isolation in the system and the switch numbers are reduced in this topology compared with other multilevel structures. In this system, battery is used as backup, where PV and wind have complementary nature. The performance of proposed inverter and hybrid system is validated with simulation results using MATLAB/SIMULINK software and experimental results based PCI-1716 data acquisition system.

  15. The solar wind plasma density control of night-time auroral particle precipitation

    Directory of Open Access Journals (Sweden)

    V. G. Vorobjev

    2004-03-01

    Full Text Available DMSP F6 and F7 spacecraft observations of the average electron and ion energy, and energy fluxes in different night-time precipitation regions for the whole of 1986 were used to examine the precipitation features associated with solar wind density changes. It was found that during magnetic quietness |AL|<100nT, the enhancement of average ion fluxes was observed at least two times, along with the solar wind plasma density increase from 2 to 24cm–3. More pronounced was the ion flux enhancement that occurred in the b2i–b4s and b4s–b5 regions, which are approximately corresponding to the statistical auroral oval and map to the magnetospheric plasma sheet tailward of the isotropy boundary. The average ion energy decrease of about 2–4kev was registered simultaneously with this ion flux enhancement. The results verify the occurrence of effective penetration of the solar wind plasma into the magnetospheric tail plasma sheet. Key words. Ionosphere (auroral ionosphere, particle precipitation – Magnetospheric physics (solar windmagnetosphere interaction

  16. Density Fluctuations in the Solar Wind Driven by Alfvén Wave Parametric Decay

    Science.gov (United States)

    Bowen, Trevor A.; Badman, Samuel; Hellinger, Petr; Bale, Stuart D.

    2018-02-01

    Measurements and simulations of inertial compressive turbulence in the solar wind are characterized by anti-correlated magnetic fluctuations parallel to the mean field and density structures. This signature has been interpreted as observational evidence for non-propagating pressure balanced structures, kinetic ion-acoustic waves, as well as the MHD slow-mode. Given the high damping rates of parallel propagating compressive fluctuations, their ubiquity in satellite observations is surprising and suggestive of a local driving process. One possible candidate for the generation of compressive fluctuations in the solar wind is the Alfvén wave parametric instability. Here, we test the parametric decay process as a source of compressive waves in the solar wind by comparing the collisionless damping rates of compressive fluctuations with growth rates of the parametric decay instability daughter waves. Our results suggest that generation of compressive waves through parametric decay is overdamped at 1 au, but that the presence of slow-mode-like density fluctuations is correlated with the parametric decay of Alfvén waves.

  17. Quark number density and susceptibility calculation with one correction in mean field potential

    International Nuclear Information System (INIS)

    Singh, S. Somorendro

    2016-01-01

    We calculate quark number density and susceptibility of a model which has one loop correction in mean field potential. The calculation shows continuous increasing in the number density and susceptibility up to the temperature T = 0.4 GeV. Then the value of number density and susceptibility approach to the lattice result for higher value of temperature. The result indicates that the calculated values of the model fit well and the result increase the temperature to reach the lattice data with the one loop correction in the mean field potential. (author)

  18. Proposed Columbia Wind Farm number-sign 1. Joint NEPA/SEPA draft environmental impact statement

    International Nuclear Information System (INIS)

    1995-03-01

    This Draft Environmental Impact Statement (DEIS) addresses the Columbia Wind Farm number-sign 1 (Project) proposal for construction and operation of a 25 megawatt (MW) wind power project in the Columbia Hills area southeast of Goldendale in Klickitat County, Washington. The Project would be constructed on private land by Conservation and Renewable Energy System (CARES) (the Applicant). An Environmental Impact Statement is required under both NEPA and SEPA guidelines and is issued under Section 102 (2) (C) of the National Environmental Policy Act (NEPA) at 42 U.S.C. 4321 et seq and under the Washington State Environmental Policy Act (SEPA) as provided by RCW 43.21C.030 (2) (c). Bonneville Power Administration is the NEPA lead agency; Klickitat County is the nominal SEPA lead agency and CARES is the SEPA co-lead agency for this DEIS. The Project site is approximately 395 hectares (975 acres) in size. The Proposed Action would include approximately 91 model AWT-26 wind turbines. Under the No Action Alternative, the Project would not be constructed and existing grazing and agricultural activities on the site would continue

  19. Cryogenic wind tunnel technology. A way to measurement at higher Reynolds numbers

    Science.gov (United States)

    Beck, J. W.

    1984-01-01

    The goals, design, problems, and value of cryogenic transonic wind tunnels being developed in Europe are discussed. The disadvantages inherent in low-Reynolds-number (Re) wind tunnel simulations of aircraft flight at high Re are reviewed, and the cryogenic tunnel is shown to be the most practical method to achieve high Re. The design proposed for the European Transonic Wind tunnel (ETW) is presented: parameters include cross section. DISPLAY 83A46484/2 = 4 sq m, operating pressure = 5 bar, temperature = 110-120 K, maximum Re = 40 x 10 to the 6th, liquid N2 consumption = 40,000 metric tons/year, and power = 39,5 MW. The smaller Cologne subsonic tunnel being adapted to cryogenic use for preliminary studies is described. Problems of configuration, materials, and liquid N2 evaporation and handling and the research underway to solve them are outlined. The benefits to be gained by the construction of these costly installations are seen more in applied aerodynamics than in basic research in fluid physics. The need for parallel development of both high Re tunnels and computers capable of performing high-Re numerical analysis is stressed.

  20. Effect of the number of blades on the dynamics of floating straight-bladed vertical axis wind turbines

    DEFF Research Database (Denmark)

    Cheng, Zhengshun; Aagaard Madsen, Helge; Gao, Zhen

    2017-01-01

    Floating vertical axis wind turbines (VAWTs) are promising solutions for exploiting the wind energy resource in deep waters due to their potential cost-of-energy reduction. The number of blades is one of the main concerns when designing a VAWT for offshore application. In this paper, the effect...

  1. High-performance permanent magnet brushless motors with balanced concentrated windings and similar slot and pole numbers

    International Nuclear Information System (INIS)

    Stumberger, Bojan; Stumberger, Gorazd; Hadziselimovic, Miralem; Hamler, Anton; Trlep, Mladen; Gorican, Viktor; Jesenik, Marko

    2006-01-01

    The paper presents a comparison between the performances of exterior-rotor permanent magnet brushless motors with distributed windings and the performances of exterior-rotor permanent magnet brushless motors with concentrated windings. Finite element method analysis is employed to determine the performance of each motor. It is shown that motors with concentrated windings and similar slot and pole numbers exhibit similar or better performances than motors with distributed windings for brushless AC (BLAC) operation mode and brushless DC (BLDC) operation mode as well

  2. The effect of adsorbed liquid and material density on saltation threshold: Insight from laboratory and wind tunnel experiments

    Science.gov (United States)

    Yu, Xinting; Hörst, Sarah M.; He, Chao; Bridges, Nathan T.; Burr, Devon M.; Sebree, Joshua A.; Smith, James K.

    2017-11-01

    Saltation threshold, the minimum wind speed for sediment transport, is a fundamental parameter in aeolian processes. Measuring this threshold using boundary layer wind tunnels, in which particles are mobilized by flowing air, for a subset of different planetary conditions can inform our understanding of physical processes of sediment transport. The presence of liquid, such as water on Earth or methane on Titan, may affect the threshold values to a great extent. Sediment density is also crucial for determining threshold values. Here we provide quantitative data on density and water content of common wind tunnel materials (including chromite, basalt, quartz sand, beach sand, glass beads, gas chromatograph packing materials, walnut shells, iced tea powder, activated charcoal, instant coffee, and glass bubbles) that have been used to study conditions on Earth, Titan, Mars, and Venus. The measured density values for low density materials are higher compared to literature values (e.g., ∼30% for walnut shells), whereas for the high density materials, there is no such discrepancy. We also find that low density materials have much higher water content and longer atmospheric equilibration timescales compared to high density sediments. We used thermogravimetric analysis (TGA) to quantify surface and internal water and found that over 80% of the total water content is surface water for low density materials. In the Titan Wind Tunnel (TWT), where Reynolds number conditions similar to those on Titan can be achieved, we performed threshold experiments with the standard walnut shells (125-150 μm, 7.2% water by mass) and dried walnut shells, in which the water content was reduced to 1.7%. The threshold results for the two scenarios are almost the same, which indicates that humidity had a negligible effect on threshold for walnut shells in this experimental regime. When the water content is lower than 11.0%, the interparticle forces are dominated by adsorption forces, whereas at

  3. Room for wind. An investigation into the possibilities for the erection of large numbers of wind turbines. Ruimte voor wind. Een studie naar de plaatsingsmogelijkheden van grote aantallen windturbines

    Energy Technology Data Exchange (ETDEWEB)

    Arkesteijn, L; Van Huis, G; Reckman, E

    1987-01-01

    The Dutch government aims to realize a wind power capacity in The Netherlands of 1000 MW in the year 2000. Environmental impacts of the erection of a large number of 200 kW and 1 MW wind turbines are studied. Four siting models have been developed in which attention is paid to environmental and economic aspects, the possibilities to introduce the electric power into the national power grid and the availability and reliability of enough wind. Noise pollution and danger for birds are to be avoided. The choice between the construction of wind parks where a number of wind turbines is concentrated in a small area or a more dispersed construction is somewhat difficult if all relevant factors are to be taken into consideration. Without government's interference the target of 1000 MW in the year 2000 will probably not be attained. It is therefore desirable to practise an active energy policy in favor of wind energy, for which many ways are possible.

  4. Summer sudden Na number density enhancements measured with the ALOMAR Weber Na Lidar

    Directory of Open Access Journals (Sweden)

    D. Heinrich

    2008-05-01

    Full Text Available We present summer Na-densities and atmospheric temperatures measured 80 to 110 km above the Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR. The Weber Na Lidar is part of ALOMAR, located at 69° N in Norway, 150 km north of the Arctic Circle. The sun does not set here during the summer months, and measurements require a narrowband Faraday Anomalous Dispersion Optical Filter (FADOF.

    We discuss an observed sudden enhancement in the Na number density around 22:00 UT on 1 to 2 June 2006. We compare this observation with previous summer measurements and find a frequent appearance of Na number density enhancements near local midnight. We describe the time of appearance, the altitude distribution, the duration and the strength of these enhancements and compare them to winter observations. We investigate possible formation mechanisms and, as others before, we find a strong link between these Na number density enhancements and sporadic E layers.

  5. Summer sudden Na number density enhancements measured with the ALOMAR Weber Na Lidar

    Directory of Open Access Journals (Sweden)

    D. Heinrich

    2008-05-01

    Full Text Available We present summer Na-densities and atmospheric temperatures measured 80 to 110 km above the Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR. The Weber Na Lidar is part of ALOMAR, located at 69° N in Norway, 150 km north of the Arctic Circle. The sun does not set here during the summer months, and measurements require a narrowband Faraday Anomalous Dispersion Optical Filter (FADOF. We discuss an observed sudden enhancement in the Na number density around 22:00 UT on 1 to 2 June 2006. We compare this observation with previous summer measurements and find a frequent appearance of Na number density enhancements near local midnight. We describe the time of appearance, the altitude distribution, the duration and the strength of these enhancements and compare them to winter observations. We investigate possible formation mechanisms and, as others before, we find a strong link between these Na number density enhancements and sporadic E layers.

  6. Solar wind electron densities from Viking dual-frequency radio measurements

    International Nuclear Information System (INIS)

    Muhleman, D.O.; Anderson, J.D.

    1981-01-01

    Simultaneous phase coherent, two-frequency measurements of the time delay between the Earth station and the Viking spacecraft have been analyzed in terms of the electron density profiles from 4 solar radii (R/sub sun/) to 200 R/sub sun/. The measurements were made during a period of solar activity minimum (1976--1977) and show a strong solar latitude effect. The data were analyzed with both a model independent, direct numerical inversion technique and with model fitting, yielding essentially the same results. It is shown that the solar wind density can be represented by two power laws near the solar equator proportional to r/sup -2.7/ and r/sup -2.04/. However, the more rapidly falling term quickly disappears at moderate latitudes (approx.20 0 ), leaving only the inverse-square behavior

  7. A Spatial Model for the Instantaneous Estimation of Wind Power at a Large Number of Unobserved Sites

    DEFF Research Database (Denmark)

    Lenzi, Amanda; Guillot, Gilles; Pinson, Pierre

    2015-01-01

    We propose a hierarchical Bayesian spatial model to obtain predictive densities of wind power at a set of un-monitored locations. The model consists of a mixture of Gamma density for the non-zero values and degenerated distributions at zero. The spatial dependence is described through a common...... Gaussian random field with a Matérn covariance. For inference and prediction, we use the GMRF-SPDE approximation implemented in the R-INLA package. We showcase the method outlined here on data for 336 wind farms located in Denmark. We test the predictions derived from our method with model-diagnostic tools...

  8. POWER SPECTRAL DENSITY OF FLUCTUATIONS OF BULK AND THERMAL SPEEDS IN THE SOLAR WIND

    International Nuclear Information System (INIS)

    Šafránková, J.; Němeček, Z.; Němec, F.; Přech, L.; Chen, C. H. K.; Zastenker, G. N.

    2016-01-01

    This paper analyzes solar wind power spectra of bulk and thermal speed fluctuations that are computed with a time resolution of 32 ms in the frequency range of 0.001–2 Hz. The analysis uses measurements of the Bright Monitor of the Solar Wind on board the Spektr-R spacecraft that are limited to 570 km s 1 bulk speed. The statistics, based on more than 42,000 individual spectra, show that: (1) the spectra of bulk and thermal speeds can be fitted by two power-law segments; (2) despite their large variations, the parameters characterizing frequency spectrum fits computed on each particular time interval are very similar for both quantities; (3) the median slopes of the bulk and thermal speeds of the segment attributed to the MHD scale are 1.43 and 1.38, respectively, whereas they are 3.08 and 2.43 in the kinetic range; (4) the kinetic range slopes of bulk and thermal speed spectra become equal when either the ion density or magnetic field strength are high; (5) the break between MHD and kinetic scales seems to be controlled by the ion β parameter; (6) the best scaling parameter for bulk and thermal speed variations is a sum of the inertial length and proton thermal gyroradius; and (7) the above conclusions can be applied to the density variations if the background magnetic field is very low.

  9. POWER SPECTRAL DENSITY OF FLUCTUATIONS OF BULK AND THERMAL SPEEDS IN THE SOLAR WIND

    Energy Technology Data Exchange (ETDEWEB)

    Šafránková, J.; Němeček, Z.; Němec, F.; Přech, L. [Charles University, Faculty of Mathematics and Physics, V Holešovičkách 2, 180 00 Prague 8 (Czech Republic); Chen, C. H. K. [Department of Physics, Imperial College London, London SW7 2AZ (United Kingdom); Zastenker, G. N., E-mail: jana.safrankova@mff.cuni.cz [Space Research Institute of Russian Academy of Sciences, Moscow, Russia, Profsoyuznaya ul. 84/32, Moscow 117997 (Russian Federation)

    2016-07-10

    This paper analyzes solar wind power spectra of bulk and thermal speed fluctuations that are computed with a time resolution of 32 ms in the frequency range of 0.001–2 Hz. The analysis uses measurements of the Bright Monitor of the Solar Wind on board the Spektr-R spacecraft that are limited to 570 km s{sup 1} bulk speed. The statistics, based on more than 42,000 individual spectra, show that: (1) the spectra of bulk and thermal speeds can be fitted by two power-law segments; (2) despite their large variations, the parameters characterizing frequency spectrum fits computed on each particular time interval are very similar for both quantities; (3) the median slopes of the bulk and thermal speeds of the segment attributed to the MHD scale are 1.43 and 1.38, respectively, whereas they are 3.08 and 2.43 in the kinetic range; (4) the kinetic range slopes of bulk and thermal speed spectra become equal when either the ion density or magnetic field strength are high; (5) the break between MHD and kinetic scales seems to be controlled by the ion β parameter; (6) the best scaling parameter for bulk and thermal speed variations is a sum of the inertial length and proton thermal gyroradius; and (7) the above conclusions can be applied to the density variations if the background magnetic field is very low.

  10. Periodic Density Structures and the Origin of the Slow Solar Wind

    Science.gov (United States)

    Viall-Kepko, Nicholeen M.; Vourlidas, Angelos

    2015-01-01

    The source of the slow solar wind has challenged scientists for years. Periodic density structures (PDSs), observed regularly in the solar wind at 1 AU (Astronomical Unit), can be used to address this challenge. These structures have length scales of hundreds to several thousands of megameters and frequencies of tens to hundreds of minutes. Two lines of evidence indicate that PDSs are formed in the solar corona as part of the slow solar wind release and/or acceleration processes. The first is corresponding changes in compositional data in situ, and the second is PDSs observed in the inner Heliospheric Imaging data on board the Solar Terrestrial Relations Observatory (STEREO)/Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) suite. The periodic nature of these density structures is both a useful identifier as well as an important physical constraint on their origin. In this paper, we present the results of tracking periodic structures identified in the inner Heliospheric Imager in SECCHI back in time through the corresponding outer coronagraph (COR2) images. We demonstrate that the PDSs are formed around or below 2.5 solar radii-the inner edge of the COR2 field of view. We compute the occurrence rates of PDSs in 10 days of COR2 images both as a function of their periodicity and location in the solar corona, and we find that this set of PDSs occurs preferentially with a periodicity of approximately 90 minutes and occurs near streamers. Lastly, we show that their acceleration and expansion through COR2 is self-similar, thus their frequency is constant at distances beyond 2.5 solar radii.

  11. On extending Kohn-Sham density functionals to systems with fractional number of electrons.

    Science.gov (United States)

    Li, Chen; Lu, Jianfeng; Yang, Weitao

    2017-06-07

    We analyze four ways of formulating the Kohn-Sham (KS) density functionals with a fractional number of electrons, through extending the constrained search space from the Kohn-Sham and the generalized Kohn-Sham (GKS) non-interacting v-representable density domain for integer systems to four different sets of densities for fractional systems. In particular, these density sets are (I) ensemble interacting N-representable densities, (II) ensemble non-interacting N-representable densities, (III) non-interacting densities by the Janak construction, and (IV) non-interacting densities whose composing orbitals satisfy the Aufbau occupation principle. By proving the equivalence of the underlying first order reduced density matrices associated with these densities, we show that sets (I), (II), and (III) are equivalent, and all reduce to the Janak construction. Moreover, for functionals with the ensemble v-representable assumption at the minimizer, (III) reduces to (IV) and thus justifies the previous use of the Aufbau protocol within the (G)KS framework in the study of the ground state of fractional electron systems, as defined in the grand canonical ensemble at zero temperature. By further analyzing the Aufbau solution for different density functional approximations (DFAs) in the (G)KS scheme, we rigorously prove that there can be one and only one fractional occupation for the Hartree Fock functional, while there can be multiple fractional occupations for general DFAs in the presence of degeneracy. This has been confirmed by numerical calculations using the local density approximation as a representative of general DFAs. This work thus clarifies important issues on density functional theory calculations for fractional electron systems.

  12. Ulysses observations of a 'density hole' in the high-speed solar wind

    International Nuclear Information System (INIS)

    Riley, P.; Gosling, J.T.; McComas, D.J.; Forsyth, R.J.

    1998-01-01

    Ulysses observations at mid and high heliographic latitudes have revealed a solar wind devoid of the large variations in density, temperature, and speed that are commonly observed at low latitudes. One event, however, observed on May 1, 1996, while Ulysses was located at ∼3.7AU and 38.5 degree, stands out in the plasma data set. The structure, which is unique in the Ulysses high-latitude data set, is seen as a drop in proton density of almost an order of magnitude and a comparable rise in proton temperature. The event lasts ∼3(1)/(2) hours giving the structure a size of ∼9.6x10 6 km (0.06 AU) along the spacecraft trajectory. Minimum variance analysis of this interval indicates that the angle between the average magnetic field direction and the minimum variance direction is ∼92 degree, suggesting that the 'density hole' may be approximated by a series of planar slabs separated by several tangential discontinuities. We discuss several possible explanations for the origin of this structure, but ultimately the origin of the density hole remains unknown. copyright 1998 American Geophysical Union

  13. Empirical model for the electron density peak height disturbance in response to solar wind conditions

    Science.gov (United States)

    Blanch, E.; Altadill, D.

    2009-04-01

    Geomagnetic storms disturb the quiet behaviour of the ionosphere, its electron density and the electron density peak height, hmF2. Many works have been done to predict the variations of the electron density but few efforts have been dedicated to predict the variations the hmF2 under disturbed helio-geomagnetic conditions. We present the results of the analyses of the F2 layer peak height disturbances occurred during intense geomagnetic storms for one solar cycle. The results systematically show a significant peak height increase about 2 hours after the beginning of the main phase of the geomagnetic storm, independently of both the local time position of the station at the onset of the storm and the intensity of the storm. An additional uplift is observed in the post sunset sector. The duration of the uplift and the height increase are dependent of the intensity of the geomagnetic storm, the season and the local time position of the station at the onset of the storm. An empirical model has been developed to predict the electron density peak height disturbances in response to solar wind conditions and local time which can be used for nowcasting and forecasting the hmF2 disturbances for the middle latitude ionosphere. This being an important output for EURIPOS project operational purposes.

  14. Electron number density profiles derived from radio occultation on the CASSIOPE spacecraft

    DEFF Research Database (Denmark)

    Shume, E. B.; Vergados, P.; Komjathy, A.

    2017-01-01

    This paper presents electron number density profiles derived from high resolution Global Positioning System (GPS) radio occultation (RO) observations performed using the Enhanced Polar Outflow Probe (e-POP) payload on the high inclination CAScade, Smallsat and IOnospheric Polar Explorer (CASSIOPE...... good agreement with density profiles estimated from ionosonde data, measured over nearby stations to the latitude and longitude of the RO tangent points, (2) in good agreement with density profiles inferred from GPS RO measured by the Constellation Observing System for Meteorology, Ionosphere...

  15. Self-assisted GaAs nanowires with selectable number density on Silicon without oxide layer

    International Nuclear Information System (INIS)

    Bietti, S; Somaschini, C; Esposito, L; Sanguinetti, S; Frigeri, C; Fedorov, A; Geelhaar, L

    2014-01-01

    We present the growth of self-assisted GaAs nanowires (NWs) with selectable number density on bare Si(1 1 1), not covered by the silicon oxide. We determine the number density of the NWs by initially self-assembling GaAs islands on whose top a single NW is nucleated. The number density of the initial GaAs base islands can be tuned by droplet epitaxy and the same degree of control is then transferred to the NWs. This procedure is completely performed during a single growth in an ultra-high vacuum environment and requires neither an oxide layer covering the substrate, nor any pre-patterning technique. (paper)

  16. Low density lesion in solid mass on CT: Pathologic change and housfield number

    International Nuclear Information System (INIS)

    Han, Tae Il; Lim, Joo Won; Ryu, Kyung Nam; Ko, Young Tae; Song, Mi Jin; Lee, Dong Ho; Lee, Ju Hie

    1994-01-01

    We retrospectively reviewed the pathologic changes and housfield unit of the low density lesion in solid mass on CT. Pathologically proved solid mass was evaluated in regard to the shape and margin of the low density in the mass on the CT scans of 23 patient. The CT number of the low density lesion was correlated with the pathologic changes. Pathologic changes of the low density lesions were; necrosis (n=17), hemorrhage (n=13), cyst (n=4), myxoid degeneration (n=2), hyaline degeneration (n=1), fibrosis (n=1), and mixed cellularity (n=1). In 14 cases, more than 2 pathologic changes were seen. In 11 cases, necrosis was associated with hemorrhage. The CT number ranged from 11.5 to 44.9 Housfield unit(HU) (mean, 25.2 HU). The average CT number was 26.9 HU in hemorrhage and necrosis, 17.2 HU in cystic change, 20.9 HU in myxoid degeneration, 35.7 HU in hyaline de generation, 22.3 HU in fibrosis, and 21.4 HU in mixed cellularity. The hemorrhage and necrosis in 17 cases showed irregular margin, amorphous shape, and showed centrifugal distribution. The cystic change in 4 cases showed well defined margin, round shape, and peripheral location in solid mass. The low density lesions in solid mass on CT represented variable pathologic changes; necrosis, hemorrhage, cyst, myxoid degeneration, hyaline degeneration, fibrosis, and mixed cellularity. Pathologic changes would not be differentiated on the basis of CT number

  17. Dependence of inhomogeneous vibrational linewidth broadening on attractive forces from local liquid number densities

    International Nuclear Information System (INIS)

    George, S.M.; Harris, C.B.

    1982-01-01

    The dependence of inhomogeneous vibrational linewidth broadening on attractive forces form slowly varying local liquid number densities is examined. The recently developed Schweizer--Chandler theory of vibrational dephasing is used to compute absolute inhomogeneous broadening linewidths. The computed linewidths are compared to measured inhomogeneous broadening linewidths determined using picosecond vibrational dephasing experiments. There is a similarity between correlations of the Schweizer--Chandler and George--Auweter--Harris predicted inhomogeneous broadening linewidths and the measured inhomogeneous broadening linewidths. For the methyl stretches under investigation, this correspondence suggests that the width of the number density distribution in the liquid determines the relative inhomogeneous broadening magnitudes

  18. Topological relics of symmetry breaking: winding numbers and scaling tilts from random vortex–antivortex pairs

    International Nuclear Information System (INIS)

    Zurek, W H

    2013-01-01

    I show that random distributions of vortex–antivortex pairs (rather than of individual vortices) lead to scaling of typical winding numbers W trapped inside a loop of circumference C with the square root of that circumference, W∼√C, when the expected winding numbers are large, |W| ≫ 1. Such scaling is consistent with the Kibble–Zurek mechanism (KZM), with 〈W 2 〉 inversely proportional to ξ-hat , the typical size of the domain that can break symmetry in unison. (The dependence of ξ-hat on quench rate is predicted by KZM from critical exponents of the phase transition.) Thus, according to KZM, the dispersion √ 2 > scales as √(C/ ξ-hat ) for large W. By contrast, a distribution of individual vortices with randomly assigned topological charges would result in the dispersion scaling with the square root of the area inside C (i.e., √ 2 > ∼ C). Scaling of the dispersion of W as well as of the probability of detection of non-zero W with C and ξ-hat can be also studied for loops so small that non-zero windings are rare. In this case I show that dispersion varies not as 1/√( ξ-hat ), but as 1/ ξ-hat , which results in a doubling of the scaling of dispersion with the quench rate when compared to the large |W| regime. Moreover, the probability of trapping of non-zero W becomes approximately equal to 〈W 2 〉, and scales as 1/ ξ-hat 2 . This quadruples—as compared with √ 2 > ≃ √C/ξ-circumflex valid for large W—the exponent in the power law dependence of the frequency of trapping of |W| = 1 on ξ-hat when the probability of |W| > 1 is negligible. This change of the power law exponent by a factor of four—from 1/√( ξ-hat ) for the dispersion of large W to 1/ ξ-hat 2 for the frequency of non-zero W when |W| > 1 is negligibly rare—is of paramount importance for experimental tests of KZM. (paper)

  19. Experimental tests of the effect of rotor diameter ratio and blade number to the cross-flow wind turbine performance

    Science.gov (United States)

    Susanto, Sandi; Tjahjana, Dominicus Danardono Dwi Prija; Santoso, Budi

    2018-02-01

    Cross-flow wind turbine is one of the alternative energy harvester for low wind speeds area. Several factors that influence the power coefficient of cross-flow wind turbine are the diameter ratio of blades and the number of blades. The aim of this study is to find out the influence of the number of blades and the diameter ratio on the performance of cross-flow wind turbine and to find out the best configuration between number of blades and diameter ratio of the turbine. The experimental test were conducted under several variation including diameter ratio between outer and inner diameter of the turbine and number of blades. The variation of turbine diameter ratio between inner and outer diameter consisted of 0.58, 0.63, 0.68 and 0.73 while the variations of the number of blades used was 16, 20 and 24. The experimental test were conducted under certain wind speed which are 3m/s until 4 m/s. The result showed that the configurations between 0.68 diameter ratio and 20 blade numbers is the best configurations that has power coefficient of 0.049 and moment coefficient of 0.185.

  20. Bearing failure detection of micro wind turbine via power spectral density analysis for stator current signals spectrum

    Science.gov (United States)

    Mahmood, Faleh H.; Kadhim, Hussein T.; Resen, Ali K.; Shaban, Auday H.

    2018-05-01

    The failure such as air gap weirdness, rubbing, and scrapping between stator and rotor generator arise unavoidably and may cause extremely terrible results for a wind turbine. Therefore, we should pay more attention to detect and identify its cause-bearing failure in wind turbine to improve the operational reliability. The current paper tends to use of power spectral density analysis method of detecting internal race and external race bearing failure in micro wind turbine by estimation stator current signal of the generator. The failure detector method shows that it is well suited and effective for bearing failure detection.

  1. Arbitrary-order Hilbert Spectral Analysis and Intermittency in Solar Wind Density Fluctuations

    Science.gov (United States)

    Carbone, Francesco; Sorriso-Valvo, Luca; Alberti, Tommaso; Lepreti, Fabio; Chen, Christopher H. K.; Němeček, Zdenek; Šafránková, Jana

    2018-05-01

    The properties of inertial- and kinetic-range solar wind turbulence have been investigated with the arbitrary-order Hilbert spectral analysis method, applied to high-resolution density measurements. Due to the small sample size and to the presence of strong nonstationary behavior and large-scale structures, the classical analysis in terms of structure functions may prove to be unsuccessful in detecting the power-law behavior in the inertial range, and may underestimate the scaling exponents. However, the Hilbert spectral method provides an optimal estimation of the scaling exponents, which have been found to be close to those for velocity fluctuations in fully developed hydrodynamic turbulence. At smaller scales, below the proton gyroscale, the system loses its intermittent multiscaling properties and converges to a monofractal process. The resulting scaling exponents, obtained at small scales, are in good agreement with those of classical fractional Brownian motion, indicating a long-term memory in the process, and the absence of correlations around the spectral-break scale. These results provide important constraints on models of kinetic-range turbulence in the solar wind.

  2. Experimental studies of Savonius wind turbines with variations sizes and fin numbers towards performance

    Science.gov (United States)

    Utomo, Ilham Satrio; Tjahjana, Dominicus Danardono Dwi Prija; Hadi, Syamsul

    2018-02-01

    The use of renewable energy in Indonesia is still low. Especially the use of wind energy. Wind turbine Savonius is one turbine that can work with low wind speed. However, Savonius wind turbines still have low efficiency. Therefore it is necessary to modify. Modifications by using the fin are expected to increase the positive drag force by creating a flow that can enter the overlap ratio of the gap. This research was conducted using experimental approach scheme. Parameters generated from the experiment include: power generator, power coefficient, torque coefficient. The experimental data will be collected by variation of fin area, horizontal finning, at wind speed 3 m/s - 4,85 m/s. Experimental results show that with the addition of fin can improve the performance of wind turbine Savonius 11%, and by using the diameter of 115 mm fin is able to provide maximum performance in wind turbine Savonius.

  3. The application of cryogenics to high Reynolds number testing in wind tunnels. I - Evolution, theory, and advantages

    Science.gov (United States)

    Kilgore, R. A.; Dress, D. A.

    1984-01-01

    During the time which has passed since the construction of the first wind tunnel in 1870, wind tunnels have been developed to a high degree of sophistication. However, their development has consistently failed to keep pace with the demands placed on them. One of the more serious problems to be found with existing transonic wind tunnels is their inability to test subscale aircraft models at Reynolds numbers sufficiently near full-scale values to ensure the validity of using the wind tunnel data to predict flight characteristics. The Reynolds number capability of a wind tunnel may be increased by a number of different approaches. However, the best solution in terms of model, balance, and model support loads, as well as in terms of capital and operating cost appears to be related to the reduction of the temperature of the test gas to cryogenic temperatures. The present paper has the objective to review the evolution of the cryogenic wind tunnel concept and to describe its more important advantages.

  4. Studies on effective atomic number, electron density and kerma for some fatty acids and carbohydrates

    DEFF Research Database (Denmark)

    Manohara, S.R.; Hanagodimath, S.M.; Gerward, Leif

    2008-01-01

    The effective atomic number, Z(eff), the effective electron density, N-el, and kerma have been calculated for some fatty acids and carbohydrates for photon interaction in the extended energy range from 1 keV to 100 GeV using an accurate database of photon-interaction cross sections and the WinXCo...

  5. THE STELLAR NUMBER DENSITY DISTRIBUTION IN THE LOCAL SOLAR NEIGHBORHOOD IS NORTH-SOUTH ASYMMETRIC

    Energy Technology Data Exchange (ETDEWEB)

    Yanny, Brian [Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Gardner, Susan [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506-0055 (United States)

    2013-11-10

    We study the number density distribution of a sample of K and M dwarf stars, matched north and south of the Galactic plane within a distance of 2 kpc from the Sun, using observations from the Ninth Data Release of the Sloan Digital Sky Survey. We determine distances using the photometric parallax method, and in this context systematic effects exist which could potentially impact the determination of the number density profile with height from the Galactic plane—and ultimately affect a number density north-south asymmetry. They include: (1) the calibration of the various photometric parallax relations, (2) the ability to separate dwarfs from giants in our sample, (3) the role of stellar population differences such as age and metallicity, (4) the ability to determine the offset of the Sun from the Galactic plane, and (5) the correction for reddening from dust in the Galactic plane, though our stars are at high Galactic latitudes. We find the various analyzed systematic effects to have a negligible impact on our observed asymmetry, and using a new and larger sample of stars we confirm and refine the earlier discovery of Widrow et al. of a significant Galactic north-south asymmetry in the stellar number density distribution.

  6. THE STELLAR NUMBER DENSITY DISTRIBUTION IN THE LOCAL SOLAR NEIGHBORHOOD IS NORTH-SOUTH ASYMMETRIC

    Energy Technology Data Exchange (ETDEWEB)

    Yanny, Brian; Gardner, Susan

    2013-10-17

    We study the number density distribution of a sample of K and M dwarf stars, matched North and South of the Galactic plane within a distance of 2 kpc from the sun, using observations from the Ninth Data Release of the Sloan Digital Sky Survey. We determine distances using the photometric parallax method, and in this context systematic effects exist which could potentially impact the determination of the number density profile with height from the Galactic plane --- and ultimately affect a number density North-South asymmetry. They include: (i) the calibration of the various photometric parallax relations, (ii) the ability to separate dwarfs from giants in our sample, (iii) the role of stellar population differences such as age and metallicity, (iv) the ability to determine the offset of the sun from the Galactic plane, and (v) the correction for reddening from dust in the Galactic plane, though our stars are at high Galactic latitudes. We find the various analyzed systematic effects to have a negligible impact on our observed asymmetry, and using a new and larger sample of stars we confirm and refine the earlier discovery of Widrow et al. of a significant Galactic North-South asymmetry in the stellar number density distribution.

  7. Dependence of regular background noise of VLF radiation and thunder-storm activity on solar wind proton density

    International Nuclear Information System (INIS)

    Sobolev, A.V.; Kozlov, V.I.

    1997-01-01

    Correlation of the intensity of slowly changing regular background noise within 9.7 kHz frequency in Yakutsk (L = 3) and of the solar wind density protons was determined. This result explains the reverse dependence of the intensity of the regular background noise on the solar activity, 27-day frequency, increase before and following geomagnetic storms, absence of relation with K p index of geomagnetic activity. Conclusion is made that growth of density of the solar wind protons results in increase of the regular background noise and thunderstorm activity

  8. On the continuum theory of the one-fluid solar wind for small Prandtl number

    International Nuclear Information System (INIS)

    Johnson, R.S.

    1976-01-01

    The continuum theory for a single-species gas expanding into a vacuum (or near vacuum) is considered. The gas is assumed compressible, viscous and heat conducting with a constant Prandtl number and viscosity proportional to (temperature) sup(ω), ω > 1. The gas is under the influence of a gravitational field centred on the Sun. For small Prandtl number (which is realistic for the one-fluid solar wind), the method of matched asymptotic expansions is used to construct a solution describing the complete flow field from the surface of the Sun to infinity. The first two regions correspond to those found by Roberts and Soward (Proc. R. Soc. Lond.; A328:185 (1972)) for large thermal conductivity; the next involves the viscous terms, and in the fourth the viscous terms dominate. It it shown from the fourth region that either the flow remains supersonic but terminates at a finite point, or the flow becomes subsonic through a diffuse shock layer and approaches a non-zero pressure at infinity. It is seen that the existence of a critical point (subsonic/supersonic transition) together with a known pressure at infinity can uniquely determine the complete solution. However, to correspond with typical results near the Sun and at the Earth's orbit the pressure at infinity is found to be very much larger than that generally accepted. (author)

  9. Construction of a voxel model from CT images with density derived from CT numbers

    International Nuclear Information System (INIS)

    Cheng Mengyun; Zeng Qin; Cao Ruifen; Li Gui; Zheng Huaqing; Huang Shanqing; Song Gang; Wu Yican

    2011-01-01

    The voxel models representing human anatomy have been developed to calculate dose distribution in human body, while the density and elemental composition are the most important physical properties of voxel model. Usually, when creating the Monte Carlo input files, the average tissue densities recommended in ICRP Publication were used to assign each voxel in the existing voxel models. As each tissue consists of many voxels with different densities, the conventional method of average tissue densities failed to take account of the voxel's discrepancy, and therefore could not represent human anatomy faithfully. To represent human anatomy more faithfully, a method was implemented to assign each voxel, the densities of which were derived from CT number. In order to compare with the traditional method, we constructed two models from the cadaver specimen dataset. A CT-based pelvic voxel model called Pelvis-CT model was constructed, the densities of which were derived from the CT numbers. A color photograph-based pelvic voxel model called Pelvis-Photo model was also constructed, the densities of which were taken from ICRP Publication. The CT images and the color photographs were obtained from the same female cadaver specimen. The Pelvis-CT and Pelvis-Photo models were both ported into Monte Carlo code MCNP to calculate the conversion coefficients from kerma free-in-air to absorbed dose for external monoenergetic photon beams with energies of 0.1, 1 and 10 MeV under anterior-posterior (AP) geometry. The results were compared with those of given in ICRP Publication 74. Differences of up to 50% were observed between conversion coefficients of Pelvis-CT and Pelvis- Photo models, moreover the discrepancies decreased for the photon beams with higher energies. The overall trend of conversion coefficients of the Pelvis-CT model agreed well with that of ICRP Publication 74 data. (author)

  10. Area vs. density: influence of visual variables and cardinality knowledge in early number comparison.

    Science.gov (United States)

    Abreu-Mendoza, Roberto A; Soto-Alba, Elia E; Arias-Trejo, Natalia

    2013-01-01

    Current research in the number development field has focused in individual differences regarding the acuity of children's approximate number system (ANS). The most common task to evaluate children's acuity is through non-symbolic numerical comparison. Efforts have been made to prevent children from using perceptual cues by controlling the visual properties of the stimuli (e.g., density, contour length, and area); nevertheless, researchers have used these visual controls interchangeably. Studies have also tried to understand the relation between children's cardinality knowledge and their performance in a number comparison task; divergent results may in fact be rooted in the use of different visual controls. The main goal of the present study is to explore how the usage of different visual controls (density, total filled area, and correlated and anti-correlated area) affects children's performance in a number comparison task, and its relationship to children's cardinality knowledge. For that purpose, 77 preschoolers participated in three tasks: (1) counting list elicitation to test whether children could recite the counting list up to ten, (2) give a number to evaluate children's cardinality knowledge, and (3) number comparison to evaluate their ability to compare two quantities. During this last task, children were asked to point at the set with more geometric figures when two sets were displayed on a screen. Children were exposed only to one of the three visual controls. Results showed that overall, children performed above chance in the number comparison task; nonetheless, density was the easiest control, while correlated and anti-correlated area was the most difficult in most cases. Only total filled area was sensitive to discriminate cardinal principal knowers from non-cardinal principal knowers. How this finding helps to explain conflicting evidence from previous research, and how the present outcome relates to children's number word knowledge is discussed.

  11. Periodic fluctuations in correlation-based connectivity density time series: Application to wind speed-monitoring network in Switzerland

    Science.gov (United States)

    Laib, Mohamed; Telesca, Luciano; Kanevski, Mikhail

    2018-02-01

    In this paper, we study the periodic fluctuations of connectivity density time series of a wind speed-monitoring network in Switzerland. By using the correlogram-based robust periodogram annual periodic oscillations were found in the correlation-based network. The intensity of such annual periodic oscillations is larger for lower correlation thresholds and smaller for higher. The annual periodicity in the connectivity density seems reasonably consistent with the seasonal meteo-climatic cycle.

  12. On Lunar Exospheric Column Densities and Solar Wind Access Beyond the Terminator from ROSAT Soft X-Ray Observations of Solar Wind Charge Exchange

    Science.gov (United States)

    Collier, Michael R.; Snowden, S. L.; Sarantos, M.; Benna, M.; Carter, J. A.; Cravens, T. E.; Farrell, W. M.; Fatemi, S.; Hills, H. Kent; Hodges, R. R.; hide

    2014-01-01

    We analyze the Rontgen satellite (ROSAT) position sensitive proportional counter soft X-ray image of the Moon taken on 29 June 1990 by examining the radial profile of the surface brightness in three wedges: two 19 deg wedges (one north and one south) 13-32 deg off the terminator toward the dark side and one wedge 38 deg wide centered on the antisolar direction. The radial profiles of both the north and the south wedges show significant limb brightening that is absent in the 38 deg wide antisolar wedge. An analysis of the soft X-ray intensity increase associated with the limb brightening shows that its magnitude is consistent with that expected due to solar wind charge exchange (SWCX) with the tenuous lunar atmosphere based on lunar exospheric models and hybrid simulation results of solar wind access beyond the terminator. Soft X-ray imaging thus can independently infer the total lunar limb column density including all species, a property that before now has not been measured, and provide a large-scale picture of the solar wind-lunar interaction. Because the SWCX signal appears to be dominated by exospheric species arising from solar wind implantation, this technique can also determine how the exosphere varies with solar wind conditions. Now, along with Mars, Venus, and Earth, the Moon represents another solar system body at which SWCX has been observed.

  13. Power density investigation on the press-pack IGBT 3L-HB-VSCs applied to large wind turbine

    DEFF Research Database (Denmark)

    Senturk, Osman Selcuk; Munk-Nielsen, Stig; Teodorescu, Remus

    2011-01-01

    capabilities, DC capacitor sizes, converter cabinet volumes of the three 3LHB- VSCs utilizing press-pack IGBTs are investigated in order to quantify and compare the power densities of the 3L-HB-VSCs employed as grid-side converters. Also, the suitable transformer types for the 3L-HB-VSCs are determined......With three different DC-side and AC-side connections, the three-level H-bridge voltage source converters (3L-HB-VSCs) are alternatives to 3L neutral-point-clamped VSCs (3L-NPC-VSCs) for interfacing large wind turbines with electricity grids. In order to assess their feasibility for large wind...... turbines, they should be investigated in terms of power density, which is one of the most important design criteria for wind turbine converters due to turbine nacelle space limitation. In this study, by means of the converter electro-thermal models based on the converter characteristics, the power...

  14. The effect of tip speed ratio on a vertical axis wind turbine at high Reynolds numbers

    Science.gov (United States)

    Parker, Colin M.; Leftwich, Megan C.

    2016-05-01

    This work visualizes the flow surrounding a scaled model vertical axis wind turbine at realistic operating conditions. The model closely matches geometric and dynamic properties—tip speed ratio and Reynolds number—of a full-size turbine. The flow is visualized using particle imaging velocimetry (PIV) in the midplane upstream, around, and after (up to 4 turbine diameters downstream) the turbine, as well as a vertical plane behind the turbine. Time-averaged results show an asymmetric wake behind the turbine, regardless of tip speed ratio, with a larger velocity deficit for a higher tip speed ratio. For the higher tip speed ratio, an area of averaged flow reversal is present with a maximum reverse flow of -0.04U_∞. Phase-averaged vorticity fields—achieved by syncing the PIV system with the rotation of the turbine—show distinct structures form from each turbine blade. There were distinct differences in results by tip speed ratios of 0.9, 1.3, and 2.2 of when in the cycle structures are shed into the wake—switching from two pairs to a single pair of vortices being shed—and how they convect into the wake—the middle tip speed ratio vortices convect downstream inside the wake, while the high tip speed ratio pair is shed into the shear layer of the wake. Finally, results show that the wake structure is much more sensitive to changes in tip speed ratio than to changes in Reynolds number.

  15. Correlation of theory to wind-tunnel data at Reynolds numbers below 500,000

    Science.gov (United States)

    Evangelista, Raquel; Mcghee, Robert J.; Walker, Betty S.

    1989-01-01

    This paper presents results obtained from two airfoil analysis methods compared with previously published wind tunnel test data at chord Reynolds numbers below 500,000. The analysis methods are from the Eppler-Somers airfoil design/analysis code and from ISES, the Drela-Giles Airfoil design/analysis code. The experimental data are from recent tests of the Eppler 387 airfoil in the NASA Langley Low Turbulence Pressure Tunnel. For R not less than 200,000, lift and pitching moment predictions from both theories compare well with experiment. Drag predictions from both theories also agree with experiment, although to different degrees. However, most of the drag predictions from the Eppler-Somers code are accompanied with separation bubble warnings which indicate that the drag predictions are too low. With the Drela-Giles code, there is a large discrepancy between the computed and experimental pressure distributions in cases with laminar separation bubbles, although the drag polar predictions are similar in trend to experiment.

  16. Perturbation theory of the quark-gluon plasma at finite temperature and baryon number density

    International Nuclear Information System (INIS)

    Anon.

    1984-01-01

    At very high energy densities, hadronic matter becomes an almost ideal gas of quarks and gluons. In these circumstances, the effects of particle interactions are small, and to some order in perturbation theory are computable by methods involving weak coupling expansions. To illustrate the perturbative methods which may be used to compute the thermodynamic potential, the results and methods which are employed to compute to first order in α/sub s/ are reviewed. The problem of the plasmon effect, and the necessity of using non-perturbative methods when going beyond first order in α/sub s/ in evaluating the thermodynamic potential are discussed. The results at zero temperature and finite baryon number density to second order in α/sub s/ are also reviewed. The method of renormalization group improving the weak coupling expansions by replacing the expansion by an expansion in a temperature and baryon number density dependent coupling which approaches zero at high energy densities is discussed. Non-perturbative effects such as instantons are briefly mentioned and the breakdown of perturbation theory for the thermodynamical at order α/sub s/ 3 for finite temperature is presented

  17. Spectroscopic measurements of plasma temperatures and electron number density in a uranium hollow cathode discharge lamp

    International Nuclear Information System (INIS)

    Shah, M.L.; Suri, B.M.; Gupta, G.P.

    2015-01-01

    The HCD (Hollow Cathode Discharge) lamps have been used as a source of free atoms of any metal, controllable by direct current in the lamp. The plasma parameters including neutral species temperature, atomic excitation temperature and electron number density in a see-through type, homemade uranium hollow cathode discharge lamp with neon as a buffer gas have been investigated using optical emission spectroscopic techniques. The neutral species temperature has been measured using the Doppler broadening of a neon atomic spectral line. The atomic excitation temperature has been measured using the Boltzmann plot method utilizing uranium atomic spectral lines. The electron number density has been determined from the Saha-Boltzmann equation utilizing uranium atomic and ionic spectral lines. To the best of our knowledge, all these three plasma parameters are simultaneously measured for the first time in a uranium hollow cathode discharge lamp

  18. Cloud Liquid Water, Mean Droplet Radius and Number Density Measurements Using a Raman Lidar

    Science.gov (United States)

    Whiteman, David N.; Melfi, S. Harvey

    1999-01-01

    A new technique for measuring cloud liquid water, mean droplet radius and droplet number density is outlined. The technique is based on simultaneously measuring Raman and Mie scattering from cloud liquid droplets using a Raman lidar. Laboratory experiments on liquid micro-spheres have shown that the intensity of Raman scattering is proportional to the amount of liquid present in the spheres. This fact is used as a constraint on calculated Mie intensity assuming a gamma function particle size distribution. The resulting retrieval technique is shown to give stable solutions with no false minima. It is tested using Raman lidar data where the liquid water signal was seen as an enhancement to the water vapor signal. The general relationship of retrieved average radius and number density is consistent with traditional cloud physics models. Sensitivity to the assumed maximum cloud liquid water amount and the water vapor mixing ratio calibration are tested. Improvements to the technique are suggested.

  19. Detection of density-dependent effects on caribou numbers from a series of census data

    Directory of Open Access Journals (Sweden)

    Francois Messier

    1991-10-01

    Full Text Available The main objective of this paper is to review and discuss the applicability of statistical procedures for the detection of density dependence based on a series of annual or multi-annual censuses. Regression models for which the statistic value under the null hypothesis of density independence is set a priori (slope = 0 or 1, generate spurious indications of density dependence. These tests are inappropriate because low sample sizes, high variance, and sampling error consistently bias the slope when applied to a finite number of population estimates. Two distribution-free tests are reviewed for which the rejection region for the hypothesis of density independence is derived intrinsically from the data through a computer-assisted permutation process. The "randomization test" gives the best results as the presence of a pronounced trend in the sequence of population estimates does not affect test results. The other non-parametric test, the "permutation test", gives reliable results only if the population fluctuates around a long-term equilibrium density. Both procedures are applied to three sets of data (Pukaskwa herd, Avalon herd, and a hypothetical example that represent quite divergent population trajectories over time.

  20. Reducing the Density and Number of Tobacco Retailers: Policy Solutions and Legal Issues.

    Science.gov (United States)

    Ackerman, Amy; Etow, Alexis; Bartel, Sara; Ribisl, Kurt M

    2017-02-01

    Because higher density of tobacco retailers is associated with greater tobacco use, U.S. communities seek ways to reduce the density and number of tobacco retailers. This approach can reduce the concentration of tobacco retailers in poorer communities, limit youth exposure to tobacco advertising, and prevent misleading associations between tobacco and health messaging. Communities can reduce the density and number of tobacco retailers by imposing minimum distance requirements between existing retailers, capping the number of retailers in a given geographic area, establishing a maximum number of retailers proportional to population size, and prohibiting sales at certain types of establishments, such as pharmacies, or within a certain distance of locations serving youth. Local governments use direct regulation, licensing, or zoning laws to enact these changes. We analyze each approach under U.S. constitutional law to assist communities in selecting and implementing one or more of these methods. There are few published legal opinions that address these strategies in the context of tobacco control. But potential constitutional challenges include violations of the Takings Clause of the Fifth Amendment, which protects property owners from onerous government regulations, and under the Fourteenth Amendment's Equal Protection and Due Process Clauses, which protect business owners from arbitrary or unreasonable regulations that do not further a legitimate government interest. Because there is an evidentiary basis linking the density of tobacco retailers to smoking rates in a community, courts are likely to reject constitutional challenges to carefully crafted laws that reduce the number of tobacco retailers. Our review of the relevant constitutional issues confirms that local governments have the authority to utilize laws and policies to reduce the density and number of tobacco retailers in their communities, given existing public health data. The analysis guides policy

  1. Effect of error propagation of nuclide number densities on Monte Carlo burn-up calculations

    International Nuclear Information System (INIS)

    Tohjoh, Masayuki; Endo, Tomohiro; Watanabe, Masato; Yamamoto, Akio

    2006-01-01

    As a result of improvements in computer technology, the continuous energy Monte Carlo burn-up calculation has received attention as a good candidate for an assembly calculation method. However, the results of Monte Carlo calculations contain the statistical errors. The results of Monte Carlo burn-up calculations, in particular, include propagated statistical errors through the variance of the nuclide number densities. Therefore, if statistical error alone is evaluated, the errors in Monte Carlo burn-up calculations may be underestimated. To make clear this effect of error propagation on Monte Carlo burn-up calculations, we here proposed an equation that can predict the variance of nuclide number densities after burn-up calculations, and we verified this equation using enormous numbers of the Monte Carlo burn-up calculations by changing only the initial random numbers. We also verified the effect of the number of burn-up calculation points on Monte Carlo burn-up calculations. From these verifications, we estimated the errors in Monte Carlo burn-up calculations including both statistical and propagated errors. Finally, we made clear the effects of error propagation on Monte Carlo burn-up calculations by comparing statistical errors alone versus both statistical and propagated errors. The results revealed that the effects of error propagation on the Monte Carlo burn-up calculations of 8 x 8 BWR fuel assembly are low up to 60 GWd/t

  2. Effects of the sowing density on he yield and the number of seeds in seed maize

    Directory of Open Access Journals (Sweden)

    Jovin Predrag

    2006-01-01

    Full Text Available Higher sowing densities (57,100, 71,400 and 85,500 plants ha-1 of the female component did not significantly affect the yield increase in the hybrid ZP 196 (4.56,4.61 and 4.701 ha-1 under natural conditions of cultivation, but they significantly affected the increase of the number of germinated seeds (21,272,000, 23,893,000 and 24,226,000 ha-1. In the seed production under irrigation conditions of the hybrid ZP 677, greater densities (71,400, 85,500 and 99,900 plants ha-1 did not significantly affect the increase of neither the yield (3.39,3.44 and 3.60 tha-1 nor the number of geminated seeds (11,238,000,11,651,000 and 12,427,000 ha-1. On the other hand, higher sowing densities (71,400,85,500 and 99,900 plants ha-1 of the female component significantly increased both, the yield (4.01, 4.38 and 4.40 t ha-1 and the number of germinated seeds (13,122,000,15,022,000 and 15,560,000 ha-1 in the hybrid ZP 680 under irrigation conditions.

  3. Distribution of E/N and N/e/ in a cross-flow electric discharge laser. [electric field to neutral gas density and electron number density

    Science.gov (United States)

    Dunning, J. W., Jr.; Lancashire, R. B.; Manista, E. J.

    1976-01-01

    Measurements have been conducted of the effect of the convection of ions and electrons on the discharge characteristics in a large scale laser. The results are presented for one particular distribution of ballast resistance. Values of electric field, current density, input power density, ratio of electric field to neutral gas density (E/N), and electron number density were calculated on the basis of measurements of the discharge properties. In a number of graphs, the E/N ratio, current density, power density, and electron density are plotted as a function of row number (downstream position) with total discharge current and gas velocity as parameters. From the dependence of the current distribution on the total current, it appears that the electron production in the first two rows significantly affects the current flowing in the succeeding rows.

  4. Influence of density and mean atomic number on CT attenuation corrected PET: Phantom studies

    International Nuclear Information System (INIS)

    Maintas, D.; Houzard, C.; Galy, G.; Maintas, C.; Itti, R.; Cachin, F.; Mognetti, Th.; Slosman

    2007-01-01

    Aim: the aim of this work is to study the influence of medium density on the CT or external source attenuation corrected images, by simulation on a phantom, with various positron emission tomographs. Material and method: a series of experiments on a cylindrical phantom filled with water marked with [18 F]-FDG, containing six vials filled per pair with mediums of different densities or solutions of KI, CaCl 2 and saccharose with various densities, was carried out under comparable conditions on three different tomographs. In only one of the vials of each pair, an identical radioactivity of [18 F]-FDG was added, three to five fold the surrounding activity. The reconstructions and attenuation corrections suggested by the manufacturers, were carried out under the usual conditions of each site. The activity of each structure was estimated by the methods of profiles and regions of interest, on the non attenuation corrected images (N.A.C.), the images corrected by CT (C.T.A.C.), and/or external source (G.P.A.C.). Results: with all three tomographs, the activities estimated on the N.A.C. images present an inverse correlation to the medium density (important absorption by dense material). On C.T.A.C. images, we observed with only two of the three tomographs, an overestimation of the activity in the 'radioactive' vials, depending on the medium mean Z number and density (over correction), and a artifactual 'activity' in the denser 'cold' vial (incorrect attenuation correction. The dense saccharose solutions, with non elevated Z number, do not affect the CT attenuation correction. (authors)

  5. Construction of a voxel model from CT images with density derived from CT numbers

    International Nuclear Information System (INIS)

    Cheng Mengyun; Zeng Qin; Cao Ruifen; Li Gui; Zheng Huaqing; Huang Shanqing; Song Gang; Wu Yican

    2010-01-01

    The voxel models representing human anatomy have been developed to calculate dose distribution in human body, while the density is the most important physical property of voxel model. Traditionally, when creating the Monte Carlo input files, the average tissue parameters recommended in ICRP report were used to assign each voxel in the existing voxel models. However, as each tissue consists of many voxels in which voxels are different in their densities, the method of assigning average tissue parameters doesn't take account of the voxel's discrepancy, and can't represent human anatomy faithfully. To represent human anatomy more faithfully, a method was implemented to assign each voxel, the density of which was derived from CT number. In order to compare with the traditional method, we have constructed two models from a same cadaver specimen date set. A CT-based pelvic voxel model called Pelvis-CT model, was constructed, the densities of which were derived from the CT numbers. A color photograph-based pelvic voxel model called Pelvis-Photo model, was also constructed, the densities of which were taken from ICRP Publication. The CT images and color photographs were obtained from the same female cadaver specimen. The Pelvis-CT and Pelvis-Photo models were ported into Monte Carlo code MCNP to calculate the conversion coefficients from kerma free-in-air to absorbed dose for external monoenergetic photon beams with energies of 0.1, 1 and 10 MeV under anterior-posterior (AP) geometries. The results were compared with those of given in ICRP74. Differences of up to 50% were observed between conversion coefficients of Pelvis-CT and Pelvis-Photo models, moreover the discrepancies decreased for the photon beams with higher energies. The overall trend of conversion coefficients of the Pelvis-CT model were agreed well with that of ICRP74 data. (author)

  6. Design and analysis of a direct-drive wind power generator with ultra-high torque density

    Science.gov (United States)

    Jian, Linni; Shi, Yujun; Wei, Jin; Zheng, Yanchong

    2015-05-01

    In order to get rid of the nuisances caused by mechanical gearboxes, generators with low rated speed, which can be directly connected to wind turbines, are attracting increasing attention. The purpose of this paper is to propose a new direct-drive wind power generator (DWPG), which can offer ultra-high torque density. First, magnetic gear (MG) is integrated to achieve non-contact torque transmission and speed variation. Second, armature windings are engaged to achieve electromechanical energy conversion. Interior permanent magnet (PM) design on the inner rotor is adopted to boost the torque transmission capability of the integrated MG. Nevertheless, due to lack of back iron on the stator, the proposed generator does not exhibit prominent salient feature, which usually exists in traditional interior PM (IPM) machines. This makes it with good controllability and high power factor as the surface-mounted permanent magnet machines. The performance is analyzed using finite element method. Investigation on the magnetic field harmonics demonstrates that the permanent-magnetic torque offered by the MG can work together with the electromagnetic torque offered by the armature windings to balance the driving torque captured by the wind turbine. This allows the proposed generator having the potential to offer even higher torque density than its integrated MG.

  7. Two-colour QCD at finite fundamental quark-number density and related theories

    International Nuclear Information System (INIS)

    Hands, S.J.; Kogut, J.B.; Morrison, S.E.; Sinclair, D.K.

    2001-01-01

    We are simulating SU(2) Yang-Mills theory with four flavours of dynamical quarks in the fundamental representation of SU(2) 'colour' at finite chemical potential, μ for quark number, as a model for QCD at finite baryon number density. In particular we observe that for μ large enough this theory undergoes a phase transition to a state with a diquark condensate which breaks quark-number symmetry. In this phase we examine the spectrum of light scalar and pseudoscalar bosons and see evidence for the Goldstone boson associated with this spontaneous symmetry breaking. This theory is closely related to QCD at finite chemical potential for isospin, a theory which we are now studying for SU(3) colour

  8. Two-colour QCD at finite fundamental quark-number density and related theories

    International Nuclear Information System (INIS)

    Hands, S. J.; Kogut, J. B.; Morrison, S. E.; Sinclair, D. K.

    2000-01-01

    We are simulating SU(2) Yang-Mills theory with four flavours of dynamical quarks in the fundamental representation of SU(2) colour at finite chemical potential, p for quark number, as a model for QCD at finite baryon number density. In particular we observe that for p large enough this theory undergoes a phase transition to a state with a diquark condensate which breaks quark-number symmetry. In this phase we examine the spectrum of light scalar and pseudoscalar bosons and see evidence for the Goldstone boson associated with this spontaneous symmetry breaking. This theory is closely related to QCD at finite chemical potential for isospin, a theory which we are now studying for SU(3) colour

  9. The effects of variability on the number-flux-density relationship for radio sources

    International Nuclear Information System (INIS)

    Schuch, N.J.

    1981-01-01

    It has been known for some time that the number-flux-density relationship for radio sources requires a population of sources whose properties evolve with cosmological epoch, at least in models where the redshifts are all taken to be cosmological. In particular, the surveys made at metre wavelengths show, for bright sources, a slope of the log N -log S curve which is steeper than the value -1.5 expected in a static, non-evolving Euclidean universe. Here, N is the number of radio sources brighter than flux density S. Expansion without evolution in conventional geometrical models predicts slopes flatter than -1.5. If the radio survey is carried out at higher frequencies (typically 2.7 or 5 GHz - 11 or 6 cm wavelength), the slope of the log N -log S curve is steeper than -1.5 but not so steep as the slopes found for the low-frequency surveys. Many of the sources found in high-frequency surveys have radio spectra with relatively higher flux-densities in the centimetre range; these sources are frequently variable at high frequencies, with time-scales from a month or two upwards. Some possible effects of the variations on the observed counts of radio sources are considered. (author)

  10. Effect of number of blades on aerodynamic forces on a straight-bladed Vertical Axis Wind Turbine

    International Nuclear Information System (INIS)

    Li, Qing'an; Maeda, Takao; Kamada, Yasunari; Murata, Junsuke; Furukawa, Kazuma; Yamamoto, Masayuki

    2015-01-01

    Small wind turbine performance and safety standard for straight-bladed Vertical Axis Wind Turbine (VAWT) have not been developed in the world because of the lack of fundament experimental data. This paper focuses on the evaluation of aerodynamic forces depending on several numbers of blades in wind tunnel experiment. In the present study, the test airfoil of blade is symmetry airfoil of NACA 0021 and the number of blades is from two to five. Pressure acting on the surface of rotor blade is measured during rotation by multiport pressure devices and transmitted to a stationary system through wireless LAN. And then, the aerodynamic forces (tangential force, normal force et al.) are discussed as a function of azimuth angle, achieving a quantitative analysis of the effect of numbers of blades. Finally, the loads are compared with the experimental data of six-component balance. As a result, it is clarified that the power coefficient decreases with the increase of numbers of blades. Furthermore, the power which is absorbed from wind by wind turbine mainly depends on upstream region of azimuth angle of θ = 0°∼180°. In this way, these results are very important for developing the simple design equations and applications for straight-bladed VAWT. - Highlights: • Aerodynamic forces are measured by not only torque meter but also six-component balance. • The pressure distribution on the surface of rotor blade is directly measured by multiport pressure devices. • The power coefficient decreases with the increase of numbers of blades. • The fluctuation amplitudes from six-component balance show larger value than the results of pressure distribution.

  11. Bird numbers and distribution in the Horns Rev offshore wind farm area. Annual status report 2003

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-07-01

    This report presents data from six aerial surveys of birds in the Horns Rev wind farm area in 2003. Including 16 surveys conducted before construction of the wind farm started and three during the construction phase, a total of 25 surveys have been performed in the area since August 1999. Up until August 2002 the study area was surveyed from 26 north-south oriented, parallel transect lines. After that time four short transects were added eastwards from the previously easternmost transect. From August 2002 slight adjustments to the transect lines in the wind farm area had to be made in order to avoid collision, as survey altitude was 76 m and wind turbines are 110 m to highest wing tip. The six surveys in 2003 were performed on 13 February, 16 March, 23 April, 5 September, 4 and 30 December. The operational phase of the wind farm commenced in 2002. Hence the six surveys from 2003 are all considered post-construction data sets. A preliminary evaluation of the potential impact of the wind turbines on bird distributions has been carried out by comparison of these data to those from the 16 pre-construction surveys. (au)

  12. Oxygen-promoted catalyst sintering influences number density, alignment, and wall number of vertically aligned carbon nanotubes.

    Science.gov (United States)

    Shi, Wenbo; Li, Jinjing; Polsen, Erik S; Oliver, C Ryan; Zhao, Yikun; Meshot, Eric R; Barclay, Michael; Fairbrother, D Howard; Hart, A John; Plata, Desiree L

    2017-04-20

    A lack of synthetic control and reproducibility during vertically aligned carbon nanotube (CNT) synthesis has stifled many promising applications of organic nanomaterials. Oxygen-containing species are particularly precarious in that they have both beneficial and deleterious effects and are notoriously difficult to control. Here, we demonstrated diatomic oxygen's ability, independent of water, to tune oxide-supported catalyst thin film dewetting and influence nanoscale (diameter and wall number) and macro-scale (alignment and density) properties for as-grown vertically aligned CNTs. In particular, single- or few-walled CNT forests were achieved at very low oxygen loading, with single-to-multi-walled CNT diameters ranging from 4.8 ± 1.3 nm to 6.4 ± 1.1 nm over 0-800 ppm O 2 , and an expected variation in alignment, where both were related to the annealed catalyst morphology. Morphological differences were not the result of subsurface diffusion, but instead occurred via Ostwald ripening under several hundred ppm O 2 , and this effect was mitigated by high H 2 concentrations and not due to water vapor (as confirmed in O 2 -free water addition experiments), supporting the importance of O 2 specifically. Further characterization of the interface between the Fe catalyst and Al 2 O 3 support revealed that either oxygen-deficit metal oxide or oxygen-adsorption on metals could be functional mechanisms for the observed catalyst nanoparticle evolution. Taken as a whole, our results suggest that the impacts of O 2 and H 2 on the catalyst evolution have been underappreciated and underleveraged in CNT synthesis, and these could present a route toward facile manipulation of CNT forest morphology through control of the reactive gaseous atmosphere alone.

  13. Methodology for attainment of density and effective atomic number through dual energy technique using microtomographic images

    International Nuclear Information System (INIS)

    Alves, H.; Lima, I.; Lopes, R.T.

    2014-01-01

    Dual energy technique for computerized microtomography shows itself as a promising method for identification of mineralogy on geological samples of heterogeneous composition. It can also assist with differentiating very similar objects regarding the attenuation coefficient, which are usually not separable during image processing and analysis of microtomographic data. Therefore, the development of a feasible and applicable methodology of dual energy in the analysis of microtomographic images was sought. - Highlights: • Dual energy technique is promising for identification of distribution of minerals. • A feasible methodology of dual energy in analysis of tomographic images was sought. • The dual energy technique is efficient for density and atomic number identification. • Simulation showed that the proposed methodology agrees with theoretical data. • Nondestructive characterization of distribution of density and chemical composition

  14. Effective atomic numbers, electron densities and kinetic energy released in matter of vitamins for photon interaction

    Science.gov (United States)

    Shantappa, A.; Hanagodimath, S. M.

    2014-01-01

    Effective atomic numbers, electron densities of some vitamins (Retinol, Riboflavin, Niacin, Biotin, Folic acid, Cobalamin, Phylloquinone and Flavonoids) composed of C, H, O, N, Co, P and S have been calculated for total and partial photon interactions by the direct method for energy range 1 keV-100 GeV by using WinXCOM and kinetic energy released in matter (Kerma) relative to air is calculated in energy range of 1 keV-20 MeV. Change in effective atomic number and electron density with energy is calculated for all photon interactions. Variation of photon mass attenuation coefficients with energy are shown graphically only for total photon interaction. It is observed that change in mass attenuation coefficient with composition of different chemicals is very large below 100 keV and moderate between 100 keV and 10 MeV and negligible above 10 MeV. Behaviour of vitamins is almost indistinguishable except biotin and cobalamin because of large range of atomic numbers from 1(H) to 16 (S) and 1(H) to 27(Co) respectively. K a value shows a peak due to the photoelectric effect around K-absorption edge of high- Z constituent of compound for biotin and cobalamin.

  15. Estimation of Extreme Response and Failure Probability of Wind Turbines under Normal Operation using Probability Density Evolution Method

    DEFF Research Database (Denmark)

    Sichani, Mahdi Teimouri; Nielsen, Søren R.K.; Liu, W. F.

    2013-01-01

    Estimation of extreme response and failure probability of structures subjected to ultimate design loads is essential for structural design of wind turbines according to the new standard IEC61400-1. This task is focused on in the present paper in virtue of probability density evolution method (PDEM......), which underlies the schemes of random vibration analysis and structural reliability assessment. The short-term rare failure probability of 5-mega-watt wind turbines, for illustrative purposes, in case of given mean wind speeds and turbulence levels is investigated through the scheme of extreme value...... distribution instead of any other approximate schemes of fitted distribution currently used in statistical extrapolation techniques. Besides, the comparative studies against the classical fitted distributions and the standard Monte Carlo techniques are carried out. Numerical results indicate that PDEM exhibits...

  16. Bird numbers and distributions in the Horns Rev offshore wind farm area. Annual status report 2004

    Energy Technology Data Exchange (ETDEWEB)

    Krag Petersen, I.

    2005-07-01

    This report presents data from four aerial surveys of birds in the Horns Rev wind farm area in 2004. Three surveys from the winter and spring of 2004 are thoroughly reported here. The fourth survey of 9 September 2004 is reported in general terms, but not included in presentations of distribution and effect analyses of the wind farm. Data from this survey will be thoroughly dealt with in a future report. Including the four surveys of 2004, a total of 29 surveys have been performed in that area since August 1999. (au)

  17. Electron density and effective atomic number (Zeff) determination through x-ray Moiré deflectometry

    Science.gov (United States)

    Valdivia Leiva, Maria Pia; Stutman, Dan; Finkenthal, Michael

    2014-10-01

    Talbot-Lau based Moiré deflectometry is a powerful density diagnostic capable of delivering refraction information and attenuation from a single image, through the accurate detection of X-ray phase-shift and intensity. The technique is able to accurately measure both the real part of the index of refraction δ (directly related to electron density) and the attenuation coefficient μ of an object placed in the x-ray beam. Since the atomic number Z (or Zeff for a composite sample) is proportional to these quantities, an elemental map of the effective atomic number can be obtained with the ratio of the phase and the absorption image. The determination of Zeff from refraction and attenuation measurements with Moiré deflectometry could be of high interest in various fields of HED research such as shocked materials and ICF experiments as Zeff is linked, by definition, to the x-ray absorption properties of a specific material. This work is supported by U.S. DoE/NNSA Grant No. 435 DENA0001835.

  18. Calculation of radiation attenuation coefficients, effective atomic numbers and electron densities for some building materials

    International Nuclear Information System (INIS)

    Damla, N.; Baltas, H.; Celik, A.; Kiris, E.; Cevik, U.

    2008-01-01

    Some building materials, regularly used in Turkey, such as sand, cement, gas concrete (lightweight, aerated concrete), tile and brick, have been investigated in terms of mass attenuation coefficient, effective atomic, numbers (Z eff ), effective electron densities (N e ) and photon interaction cross section (σ a ) at 14 different energies from 81- to 1332-keV gamma-ray energies. The gamma rays were detected by using gamma-ray spectroscopy, a High Purity Germanium (HPGe) detector. The elemental compositions of samples were analysed using an energy dispersive X-ray fluorescence spectrometer. Mass attenuation coefficients of these samples have been compared with tabulations based upon the results of WinXcom. The theoretical mass attenuation coefficients were estimated using the mixture rule and the experimental values of investigated parameters were compared with the calculated values. The agreement of measured values of mass attenuation coefficient, effective atomic numbers, effective electron densities and photon interaction cross section with the theory has been found to be quite satisfactory. (authors)

  19. Power density investigations for the large wind turbines' grid-side press-pack IGBT 3L-NPC-VSCs

    DEFF Research Database (Denmark)

    Senturk, Osman Selcuk; Helle, Lars; Munk-Nielsen, Stig

    2012-01-01

    -thermal models are required to be derived, implemented, and utilized. In this study, employed as a grid-side medium voltage full-scale voltage source converters (VSCs) in a multi-MW wind turbine, press-pack IGBT three-level neutral-point-clamped VSC (3L-NPC-VSC), 3L active NPC-VSC (3L-ANPC-VSC), and 3L neutral......Power density is the important design criterion in wind turbine converter design provided that satisfactory converter performance is guaranteed. In order to assess a converter in terms of power density, which is dependent on converter electrical and thermal behaviors, converter electro......-point-piloted VSC (3L-NPP-VSC) are characterized in terms of converter operating principles, physical structure, power loss, and DC bus capacitor size for establishing the basis for converter electro-thermal modeling. Via the practical implementations of the converter electro-thermal models in a computation...

  20. Sustainable Energy Solutions Task 5.1: Expand the Number of Faculty Working in Wind Energy: Wind Energy Storage

    Energy Technology Data Exchange (ETDEWEB)

    Twomey, Janet M. [Wichita State Univ., KS (United States)

    2010-03-01

    Energy storage to reduce peak-load demands on utilities is emerging as an important way to address the intermittency of renewable energy resources. Wind energy produced in the middle of the night may be wasted unless it can be stored, and conversely, solar energy production could be used after the sun goes down if we had an efficient way to store it. It is uses an electrochemical process to convert hydrogen gas into electricity. The role of fuel cells in energy storage is a very important criteria and it is compared with regular batteries for the advantages of fuel cells over the latter. For this reason fuel cells can be employed. PEM fuel cells can be effectively used for this reason. But the performance and durability of PEM fuel cells are significantly affected by the various components used in a PEM cell. Several parameters affect the performance and durability of fuel cells. They are water management, degradation of components, cell contamination, reactant starvation and thermal management. Water management is the parameter which plays a major role in the performance of a fuel cell. Based on the reviews, improvement of condensation on the cathode side of a fuel cell is expected to improve the performance of the fuel cell by reducing cathode flooding. Microchannels and minichannels can enhance condensation on the cathode side of a fuel cell. Computational fluid dynamics (CFD) analysis was performed to evaluate and compare the condensation of steam in mini and microchannels with hydraulic diameter of 2mm, 2.66mm, 200µm and 266µm respectively. The simulation was run at various mass flux values ranging from 0.5 kg/m2s and 4 kg/m2s. The length of the mini and microchannels were in the range of 20 mm to 100 mm. CFD software’s GAMBIT and FLUENT were used for simulating the condensation process through the mini and microchannels. Steam flowed through the channels, whose walls were cooled by natural convection of air at room temperature. The

  1. Plant Density Effect on Grain Number and Weight of Two Winter Wheat Cultivars at Different Spikelet and Grain Positions

    OpenAIRE

    Li, Yong; Cui, Zhengyong; Ni, Yingli; Zheng, Mengjing; Yang, Dongqing; Jin, Min; Chen, Jin; Wang, Zhenlin; Yin, Yanping

    2016-01-01

    In winter wheat, grain development is asynchronous. The grain number and grain weight vary significantly at different spikelet and grain positions among wheat cultivars grown at different plant densities. In this study, two winter wheat (Triticum aestivum L.) cultivars, 'Wennong6' and 'Jimai20', were grown under four different plant densities for two seasons, in order to study the effect of plant density on the grain number and grain weight at different spikelet and grain positions. The resul...

  2. Constraining the cosmic radiation density due to lepton number with Big Bang Nucleosynthesis

    International Nuclear Information System (INIS)

    Mangano, Gianpiero; Miele, Gennaro; Pisanti, Ofelia; Sarikas, Srdjan; Pastor, Sergio

    2011-01-01

    The cosmic energy density in the form of radiation before and during Big Bang Nucleosynthesis (BBN) is typically parameterized in terms of the effective number of neutrinos N eff . This quantity, in case of no extra degrees of freedom, depends upon the chemical potential and the temperature characterizing the three active neutrino distributions, as well as by their possible non-thermal features. In the present analysis we determine the upper bounds that BBN places on N eff from primordial neutrino-antineutrino asymmetries, with a careful treatment of the dynamics of neutrino oscillations. We consider quite a wide range for the total lepton number in the neutrino sector, η ν = η ν e +η ν μ +η ν τ and the initial electron neutrino asymmetry η ν e in , solving the corresponding kinetic equations which rule the dynamics of neutrino (antineutrino) distributions in phase space due to collisions, pair processes and flavor oscillations. New bounds on both the total lepton number in the neutrino sector and the ν e −ν-bar e asymmetry at the onset of BBN are obtained fully exploiting the time evolution of neutrino distributions, as well as the most recent determinations of primordial 2 H/H density ratio and 4 He mass fraction. Note that taking the baryon fraction as measured by WMAP, the 2 H/H abundance plays a relevant role in constraining the allowed regions in the η ν −η ν e in plane. These bounds fix the maximum contribution of neutrinos with primordial asymmetries to N eff as a function of the mixing parameter θ 13 , and point out the upper bound N eff ∼ eff by the Planck satellite will likely provide insight on the nature of the radiation content of the universe

  3. Constraining the cosmic radiation density due to lepton number with Big Bang Nucleosynthesis

    Science.gov (United States)

    Mangano, Gianpiero; Miele, Gennaro; Pastor, Sergio; Pisanti, Ofelia; Sarikas, Srdjan

    2011-03-01

    The cosmic energy density in the form of radiation before and during Big Bang Nucleosynthesis (BBN) is typically parameterized in terms of the effective number of neutrinos Neff. This quantity, in case of no extra degrees of freedom, depends upon the chemical potential and the temperature characterizing the three active neutrino distributions, as well as by their possible non-thermal features. In the present analysis we determine the upper bounds that BBN places on Neff from primordial neutrino-antineutrino asymmetries, with a careful treatment of the dynamics of neutrino oscillations. We consider quite a wide range for the total lepton number in the neutrino sector, ην = ηνe+ηνμ+ηντ and the initial electron neutrino asymmetry ηνein, solving the corresponding kinetic equations which rule the dynamics of neutrino (antineutrino) distributions in phase space due to collisions, pair processes and flavor oscillations. New bounds on both the total lepton number in the neutrino sector and the νe-bar nue asymmetry at the onset of BBN are obtained fully exploiting the time evolution of neutrino distributions, as well as the most recent determinations of primordial 2H/H density ratio and 4He mass fraction. Note that taking the baryon fraction as measured by WMAP, the 2H/H abundance plays a relevant role in constraining the allowed regions in the ην-ηνein plane. These bounds fix the maximum contribution of neutrinos with primordial asymmetries to Neff as a function of the mixing parameter θ13, and point out the upper bound Nefflesssim3.4. Comparing these results with the forthcoming measurement of Neff by the Planck satellite will likely provide insight on the nature of the radiation content of the universe.

  4. Do Transient Electrodynamic Processes Support Enhanced Neutral Mass Densities in Earth's Cusp-Region Thermosphere via Divergent Upward Winds?

    Science.gov (United States)

    Conde, M.; Larsen, M. F.; Troyer, R.; Gillespie, D.; Kosch, M.

    2017-12-01

    Satellite accelerometer measurements show that Earth's thermosphere contains two substantial and permanent regions of enhanced mass density that are located at around 400 km altitude near the footprints of the north and south geomagnetic cusps. The additional mass in these regions must be supported against gravity, which requires that similarly localized perturbations must occur in one or more of the other fields (beyond mass density) that appear in the momentum conservation equation for the thermospheric neutral fluid. However more than a decade after the density enhancements were first discovered, there are still no observations of any other corresponding perturbations to terms appearing directly in this equation that would indicate what is supporting the extra mass. To date, most candidate mechanisms involve high-altitude transient electrodynamic heating (at 250 km and above) that drives upwelling and associated horizontal divergence. Indeed, there are very few viable mechanisms that don't ultimately cause substantial localized neutral wind perturbations to occur near the density anomalies. Thus, we report here on a study to search for signatures of these localized perturbations in winds, using several data sources. These are the WATS instrument that flew aboard the DE-2 spacecraft, the C-REX-1 rocket flight through the CUSP in 2014, and two ground-based Fabry-Perot instruments that are located in Antarctica at latitudes that pass under the geomagnetic cusps - i.e. at McMurdo and South Pole stations. Using these data, we will present both climatological averages and also individual case studies to illustrate what localized signatures occur (if any) in the neutral wind fields near the cusp-region density anomalies.

  5. Wind power plants. Hydraulic transmission with control systems for unrestricted number of revolutions

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, R

    1976-09-01

    Basic ideas are presented for the design of a hydraulic transmission with its control system adapted to an electric generator operated by a wind turbine with unrestricted revolutions. The settlement of the principle is shown by means of commercially available parts. The relations of the installed effect, its cost and the length of operational life are discussed. The control system is directly integrated to the hydraulic circuits.

  6. Systematic measurements of opacity dependence on temperature, density, and atomic number at stellar interior conditions

    Science.gov (United States)

    Nagayama, Taisuke

    2017-10-01

    Model predictions for iron opacity are notably different from measurements performed at matter conditions similar to the boundary between the solar radiation and convection zones. The calculated iron opacities have narrower spectral lines, weaker quasi-continuum at short wavelength, and deeper opacity windows than the measurements. If correct, these measurements help resolve a decade old problem in solar physics. A key question is therefore: What is responsible for the model-data discrepancy? The answer is complex because the experiments are challenging and opacity theories depend on multiple entangled physical processes such as the influence of completeness and accuracy of atomic states, line broadening, contributions from myriad transitions from excited states, and multi-photon absorption processes. To help determine the cause of this discrepancy, a systematic study of opacity variation with temperature, density, and atomic number is underway. Measurements of chromium, iron, and nickel opacities have been performed at two different temperatures and densities. The collection of measured opacities provides constraints on hypotheses to explain the discrepancy. We will discuss implications of measured opacities, experimental errors, and possible opacity model refinements. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA0003525.

  7. Jet Impingement Heat Transfer at High Reynolds Numbers and Large Density Variations

    DEFF Research Database (Denmark)

    Jensen, Michael Vincent; Walther, Jens Honore

    2010-01-01

    Jet impingement heat transfer from a round gas jet to a flat wall has been investigated numerically in a configuration with H/D=2, where H is the distance from the jet inlet to the wall and D is the jet diameter. The jet Reynolds number was 361000 and the density ratio across the wall boundary...... layer was 3.3 due to a substantial temperature difference of 1600K between jet and wall. Results are presented which indicate very high heat flux levels and it is demonstrated that the jet inlet turbulence intensity significantly influences the heat transfer results, especially in the stagnation region....... The results also show a noticeable difference in the heat transfer predictions when applying different turbulence models. Furthermore calculations were performed to study the effect of applying temperature dependent thermophysical properties versus constant properties and the effect of calculating the gas...

  8. Studies on effective atomic number, electron density and kerma for some fatty acids and carbohydrates

    International Nuclear Information System (INIS)

    Manohara, S R; Hanagodimath, S M; Gerward, L

    2008-01-01

    The effective atomic number, Z eff , the effective electron density, N el , and kerma have been calculated for some fatty acids and carbohydrates for photon interaction in the extended energy range from 1 keV to 100 GeV using an accurate database of photon-interaction cross sections and the WinXCom program. The significant variation of Z eff and N el is due to the variations in the dominance of different interaction processes in different energy regions. The maximum values of Z eff and N el are found in the low-energy range, where photoelectric absorption is the main interaction process. The minimum values of Z eff and N el are found at intermediate energies, typically 0.05 MeV eff is equal to the mean atomic number of the bio-molecule. Wherever possible, the calculations are compared with experimental results. A comparison is also made with the single values of the Z eff and N el provided by the program XMuDat. It is also observed that carbohydrates have a larger kerma than fatty acids in the low-energy region, where photoelectric absorption dominates. In contrast, fatty acids have a larger kerma than carbohydrates in the MeV range, where Compton scattering is the main interaction process. (note)

  9. Incorporating wind availability into land use regression modelling of air quality in mountainous high-density urban environment.

    Science.gov (United States)

    Shi, Yuan; Lau, Kevin Ka-Lun; Ng, Edward

    2017-08-01

    Urban air quality serves as an important function of the quality of urban life. Land use regression (LUR) modelling of air quality is essential for conducting health impacts assessment but more challenging in mountainous high-density urban scenario due to the complexities of the urban environment. In this study, a total of 21 LUR models are developed for seven kinds of air pollutants (gaseous air pollutants CO, NO 2 , NO x , O 3 , SO 2 and particulate air pollutants PM 2.5 , PM 10 ) with reference to three different time periods (summertime, wintertime and annual average of 5-year long-term hourly monitoring data from local air quality monitoring network) in Hong Kong. Under the mountainous high-density urban scenario, we improved the traditional LUR modelling method by incorporating wind availability information into LUR modelling based on surface geomorphometrical analysis. As a result, 269 independent variables were examined to develop the LUR models by using the "ADDRESS" independent variable selection method and stepwise multiple linear regression (MLR). Cross validation has been performed for each resultant model. The results show that wind-related variables are included in most of the resultant models as statistically significant independent variables. Compared with the traditional method, a maximum increase of 20% was achieved in the prediction performance of annual averaged NO 2 concentration level by incorporating wind-related variables into LUR model development. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Constraining the cosmic radiation density due to lepton number with Big Bang Nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Mangano, Gianpiero; Miele, Gennaro; Pisanti, Ofelia; Sarikas, Srdjan [Istituto Nazionale di Fisica Nucleare – Sezione di Napoli, Complesso Universitario di Monte S. Angelo, I-80126 Napoli (Italy); Pastor, Sergio, E-mail: mangano@na.infn.it, E-mail: miele@na.infn.it, E-mail: pastor@ific.uv.es, E-mail: pisanti@na.infn.it, E-mail: sarikas@na.infn.it [Instituto de Física Corpuscular (CSIC-Universitat de València), Ed. Institutos de Investigación, Apdo. correos 22085, E-46071 Valencia (Spain)

    2011-03-01

    The cosmic energy density in the form of radiation before and during Big Bang Nucleosynthesis (BBN) is typically parameterized in terms of the effective number of neutrinos N{sub eff}. This quantity, in case of no extra degrees of freedom, depends upon the chemical potential and the temperature characterizing the three active neutrino distributions, as well as by their possible non-thermal features. In the present analysis we determine the upper bounds that BBN places on N{sub eff} from primordial neutrino-antineutrino asymmetries, with a careful treatment of the dynamics of neutrino oscillations. We consider quite a wide range for the total lepton number in the neutrino sector, η{sub ν} = η{sub ν{sub e}}+η{sub ν{sub μ}}+η{sub ν{sub τ}} and the initial electron neutrino asymmetry η{sub ν{sub e}{sup in}}, solving the corresponding kinetic equations which rule the dynamics of neutrino (antineutrino) distributions in phase space due to collisions, pair processes and flavor oscillations. New bounds on both the total lepton number in the neutrino sector and the ν{sub e}−ν-bar {sub e} asymmetry at the onset of BBN are obtained fully exploiting the time evolution of neutrino distributions, as well as the most recent determinations of primordial {sup 2}H/H density ratio and {sup 4}He mass fraction. Note that taking the baryon fraction as measured by WMAP, the {sup 2}H/H abundance plays a relevant role in constraining the allowed regions in the η{sub ν}−η{sub ν{sub e}{sup in}} plane. These bounds fix the maximum contribution of neutrinos with primordial asymmetries to N{sub eff} as a function of the mixing parameter θ{sub 13}, and point out the upper bound N{sub eff}∼<3.4. Comparing these results with the forthcoming measurement of N{sub eff} by the Planck satellite will likely provide insight on the nature of the radiation content of the universe.

  11. Determination of CT number and density profile of binderless, pre-treated and tannin-based Rhizophora spp. particleboards using computed tomography imaging and electron density phantom

    International Nuclear Information System (INIS)

    Yusof, Mohd Fahmi Mohd; Hamid, Puteri Nor Khatijah Abdul; Tajuddin, Abdul Aziz; Bauk, Sabar; Hashim, Rokiah

    2015-01-01

    Plug density phantoms were constructed in accordance to CT density phantom model 062M CIRS using binderless, pre-treated and tannin-based Rhizophora Spp. particleboards. The Rhizophora Spp. plug phantoms were scanned along with the CT density phantom using Siemens Somatom Definition AS CT scanner at three CT energies of 80, 120 and 140 kVp. 15 slices of images with 1.0 mm thickness each were taken from the central axis of CT density phantom for CT number and CT density profile analysis. The values were compared to water substitute plug phantom from the CT density phantom. The tannin-based Rhizophora Spp. gave the nearest value of CT number to water substitute at 80 and 120 kVp CT energies with χ 2 value of 0.011 and 0.014 respectively while the binderless Rhizphora Spp. gave the nearest CT number to water substitute at 140 kVp CT energy with χ 2 value of 0.023. The tannin-based Rhizophora Spp. gave the nearest CT density profile to water substitute at all CT energies. This study indicated the suitability of Rhizophora Spp. particleboard as phantom material for the use in CT imaging studies

  12. Determination of CT number and density profile of binderless, pre-treated and tannin-based Rhizophora spp. particleboards using computed tomography imaging and electron density phantom

    Energy Technology Data Exchange (ETDEWEB)

    Yusof, Mohd Fahmi Mohd, E-mail: mfahmi@usm.my; Hamid, Puteri Nor Khatijah Abdul; Tajuddin, Abdul Aziz [School of Physics, Universiti Sains Malaysia, 11800 Penang (Malaysia); Bauk, Sabar [School of Distance Education, Universiti Sains Malaysia, 11800 Penang (Malaysia); Hashim, Rokiah [School of Industrial Technologies, Universiti Sains Malaysia, 11800 Penang (Malaysia)

    2015-04-29

    Plug density phantoms were constructed in accordance to CT density phantom model 062M CIRS using binderless, pre-treated and tannin-based Rhizophora Spp. particleboards. The Rhizophora Spp. plug phantoms were scanned along with the CT density phantom using Siemens Somatom Definition AS CT scanner at three CT energies of 80, 120 and 140 kVp. 15 slices of images with 1.0 mm thickness each were taken from the central axis of CT density phantom for CT number and CT density profile analysis. The values were compared to water substitute plug phantom from the CT density phantom. The tannin-based Rhizophora Spp. gave the nearest value of CT number to water substitute at 80 and 120 kVp CT energies with χ{sup 2} value of 0.011 and 0.014 respectively while the binderless Rhizphora Spp. gave the nearest CT number to water substitute at 140 kVp CT energy with χ{sup 2} value of 0.023. The tannin-based Rhizophora Spp. gave the nearest CT density profile to water substitute at all CT energies. This study indicated the suitability of Rhizophora Spp. particleboard as phantom material for the use in CT imaging studies.

  13. Whole genome DNA copy number changes identified by high density oligonucleotide arrays

    Directory of Open Access Journals (Sweden)

    Huang Jing

    2004-05-01

    Full Text Available Abstract Changes in DNA copy number are one of the hallmarks of the genetic instability common to most human cancers. Previous micro-array-based methods have been used to identify chromosomal gains and losses; however, they are unable to genotype alleles at the level of single nucleotide polymorphisms (SNPs. Here we describe a novel algorithm that uses a recently developed high-density oligonucleotide array-based SNP genotyping method, whole genome sampling analysis (WGSA, to identify genome-wide chromosomal gains and losses at high resolution. WGSA simultaneously genotypes over 10,000 SNPs by allele-specific hybridisation to perfect match (PM and mismatch (MM probes synthesised on a single array. The copy number algorithm jointly uses PM intensity and discrimination ratios between paired PM and MM intensity values to identify and estimate genetic copy number changes. Values from an experimental sample are compared with SNP-specific distributions derived from a reference set containing over 100 normal individuals to gain statistical power. Genomic regions with statistically significant copy number changes can be identified using both single point analysis and contiguous point analysis of SNP intensities. We identified multiple regions of amplification and deletion using a panel of human breast cancer cell lines. We verified these results using an independent method based on quantitative polymerase chain reaction and found that our approach is both sensitive and specific and can tolerate samples which contain a mixture of both tumour and normal DNA. In addition, by using known allele frequencies from the reference set, statistically significant genomic intervals can be identified containing contiguous stretches of homozygous markers, potentially allowing the detection of regions undergoing loss of heterozygosity (LOH without the need for a matched normal control sample. The coupling of LOH analysis, via SNP genotyping, with copy number

  14. Preliminary scaling laws for plasma current, ion kinetic temperature, and plasma number density in the NASA Lewis bumpy torus plasma

    Science.gov (United States)

    Roth, J. R.

    1976-01-01

    Parametric variation of independent variables which may affect the characteristics of bumpy torus plasma have identified those which have a significant effect on the plasma current, ion kinetic temperature, and plasma number density, and those which do not. Empirical power law correlations of the plasma current, and the ion kinetic temperature and number density were obtained as functions of potential applied to the midplane electrode rings, the background neutral gas pressure, and the magnetic field strength. Additional parameters studied included the type of gas, the polarity of the midplane electrode rings, the mode of plasma operation, and the method of measuring the plasma number density. No significant departures from the scaling laws appear to occur at the highest ion kinetic temperatures or number densities obtained to date.

  15. A Model-Independent Discussion of Quark Number Density and Quark Condensate at Zero Temperature and Finite Quark Chemical Potential

    International Nuclear Information System (INIS)

    Xu Shu-Sheng; Shi Chao; Cui Zhu-Fang; Zong Hong-Shi; Jiang Yu

    2015-01-01

    Generally speaking, the quark propagator is dependent on the quark chemical potential in the dense quantum chromodynamics (QCD). By means of the generating functional method, we prove that the quark propagator actually depends on p_4 + iμ from the first principle of QCD. The relation between quark number density and quark condensate is discussed by analyzing their singularities. It is concluded that the quark number density has some singularities at certain μ when T = 0, and the variations of the quark number density as well as the quark condensate are located at the same point. In other words, at a certain μ the quark number density turns to nonzero, while the quark condensate begins to decrease from its vacuum value. (paper)

  16. Imaging Plasma Density Structures in the Soft X-Rays Generated by Solar Wind Charge Exchange with Neutrals

    Science.gov (United States)

    Sibeck, David G.; Allen, R.; Aryan, H.; Bodewits, D.; Brandt, P.; Branduardi-Raymont, G.; Brown, G.; Carter, J. A.; Collado-Vega, Y. M.; Collier, M. R.; Connor, H. K.; Cravens, T. E.; Ezoe, Y.; Fok, M.-C.; Galeazzi, M.; Gutynska, O.; Holmström, M.; Hsieh, S.-Y.; Ishikawa, K.; Koutroumpa, D.; Kuntz, K. D.; Leutenegger, M.; Miyoshi, Y.; Porter, F. S.; Purucker, M. E.; Read, A. M.; Raeder, J.; Robertson, I. P.; Samsonov, A. A.; Sembay, S.; Snowden, S. L.; Thomas, N. E.; von Steiger, R.; Walsh, B. M.; Wing, S.

    2018-06-01

    Both heliophysics and planetary physics seek to understand the complex nature of the solar wind's interaction with solar system obstacles like Earth's magnetosphere, the ionospheres of Venus and Mars, and comets. Studies with this objective are frequently conducted with the help of single or multipoint in situ electromagnetic field and particle observations, guided by the predictions of both local and global numerical simulations, and placed in context by observations from far and extreme ultraviolet (FUV, EUV), hard X-ray, and energetic neutral atom imagers (ENA). Each proposed interaction mechanism (e.g., steady or transient magnetic reconnection, local or global magnetic reconnection, ion pick-up, or the Kelvin-Helmholtz instability) generates diagnostic plasma density structures. The significance of each mechanism to the overall interaction (as measured in terms of atmospheric/ionospheric loss at comets, Venus, and Mars or global magnetospheric/ionospheric convection at Earth) remains to be determined but can be evaluated on the basis of how often the density signatures that it generates are observed as a function of solar wind conditions. This paper reviews efforts to image the diagnostic plasma density structures in the soft (low energy, 0.1-2.0 keV) X-rays produced when high charge state solar wind ions exchange electrons with the exospheric neutrals surrounding solar system obstacles. The introduction notes that theory, local, and global simulations predict the characteristics of plasma boundaries such the bow shock and magnetopause (including location, density gradient, and motion) and regions such as the magnetosheath (including density and width) as a function of location, solar wind conditions, and the particular mechanism operating. In situ measurements confirm the existence of time- and spatial-dependent plasma density structures like the bow shock, magnetosheath, and magnetopause/ionopause at Venus, Mars, comets, and the Earth. However, in situ

  17. Modeling of isothermal bubbly flow with interfacial area transport equation and bubble number density approach

    Energy Technology Data Exchange (ETDEWEB)

    Sari, Salih [Hacettepe University, Department of Nuclear Engineering, Beytepe, 06800 Ankara (Turkey); Erguen, Sule [Hacettepe University, Department of Nuclear Engineering, Beytepe, 06800 Ankara (Turkey); Barik, Muhammet; Kocar, Cemil; Soekmen, Cemal Niyazi [Hacettepe University, Department of Nuclear Engineering, Beytepe, 06800 Ankara (Turkey)

    2009-03-15

    In this study, isothermal turbulent bubbly flow is mechanistically modeled. For the modeling, Fluent version 6.3.26 is used as the computational fluid dynamics solver. First, the mechanistic models that simulate the interphase momentum transfer between the gas (bubbles) and liquid (continuous) phases are investigated, and proper models for the known flow conditions are selected. Second, an interfacial area transport equation (IATE) solution is added to Fluent's solution scheme in order to model the interphase momentum transfer mechanisms. In addition to solving IATE, bubble number density (BND) approach is also added to Fluent and this approach is also used in the simulations. Different source/sink models derived for the IATE and BND models are also investigated. The simulations of experiments based on the available data in literature are performed by using IATE and BND models in two and three-dimensions. The results show that the simulations performed by using IATE and BND models agree with each other and with the experimental data. The simulations performed in three-dimensions give better agreement with the experimental data.

  18. Modeling of isothermal bubbly flow with interfacial area transport equation and bubble number density approach

    International Nuclear Information System (INIS)

    Sari, Salih; Erguen, Sule; Barik, Muhammet; Kocar, Cemil; Soekmen, Cemal Niyazi

    2009-01-01

    In this study, isothermal turbulent bubbly flow is mechanistically modeled. For the modeling, Fluent version 6.3.26 is used as the computational fluid dynamics solver. First, the mechanistic models that simulate the interphase momentum transfer between the gas (bubbles) and liquid (continuous) phases are investigated, and proper models for the known flow conditions are selected. Second, an interfacial area transport equation (IATE) solution is added to Fluent's solution scheme in order to model the interphase momentum transfer mechanisms. In addition to solving IATE, bubble number density (BND) approach is also added to Fluent and this approach is also used in the simulations. Different source/sink models derived for the IATE and BND models are also investigated. The simulations of experiments based on the available data in literature are performed by using IATE and BND models in two and three-dimensions. The results show that the simulations performed by using IATE and BND models agree with each other and with the experimental data. The simulations performed in three-dimensions give better agreement with the experimental data

  19. Urban renewal based wind environment at pedestrian level in high-density and high-rise urban areas in Sai Ying Pun, Hong Kong

    Science.gov (United States)

    Yao, J. W.; Zheng, J. Y.; Zhao, Y.; Shao, Y. H.; Yuan, F.

    2017-11-01

    In high-density and high-rise urban areas, pedestrian level winds contribute to improve comfort, safety and diffusion of heat in urban areas. Outdoor wind study is extremely vital and a prerequisite in high-density cities considering that the immediate pedestrian level wind environment is fundamentally impacted by the presence of a series of high-rise buildings. In this paper, the research site of Sai Ying Pun in Hong Kong will be analysed in terms of geography, climate and urban morphology, while the surrounding natural ventilation has also been simulated by the wind tunnel experiment Computational Fluid Dynamics (CFD). It has found that, the existing problems in this district are the contradiction between planning control and commercial interests, which means some areas around tall buildings are not benefit to the residents because of the unhealthy wind environment. Therefore, some recommendation of urban renewal strategy has been provided.

  20. An innovative method for offshore wind farm site selection based on the interval number with probability distribution

    Science.gov (United States)

    Wu, Yunna; Chen, Kaifeng; Xu, Hu; Xu, Chuanbo; Zhang, Haobo; Yang, Meng

    2017-12-01

    There is insufficient research relating to offshore wind farm site selection in China. The current methods for site selection have some defects. First, information loss is caused by two aspects: the implicit assumption that the probability distribution on the interval number is uniform; and ignoring the value of decision makers' (DMs') common opinion on the criteria information evaluation. Secondly, the difference in DMs' utility function has failed to receive attention. An innovative method is proposed in this article to solve these drawbacks. First, a new form of interval number and its weighted operator are proposed to reflect the uncertainty and reduce information loss. Secondly, a new stochastic dominance degree is proposed to quantify the interval number with a probability distribution. Thirdly, a two-stage method integrating the weighted operator with stochastic dominance degree is proposed to evaluate the alternatives. Finally, a case from China proves the effectiveness of this method.

  1. High Channel Count, High Density Microphone Arrays for Wind Tunnel Environments, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The Interdisciplinary Consulting Corporation (IC2) proposes the development of high channel count, high density, reduced cost per channel, directional microphone...

  2. Number and density discrimination rely on a common metric: Similar psychophysical effects of size, contrast, and divided attention.

    Science.gov (United States)

    Tibber, Marc S; Greenwood, John A; Dakin, Steven C

    2012-06-04

    While observers are adept at judging the density of elements (e.g., in a random-dot image), it has recently been proposed that they also have an independent visual sense of number. To test the independence of number and density discrimination, we examined the effects of manipulating stimulus structure (patch size, element size, contrast, and contrast-polarity) and available attentional resources on both judgments. Five observers made a series of two-alternative, forced-choice discriminations based on the relative numerosity/density of two simultaneously presented patches containing 16-1,024 Gaussian blobs. Mismatches of patch size and element size (across reference and test) led to bias and reduced sensitivity in both tasks, whereas manipulations of contrast and contrast-polarity had varied effects on observers, implying differing strategies. Nonetheless, the effects reported were consistent across density and number judgments, the only exception being when luminance cues were made available. Finally, density and number judgment were similarly impaired by attentional load in a dual-task experiment. These results are consistent with a common underlying metric to density and number judgments, with the caveat that additional cues may be exploited when they are available.

  3. Detection of enhancement in number densities of background galaxies due to magnification by massive galaxy clusters

    Energy Technology Data Exchange (ETDEWEB)

    Chiu, I.; Dietrich, J. P.; Mohr, J.; Applegate, D. E.; Benson, B. A.; Bleem, L. E.; Bayliss, M. B.; Bocquet, S.; Carlstrom, J. E.; Capasso, R.; Desai, S.; Gangkofner, C.; Gonzalez, A. H.; Gupta, N.; Hennig, C.; Hoekstra, H.; von der Linden, A.; Liu, J.; McDonald, M.; Reichardt, C. L.; Saro, A.; Schrabback, T.; Strazzullo, V.; Stubbs, C. W.; Zenteno, A.

    2016-02-18

    We present a detection of the enhancement in the number densities of background galaxies induced from lensing magnification and use it to test the Sunyaev-Zel'dovich effect (SZE-) inferred masses in a sample of 19 galaxy clusters with median redshift z similar or equal to 0.42 selected from the South Pole Telescope SPT-SZ survey. These clusters are observed by the Megacam on the Magellan Clay Telescope though gri filters. Two background galaxy populations are selected for this study through their photometric colours; they have median redshifts zmedian similar or equal to 0.9 (low-z background) and z(median) similar or equal to 1.8 (high-z background). Stacking these populations, we detect the magnification bias effect at 3.3 sigma and 1.3 sigma for the low-and high-z backgrounds, respectively. We fit Navarro, Frenk and White models simultaneously to all observed magnification bias profiles to estimate the multiplicative factor. that describes the ratio of the weak lensing mass to the mass inferred from the SZE observable-mass relation. We further quantify systematic uncertainties in. resulting from the photometric noise and bias, the cluster galaxy contamination and the estimations of the background properties. The resulting. for the combined background populations with 1 sigma uncertainties is 0.83 +/- 0.24(stat) +/- 0.074(sys), indicating good consistency between the lensing and the SZE-inferred masses. We use our best-fitting eta to predict the weak lensing shear profiles and compare these predictions with observations, showing agreement between the magnification and shear mass constraints. This work demonstrates the promise of using the magnification as a complementary method to estimate cluster masses in large surveys.

  4. Effect of the number of blades and solidity on the performance of a vertical axis wind turbine

    Science.gov (United States)

    Delafin, PL; Nishino, T.; Wang, L.; Kolios, A.

    2016-09-01

    Two, three and four bladed ϕ-shape Vertical Axis Wind Turbines are simulated using a free-wake vortex model. Two versions of the three and four bladed turbines are considered, one having the same chord length as the two-bladed turbine and the other having the same solidity as the two-bladed turbine. Results of the two-bladed turbine are validated against published experimental data of power coefficient and instantaneous torque. The effect of solidity on the power coefficient is presented and the instantaneous torque, thrust and lateral force of the two-, three- and four-bladed turbines are compared for the same solidity. It is found that increasing the number of blades from two to three significantly reduces the torque, thrust and lateral force ripples. Adding a fourth blade further reduces the ripples except for the torque at low tip speed ratio. This work aims to help choosing the number of blades during the design phase of a vertical axis wind turbine.

  5. A method for conversion of Hounsfield number to electron density and prediction of macroscopic pair production cross-sections

    International Nuclear Information System (INIS)

    Knoeoes, T.; Nilsson, M.; Ahlgren, L.

    1986-01-01

    A method for the determination of electron density using a narrow beam attenuation geometry is described. The method does not require that the elemental composition of the phantom materials is known. The Hounsfield numbers for the phantom materials used were determined using five different CT scanners. A relationship between Hounsfield number and electron density can thus be established, which is of considerable value in radiation therapy treatment planning procedures. Measurements of the ratio coherent/incoherent scattering of low energy photons in a certain geometry has proven valuable for determination of atomic number, which in its turn can be used for estimation of macroscopic pair production coefficients for high energy photons. The combination of knowledge of electron density with methods for determination of processes, dependent on atomic number, can form a base for adequate composition of phantom materials for purposes of testing dose calculation algorithms for photons and electrons. (orig.)

  6. Random function representation of stationary stochastic vector processes for probability density evolution analysis of wind-induced structures

    Science.gov (United States)

    Liu, Zhangjun; Liu, Zenghui

    2018-06-01

    This paper develops a hybrid approach of spectral representation and random function for simulating stationary stochastic vector processes. In the proposed approach, the high-dimensional random variables, included in the original spectral representation (OSR) formula, could be effectively reduced to only two elementary random variables by introducing the random functions that serve as random constraints. Based on this, a satisfactory simulation accuracy can be guaranteed by selecting a small representative point set of the elementary random variables. The probability information of the stochastic excitations can be fully emerged through just several hundred of sample functions generated by the proposed approach. Therefore, combined with the probability density evolution method (PDEM), it could be able to implement dynamic response analysis and reliability assessment of engineering structures. For illustrative purposes, a stochastic turbulence wind velocity field acting on a frame-shear-wall structure is simulated by constructing three types of random functions to demonstrate the accuracy and efficiency of the proposed approach. Careful and in-depth studies concerning the probability density evolution analysis of the wind-induced structure have been conducted so as to better illustrate the application prospects of the proposed approach. Numerical examples also show that the proposed approach possesses a good robustness.

  7. Neutral wind and density perturbations in the thermosphere created by gravity waves observed by the TIDDBIT sounder

    Science.gov (United States)

    Vadas, Sharon L.; Crowley, Geoff

    2017-06-01

    In this paper, we study the 10 traveling ionospheric disturbances (TIDs) observed at zobs˜283 km by the TIDDBIT ionospheric sounder on 30 October 2007 at 0400-0700 UT near Wallops Island, USA. These TIDs propagated northwest/northward and were previously found to be secondary gravity waves (GWs) from tropical storm Noel. An instrumented sounding rocket simultaneously measured a large neutral wind peak uH' with a similar azimuth at z ˜ 325 km. Using the measured TID amplitudes and wave vectors from the TIDDBIT system, together with ion-neutral theory, GW dissipative polarization relations and ray tracing, we determine the GW neutral horizontal wind and density perturbations as a function of altitude from 220 to 380 km. We find that there is a serious discrepancy between the GW dissipative theory and the observations unless the molecular viscosity, μ, decreases with altitude in the middle to upper thermosphere. Assuming that μ∝ρ¯q, where ρ¯ is the density, we find using GW dissipative theory that the GWs could have been observed at zobs and that one or more of the GWs could have caused the uH' wind peak at z≃325 km if q ˜ 0.67 for z≥220 km. This implies that the kinematic viscosity, ν=μ/ρ¯, increases less rapidly with altitude for z≥220 km: ν∝1/ρ¯0.33. This dependence makes sense because as ρ¯→0, the distance between molecules goes to infinity, which implies no molecular collisions and therefore no molecular viscosity μ.

  8. MODEL-OBSERVATION COMPARISONS OF ELECTRON NUMBER DENSITIES IN THE COMA OF 67P/CHURYUMOV–GERASIMENKO DURING 2015 JANUARY

    Energy Technology Data Exchange (ETDEWEB)

    Vigren, E.; Edberg, N. J. T.; Eriksson, A. I.; Johansson, F.; Odelstad, E. [Swedish Institute of Space Physics, Uppsala (Sweden); Altwegg, K.; Tzou, C.-Y. [Physikalisches Institut, University of Bern, Bern (Switzerland); Galand, M. [Department of Physics, Imperial College London, London (United Kingdom); Henri, P.; Valliéres, X., E-mail: erik.vigren@irfu.se [Laboratoire de Physique et Chimie de l’Environnement et de l’Espace, Orleans (France)

    2016-09-01

    During 2015 January 9–11, at a heliocentric distance of ∼2.58–2.57 au, the ESA Rosetta spacecraft resided at a cometocentric distance of ∼28 km from the nucleus of comet 67P/Churyumov–Gerasimenko, sweeping the terminator at northern latitudes of 43°N–58°N. Measurements by the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis/Comet Pressure Sensor (ROSINA/COPS) provided neutral number densities. We have computed modeled electron number densities using the neutral number densities as input into a Field Free Chemistry Free model, assuming H{sub 2}O dominance and ion-electron pair formation by photoionization only. A good agreement (typically within 25%) is found between the modeled electron number densities and those observed from measurements by the Mutual Impedance Probe (RPC/MIP) and the Langmuir Probe (RPC/LAP), both being subsystems of the Rosetta Plasma Consortium. This indicates that ions along the nucleus-spacecraft line were strongly coupled to the neutrals, moving radially outward with about the same speed. Such a statement, we propose, can be further tested by observations of H{sub 3}O{sup +}/H{sub 2}O{sup +} number density ratios and associated comparisons with model results.

  9. Time-dependent occupation numbers in reduced-density-matrix-functional theory: Application to an interacting Landau-Zener model

    International Nuclear Information System (INIS)

    Requist, Ryan; Pankratov, Oleg

    2011-01-01

    We prove that if the two-body terms in the equation of motion for the one-body reduced density matrix are approximated by ground-state functionals, the eigenvalues of the one-body reduced density matrix (occupation numbers) remain constant in time. This deficiency is related to the inability of such an approximation to account for relative phases in the two-body reduced density matrix. We derive an exact differential equation giving the functional dependence of these phases in an interacting Landau-Zener model and study their behavior in short- and long-time regimes. The phases undergo resonances whenever the occupation numbers approach the boundaries of the interval [0,1]. In the long-time regime, the occupation numbers display correlation-induced oscillations and the memory dependence of the functionals assumes a simple form.

  10. Comparison of several measure-correlate-predict models using support vector regression techniques to estimate wind power densities. A case study

    International Nuclear Information System (INIS)

    Díaz, Santiago; Carta, José A.; Matías, José M.

    2017-01-01

    Highlights: • Eight measure-correlate-predict (MCP) models used to estimate the wind power densities (WPDs) at a target site are compared. • Support vector regressions are used as the main prediction techniques in the proposed MCPs. • The most precise MCP uses two sub-models which predict wind speed and air density in an unlinked manner. • The most precise model allows to construct a bivariable (wind speed and air density) WPD probability density function. • MCP models trained to minimise wind speed prediction error do not minimise WPD prediction error. - Abstract: The long-term annual mean wind power density (WPD) is an important indicator of wind as a power source which is usually included in regional wind resource maps as useful prior information to identify potentially attractive sites for the installation of wind projects. In this paper, a comparison is made of eight proposed Measure-Correlate-Predict (MCP) models to estimate the WPDs at a target site. Seven of these models use the Support Vector Regression (SVR) and the eighth the Multiple Linear Regression (MLR) technique, which serves as a basis to compare the performance of the other models. In addition, a wrapper technique with 10-fold cross-validation has been used to select the optimal set of input features for the SVR and MLR models. Some of the eight models were trained to directly estimate the mean hourly WPDs at a target site. Others, however, were firstly trained to estimate the parameters on which the WPD depends (i.e. wind speed and air density) and then, using these parameters, the target site mean hourly WPDs. The explanatory features considered are different combinations of the mean hourly wind speeds, wind directions and air densities recorded in 2014 at ten weather stations in the Canary Archipelago (Spain). The conclusions that can be drawn from the study undertaken include the argument that the most accurate method for the long-term estimation of WPDs requires the execution of a

  11. Interplanetary Type III Bursts and Electron Density Fluctuations in the Solar Wind

    Czech Academy of Sciences Publication Activity Database

    Krupař, Vratislav; Maksimovic, M.; Kontar, E. P.; Zaslavsky, A.; Santolík, Ondřej; Souček, Jan; Krupařová, Oksana; Eastwood, J. P.; Szabo, A.

    2018-01-01

    Roč. 857, č. 2 (2018), č. článku 82. ISSN 0004-637X R&D Projects: GA ČR(CZ) GJ17-06818Y; GA ČR GA17-08772S; GA ČR(CZ) GA17-06065S Grant - others:AV ČR(CZ) AP1401 Program:Akademická prémie - Praemium Academiae Institutional support: RVO:68378289 Keywords : scattering * Sun: radio radiation * solar wind * radio-burst Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics ) Impact factor: 5.533, year: 2016 http://iopscience.iop.org/article/10.3847/1538-4357/aab60f/meta#references

  12. Influence of the level of fit of a density probability function to wind-speed data on the WECS mean power output estimation

    International Nuclear Information System (INIS)

    Carta, Jose A.; Ramirez, Penelope; Velazquez, Sergio

    2008-01-01

    Static methods which are based on statistical techniques to estimate the mean power output of a WECS (wind energy conversion system) have been widely employed in the scientific literature related to wind energy. In the static method which we use in this paper, for a given wind regime probability distribution function and a known WECS power curve, the mean power output of a WECS is obtained by resolving the integral, usually using numerical evaluation techniques, of the product of these two functions. In this paper an analysis is made of the influence of the level of fit between an empirical probability density function of a sample of wind speeds and the probability density function of the adjusted theoretical model on the relative error ε made in the estimation of the mean annual power output of a WECS. The mean power output calculated through the use of a quasi-dynamic or chronological method, that is to say using time-series of wind speed data and the power versus wind speed characteristic of the wind turbine, serves as the reference. The suitability of the distributions is judged from the adjusted R 2 statistic (R a 2 ). Hourly mean wind speeds recorded at 16 weather stations located in the Canarian Archipelago, an extensive catalogue of wind-speed probability models and two wind turbines of 330 and 800 kW rated power are used in this paper. Among the general conclusions obtained, the following can be pointed out: (a) that the R a 2 statistic might be useful as an initial gross indicator of the relative error made in the mean annual power output estimation of a WECS when a probabilistic method is employed; (b) the relative errors tend to decrease, in accordance with a trend line defined by a second-order polynomial, as R a 2 increases

  13. Influence of the level of fit of a density probability function to wind-speed data on the WECS mean power output estimation

    Energy Technology Data Exchange (ETDEWEB)

    Carta, Jose A. [Department of Mechanical Engineering, University of Las Palmas de Gran Canaria, Campus de Tafira s/n, 35017 Las Palmas de Gran Canaria, Canary Islands (Spain); Ramirez, Penelope; Velazquez, Sergio [Department of Renewable Energies, Technological Institute of the Canary Islands, Pozo Izquierdo Beach s/n, 35119 Santa Lucia, Gran Canaria, Canary Islands (Spain)

    2008-10-15

    Static methods which are based on statistical techniques to estimate the mean power output of a WECS (wind energy conversion system) have been widely employed in the scientific literature related to wind energy. In the static method which we use in this paper, for a given wind regime probability distribution function and a known WECS power curve, the mean power output of a WECS is obtained by resolving the integral, usually using numerical evaluation techniques, of the product of these two functions. In this paper an analysis is made of the influence of the level of fit between an empirical probability density function of a sample of wind speeds and the probability density function of the adjusted theoretical model on the relative error {epsilon} made in the estimation of the mean annual power output of a WECS. The mean power output calculated through the use of a quasi-dynamic or chronological method, that is to say using time-series of wind speed data and the power versus wind speed characteristic of the wind turbine, serves as the reference. The suitability of the distributions is judged from the adjusted R{sup 2} statistic (R{sub a}{sup 2}). Hourly mean wind speeds recorded at 16 weather stations located in the Canarian Archipelago, an extensive catalogue of wind-speed probability models and two wind turbines of 330 and 800 kW rated power are used in this paper. Among the general conclusions obtained, the following can be pointed out: (a) that the R{sub a}{sup 2} statistic might be useful as an initial gross indicator of the relative error made in the mean annual power output estimation of a WECS when a probabilistic method is employed; (b) the relative errors tend to decrease, in accordance with a trend line defined by a second-order polynomial, as R{sub a}{sup 2} increases. (author)

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

    Science.gov (United States)

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

    2011-01-01

    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 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.

  15. Applicability of Synthetic Aperture Radar Wind Retrievals on Offshore Wind Resources Assessment in Hangzhou Bay, China

    DEFF Research Database (Denmark)

    Chang, Rui; Zhu, Rong; Badger, Merete

    2014-01-01

    In view of the high cost and sparse spatial resolution of offshore meteorological observations, ocean winds retrieved from satellites are valuable in offshore wind resource assessment as a supplement to in situ measurements. This study examines satellite synthetic aperture radar (SAR) images from...... ENVISAT advanced SAR (ASAR) for mapping wind resources with high spatial resolution. Around 181 collected pairs of wind data from SAR wind maps and from 13 meteorological stations in Hangzhou Bay are compared. The statistical results comparing in situ wind speed and SAR-based wind speed show a standard...... density functions are compared at one meteorological station. The SAR-based results appear not to estimate the mean wind speed, Weibull scale and shape parameters and wind power density from the full in situ data set so well due to the lower number of satellite samples. Distributions calculated from...

  16. Concept of effective atomic number and effective mass density in dual-energy X-ray computed tomography

    International Nuclear Information System (INIS)

    Bonnin, Anne; Duvauchelle, Philippe; Kaftandjian, Valérie; Ponard, Pascal

    2014-01-01

    This paper focuses on dual-energy X-ray computed tomography and especially the decomposition of the measured attenuation coefficient in a mass density and atomic number basis. In particular, the concept of effective atomic number is discussed. Although the atomic number is well defined for chemical elements, the definition of an effective atomic number for any compound is not an easy task. After reviewing different definitions available in literature, a definition related to the method of measurement and X-ray energy, is suggested. A new concept of effective mass density is then introduced in order to characterize material from dual-energy computed tomography. Finally, this new concept and definition are applied on a simulated case, focusing on explosives identification in luggage

  17. Summary of experience from a large number of construction inspections; Wind power plant projects; Erfarenhetsaaterfoering fraan entreprenadbesiktningar

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, Bertil; Holmberg, Rikard

    2010-08-15

    This report presents a summary of experience from a large number of construction inspections of wind power projects. The working method is based on the collection of construction experience in form of questionnaires. The questionnaires were supplemented by a number of in-depth interviews to understand more in detail what is perceived to be a problem and if there were suggestions for improvements. The results in this report is based on inspection protocols from 174 wind turbines, which corresponds to about one-third of the power plants built in the time period. In total the questionnaires included 4683 inspection remarks as well as about one hundred free text comments. 52 of the 174 inspected power stations were rejected, corresponding to 30%. It has not been possible to identify any over represented type of remark as a main cause of rejection, but the rejection is usually based on a total number of remarks that is too large. The average number of remarks for a power plant is 27. Most power stations have between 20 and 35 remarks. The most common remarks concern shortcomings in marking and documentation. These are easily adjusted, and may be regarded as less serious. There are, however, a number of remarks which are recurrent and quite serious, mainly regarding gearbox, education and lightning protection. Usually these are also easily adjusted, but the consequences if not corrected can be very large. The consequences may be either shortened life of expensive components, e.g. oil problems in gear boxes, or increased probability of serious accidents, e.g. maladjusted lightning protection. In the report, comparison between power stations with various construction period, size, supplier, geography and topography is also presented. The general conclusion is that the differences are small. The results of the evaluation of questionnaires correspond well with the result of the in-depth interviews with clients. The problem that clients agreed upon as the greatest is the lack

  18. THE NUMBER DENSITY AND MASS DENSITY OF STAR-FORMING AND QUIESCENT GALAXIES AT 0.4 ≤ z ≤ 2.2

    International Nuclear Information System (INIS)

    Brammer, Gabriel B.; Whitaker, K. E.; Van Dokkum, P. G.; Lee, K.-S.; Muzzin, A.; Marchesini, D.; Franx, M.; Kriek, M.; Labbe, I.; Quadri, R. F.; Williams, R.; Rudnick, G.

    2011-01-01

    We study the buildup of the bimodal galaxy population using the NEWFIRM Medium-Band Survey, which provides excellent redshifts and well-sampled spectral energy distributions of ∼27, 000 galaxies with K 3 x 10 10 M sun increases by a factor of ∼10 from z ∼ 2 to the present day, whereas the mass density in star-forming galaxies is flat or decreases over the same time period. Modest mass growth by a factor of ∼2 of individual quiescent galaxies can explain roughly half of the strong density evolution at masses >10 11 M sun , due to the steepness of the exponential tail of the mass function. The rest of the density evolution of massive, quiescent galaxies is likely due to transformation (e.g., quenching) of the massive star-forming population, a conclusion which is consistent with the density evolution we observe for the star-forming galaxies themselves, which is flat or decreasing with cosmic time. Modest mass growth does not explain the evolution of less massive quiescent galaxies (∼10 10.5 M sun ), which show a similarly steep increase in their number densities. The less massive quiescent galaxies are therefore continuously formed by transforming galaxies from the star-forming population.

  19. Late-Holocene climate evolution at the WAIS Divide site, West Antarctica: Bubble number-density estimates

    Science.gov (United States)

    Fegyveresi, John M.; Alley, R.B.; Spencer, M.K.; Fitzpatrick, J.J.; Steig, E.J.; White, J.W.C.; McConnell, J.R.; Taylor, K.C.

    2011-01-01

    A surface cooling of ???1.7??C occurred over the ???two millennia prior to ???1700 CE at the West Antarctic ice sheet (WAIS) Divide site, based on trends in observed bubble number-density of samples from the WDC06A ice core, and on an independently constructed accumulation-rate history using annual-layer dating corrected for density variations and thinning from ice flow. Density increase and grain growth in polar firn are both controlled by temperature and accumulation rate, and the integrated effects are recorded in the number-density of bubbles as the firn changes to ice. Numberdensity is conserved in bubbly ice following pore close-off, allowing reconstruction of either paleotemperature or paleo-accumulation rate if the other is known. A quantitative late-Holocene paleoclimate reconstruction is presented for West Antarctica using data obtained from the WAIS Divide WDC06A ice core and a steady-state bubble number-density model. The resultant temperature history agrees closely with independent reconstructions based on stable-isotopic ratios of ice. The ???1.7??C cooling trend observed is consistent with a decrease in Antarctic summer duration from changing orbital obliquity, although it remains possible that elevation change at the site contributed part of the signal. Accumulation rate and temperature dropped together, broadly consistent with control by saturation vapor pressure.

  20. Open circuit V-I characteristics of a coreless ironless electric generator for low density wind power generation

    Science.gov (United States)

    Razali, Akhtar; Rahman, Fadhlur; Azlan, Syaiful; Razali Hanipah, Mohd; Azri Hizami, Mohd

    2018-04-01

    Cogging is an attraction of magnetism between permanent magnets and soft ironcore lamination in a conventional electric ironcore generator. The presence of cog in the generator is seen somehow restricted the application of the generator in an application where low rotational torque is required. Cog torque requires an additional input power to overcome, hence became one of the power loss sources. With the increasing of power output, the cogging is also proportionally increased. This leads to the increasing of the supplied power of the driver motor to overcome the cog. Therefore, this research is embarked to study fundamentally about the possibility of removing ironcore lamination in an electric generator. This research deals with removal of ironcore lamination in electric generator to eliminate cog torque. A confinement technique is proposed to confine and focus magnetic flux by introducing opposing permanent magnets arrangement. The concept is then fabricated and experimentally validated to qualify its no-load characteristics. The rotational torque and power output are measured and efficiency is then analyzed. Results indicated that the generator produced RMS voltage of 416VAC at rotational speed of 1762 RPM. Torque required to rotate the generator was at 2Nm for various rotational speed. The generator has shown 30% lesser rotational torque compared to the conventional ironcore type generator due to the absent of cogging torque in the system. Lesser rotational torque required to rotate has made this type of generator has a potential to be used for low wind density wind turbine application.

  1. The spectrum of small-scale density fluctuations in the solar wind

    International Nuclear Information System (INIS)

    Readhead, A.C.S.; Kemp, M.C.; Hewish, A.

    1978-01-01

    Interplanetary scintillation observations at frequencies between 74 and 1400 MHz and solar elongations in the range 10 to 90 0 are combined to determine the form of the wavenumber spectrum of electron density fluctuations in the range 10 -3 -1 /km (where k = 2π/lambda). The data are best explained by a spectrum in which there is a genuine scale-length; they are not consistent with a simple power-law spectrum. This suggests that turbulence may be less important than some kind of plasma instability in generating small-scale density fluctuations. The relevance of these conclusions to the use of IPS for determining radio source structure is discussed. (author)

  2. Diagnosis of Unmagnetized Plasma Electron Number Density and Electron-neutral Collision Frequency by Using Microwave

    International Nuclear Information System (INIS)

    Yuan Zhongcai; Shi Jiaming; Xu Bo

    2005-01-01

    The plasma diagnostic method using the transmission attenuation of microwaves at double frequencies (PDMUTAMDF) indicates that the frequency and the electron-neutral collision frequency of the plasma can be deduced by utilizing the transmission attenuation of microwaves at two neighboring frequencies in a non-magnetized plasma. Then the electron density can be obtained from the plasma frequency. The PDMUTAMDF is a simple method to diagnose the plasma indirectly. In this paper, the interaction of electromagnetic waves and the plasma is analyzed. Then, based on the attenuation and the phase shift of a microwave in the plasma, the principle of the PDMUTAMDF is presented. With the diagnostic method, the spatially mean electron density and electron collision frequency of the plasma can be obtained. This method is suitable for the elementary diagnosis of the atmospheric-pressure plasma

  3. Preliminary wing model tests in the variable density wind tunnel of the National Advisory Committee for Aeronautics

    Science.gov (United States)

    Munk, Max M

    1926-01-01

    This report contains the results of a series of tests with three wing models. By changing the section of one of the models and painting the surface of another, the number of models tested was increased to five. The tests were made in order to obtain some general information on the air forces on wing sections at a high Reynolds number and in particular to make sure that the Reynolds number is really the important factor, and not other things like the roughness of the surface and the sharpness of the trailing edge. The few tests described in this report seem to indicate that the air forces at a high Reynolds number are not equivalent to respective air forces at a low Reynolds number (as in an ordinary atmospheric wind tunnel). The drag appears smaller at a high Reynolds number and the maximum lift is increased in some cases. The roughness of the surface and the sharpness of the trailing edge do not materially change the results, so that we feel confident that tests with systematic series of different wing sections will bring consistent results, important and highly useful to the designer.

  4. Graphite-high density polyethylene laminated composites with high thermal conductivity made by filament winding

    Directory of Open Access Journals (Sweden)

    W. Lv

    2018-03-01

    Full Text Available The low thermal conductivity of polymers limits their use in numerous applications, where heat transfer is important. The two primary approaches to overcome this limitation, are to mix in other materials with high thermal conductivity, or mechanically stretch the polymers to increase their intrinsic thermal conductivity. Progress along both of these pathways has been stifled by issues associated with thermal interface resistance and manufacturing scalability respectively. Here, we report a novel polymer composite architecture that is enabled by employing typical composites manufacturing method such as filament winding with the twist that the polymer is in fiber form and the filler in form of sheets. The resulting novel architecture enables accession of the idealized effective medium composite behavior as it minimizes the interfacial resistance. The process results in neat polymer and 50 vol% graphite/polymer plates with thermal conductivity of 42 W·m–1·K–1 (similar to steel and 130 W·m–1·K–1 respectively.

  5. The Effect of Air Density on Sand Transport Structures and the Adobe Abrasion Profile: A Field Wind-Tunnel Experiment Over a Wide Range of Altitude

    Science.gov (United States)

    Han, Qingjie; Qu, Jianjun; Dong, Zhibao; Zu, Ruiping; Zhang, Kecun; Wang, Hongtao; Xie, Shengbo

    2014-02-01

    Aeolian sand transport results from interactions between the surface and the airflow above. Air density strongly constrains airflow characteristics and the resulting flow of sand, and therefore should not be neglected in sand transport models. In the present study, we quantify the influence of air density on the sand flow structure, sand transport rate, adobe abrasion profiles, and abrasion rate using a portable wind-tunnel in the field. For a given wind speed, the flow's ability to transport sand decreases at low air density, so total sand transport decreases, but the saltation height increases. Thus, the damage to human structures increases compared with what occurs at lower altitudes. The adobe abrasion rate by the cloud of blowing sand decreases exponentially with increasing height above the surface, while the wind erosion and dust emission intensity both increase with increasing air density. Long-term feedback processes between air density and wind erosion suggest that the development of low-altitude areas due to long-term deflation plays a key role in dust emission, and will have a profound significance for surface Aeolian processes and geomorphology.

  6. Joint constraints on galaxy bias and σ{sub 8} through the N-pdf of the galaxy number density

    Energy Technology Data Exchange (ETDEWEB)

    Arnalte-Mur, Pablo; Martínez, Vicent J. [Observatori Astronòmic de la Universitat de València, C/ Catedràtic José Beltrán, 2, 46980 Paterna, València (Spain); Vielva, Patricio; Sanz, José L. [Instituto de Física de Cantabria (CSIC-UC), Avda. de Los Castros s/n, E-39005—Santander (Spain); Saar, Enn [Cosmology Department, Tartu Observatory, Observatooriumi 1, Tõravere (Estonia); Paredes, Silvestre, E-mail: pablo.arnalte@uv.es, E-mail: vielva@ifca.unican.es, E-mail: martinez@uv.es, E-mail: sanz@ifca.unican.es, E-mail: saar@to.ee, E-mail: silvestre.paredes@upct.es [Departamento de Matemática Aplicada y Estadística, Universidad Politécnica de Cartagena, C/Dr. Fleming s/n, 30203 Cartagena (Spain)

    2016-03-01

    We present a full description of the N-probability density function of the galaxy number density fluctuations. This N-pdf is given in terms, on the one hand, of the cold dark matter correlations and, on the other hand, of the galaxy bias parameter. The method relies on the assumption commonly adopted that the dark matter density fluctuations follow a local non-linear transformation of the initial energy density perturbations. The N-pdf of the galaxy number density fluctuations allows for an optimal estimation of the bias parameter (e.g., via maximum-likelihood estimation, or Bayesian inference if there exists any a priori information on the bias parameter), and of those parameters defining the dark matter correlations, in particular its amplitude (σ{sub 8}). It also provides the proper framework to perform model selection between two competitive hypotheses. The parameters estimation capabilities of the N-pdf are proved by SDSS-like simulations (both, ideal log-normal simulations and mocks obtained from Las Damas simulations), showing that our estimator is unbiased. We apply our formalism to the 7th release of the SDSS main sample (for a volume-limited subset with absolute magnitudes M{sub r} ≤ −20). We obtain b-circumflex  = 1.193 ± 0.074 and σ-bar{sub 8} = 0.862 ± 0.080, for galaxy number density fluctuations in cells of the size of 30h{sup −1}Mpc. Different model selection criteria show that galaxy biasing is clearly favoured.

  7. Joint constraints on galaxy bias and σ8 through the N-pdf of the galaxy number density

    International Nuclear Information System (INIS)

    Arnalte-Mur, Pablo; Martínez, Vicent J.; Vielva, Patricio; Sanz, José L.; Saar, Enn; Paredes, Silvestre

    2016-01-01

    We present a full description of the N-probability density function of the galaxy number density fluctuations. This N-pdf is given in terms, on the one hand, of the cold dark matter correlations and, on the other hand, of the galaxy bias parameter. The method relies on the assumption commonly adopted that the dark matter density fluctuations follow a local non-linear transformation of the initial energy density perturbations. The N-pdf of the galaxy number density fluctuations allows for an optimal estimation of the bias parameter (e.g., via maximum-likelihood estimation, or Bayesian inference if there exists any a priori information on the bias parameter), and of those parameters defining the dark matter correlations, in particular its amplitude (σ 8 ). It also provides the proper framework to perform model selection between two competitive hypotheses. The parameters estimation capabilities of the N-pdf are proved by SDSS-like simulations (both, ideal log-normal simulations and mocks obtained from Las Damas simulations), showing that our estimator is unbiased. We apply our formalism to the 7th release of the SDSS main sample (for a volume-limited subset with absolute magnitudes M r  ≤ −20). We obtain b-circumflex  = 1.193 ± 0.074 and σ-bar 8  = 0.862 ± 0.080, for galaxy number density fluctuations in cells of the size of 30h −1 Mpc. Different model selection criteria show that galaxy biasing is clearly favoured

  8. Determination of the Rb atomic number density in dense rubidium vapors by absorption measurements of Rb2 triplet bands

    International Nuclear Information System (INIS)

    Horvatic, Vlasta; Veza, Damir; Niemax, Kay; Vadla, Cedomil

    2008-01-01

    A simple and accurate way of determining atom number densities in dense rubidium vapors is presented. The method relies on the experimental finding that the reduced absorption coefficients of the Rb triplet satellite bands between 740 nm and 750 nm and the triplet diffuse band between 600 nm and 610 nm are not temperature dependent in the range between 600 K and 800 K. Therefore, the absolute values of the reduced absorption coefficients of these molecular bands can provide accurate information about atomic number density of the vapor. The rubidium absorption spectrum was measured by spatially resolved white-light absorption in overheated rubidium vapor generated in a heat pipe oven. The absolute values for the reduced absorption coefficients of the triplet bands were determined at lower vapor densities, by using an accurate expression for the reduced absorption coefficient in the quasistatic wing of the Rb D1 line, and measured triplet satellite bands to the resonance wing optical depth ratio. These triplet satellite band data were used to calibrate in absolute scale the reduced absorption coefficients of the triplet diffuse band at higher temperatures. The obtained values for the reduced absorption coefficient of these Rb molecular features can be used for accurate determination of rubidium atomic number densities in the range from about 5 x 10 16 cm -3 to 1 x 10 18 cm -3

  9. Kinetic and electron-electron energies for convex sums of ground state densities with degeneracies and fractional electron number

    Energy Technology Data Exchange (ETDEWEB)

    Levy, Mel, E-mail: ayers@mcmaster.ca, E-mail: mlevy@tulane.edu [Department of Chemistry, Duke University, Durham, North Carolina 27708 (United States); Department of Physics, North Carolina A and T State University, Greensboro, North Carolina 27411 (United States); Department of Chemistry, Tulane University, New Orleans, Louisiana 70118 (United States); Anderson, James S. M.; Zadeh, Farnaz Heidar; Ayers, Paul W., E-mail: ayers@mcmaster.ca, E-mail: mlevy@tulane.edu [Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario (Canada)

    2014-05-14

    Properties of exact density functionals provide useful constraints for the development of new approximate functionals. This paper focuses on convex sums of ground-level densities. It is observed that the electronic kinetic energy of a convex sum of degenerate ground-level densities is equal to the convex sum of the kinetic energies of the individual degenerate densities. (The same type of relationship holds also for the electron-electron repulsion energy.) This extends a known property of the Levy-Valone Ensemble Constrained-Search and the Lieb Legendre-Transform refomulations of the Hohenberg-Kohn functional to the individual components of the functional. Moreover, we observe that the kinetic and electron-repulsion results also apply to densities with fractional electron number (even if there are no degeneracies), and we close with an analogous point-wise property involving the external potential. Examples where different degenerate states have different kinetic energy and electron-nuclear attraction energy are given; consequently, individual components of the ground state electronic energy can change abruptly when the molecular geometry changes. These discontinuities are predicted to be ubiquitous at conical intersections, complicating the development of universally applicable density-functional approximations.

  10. THE H I MASS DENSITY IN GALACTIC HALOS, WINDS, AND COLD ACCRETION AS TRACED BY Mg II ABSORPTION

    Energy Technology Data Exchange (ETDEWEB)

    Kacprzak, Glenn G. [Swinburne University of Technology, Victoria 3122 (Australia); Churchill, Christopher W., E-mail: gkacprzak@astro.swin.edu.au, E-mail: cwc@nmsu.edu [New Mexico State University, Las Cruces, NM 88003 (United States)

    2011-12-20

    It is well established that Mg II absorption lines detected in background quasar spectra arise from gas structures associated with foreground galaxies. The degree to which galaxy evolution is driven by the gas cycling through halos is highly uncertain because their gas mass density is poorly constrained. Fitting the Mg II equivalent width (W) distribution with a Schechter function and applying the N(H I)-W correlation of Menard and Chelouche, we computed {Omega}(H I){sub MgII} {identical_to} {Omega}(H I){sub halo} = 1.41{sup +0.75}{sub -0.44} Multiplication-Sign 10{sup -4} for 0.4 {<=} z {<=} 1.4. We exclude damped Ly{alpha}'s (DLAs) from our calculations so that {Omega}(H I){sub halo} comprises accreting and/or outflowing halo gas not locked up in cold neutral clouds. We deduce that the cosmic H I gas mass density fraction in galactic halos traced by Mg II absorption is {Omega}(H I){sub halo}/{Omega}(H I){sub DLA} {approx_equal} 15% and {Omega}(H I){sub halo}/{Omega}{sub b} {approx_equal} 0.3%. Citing several lines of evidence, we propose that infall/accretion material is sampled by small W whereas outflow/winds are sampled by large W, and find that {Omega}(H I){sub infall} is consistent with {Omega}(H I){sub outflow} for bifurcation at W = 1.23{sup +0.15}{sub -0.28} Angstrom-Sign ; cold accretion would then comprise no more than {approx}7% of the total H I mass density. We discuss evidence that (1) the total H I mass cycling through halos remains fairly constant with cosmic time and that the accretion of H I gas sustains galaxy winds, and (2) evolution in the cosmic star formation rate depends primarily on the rate at which cool H I gas cycles through halos.

  11. Effective atomic numbers and effective electron densities for trommel sieve waste and some commonly used building materials

    International Nuclear Information System (INIS)

    Kurudirek, M.; Canimkurbey, B.; Coban, M.; Ayguen, M.; Erzeneoglu, S. Z.

    2010-01-01

    Trommel sieve waste and some commonly used building materials (Portland cement, lime and pointing) have been investigated in terms of effective atomic numbers (Z e ff) and effective electron densities (N e ) by using X- and γ- rays at 22.1, 25 and 88 keV photon energies. A high resolution Si(Li) detector was employed to detect X- and/or γ- radiation coming through in a narrow beam good geometry set-up. Chemical compositions of the materials used in the present study were determined using a wave length dispersive X-ray fluorescence spectrometer (WDXRFS). The variations in photon interaction parameters were discussed regarding the photon energy and chemical composition. The experimental values of effective atomic numbers and effective electron densities were compared with the ones obtained from theory.

  12. A Numbers Game: Ribosome Densities, Bacterial Growth, and Antibiotic-Mediated Stasis and Death

    Directory of Open Access Journals (Sweden)

    Bruce R. Levin

    2017-02-01

    Full Text Available We postulate that the inhibition of growth and low rates of mortality of bacteria exposed to ribosome-binding antibiotics deemed bacteriostatic can be attributed almost uniquely to these drugs reducing the number of ribosomes contributing to protein synthesis, i.e., the number of effective ribosomes. We tested this hypothesis with Escherichia coli K-12 MG1655 and constructs that had been deleted for 1 to 6 of the 7 rRNA (rrn operons. In the absence of antibiotics, constructs with fewer rrn operons have lower maximum growth rates and longer lag phases than those with more ribosomal operons. In the presence of the ribosome-binding “bacteriostatic” antibiotics tetracycline, chloramphenicol, and azithromycin, E. coli strains with 1 and 2 rrn operons are killed at a substantially higher rate than those with more rrn operons. This increase in the susceptibility of E. coli with fewer rrn operons to killing by ribosome-targeting bacteriostatic antibiotics is not reflected in their greater sensitivity to killing by the bactericidal antibiotic ciprofloxacin, which does not target ribosomes, but also to killing by gentamicin, which does. Finally, when such strains are exposed to these ribosome-targeting bacteriostatic antibiotics, the time before these bacteria start to grow again when the drugs are removed, referred to as the post-antibiotic effect (PAE, is markedly greater for constructs with fewer rrn operons than for those with more rrn operons. We interpret the results of these other experiments reported here as support for the hypothesis that the reduction in the effective number of ribosomes due to binding to these structures provides a sufficient explanation for the action of bacteriostatic antibiotics that target these structures.

  13. [Particle Size and Number Density Online Analysis for Particle Suspension with Polarization-Differentiation Elastic Light Scattering Spectroscopy].

    Science.gov (United States)

    Chen, Wei-kang; Fang, Hui

    2016-03-01

    The basic principle of polarization-differentiation elastic light scattering spectroscopy based techniques is that under the linear polarized light incidence, the singlely scattered light from the superficial biological tissue and diffusively scattered light from the deep tissue can be separated according to the difference of polarization characteristics. The novel point of the paper is to apply this method to the detection of particle suspension and, to realize the simultaneous measurement of its particle size and number density in its natural status. We design and build a coaxial cage optical system, and measure the backscatter signal at a specified angle from a polystyrene microsphere suspension. By controlling the polarization direction of incident light with a linear polarizer and adjusting the polarization direction of collected light with another linear polarizer, we obtain the parallel polarized elastic light scattering spectrum and cross polarized elastic light scattering spectrum. The difference between the two is the differential polarized elastic light scattering spectrum which include only the single scattering information of the particles. We thus compare this spectrum to the Mie scattering calculation and extract the particle size. We then also analyze the cross polarized elastic light scattering spectrum by applying the particle size already extracted. The analysis is based on the approximate expressions taking account of light diffusing, from which we are able to obtain the number density of the particle suspension. We compare our experimental outcomes with the manufacturer-provided values and further analyze the influence of the particle diameter standard deviation on the number density extraction, by which we finally verify the experimental method. The potential applications of the method include the on-line particle quality monitoring for particle manufacture as well as the fat and protein density detection of milk products.

  14. Plant Density Effect on Grain Number and Weight of Two Winter Wheat Cultivars at Different Spikelet and Grain Positions

    Science.gov (United States)

    Ni, Yingli; Zheng, Mengjing; Yang, Dongqing; Jin, Min; Chen, Jin; Wang, Zhenlin; Yin, Yanping

    2016-01-01

    In winter wheat, grain development is asynchronous. The grain number and grain weight vary significantly at different spikelet and grain positions among wheat cultivars grown at different plant densities. In this study, two winter wheat (Triticum aestivum L.) cultivars, ‘Wennong6’ and ‘Jimai20’, were grown under four different plant densities for two seasons, in order to study the effect of plant density on the grain number and grain weight at different spikelet and grain positions. The results showed that the effects of spikelet and grain positions on grain weight varied with the grain number of spikelets. In both cultivars, the single-grain weight of the basal and middle two-grain spikelets was higher at the 2nd grain position than that at the 1st grain position, while the opposite occurred in the top two-grain spikelets. In the three-grain spikelets, the distribution of the single-grain weight was different between cultivars. In the four-grain spikelets of Wennong6, the single-grain weight was the highest at the 2nd grain position, followed by the 1st, 3rd, and 4th grain positions. Regardless of the spikelet and grain positions, the single-grain weight was the highest at the 1st and 2nd grain positions and the lowest at the 3rd and 4th grain positions. Overall, plant density affected the yield by controlling the seed-setting characteristics of the tiller spike. Therefore, wheat yield can be increased by decreasing the sterile basal and top spikelets and enhancing the grain weight at the 3rd and 4th grain positions, while maintaining it at the 1st and 2nd grain positions on the spikelet. PMID:27171343

  15. Microtubule Protofilament Number Is Modulated in a Step-Wise Fashion By the Charge of Density of An Enveloping Layer

    International Nuclear Information System (INIS)

    Raviv, U.; Nguyen, T.; Ghafouri, R.; Needleman, D.J.; Li, Y.; Miller, H.P.; Wilson, L.; Bruinsma, R.F.; Safinya, C.R.; UC, Santa Barbara; UCLA

    2007-01-01

    Microtubules are able to adjust their protofilament (PF) number and, as a consequence, their dynamics and function, to the assembly conditions and presence of cofactors. However, the principle behind such variations is poorly understood. Using synchrotron x-ray scattering and transmission electron microscopy, we studied how charged membranes, which under certain conditions can envelop preassembled MTs, regulate the PF number of those MTs. We show that the mean PF number, , is modulated primarily by the charge density of the membranes. decreases in a stepwise fashion with increasing membrane charge density. does not depend on the membrane-protein stoichiometry or the solution ionic strength. We studied the effect of taxol and found that increases logarithmically with taxol/tubulin stoichiometry. We present a theoretical model, which by balancing the electrostatic and elastic interactions in the system accounts for the trends in our findings and reveals an effective MT bending stiffness of order 10-100 k B T/nm, associated with the observed changes in PF number

  16. Column Number Density Expressions Through M = 0 and M = 1 Point Source Plumes Along Any Straight Path

    Science.gov (United States)

    Woronowicz, Michael

    2016-01-01

    Analytical expressions for column number density (CND) are developed for optical line of sight paths through a variety of steady free molecule point source models including directionally-constrained effusion (Mach number M = 0) and flow from a sonic orifice (M = 1). Sonic orifice solutions are approximate, developed using a fair simulacrum fitted to the free molecule solution. Expressions are also developed for a spherically-symmetric thermal expansion (M = 0). CND solutions are found for the most general paths relative to these sources and briefly explored. It is determined that the maximum CND from a distant location through directed effusion and sonic orifice cases occurs along the path parallel to the source plane that intersects the plume axis. For the effusive case this value is exactly twice the CND found along the ray originating from that point of intersection and extending to infinity along the plume's axis. For sonic plumes this ratio is reduced to about 4/3. For high Mach number cases the maximum CND will be found along the axial centerline path. Keywords: column number density, plume flows, outgassing, free molecule flow.

  17. Climatology of mesopause region nocturnal temperature, zonal wind, and sodium density observed by sodium lidar over Hefei, China (32°N, 117°E)

    Science.gov (United States)

    Li, T.; Ban, C.; Fang, X.; Li, J.; Wu, Z.; Xiong, J.; Feng, W.; Plane, J. M. C.

    2017-12-01

    The University of Science and Technology of China narrowband sodium temperature/wind lidar, located in Hefei, China (32°N, 117°E), was installed in November 2011 and have made routine nighttime measurements since January 2012. We obtained 154 nights ( 1400 hours) of vertical profiles of temperature, sodium density, and zonal wind, and 83 nights ( 800 hours) of vertical flux of gravity wave (GW) zonal momentum in the mesopause region (80-105 km) during the period of 2012 to 2016. In temperature, it is likely that the diurnal tide dominates below 100 km in spring, while the semidiurnal tide dominates above 100 km throughout the year. A clear semiannual variation in temperature is revealed near 90 km, likely related to the tropical mesospheric semiannual oscillation (MSAO). The variability of sodium density is positively correlated with temperature, suggesting that in addition to dynamics, the chemistry may also play an important role in the formation of sodium atoms. The observed sodium peak density is 1000 cm-3 higher than that simulated by the model. In zonal wind, the diurnal tide dominates in both spring and fall, while semidiurnal tide dominates in winter. The observed semiannual variation in zonal wind near 90 km is out-of-phase with that in temperature, consistent with tropical MSAO. The GW zonal momentum flux is mostly westward in fall and winter, anti-correlated with eastward zonal wind. The annual mean flux averaged over 87-97 km is -0.3 m2/s2 (westward), anti-correlated with eastward zonal wind of 10 m/s. The comparisons of lidar results with those observed by satellite, nearby radar, and simulated by model show generally good agreements.

  18. CARAT: A novel method for allelic detection of DNA copy number changes using high density oligonucleotide arrays

    Directory of Open Access Journals (Sweden)

    Ishikawa Shumpei

    2006-02-01

    Full Text Available Abstract Background DNA copy number alterations are one of the main characteristics of the cancer cell karyotype and can contribute to the complex phenotype of these cells. These alterations can lead to gains in cellular oncogenes as well as losses in tumor suppressor genes and can span small intervals as well as involve entire chromosomes. The ability to accurately detect these changes is central to understanding how they impact the biology of the cell. Results We describe a novel algorithm called CARAT (Copy Number Analysis with Regression And Tree that uses probe intensity information to infer copy number in an allele-specific manner from high density DNA oligonuceotide arrays designed to genotype over 100, 000 SNPs. Total and allele-specific copy number estimations using CARAT are independently evaluated for a subset of SNPs using quantitative PCR and allelic TaqMan reactions with several human breast cancer cell lines. The sensitivity and specificity of the algorithm are characterized using DNA samples containing differing numbers of X chromosomes as well as a test set of normal individuals. Results from the algorithm show a high degree of agreement with results from independent verification methods. Conclusion Overall, CARAT automatically detects regions with copy number variations and assigns a significance score to each alteration as well as generating allele-specific output. When coupled with SNP genotype calls from the same array, CARAT provides additional detail into the structure of genome wide alterations that can contribute to allelic imbalance.

  19. The dependence of C IV broad absorption line properties on accompanying Si IV and Al III absorption: relating quasar-wind ionization levels, kinematics, and column densities

    Energy Technology Data Exchange (ETDEWEB)

    Filiz Ak, N.; Brandt, W. N.; Schneider, D. P.; Trump, J. R. [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States); Hall, P. B. [Department of Physics and Astronomy, York University, 4700 Keele Street, Toronto, Ontario M3J 1P3 (Canada); Anderson, S. F. [Astronomy Department, University of Washington, Seattle, WA 98195 (United States); Hamann, F. [Department of Astronomy, University of Florida, Gainesville, FL 32611-2055 (United States); Myers, Adam D. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); Pâris, I. [Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago (Chile); Petitjean, P. [Institut d' Astrophysique de Paris, Universite Paris 6, F-75014 Paris (France); Ross, Nicholas P. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Shen, Yue [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); York, Don, E-mail: nfilizak@astro.psu.edu [Department of Astronomy and Astrophysics, The University of Chicago, Chicago, IL 60637 (United States)

    2014-08-20

    We consider how the profile and multi-year variability properties of a large sample of C IV Broad Absorption Line (BAL) troughs change when BALs from Si IV and/or Al III are present at corresponding velocities, indicating that the line of sight intercepts at least some lower ionization gas. We derive a number of observational results for C IV BALs separated according to the presence or absence of accompanying lower ionization transitions, including measurements of composite profile shapes, equivalent width (EW), characteristic velocities, composite variation profiles, and EW variability. We also measure the correlations between EW and fractional-EW variability for C IV, Si IV, and Al III. Our measurements reveal the basic correlated changes between ionization level, kinematics, and column density expected in accretion-disk wind models; e.g., lines of sight including lower ionization material generally show deeper and broader C IV troughs that have smaller minimum velocities and that are less variable. Many C IV BALs with no accompanying Si IV or Al III BALs may have only mild or no saturation.

  20. A dynamo theory prediction for solar cycle 22: Sunspot number, radio flux, exospheric temperature, and total density at 400 km

    Science.gov (United States)

    Schatten, K. H.; Hedin, A. E.

    1986-01-01

    Using the dynamo theory method to predict solar activity, a value for the smoothed sunspot number of 109 + or - 20 is obtained for solar cycle 22. The predicted cycle is expected to peak near December, 1990 + or - 1 year. Concommitantly, F(10.7) radio flux is expected to reach a smoothed value of 158 + or - 18 flux units. Global mean exospheric temperature is expected to reach 1060 + or - 50 K and global total average total thermospheric density at 400 km is expected to reach 4.3 x 10 to the -15th gm/cu cm + or - 25 percent.

  1. A dynamo theory prediction for solar cycle 22 - Sunspot number, radio flux, exospheric temperature, and total density at 400 km

    Science.gov (United States)

    Schatten, K. H.; Hedin, A. E.

    1984-01-01

    Using the 'dynamo theory' method to predict solar activity, a value for the smoothed sunspot number of 109 + or - 20 is obtained for solar cycle 22. The predicted cycle is expected to peak near December, 1990 + or - 1 year. Concommitantly, F(10.7) radio flux is expected to reach a smoothed value of 158 + or - 18 flux units. Global mean exospheric temperature is expected to reach 1060 + or - 50 K and global total average total thermospheric density at 400 km is expected to reach 4.3 x 10 to the -15th gm/cu cm + or - 25 percent.

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  3. Determination of the number density of excited and ground Zn atoms during rf magnetron sputtering of ZnO target

    Energy Technology Data Exchange (ETDEWEB)

    Maaloul, L.; Gangwar, R. K.; Stafford, L., E-mail: luc.stafford@umontreal.ca [Département de Physique, Université de Montréal, Montréal, Québec H3C 3J7 (Canada)

    2015-07-15

    A combination of optical absorption spectroscopy (OAS) and optical emission spectroscopy measurements was used to monitor the number density of Zn atoms in excited 4s4p ({sup 3}P{sub 2} and {sup 3}P{sub 0}) metastable states as well as in ground 4s{sup 2} ({sup 1}S{sub 0}) state in a 5 mTorr Ar radio-frequency (RF) magnetron sputtering plasma used for the deposition of ZnO-based thin films. OAS measurements revealed an increase by about one order of magnitude of Zn {sup 3}P{sub 2} and {sup 3}P{sub 0} metastable atoms by varying the self-bias voltage on the ZnO target from −115 to −300 V. Over the whole range of experimental conditions investigated, the triplet-to-singlet metastable density ratio was 5 ± 1, which matches the statistical weight ratio of these states in Boltzmann equilibrium. Construction of a Boltzmann plot using all Zn I emission lines in the 200–500 nm revealed a constant excitation temperature of 0.33 ± 0.04 eV. In combination with measured populations of Zn {sup 3}P{sub 2} and {sup 3}P{sub 0} metastable atoms, this temperature was used to extrapolate the absolute number density of ground state Zn atoms. The results were found to be in excellent agreement with those obtained previously by actinometry on Zn atoms using Ar as the actinometer gas [L. Maaloul and L. Stafford, J. Vac. Sci. Technol., A 31, 061306 (2013)]. This set of data was then correlated to spectroscopic ellipsometry measurements of the deposition rate of Zn atoms on a Si substrate positioned at 12 cm away from the ZnO target. The deposition rate scaled linearly with the number density of Zn atoms. In sharp contrast with previous studies on RF magnetron sputtering of Cu targets, these findings indicate that metastable atoms play a negligible role on the plasma deposition dynamics of Zn-based coatings.

  4. Evaluation of magnetic helicity density in the wave number domain using multi-point measurements in space

    Directory of Open Access Journals (Sweden)

    Y. Narita

    2009-10-01

    Full Text Available We develop an estimator for the magnetic helicity density, a measure of the spiral geometry of magnetic field lines, in the wave number domain as a wave diagnostic tool based on multi-point measurements in space. The estimator is numerically tested with a synthetic data set and then applied to an observation of magnetic field fluctuations in the Earth foreshock region provided by the four-point measurements of the Cluster spacecraft. The energy and the magnetic helicity density are determined in the frequency and the wave number domain, which allows us to identify the wave properties in the plasma rest frame correcting for the Doppler shift. In the analyzed time interval, dominant wave components have parallel propagation to the mean magnetic field, away from the shock at about Alfvén speed and a left-hand spatial rotation sense of helicity with respect to the propagation direction, which means a right-hand temporal rotation sense of polarization. These wave properties are well explained by the right-hand resonant beam instability as the driving mechanism in the foreshock. Cluster observations allow therefore detailed comparisons with various theories of waves and instabilities.

  5. Two types of nonlinear wave equations for diffractive beams in bubbly liquids with nonuniform bubble number density.

    Science.gov (United States)

    Kanagawa, Tetsuya

    2015-05-01

    This paper theoretically treats the weakly nonlinear propagation of diffracted sound beams in nonuniform bubbly liquids. The spatial distribution of the number density of the bubbles, initially in a quiescent state, is assumed to be a slowly varying function of the spatial coordinates; the amplitude of variation is assumed to be small compared to the mean number density. A previous derivation method of nonlinear wave equations for plane progressive waves in uniform bubbly liquids [Kanagawa, Yano, Watanabe, and Fujikawa (2010). J. Fluid Sci. Technol. 5(3), 351-369] is extended to handle quasi-plane beams in weakly nonuniform bubbly liquids. The diffraction effect is incorporated by adding a relation that scales the circular sound source diameter to the wavelength into the original set of scaling relations composed of nondimensional physical parameters. A set of basic equations for bubbly flows is composed of the averaged equations of mass and momentum, the Keller equation for bubble wall, and supplementary equations. As a result, two types of evolution equations, a nonlinear Schrödinger equation including dissipation, diffraction, and nonuniform effects for high-frequency short-wavelength case, and a Khokhlov-Zabolotskaya-Kuznetsov equation including dispersion and nonuniform effects for low-frequency long-wavelength case, are derived from the basic set.

  6. Au/SiO2 nanocomposite film substrates with a high number density of Au nanoparticles for molecular conductance measurement

    International Nuclear Information System (INIS)

    Kim, Dae-Gun; Koyama, Emiko; Kikkawa, Yoshihiro; Kirihara, Kazuhiro; Naitoh, Yasuhisa; Kim, Deok-Soo; Tokuhisa, Hideo; Kanesato, Masatoshi; Koshizaki, Naoto

    2007-01-01

    Au/SiO 2 nanocomposite films consisting of an extremely high number density of Au nanoparticles dispersed in a SiO 2 matrix a few nanometres thick were deposited by a co-sputtering method, and employed for molecular conductance measurement by immobilizing and bridging conjugated biphenyl molecules on dispersed Au nanoparticles. The number density of Au nanoparticles in the insulating SiO 2 matrix was approximately 14 000 μm 2 , and the average interparticle distance from their neighbours was about 8 nm. The current increased considerably up to the range of nanoamperes after the immobilization of the conjugated biphenyl molecules, 10 5 times larger than without molecules before immobilization. Although the Au nanoparticles can be connected to only 30% of all combinations of neighbouring Au nanoparticles by biphenyl molecules 2.4 nm long from the topological analysis, the biphenyl molecules can bridge most of the Au nanoparticles, and their bridging continuity is over 100 nm in length. Thus the measured current is suggested to come from the continuously bridged molecules between the Au nanoparticles. Furthermore the I-V data of the whole Au/SiO 2 nanocomposite film immobilized with conjugated molecules are confirmed to be in a reasonable range in comparison with the scanning tunnelling spectroscopy data of similar conjugated molecules

  7. Tomography of atomic number and density of materials using dual-energy imaging and the Alvarez and Macovski attenuation model

    Energy Technology Data Exchange (ETDEWEB)

    Paziresh, M.; Kingston, A. M., E-mail: andrew.kingston@anu.edu.au; Latham, S. J.; Fullagar, W. K.; Myers, G. M. [Department of Applied Mathematics, Research School of physics and Engineering, The Australian National University, Canberra 2601 (Australia)

    2016-06-07

    Dual-energy computed tomography and the Alvarez and Macovski [Phys. Med. Biol. 21, 733 (1976)] transmitted intensity (AMTI) model were used in this study to estimate the maps of density (ρ) and atomic number (Z) of mineralogical samples. In this method, the attenuation coefficients are represented [Alvarez and Macovski, Phys. Med. Biol. 21, 733 (1976)] in the form of the two most important interactions of X-rays with atoms that is, photoelectric absorption (PE) and Compton scattering (CS). This enables material discrimination as PE and CS are, respectively, dependent on the atomic number (Z) and density (ρ) of materials [Alvarez and Macovski, Phys. Med. Biol. 21, 733 (1976)]. Dual-energy imaging is able to identify sample materials even if the materials have similar attenuation coefficients at single-energy spectrum. We use the full model rather than applying one of several applied simplified forms [Alvarez and Macovski, Phys. Med. Biol. 21, 733 (1976); Siddiqui et al., SPE Annual Technical Conference and Exhibition (Society of Petroleum Engineers, 2004); Derzhi, U.S. patent application 13/527,660 (2012); Heismann et al., J. Appl. Phys. 94, 2073–2079 (2003); Park and Kim, J. Korean Phys. Soc. 59, 2709 (2011); Abudurexiti et al., Radiol. Phys. Technol. 3, 127–135 (2010); and Kaewkhao et al., J. Quant. Spectrosc. Radiat. Transfer 109, 1260–1265 (2008)]. This paper describes the tomographic reconstruction of ρ and Z maps of mineralogical samples using the AMTI model. The full model requires precise knowledge of the X-ray energy spectra and calibration of PE and CS constants and exponents of atomic number and energy that were estimated based on fits to simulations and calibration measurements. The estimated ρ and Z images of the samples used in this paper yield average relative errors of 2.62% and 1.19% and maximum relative errors of 2.64% and 7.85%, respectively. Furthermore, we demonstrate that the method accounts for the beam hardening effect in density (

  8. Global solar magetic field organization in the extended corona: influence on the solar wind speed and density over the cycle.

    Science.gov (United States)

    Réville, V.; Velli, M.; Brun, S.

    2017-12-01

    The dynamics of the solar wind depends intrinsically on the structure of the global solar magnetic field, which undergoes fundamental changes over the 11yr solar cycle. For instance, the wind terminal velocity is thought to be anti-correlated with the expansion factor, a measure of how the magnetic field varies with height in the solar corona, usually computed at a fixed height (≈ 2.5 Rȯ, the source surface radius which approximates the distance at which all magnetic field lines become open). However, the magnetic field expansion affects the solar wind in a more detailed way, its influence on the solar wind properties remaining significant well beyond the source surface: we demonstrate this using 3D global MHD simulations of the solar corona, constrained by surface magnetograms over half a solar cycle (1989-2001). For models to comply with the constraints provided by observed characteristics of the solar wind, namely, that the radial magnetic field intensity becomes latitude independent at some distance from the Sun (Ulysses observations beyond 1 AU), and that the terminal wind speed is anti-correlated with the mass flux, they must accurately describe expansion beyond the solar wind critical point (even up to 10Rȯ and higher in our model). We also show that near activity minimum, expansion in the higher corona beyond 2.5 Rȯ is actually the dominant process affecting the wind speed. We discuss the consequences of this result on the necessary acceleration profile of the solar wind, the location of the sonic point and of the energy deposition by Alfvén waves.

  9. MODELING THE ANOMALY OF SURFACE NUMBER DENSITIES OF GALAXIES ON THE GALACTIC EXTINCTION MAP DUE TO THEIR FIR EMISSION CONTAMINATION

    Energy Technology Data Exchange (ETDEWEB)

    Kashiwagi, Toshiya; Suto, Yasushi; Taruya, Atsushi; Yahata, Kazuhiro [Department of Physics, The University of Tokyo, Tokyo 113-0033 (Japan); Kayo, Issha [Department of Physics, Toho University, Funabashi, Chiba 274-8510 (Japan); Nishimichi, Takahiro, E-mail: kashiwagi@utap.phys.s.u-tokyo.ac.jp [Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa, Chiba 277-8568 (Japan)

    2015-02-01

    The most widely used Galactic extinction map is constructed assuming that the observed far-infrared (FIR) fluxes come entirely from Galactic dust. According to the earlier suggestion by Yahata et al., we consider how FIR emission of galaxies affects the SFD map. We first compute the surface number density of Sloan Digital Sky Survey (SDSS) DR7 galaxies as a function of the r-band extinction, A {sub r,} {sub SFD}. We confirm that the surface densities of those galaxies positively correlate with A {sub r,} {sub SFD} for A {sub r,} {sub SFD} < 0.1, as first discovered by Yahata et al. for SDSS DR4 galaxies. Next we construct an analytical model to compute the surface density of galaxies, taking into account the contamination of their FIR emission. We adopt a log-normal probability distribution for the ratio of 100 μm and r-band luminosities of each galaxy, y ≡ (νL){sub 100} {sub μm}/(νL) {sub r}. Then we search for the mean and rms values of y that fit the observed anomaly, using the analytical model. The required values to reproduce the anomaly are roughly consistent with those measured from the stacking analysis of SDSS galaxies. Due to the limitation of our statistical modeling, we are not yet able to remove the FIR contamination of galaxies from the extinction map. Nevertheless, the agreement with the model prediction suggests that the FIR emission of galaxies is mainly responsible for the observed anomaly. Whereas the corresponding systematic error in the Galactic extinction map is 0.1-1 mmag, it is directly correlated with galaxy clustering and thus needs to be carefully examined in precision cosmology.

  10. Dynamics and Structure of Three-Dimensional Trans-Alfvenic Jets. II. The Effect of Density and Winds

    OpenAIRE

    Hardee, Philip; Rosen, Alexander

    2002-01-01

    Two three-dimensional magnetohydrodynamical simulations of strongly magnetized conical jets, one with a poloidal and one with a helical magnetic field, have been performed. In the poloidal simulation a significant sheath (wind) of magnetized moving material developed and partially stabilized the jet to helical twisting. The fundamental pinch mode was not similarly affected and emission knots developed in the poloidal simulation. Thus, astrophysical jets surrounded by outflowing winds could de...

  11. Improvement of analysis precision upon the atomic number and electron density measurement by the dual x-ray CT

    Science.gov (United States)

    Imura, Yukino; Morii, Hisashi; Koike, Akifumi; Okunoyama, Takaharu; Neo, Yoichiro; Mimura, Hidenori; Aoki, Toru

    2010-08-01

    To identify the factor impairing the material identification parameters, which is provided by the dual-energy X-ray computed tomography method using a conventional X-ray tube and a CdTe detector, linear attenuation coefficient was measured by the radioactivity of radio isotopes and compared with theoretical figure. In our study, the atomic number and the electron density is calculated from the linear attenuation coefficient obtained in CT measurement by 64-channel CdTe line detector. To estimate accuracy of CdTe line sensor, it is needed to obtain the linear attenuation coefficient accurately. Using a single detector, the linear attenuation coefficient is verified for accuracy. The energy resolution of CdTe detectors and the method of reconstruction are discussed.

  12. Effects of DME mixing on number density and size properties of soot particles in counterflow non-premixed ethylene flames

    KAUST Repository

    Choi, J. H.; Choi, B. C.; Lee, S. M.; Chung, Suk-Ho; Jung, K. S.; Jeong, W. L.; Choi, S. K.; Park, S. K.

    2015-01-01

    In order to investigate the effect of DME mixing on the number density and size of soot particles, DME was mixed in a counter flow non-premixed ethylene flame with mixture ratios of 5%, 14% and 30%. A laser extinction/scattering technique has been adopted to measure the volume fraction, number density, and mean size of soot particles. The experimental results showed that the highest soot concentrations were observed for flames with mixture ratios of 5% and 14%; however, for a mixture ratio of 30% the soot concentration decreased. Numerical results showed that the concentrations of propargyl radicals (C3H3) at the 5% and 14% ratios were higher than those measured in the ethylene-based flame, and the production of benzene (C6H6) in the 5% and 14% DME mixture flames was also increased. This indicates the crucial role of propargyl in benzene ring formation. These reactions generally become stronger with increased DME mixing, except for A1- + H2 → A1 + H (-R554) and n-C4H5 + C2H2 → A1 + H (R542). Therefore, it is indicated that adding DME to ethylene flames promotes benzene ring formation. Note that although the maximum C6H6 concentration is largest in the 30% DME mixing flame, the soot volume fraction is smaller than those for the 5% and 14% mixture ratios. This is because the local C6H6 concentration decreases in the relatively low temperature region in the fuel side where soot growth occurs. © 2015, The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg.

  13. Effects of DME mixing on number density and size properties of soot particles in counterflow non-premixed ethylene flames

    KAUST Repository

    Choi, J. H.

    2015-05-01

    In order to investigate the effect of DME mixing on the number density and size of soot particles, DME was mixed in a counter flow non-premixed ethylene flame with mixture ratios of 5%, 14% and 30%. A laser extinction/scattering technique has been adopted to measure the volume fraction, number density, and mean size of soot particles. The experimental results showed that the highest soot concentrations were observed for flames with mixture ratios of 5% and 14%; however, for a mixture ratio of 30% the soot concentration decreased. Numerical results showed that the concentrations of propargyl radicals (C3H3) at the 5% and 14% ratios were higher than those measured in the ethylene-based flame, and the production of benzene (C6H6) in the 5% and 14% DME mixture flames was also increased. This indicates the crucial role of propargyl in benzene ring formation. These reactions generally become stronger with increased DME mixing, except for A1- + H2 → A1 + H (-R554) and n-C4H5 + C2H2 → A1 + H (R542). Therefore, it is indicated that adding DME to ethylene flames promotes benzene ring formation. Note that although the maximum C6H6 concentration is largest in the 30% DME mixing flame, the soot volume fraction is smaller than those for the 5% and 14% mixture ratios. This is because the local C6H6 concentration decreases in the relatively low temperature region in the fuel side where soot growth occurs. © 2015, The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg.

  14. Ozone synthesis improves by increasing number density of plasma channels and lower voltage in a nonthermal plasma

    Science.gov (United States)

    Arif Malik, Muhammad; Hughes, David

    2016-04-01

    Improvements in ozone synthesis from air and oxygen by increasing the number density of plasma channels and lower voltage for the same specific input energy (SIE) were explored in a nonthermal plasma based on a sliding discharge. The number of plasma channels and energy per pulse increased in direct proportion to the increase in the effective length of the anode (the high voltage electrode). Decreasing the discharge gap increased the energy per pulse for the same length and allowed the installation of more electrode pairs in the same space. It allowed the increase of the number of plasma channels in the same space to achieve the same SIE at a lower peak voltage with less energy per plasma channel. The ozone concentration gradually increased to ~1500 ppmv (140 to 50 g kWh-1) from air and to ~6000 ppmv (400 to 200 g kWh-1) from oxygen with a gradual increase in the SIE to ~200 J L-1, irrespective of the variations in electrode geometry, applied voltage or flow rate of the feed gas. A gradual increase in SIE beyond 200 J L-1 gradually increased the ozone concentration to a certain maximum value followed by a decline, but the rate of increase and the maximum value was higher for the greater number of plasma channels and lower peak voltage combination. The maximum ozone concentration was ~5000 ppmv (~30 g kWh-1) from air and ~22 000 ppmv (~80 g kWh-1) from oxygen. The results are explained on the basis of characteristics of the plasma and ozone synthesis mechanism.

  15. Optimal Sizing for Wind/PV/Battery System Using Fuzzy c-Means Clustering with Self-Adapted Cluster Number

    Directory of Open Access Journals (Sweden)

    Xin Liu

    2017-01-01

    Full Text Available Integrating wind generation, photovoltaic power, and battery storage to form hybrid power systems has been recognized to be promising in renewable energy development. However, considering the system complexity and uncertainty of renewable energies, such as wind and solar types, it is difficult to obtain practical solutions for these systems. In this paper, optimal sizing for a wind/PV/battery system is realized by trade-offs between technical and economic factors. Firstly, the fuzzy c-means clustering algorithm was modified with self-adapted parameters to extract useful information from historical data. Furthermore, the Markov model is combined to determine the chronological system states of natural resources and load. Finally, a power balance strategy is introduced to guide the optimization process with the genetic algorithm to establish the optimal configuration with minimized cost while guaranteeing reliability and environmental factors. A case of island hybrid power system is analyzed, and the simulation results are compared with the general FCM method and chronological method to validate the effectiveness of the mentioned method.

  16. Enhancement of phase space density by increasing trap anisotropy in a magneto-optical trap with a large number of atoms

    International Nuclear Information System (INIS)

    Vengalattore, M.; Conroy, R.S.; Prentiss, M.G.

    2004-01-01

    The phase space density of dense, cylindrical clouds of atoms in a 2D magneto-optic trap is investigated. For a large number of trapped atoms (>10 8 ), the density of a spherical cloud is limited by photon reabsorption. However, as the atom cloud is deformed to reduce the radial optical density, the temperature of the atoms decreases due to the suppression of multiple scattering leading to an increase in the phase space density. A density of 2x10 -4 has been achieved in a magneto-optic trap containing 2x10 8 atoms

  17. Sustainable Block Design Process for High-Rise and High-Density Districts with Snow and Wind Simulations for Winter Cities

    Directory of Open Access Journals (Sweden)

    Norihiro Watanabe

    2017-11-01

    Full Text Available Urban designs that consider regional climatic conditions are one of the most important approaches for developing sustainable cities. In cities that suffer from heavy snow and cold winds in winter, an urban design approach different than that used for warm cities should be used. This study presents a scientific design process (the sustainable design approach that incorporates environmental and energy assessments that use snow and wind simulations to establish guidelines for the design of urban blocks in high-rise and high-density districts so that the impact of snow and wind can be minimized in these cities. A city block in downtown Sapporo, Japan, was used as a case study, and we evaluated four conceptual models. The four models were evaluated for how they impacted the snow and wind conditions in the block as well as the snow removal energy. Based on the results, we were able to identify the design guidelines in downtown Sapporo: an urban block design with higher building height ratio without the mid-rise part can reduce the snowdrifts and lower the snow removal energy. The proposed sustainable urban design approach would be effective in improving the quality of public spaces and reducing snow removal energy in winter cities.

  18. NORSEWInD satellite wind climatology

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay; Badger, Merete; Mouche, Alexis

    The EU-NORSEWInD project www.norsewind.eu has taken place from August 2008 to July 2012 (4 years). NORSEWInD is short for Northern Seas Wind Index database. In the project ocean surface wind observations from space have been retrieved, processed and analysed. The overall aim of the work...... is to provide new offshore wind climatology map for the entire area of interest based on satellite remote sensing. This has been based on Synthetic Aperture Radar (SAR) from Envisat ASAR using 9000 scenes re-processed with ECMWF wind direction and CMOD-IFR. The number of overlapping samples range from 450...... in the Irish Sea to more than 1200 in most of the Baltic Sea. Wind resource statistics include maps at 2 km spatial resolution of mean wind speed, Weibull A and k, and energy density at 10 m above sea level. Uncertainty estimates on the number of available samples for each of the four parameters are presented...

  19. Influence of increasing numbers of RE-inverters on the power quality in the distribution grids: A PQ case study of a representative wind turbine and photovoltaic system

    Institute of Scientific and Technical Information of China (English)

    Przemyslaw JANIK; Grzegorz KOSOBUDZKI; Harald SCHWARZ

    2017-01-01

    This paper presents the selected power quality (PQ) indicia of a wind generator and a photovoltaic installation considered to be the representative of medium voltage and low voltage distribution grids.The analysis of measured values suggests that the decrease in PQ is a case of specific combination of distributed generation,grid parameters and load behaviour.Modem generators have a limited impact on PQ.On the other hand,fluctuations in power generation are regarded as an emerging PQ indicator.The growing number of distributed renewable installations causes stochastic,variable,and hardly predictable power flows in the distribution grid.The nature of fluctuations in wind and solar generation is different.In both cases,new indexes for the quantification of fluctuations are needed and are yet not standardised.Proper assessment of these fluctuations enables definition of useful fluctuation limits and rules for optimal storage system integration.

  20. A few ways of calculating the similarity parameter kappa* for real gases. [increase Reynolds number in cryogenic wind tunnels

    Science.gov (United States)

    Lorenz-Meyer, W.

    1977-01-01

    In connection with the question on the applicability of test results obtained from cryogenic wind tunnels to the large-scale model the similarity parameter is referred to. A simple method is given for calculating the similarity parameter. From the numerical values obtained it can be deduced that nitrogen behaves practically like an ideal gas when it is close to the saturation point and in a pressure range up to 4 bar. The influence of this parameter on the pressure distribution of a supercritical profile confirms this finding.

  1. Global statistics of liquid water content and effective number density of water clouds over ocean derived from combined CALIPSO and MODIS measurements

    Science.gov (United States)

    Hu, Y.; Vaughan, M.; McClain, C.; Behrenfeld, M.; Maring, H.; Anderson, D.; Sun-Mack, S.; Flittner, D.; Huang, J.; Wielicki, B.; Minnis, P.; Weimer, C.; Trepte, C.; Kuehn, R.

    2007-03-01

    This study presents an empirical relation that links layer integrated depolarization ratios, the extinction coefficients, and effective radii of water clouds, based on Monte Carlo simulations of CALIPSO lidar observations. Combined with cloud effective radius retrieved from MODIS, cloud liquid water content and effective number density of water clouds are estimated from CALIPSO lidar depolarization measurements in this study. Global statistics of the cloud liquid water content and effective number density are presented.

  2. Column Number Density Expressions Through M = 0 and M = 1 Point Source Plumes Along Any Straight Path

    Science.gov (United States)

    Woronowicz, Michael

    2017-01-01

    Providers of payloads carried aboard the International Space Station must conduct analyses to demonstrate that any planned gaseous venting events generate no more than a certain level of material that may interfere with optical measurements from other experiments or payloads located nearby. This requirement is expressed in terms of a maximum column number density (CND). Depending on the level of rarefaction, such venting may be characterized by effusion for low flow rates, or by a sonic distribution at higher levels. Since the relative locations of other sensitive payloads are often unknown because they may refer to future projects, this requirement becomes a search for the maximum CND along any path.In another application, certain astronomical observations make use of CND to estimate light attenuation from a distant star through gaseous plumes, such as the Fermi Bubbles emanating from the vicinity of the black hole at the center of our Milky Way galaxy, in order to infer the amount of material being expelled via those plumes.This paper presents analytical CND expressions developed for general straight paths based upon a free molecule point source model for steady effusive flow and for a distribution fitted to model flows from a sonic orifice. Among other things, in this Mach number range it is demonstrated that the maximum CND from a distant location occurs along the path parallel to the source plane that intersects the plume axis. For effusive flows this value is exactly twice the CND found along the ray originating from that point of intersection and extending to infinity along the plumes axis. For sonic plumes this ratio is reduced to about 43.

  3. Temporal and spatial effects of ablation plume on number density distribution of droplets in an aerosol measured by laser-induced breakdown

    International Nuclear Information System (INIS)

    Yashiro, H.; Kakehata, M.

    2013-01-01

    We proposed and experimentally demonstrated a novel method of evaluating the number density of droplets in an aerosol by laser-induced breakdown. The number density of droplets is evaluated from the volume in which the laser intensity exceeds the breakdown threshold intensity for droplets, and the number of droplets in this volume, which is evaluated by the experimentally observed breakdown probability. This measurement method requires a large number of laser shots for not only precise measurement but also highly temporally and spatially resolved density distribution in aerosol. Laser ablation plumes ejected from liquid droplets generated by breakdown disturb the density around the measurement points. Therefore, the recovery time of the density determines the maximum repetition rate of the probe laser irradiating a fixed point. The expansion range of the ablation plume determines the minimum distance at which the measurement points are unaffected by a neighboring breakdown when multiple laser beams are simultaneously irradiated. These laser irradiation procedures enable the measurement of the number density distribution of droplets in an aerosol at a large number of points within a short measurement time.

  4. Temporal and spatial effects of ablation plume on number density distribution of droplets in an aerosol measured by laser-induced breakdown

    Energy Technology Data Exchange (ETDEWEB)

    Yashiro, H.; Kakehata, M. [Electronics and Photonics Research Institute (ESPRIT), National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan)

    2013-05-07

    We proposed and experimentally demonstrated a novel method of evaluating the number density of droplets in an aerosol by laser-induced breakdown. The number density of droplets is evaluated from the volume in which the laser intensity exceeds the breakdown threshold intensity for droplets, and the number of droplets in this volume, which is evaluated by the experimentally observed breakdown probability. This measurement method requires a large number of laser shots for not only precise measurement but also highly temporally and spatially resolved density distribution in aerosol. Laser ablation plumes ejected from liquid droplets generated by breakdown disturb the density around the measurement points. Therefore, the recovery time of the density determines the maximum repetition rate of the probe laser irradiating a fixed point. The expansion range of the ablation plume determines the minimum distance at which the measurement points are unaffected by a neighboring breakdown when multiple laser beams are simultaneously irradiated. These laser irradiation procedures enable the measurement of the number density distribution of droplets in an aerosol at a large number of points within a short measurement time.

  5. Development of a standard data base for FBR core nuclear design. 10. Reevaluation of atomic number density of JOYO Mk-II core

    Energy Technology Data Exchange (ETDEWEB)

    Numata, Kazuyuki; Sato, Wakaei [Japan Nuclear Cycle Development Inst., Oarai, Ibaraki (Japan). Oarai Engineering Center; Ishikawa, Makoto; Arii, Yoshio [Nuclear Energy System Incorporation, Tokyo (Japan)

    1999-07-01

    The material composition of JOYO Mk-II core components in its initial core was reevaluated as a part of the effort for developing a standard data base for FBR core nuclear design. The special feature of the reevaluation is to treat the decay of Pu-241 isotope, so that the atomic number densities of Pu-241 and Am-241 in fuel assemblies can be exactly evaluated on the initial critical date, Nov. 22nd, 1982. Further, the atomic number densities of other core components were also evaluated to improve the analytical accuracy. Those include the control rods which were not so strictly evaluated in the past, and the dummy fuels and the neutron sources which were not treated in the analytical model so far. The results of the present reevaluation were as follows: (1) The changes of atomic number densities of the major nuclides such as Pu-239, U-235 and U-238 were about {+-}0.2 to 0.3%. On the other hand, the number density of Pu-241, which was the motivation of the present work, was reduced by 12%. From the fact, the number densities in the past analysis might be based on the isotope measurement of the manufacturing point of time without considering the decay of Pu-241. (2) As the other core components, the number densities of control rods and outer reflector-type A were largely improved. (author)

  6. A study of effective atomic numbers and electron densities of some vitamins for electron, H, He and C ion interactions

    Science.gov (United States)

    Büyükyıldız, M.

    2017-09-01

    The radiological properties of some vitamins such as Retinol, Beta-carotene, Riboflavin, Niacin, Niacinamide, Pantothenic acid, Pyridoxine, Pyridoxamine, Pyridoxal, Biotin, Folic acid, Ascorbic acid, Cholecalciferol, Alpha-tocopherol, Gamma-tocopherol, Phylloquinone have been investigated with respect to total electron interaction and some heavy charged particle interaction as means of effective atomic numbers (Z_{eff}) and electron densities (N_{eff}) for the first time. Calculations were performed for total electron interaction and heavy ions such as H, He and C ion interactions in the energy region 10keV-10MeV by using a logarithmic interpolation method. Variations in Z_{eff}'s and N_{eff}'s of given vitamins have been studied according to the energy of electron or heavy charged particles, and significant variations have been observed for all types of interaction in the given energy region. The maximum values of Z_{eff} have been found in the different energy regions for different interactions remarkably and variations in N_{eff} seem approximately to be the same with variation in Z_{eff} for the given vitamins as expected. Z_{eff} values of some vitamins were plotted together and compared with each other for electron, H, He and C interactions and the ratios of Z_{eff}/ have been changed in the range of 0.25-0.36, 0.20-0.36, 0.22-0.35 and 0.20-0.35 for electron, H, He and C interactions, respectively.

  7. Effective atomic numbers, electron densities, and tissue equivalence of some gases and mixtures for dosimetry of radiation detectors

    Directory of Open Access Journals (Sweden)

    Singh Vishwanath P.

    2012-01-01

    Full Text Available Total mass attenuation coefficients, µm, effective atomic number, Zeff, and effective electron density, Neff, of different gases - carbon dioxide, methane, acetylene, propane, butane, and pentane used in radiation detectors, have been calculated for the photon energy of 1 keV to 100 GeV. Each gas has constant Zeff values between 0.10 to 10 MeV photon energies; however, these values are way far away from ICRU tissue. Carbon dioxide gas shows the closest tissue equivalence in the entire photon energy spectrum. Relative tissue equivalences of the mixtures of gases with respect to ICRU tissue are in the range of 0.998-1.041 for air, argon (4.5% + methane (95.5%, argon (0.5% + carbon dioxide (99.5%, and nitrogen (5% + methane (7% + carbon dioxide (88%. The gas composition of xenon (0.5% + carbon dioxide (99.5% shows 1.605 times higher tissue equivalence compared to the ICRU tissue. The investigated photon interaction parameters are useful for exposure and energy absorption buildup factors calculation and design, and fabrication of gaseous detectors for ambient radiation measurement by the Geiger-Muller detector, ionization chambers and proportional counters.

  8. Morphometric analysis of the neuronal numbers and densities of the inferior olivary complex in the donkey (Equus asinus).

    Science.gov (United States)

    Alkafafy, Mohamed; Rashed, Reda; Attia, Hossam

    2011-07-01

    The morphometric interrelations between the compartments of the inferior olivary complex (IOC) in the donkey (Equus asinus) were ascertained by examining serial sections throughout the entire length of the IOC for both sides. Nissl-stained celloidin sections of four brainstems of donkeys were used. The IOC consisted of three major nuclei and four small cell groups. The total neuronal count in both sides of the IOC was 202,040±8480 cells. The medial accessory olivary nucleus (MAO) had the largest relative area (46%) and the highest number of neurons (90,800±7600). The dorsal accessory olivary nucleus (DAO) had the second largest relative area (33%), while the principal olivary nucleus (PO) had the lowest relative area (21%). However, the total neuron count in the PO was larger (60,840±1840) than DAO (50,360±4040). The average neuronal density was 2700±400 cells/mm(3). The numerical values of the current study of the IOC in the donkey were similar to those of other mammals. Copyright © 2010 Elsevier GmbH. All rights reserved.

  9. Applicability of Synthetic Aperture Radar Wind Retrievals on Offshore Wind Resources Assessment in Hangzhou Bay, China

    Directory of Open Access Journals (Sweden)

    Rui Chang

    2014-05-01

    Full Text Available In view of the high cost and sparse spatial resolution of offshore meteorological observations, ocean winds retrieved from satellites are valuable in offshore wind resource assessment as a supplement to in situ measurements. This study examines satellite synthetic aperture radar (SAR images from ENVISAT advanced SAR (ASAR for mapping wind resources with high spatial resolution. Around 181 collected pairs of wind data from SAR wind maps and from 13 meteorological stations in Hangzhou Bay are compared. The statistical results comparing in situ wind speed and SAR-based wind speed show a standard deviation (SD of 1.99 m/s and correlation coefficient of R = 0.67. The model wind directions, which are used as input for the SAR wind speed retrieval, show a high correlation coefficient (R = 0.89 but a large standard deviation (SD = 42.3° compared to in situ observations. The Weibull probability density functions are compared at one meteorological station. The SAR-based results appear not to estimate the mean wind speed, Weibull scale and shape parameters and wind power density from the full in situ data set so well due to the lower number of satellite samples. Distributions calculated from the concurrent 81 SAR and in situ samples agree well.

  10. Colloids exposed to random potential energy landscapes: From particle number density to particle-potential and particle-particle interactions

    International Nuclear Information System (INIS)

    Bewerunge, Jörg; Capellmann, Ronja F.; Platten, Florian; Egelhaaf, Stefan U.; Sengupta, Ankush; Sengupta, Surajit

    2016-01-01

    Colloidal particles were exposed to a random potential energy landscape that has been created optically via a speckle pattern. The mean particle density as well as the potential roughness, i.e., the disorder strength, were varied. The local probability density of the particles as well as its main characteristics were determined. For the first time, the disorder-averaged pair density correlation function g (1) (r) and an analogue of the Edwards-Anderson order parameter g (2) (r), which quantifies the correlation of the mean local density among disorder realisations, were measured experimentally and shown to be consistent with replica liquid state theory results.

  11. Investigation of the on-axis atom number density in the supersonic gas jet under high gas backing pressure by simulation

    Directory of Open Access Journals (Sweden)

    Guanglong Chen

    2015-10-01

    Full Text Available The supersonic gas jets from conical nozzles are simulated using 2D model. The on-axis atom number density in gas jet is investigated in detail by comparing the simulated densities with the idealized densities of straight streamline model in scaling laws. It is found that the density is generally lower than the idealized one and the deviation between them is mainly dependent on the opening angle of conical nozzle, the nozzle length and the gas backing pressure. The density deviation is then used to discuss the deviation of the equivalent diameter of a conical nozzle from the idealized deq in scaling laws. The investigation on the lateral expansion of gas jet indicates the lateral expansion could be responsible for the behavior of the density deviation. These results could be useful for the estimation of cluster size and the understanding of experimental results in laser-cluster interaction experiments.

  12. Optimizing the number and locations of turbines in a wind farm addressing energy-noise trade-off: A hybrid approach

    International Nuclear Information System (INIS)

    Mittal, Prateek; Mitra, Kishalay; Kulkarni, Kedar

    2017-01-01

    Highlights: • Concurrent resolution of turbine number and locations during micro-siting. • Effect of noise on energy-noise multi-objective optimization is demonstrated. • A hybrid algorithm is proposed utilizing probabilistic and deterministic methods. • ∼24% improved performance is achieved over the benchmark case study. • ∼29% enhanced efficiency over real-binary genetic algorithm alone can be observed. - Abstract: Micro-siting is an optimal way of placing turbines inside a wind farm while considering various design objectives and constraints. Using a well-established Jensen wake model and ISO-9613-2 noise calculation, this study performs a wind farm layout optimization based on a multi-objective trade-off between minimization of the noise propagation and maximization of the energy generation. A novel hybrid methodology is developed which is a combination of probabilistic real-binary coded multi-objective evolutionary algorithm and a newly proposed deterministic gradient based non-dominated normalized normal constraint method. Based on the Inverted Generational Distance metric, the performance of the proposed method is found to be better than the conventional normalized normal constraint method or the concerned evolutionary method alone. Moreover, in contrast to the previous studies, the generated non-dominated front is capable of providing a trade-off between various alternative energy-noise solutions, along with an additional information about the corresponding turbine numbers and their optimal location coordinates. As a result, the decision maker can choose from different competing wind turbine layouts based on existing noise and other standard regulations.

  13. Gearless wind power generator

    Energy Technology Data Exchange (ETDEWEB)

    Soederlund, L.; Ridanpaeae, P.; Vihriaelae, H.; Peraelae, R. [Tampere Univ. of Technology (Finland). Lab. of Electricity and Magnetism

    1998-10-01

    In the project a 100 kW axial flux permanent magnet wind power generator has been designed. The toroidal stator with air gap winding is placed between two rotating discs with permanent magnets. The magnet material is NdBFe due to its excellent magnetic properties compared to other materials. This type of topology enables a very large number of poles compared to conventional machine of the same size. A large number of poles is required to achieve a low rotational speed and consequently a direct driven system. The stator winding is formed by rectangular coils. The end winding is very short leading to small resistive losses. On the other hand, the absence of iron teeth causes eddy current losses in the conductors. These can be restricted to an acceptable level by keeping the wire diameter and flux density small. This means that the number of phases should be large. Several independent three phase systems may be used. The toothless stator also means that the iron losses are small and there exists no cogging torque

  14. Program to determine space vehicle response to wind turbulence

    Science.gov (United States)

    Wilkening, H. D.

    1972-01-01

    Computer program was developed as prelaunch wind monitoring tool for Saturn 5 vehicle. Program accounts for characteristic wind changes including turbulence power spectral density, wind shear, peak wind velocity, altitude, and wind direction using stored variational statistics.

  15. Investigation of Strouhal numbers of iced cable models of cable-supported bridges with respect to angle of wind attack

    Czech Academy of Sciences Publication Activity Database

    Górski, P.; Tatara, M.; Pospíšil, Stanislav; Kuznetsov, Sergeii; Marušić, A.

    2015-01-01

    Roč. 112, 2-B (2015), s. 417-432 ISSN 1897-628X R&D Projects: GA MŠk(CZ) LO1219; GA MPO(CZ) FR-TI3/654 Keywords : bridge cable * ice accretion * Strouhal number * angle of attack * vortex shedding frequency Subject RIV: JN - Civil Engineering http://suw.biblos.pk.edu.pl/resources/i5/i6/i6/i8/i4/r56684/GorskiP_InvestigationsStrouhal.pdf

  16. Children's Intuitive Sense of Number Develops Independently of Their Perception of Area, Density, Length, and Time

    Science.gov (United States)

    Odic, Darko

    2018-01-01

    Young children can quickly and intuitively represent the number of objects in a visual scene through the Approximate Number System (ANS). The precision of the ANS--indexed as the most difficult ratio of two numbers that children can reliably discriminate--is well known to improve with development: whereas infants require relatively large ratios to…

  17. Effect of Coriolis and centrifugal forces on flow and heat transfer at high rotation number and high density ratio in non orthogonally internal cooling channel

    Directory of Open Access Journals (Sweden)

    Brahim Berrabah

    2017-02-01

    Full Text Available Numerical predictions of three-dimensional flow and heat transfer are performed for a two-pass square channel with 45° staggered ribs in non-orthogonally mode-rotation using the second moment closure model. At Reynolds number of 25,000, the rotation numbers studied were 0, 0.24, 0.35 and 1.00. The density ratios were 0.13, 0.23 and 0.50. The results show that at high buoyancy parameter and high rotation number with a low density ratio, the flow in the first passage is governed by the secondary flow induced by the rotation whereas the secondary flow induced by the skewed ribs was almost distorted. As a result the heat transfer rate is enhanced on both co-trailing and co-leading sides compared to low and medium rotation number. In contrast, for the second passage, the rotation slightly reduces the heat transfer rate on co-leading side at high rotation number with a low density ratio and degrades it significantly on both co-trailing and co-leading sides at high buoyancy parameter compared to the stationary, low and medium rotation numbers. The numerical results are in fair agreement with available experimental data in the bend region and the second passage, while in the first passage were overestimated at low and medium rotation numbers.

  18. V-I characteristics of a coreless ironless electric generator in a closed-circuit mode for low wind density power generation

    Science.gov (United States)

    Razali, Akhtar; Rahman, Fadhlur; Leong, Yap Wee; Razali Hanipah, Mohd; Azri Hizami, Mohd

    2018-04-01

    This research deals with removal of ironcore lamination in electric generator to eliminate cog torque. A confinement technique is proposed to confine and focus magnetic flux by introducing opposing permanent magnets arrangement. The generator was fabricated and experimentally validated to qualify its loaded characteristics. The rotational torque and power output are measured and efficiency is then analyzed. At 100Ω load, the generator power output increased with the increased of rotational speed. Nearly 78% of efficiency was achieved when the generator was rotated at 250rpm. At this speed, the generator produced RMS voltage of 81VAC. Torque required to rotate the generator was found to be 3.2Nm. The slight increment of mechanical torque to spin the generator was due to the counter electromotive force (CEMF) existed in the copper windings. However, the torque required is still lower by nearly 30% than conventional AFPM generator. It is there concluded that this generator is suitable to be used for low wind density power generation application.

  19. Wind energy potential in Bulgaria

    International Nuclear Information System (INIS)

    Shtrakov, Stanko Vl.

    2009-01-01

    In this study, wind characteristic and wind energy potential in Bulgaria were analyzed using the wind speed data. The wind energy potential at different sites in Bulgaria has been investigated by compiling data from different sources and analyzing it using a software tool. The wind speed distribution curves were obtained by using the Weibull and Rayleigh probability density functions. The results relating to wind energy potential are given in terms of the monthly average wind speed, wind speed probability density function (PDF), wind speed cumulative density function (CDF), and wind speed duration curve. A technical and economic assessment has been made of electricity generation from three wind turbines having capacity of (60, 200, and 500 kW). The yearly energy output capacity factor and the electrical energy cost of kWh produced by the three different turbines were calculated

  20. Systematics of radiation widths and level density parameters in the mass number range region 40

    International Nuclear Information System (INIS)

    Bychkov, V.M.; Grudzevich, O.T.; Plyaskin, V.I.

    1990-01-01

    We suggest a systematics of radiation width based on a reduced radiative capture strength function for the E1-transition, which eliminates fluctuations in the analysed quantity with neutron binding energy, nuclear level density and γ-quanta energy. A smooth dependence for the fitting parameter of the radiative strength function for E1-transitions in relation to the relative atomic mass of the nucleus is obtained. 10 refs, 2 figs

  1. Stochastic generation of hourly wind speed time series

    International Nuclear Information System (INIS)

    Shamshad, A.; Wan Mohd Ali Wan Hussin; Bawadi, M.A.; Mohd Sanusi, S.A.

    2006-01-01

    In the present study hourly wind speed data of Kuala Terengganu in Peninsular Malaysia are simulated by using transition matrix approach of Markovian process. The wind speed time series is divided into various states based on certain criteria. The next wind speed states are selected based on the previous states. The cumulative probability transition matrix has been formed in which each row ends with 1. Using the uniform random numbers between 0 and 1, a series of future states is generated. These states have been converted to the corresponding wind speed values using another uniform random number generator. The accuracy of the model has been determined by comparing the statistical characteristics such as average, standard deviation, root mean square error, probability density function and autocorrelation function of the generated data to those of the original data. The generated wind speed time series data is capable to preserve the wind speed characteristics of the observed data

  2. The study of the influence of the diameter ratio and blade number to the performance of the cross flow wind turbine by using 2D computational fluid dynamics modeling

    Science.gov (United States)

    Tjahjana, Dominicus Danardono Dwi Prija; Purbaningrum, Pradityasari; Hadi, Syamsul; Wicaksono, Yoga Arob; Adiputra, Dimas

    2018-02-01

    Cross flow turbine can be one of the alternative energies for regions with low wind speed. Collision between wind and the blades which happened two times caused the cross flow turbine to have high power coefficient. Some factors that influence the turbine power coefficient are diameter ratio and blade number. The objective of the research was to study the effect of the diameter ratio and the blade number to the cross flow wind turbine performance. The study was done in two dimensional (2D) computational fluid dynamics (CFD) simulation method using the ANSYS-Fluent software. The turbine diameter ratio were 0.58, 0.63, 0.68 and 0.73. The diameter ratio resulting in the highest power coefficient value was then simulated by varying the number of blades, namely 16, 20 and 24. Each variation was tested on the wind speed of 2 m/s and at the tip speed ratio (TSR) of 0.1 to 0.4 with the interval of 0.1. The wind turbine with the ratio diameter of 0.68 and the number of blades of 20 generated the highest power coefficient of 0.5 at the TSR of 0.3.

  3. AGAINST THE WIND: RADIO LIGHT CURVES OF TYPE IA SUPERNOVAE INTERACTING WITH LOW-DENSITY CIRCUMSTELLAR SHELLS

    Energy Technology Data Exchange (ETDEWEB)

    Harris, Chelsea E.; Nugent, Peter E.; Kasen, Daniel N., E-mail: chelseaharris@berkeley.edu [Astronomy Department, University of California Berkeley, Berkeley, CA (United States)

    2016-06-01

    For decades a wide variety of observations spanning the radio through optical and on to the X-ray have attempted to uncover signs of type Ia supernovae (SNe Ia) interacting with a circumstellar medium (CSM). The goal of these studies is to constrain the nature of the hypothesized SN Ia mass-donor companion. A continuous CSM is typically assumed when interpreting observations of interaction. However, while such models have been successfully applied to core-collapse SNe, the assumption of continuity may not be accurate for SNe Ia, because shells of CSM could be formed by pre-supernova eruptions (novae). In this work, we model the interaction of SNe with a spherical, low-density, finite-extent CSM and create a suite of synthetic radio synchrotron light curves. We find that CSM shells produce sharply peaked light curves. We also identify a fiducial set of models that obey a common evolution and can be used to generate radio light curves for an interaction with an arbitrary shell. The relations obeyed by the fiducial models can be used to deduce CSM properties from radio observations; we demonstrate this by applying them to the nondetections of SN 2011fe and SN 2014J. Finally, we explore a multiple shell CSM configuration and describe its more complicated dynamics and the resultant radio light curves.

  4. Time-resolved study of the electron temperature and number density of argon metastable atoms in argon-based dielectric barrier discharges

    Science.gov (United States)

    Desjardins, E.; Laurent, M.; Durocher-Jean, A.; Laroche, G.; Gherardi, N.; Naudé, N.; Stafford, L.

    2018-01-01

    A combination of optical emission spectroscopy and collisional-radiative modelling is used to determine the time-resolved electron temperature (assuming Maxwellian electron energy distribution function) and number density of Ar 1s states in atmospheric pressure Ar-based dielectric barrier discharges in presence of either NH3 or ethyl lactate. In both cases, T e values were higher early in the discharge cycle (around 0.8 eV), decreased down to about 0.35 eV with the rise of the discharge current, and then remained fairly constant during discharge extinction. The opposite behaviour was observed for Ar 1s states, with cycle-averaged values in the 1017 m-3 range. Based on these findings, a link was established between the discharge ionization kinetics (and thus the electron temperature) and the number density of Ar 1s state.

  5. "allometry" Deterministic Approaches in Cell Size, Cell Number and Crude Fiber Content Related to the Physical Quality of Kangkong (Ipomoea reptans) Grown Under Different Plant Density Pressures

    Science.gov (United States)

    Selamat, A.; Atiman, S. A.; Puteh, A.; Abdullah, N. A. P.; Mohamed, M. T. M.; Zulkeefli, A. A.; Othman, S.

    Kangkong, especially the upland type (Ipomoea reptans) is popularly consumed as a vegetable dish in the South East Asian countries for its quality related to Vitamins (A and C) and crude fiber contents. Higher fiber contents would prevent from the occurrence of colon cancer and diverticular disease. With young stem edible portion, its cell number and size contribute to the stem crude fiber content. The mathematical approach of allometry of cell size, number, and fiber content of stem could be used in determining the 'best' plant density pressure in producing the quality young stem to be consumed. Basically, allometry is the ratio of relative increment (growth or change) rates of two parameters, or the change rate associated to the log of measured variables relationship. Kangkog grown equal or lower than 55 plants m-2 produced bigger individual plant and good quality (physical) kangkong leafy vegetable, but with lower total yield per unit area as compared to those grown at higher densities.

  6. The determination of the Dirac density matrix of the d-dimensional harmonic oscillator for an arbitrary number of closed shells

    International Nuclear Information System (INIS)

    Howard, I.A.; March, N.H.; Nieto, L.M.

    2002-01-01

    In 1959, March and Young (Nucl. Phys. 12 237) rewrote the equation of motion for the Dirac density matrix γ(x, x 0 ) in terms of sum and difference variables. Here, γ(r-bar, r-bar 0 ) for the d-dimensional isotropic harmonic oscillator for an arbitrary number of closed shells is shown to satisfy, using the variables vertical bar r-bar + r-bar 0 vertical bar/2 and vertical bar r-bar - r-bar 0 vertical bar/2, a generalized partial differential equation embracing the March-Young equation for d=1. As applications, we take in turn the cases d=1, 2, 3 and 4, and obtain both the density matrix γ (r-bar, r-bar 0 ) and the diagonal density ρ(r)=γ(r-bar, r-bar 0 ) vertical bar r-bar 0 =r-bar, this diagonal element already being known to satisfy a third-order linear homogeneous differential equation for d=1 through 3. Some comments are finally made on the d-dimensional kinetic energy density, which is important for first-principles density functional theory in allowing one to bypass one-particle Schroedinger equations (the so-called Slater-Kohn-Sham equations). (author)

  7. Global statistics of liquid water content and effective number density of water clouds over ocean derived from combined CALIPSO and MODIS measurements

    OpenAIRE

    Y. Hu; M. Vaughan; C. McClain; M. Behrenfeld; H. Maring; D. Anderson; S. Sun-Mack; D. Flittner; J. Huang; B. Wielicki; P. Minnis; C. Weimer; C. Trepte; R. Kuehn

    2007-01-01

    International audience; This study presents an empirical relation that links layer integrated depolarization ratios, the extinction coefficients, and effective radii of water clouds, based on Monte Carlo simulations of CALIPSO lidar observations. Combined with cloud effective radius retrieved from MODIS, cloud liquid water content and effective number density of water clouds are estimated from CALIPSO lidar depolarization measurements in this study. Global statistics of the cloud liquid water...

  8. On the effective atomic number and electron density: A comprehensive set of formulas for all types of materials and energies above 1 keV

    DEFF Research Database (Denmark)

    Manohara, S.R.; Hanagodimath, S.M.; Thind, K.S.

    2008-01-01

    A comprehensive and consistent set of formulas is given for calculating the effective atomic number and electron density for all types of materials and for all photon energies greater than 1 keV. The are derived from first principles using photon interaction cross sections of the constituent atom....... The theory is illustrated by calculations and experiments for molecules of medical and biological interest, glasses for radiation shielding, alloys, minerals and liquids....

  9. Performance and optimum characteristics by finite element analysis of a coreless ironless electric generator for low wind density power generation

    Science.gov (United States)

    Razali, Akhtar; Rahman, Fadhlur; Leong, Yap Wee; Razali Hanipah, Mohd; Azri Hizami, Mohd

    2018-04-01

    Cogging is an attraction of magnetism between permanent magnets and soft ironcore lamination in a conventional electric ironcore generator. The presence of cog in the generator is seen somehow restricted the application of the generator in an application where low rotational torque is required. Cog torque requires an additional input power to overcome, hence became one of the power loss sources. With the increasing of power output, the cogging is also proportionally increased. This leads to the increasing of the supplied power of the driver motor to overcome the cog. Therefore, this research is embarked to study fundamentally about the possibility of removing ironcore lamination in an electric generator. This research deals with removal of ironcore lamination in electric generator to eliminate cog torque. A confinement technique is proposed to confine and focus magnetic flux by introducing opposing permanent magnets arrangement. There were several parameters analysed using the JMAG Designer. Transient response analysis was used in the JMAG Designer. The parameters analysed were the number of coil turns per phase, gap distance between the magnet pairs as well as the magnet grade used. These few parameters were analysed under the open circuit condition. Results showed with the increasing of gap distance, output voltage produced decreased. The increment of number of turns in the coils and higher magnet grades used, these increased the output voltage of the generator. With the help of these results, a reference point is established to get optimum design parameter for fabrication of working prototype.

  10. ON THE ELECTRON-TO-NEUTRAL NUMBER DENSITY RATIO IN THE COMA OF COMET 67P/CHURYUMOV–GERASIMENKO: GUIDING EXPRESSION AND SOURCES FOR DEVIATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Vigren, E.; Eriksson, A. I.; Edberg, N. J. T.; Odelstad, E. [Swedish Institute of Space Physics, Uppsala (Sweden); Galand, M.; Schwartz, S. J., E-mail: erik.vigren@irfu.se [Department of Physics, Imperial College London, London, SW7 2AZ (United Kingdom)

    2015-10-10

    We compute partial photoionization frequencies of H{sub 2}O, CO{sub 2}, and CO, the major molecules in the coma of comet 67P/Churyumov–Gerasimenko, the target comet of the ongoing ESA Rosetta mission. Values are computed from Thermosphere Ionosphere Mesosphere Energy and Dynamics/Solar EUV Experiment solar EUV spectra for 2014 August 1, 2015 March 1, and for perihelion (2015 August, as based on prediction). From the varying total photoionization frequency of H{sub 2}O, as computed from 2014 August 1 to 2015 May 20, we derive a simple analytical expression for the electron-to-neutral number density ratio as a function of cometocentric and heliocentric distance. The underlying model assumes radial movement of the coma constituents and does not account for chemical loss or the presence of electric fields. We discuss various effects/processes that can cause deviations between values from the analytical expression and actual electron-to-neutral number density ratios. The analytical expression is thus not strictly meant as predicting the actual electron-to-neutral number density ratio, but is useful in comparisons with observations as an indicator of processes at play in the cometary coma.

  11. Fitting a mixture of von Mises distributions in order to model data on wind direction in Peninsular Malaysia

    International Nuclear Information System (INIS)

    Masseran, N.; Razali, A.M.; Ibrahim, K.; Latif, M.T.

    2013-01-01

    Highlights: • We suggest a simple way for wind direction modeling using the mixture of von Mises distribution. • We determine the most suitable probability model for wind direction regime in Malaysia. • We provide the circular density plots to show the most prominent directions of wind blows. - Abstract: A statistical distribution for describing wind direction provides information about the wind regime at a particular location. In addition, this information complements knowledge of wind speed, which allows researchers to draw some conclusions about the energy potential of wind and aids the development of efficient wind energy generation. This study focuses on modeling the frequency distribution of wind direction, including some characteristics of wind regime that cannot be represented by a unimodal distribution. To identify the most suitable model, a finite mixture of von Mises distributions were fitted to the average hourly wind direction data for nine wind stations located in Peninsular Malaysia. The data used were from the years 2000 to 2009. The suitability of each mixture distribution was judged based on the R 2 coefficient and the histogram plot with a density line. The results showed that the finite mixture of the von Mises distribution with H number of components was the best distribution to describe the wind direction distributions in Malaysia. In addition, the circular density plots of the suitable model clearly showed the most prominent directions of wind blows than the other directions

  12. Estonian wind climate

    International Nuclear Information System (INIS)

    Kull, Ain

    1999-01-01

    Estonia is situated on the eastern coast of the Baltic Sea. This is a region with intensive cyclonic activity and therefore with a relatively high mean wind speed. Atmospheric circulation and its seasonal variation determine the general character of the Estonian wind regime over the Atlantic Ocean and Eurasia. However, the Baltic sea itself is a very important factor affecting wind climate, it has an especially strong influence on the wind regime in costal areas. The mean energy density (W/m 2 ) is a wind energy characteristic that is proportional to the third power of wind speed and describes energy available in a flow of air through a unit area. The mean energy density is a characteristic which has practical importance in regional assessment of snowdrift, storm damage and wind energy

  13. Space-time scenarios of wind power generation produced using a Gaussian copula with parametrized precision matrix

    DEFF Research Database (Denmark)

    Tastu, Julija; Pinson, Pierre; Madsen, Henrik

    The emphasis in this work is placed on generating space-time trajectories (also referred to as scenarios) of wind power generation. This calls for prediction of multivariate densities describing wind power generation at a number of distributed locations and for a number of successive lead times. ...

  14. Line-Trapping of Codling Moth (Lepidoptera: Tortricidae): A Novel Approach to Improving the Precision of Capture Numbers in Traps Monitoring Pest Density.

    Science.gov (United States)

    Adams, C G; McGhee, P S; Schenker, J H; Gut, L J; Miller, J R

    2017-08-01

    This field study of codling moth, Cydia pomonella (L.), response to single versus multiple monitoring traps baited with codlemone demonstrates that precision of a given capture number is alarmingly poor when the population is held constant by releasing moths. Captures as low as zero and as high as 12 males per single trap are to be expected where the catch mode is three. Here, we demonstrate that the frequency of false negatives and overestimated positives for codling moth trapping can be substantially reduced by employing the tactic of line-trapping, where five traps were deployed 4 m apart along a row of apple trees. Codling moth traps spaced closely competed only slightly. Therefore, deploying five traps closely in a line is a sampling technique nearly as good as deploying five traps spaced widely. But line trapping offers a substantial savings in time and therefore cost when servicing aggregated versus distributed traps. As the science of pest management matures by mastering the ability to translate capture numbers into estimates of absolute pest density, it will be important to employ a tactic like line-trapping so as to shrink the troublesome variability associated with capture numbers in single traps that thwarts accurate decisions about if and when to spray. Line-trapping might similarly increase the reliability and utility of density estimates derived from capture numbers in monitoring traps for various pest and beneficial insects. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America.

  15. Coastal Ohio Wind Project

    Energy Technology Data Exchange (ETDEWEB)

    Gorsevski, Peter [Bowling Green State Univ., OH (United States); Afjeh, Abdollah [Univ. of Toledo, OH (United States); Jamali, Mohsin [Univ. of Toledo, OH (United States); Bingman, Verner [Bowling Green State Univ., OH (United States)

    2014-04-04

    to collect additional monitoring parameters such as passage rates, flight paths, flight directions, and flight altitudes of nocturnal migrating species. Our work focused on the design and development of custom built marine radar that used t-bar and parabolic dish antennas. The marine radar used in the project was Furuno (XANK250) which was coupled with a XIR3000B digitizing card from Russell Technologies for collection of the radar data. The radar data was processed by open source radR processing software using different computational techniques and methods. Additional data from thermal IR imaging cameras were collected to detect heat emitted from objects and provide information on movements of birds and bats, data which we used for different animal flight behavior analysis. Lastly, the data from the acoustic recorders were used to provide the number of bird calls for assessing patterns and peak passage rates during migration. The development of the geospatial database included collection of different data sources that are used to support offshore wind turbine development. Many different data sets were collected and organized using initial version of web-based repository software tools that can accommodate distribution of rectified pertinent data sets such as the lake depth, lake bottom engineering parameters, extent of ice, navigation pathways, wind speed, important bird habitats, fish efforts and other layers that are relevant for supporting robust offshore wind turbine developments. Additional geospatial products developed during the project included few different prototypes for offshore wind farm suitability which can involve different stakeholders and participants for solving complex planning problems and building consensus. Some of the prototypes include spatial decision support system (SDSS) for collaborative decision making, a web-based Participatory Geographic Information System (PGIS) framework for evaluating importance of different decision alternatives

  16. Effective atomic number and effective electron densities of some inorganic compounds for Compton effect in the gamma energy range 280 keV to 1115 keV

    International Nuclear Information System (INIS)

    Prasannakumar, S.; Umesh, T.K.

    2014-01-01

    The effective atomic number and effective electron densities of some inorganic compounds for Compton effect in the gamma energy range 280 keV to 1115 keV by using Compton scattering cross sections which are determined on a goniometer assembly. An ORTEC model 23210 gamma-x high purity germanium detector (HpGe) has been used to record the data along with a personal computer based MCA in the angular region 50°-110°. The effective atomic numbers so obtained were found to be equal to the total number of electrons present in the sample in accordance with the chemical formula. The results so obtained are of first of their kind at these energies and are expected to be important in a variety of applications of radiation physics and chemistry. (author)

  17. Power Curve Estimation With Multivariate Environmental Factors for Inland and Offshore Wind Farms

    KAUST Repository

    Lee, Giwhyun

    2015-04-22

    In the wind industry, a power curve refers to the functional relationship between the power output generated by a wind turbine and the wind speed at the time of power generation. Power curves are used in practice for a number of important tasks including predicting wind power production and assessing a turbine’s energy production efficiency. Nevertheless, actual wind power data indicate that the power output is affected by more than just wind speed. Several other environmental factors, such as wind direction, air density, humidity, turbulence intensity, and wind shears, have potential impact. Yet, in industry practice, as well as in the literature, current power curve models primarily consider wind speed and, sometimes, wind speed and direction. We propose an additive multivariate kernel method that can include the aforementioned environmental factors as a new power curve model. Our model provides, conditional on a given environmental condition, both the point estimation and density estimation of power output. It is able to capture the nonlinear relationships between environmental factors and the wind power output, as well as the high-order interaction effects among some of the environmental factors. Using operational data associated with four turbines in an inland wind farm and two turbines in an offshore wind farm, we demonstrate the improvement achieved by our kernel method.

  18. Increasing Leaf Vein Density via Mutagenesis in Rice Results in an Enhanced Rate of Photosynthesis, Smaller Cell Sizes and Can Reduce Interveinal Mesophyll Cell Number

    Directory of Open Access Journals (Sweden)

    Aryo B. Feldman

    2017-11-01

    Full Text Available Improvements to leaf photosynthetic rates of crops can be achieved by targeted manipulation of individual component processes, such as the activity and properties of RuBisCO or photoprotection. This study shows that simple forward genetic screens of mutant populations can also be used to rapidly generate photosynthesis variants that are useful for breeding. Increasing leaf vein density (concentration of vascular tissue per unit leaf area has important implications for plant hydraulic properties and assimilate transport. It was an important step to improving photosynthetic rates in the evolution of both C3 and C4 species and is a foundation or prerequisite trait for C4 engineering in crops like rice (Oryza sativa. A previous high throughput screen identified five mutant rice lines (cv. IR64 with increased vein densities and associated narrower leaf widths (Feldman et al., 2014. Here, these high vein density rice variants were analyzed for properties related to photosynthesis. Two lines were identified as having significantly reduced mesophyll to bundle sheath cell number ratios. All five lines had 20% higher light saturated photosynthetic capacity per unit leaf area, higher maximum carboxylation rates, dark respiration rates and electron transport capacities. This was associated with no significant differences in leaf thickness, stomatal conductance or CO2 compensation point between mutants and the wild-type. The enhanced photosynthetic rate in these lines may be a result of increased RuBisCO and electron transport component amount and/or activity and/or enhanced transport of photoassimilates. We conclude that high vein density (associated with altered mesophyll cell length and number is a trait that may confer increased photosynthetic efficiency without increased transpiration.

  19. Wind power soars

    Energy Technology Data Exchange (ETDEWEB)

    Flavin, C. [Worldwatch Inst., Washington, DC (United States)

    1996-12-31

    Opinions on the world market for wind power are presented in this paper. Some data for global wind power generating capacity are provided. European and other markets are discussed individually. Estimated potential for wind power is given for a number of countries. 3 figs.

  20. Studies on effective atomic numbers and electron densities in amino acids and sugars in the energy range 30-1333 keV

    International Nuclear Information System (INIS)

    Gowda, Shivalinge; Krishnaveni, S.; Gowda, Ramakrishna

    2005-01-01

    The effective atomic numbers and electron densities of the amino acids glycine, alanine, serine, valine, threonine, leucine, isoleucine, aspartic acid, lysine, glutamic acid, histidine, phenylalanine, arginine, tyrosine, tryptophane and the sugars arabinose, ribose, glucose, galactose, mannose, fructose, rhamnose, maltose, melibiose, melezitose and raffinose at the energies 30.8, 35.0, 81.0, 145, 276.4, 302.9, 356, 383.9, 661.6, 1173 and 1332.5 keV were calculated by using the measured total attenuation cross-sections. The interpolations of total attenuation cross-sections for photons of energy E in elements of atomic number Z was performed using the logarithmic regression analysis of the XCOM data in the photon energy region 30-1500 keV. The best-fit coefficients obtained by a piece wise interpolation method were used to find the effective atomic number and electron density of the compounds. These values are found to be in good agreement with the theoretical values calculated based on XCOM data

  1. Studies on effective atomic numbers and electron densities in amino acids and sugars in the energy range 30-1333 keV

    Energy Technology Data Exchange (ETDEWEB)

    Gowda, Shivalinge [Department of Studies in Physics, University of Mysore, Manasagangotri, Mysore 570 006 (India); Krishnaveni, S. [Department of Studies in Physics, University of Mysore, Manasagangotri, Mysore 570 006 (India); Gowda, Ramakrishna [Department of Studies in Physics, University of Mysore, Manasagangotri, Mysore 570 006 (India)]. E-mail: ramakrishnagowda@yahoo.com

    2005-10-15

    The effective atomic numbers and electron densities of the amino acids glycine, alanine, serine, valine, threonine, leucine, isoleucine, aspartic acid, lysine, glutamic acid, histidine, phenylalanine, arginine, tyrosine, tryptophane and the sugars arabinose, ribose, glucose, galactose, mannose, fructose, rhamnose, maltose, melibiose, melezitose and raffinose at the energies 30.8, 35.0, 81.0, 145, 276.4, 302.9, 356, 383.9, 661.6, 1173 and 1332.5 keV were calculated by using the measured total attenuation cross-sections. The interpolations of total attenuation cross-sections for photons of energy E in elements of atomic number Z was performed using the logarithmic regression analysis of the XCOM data in the photon energy region 30-1500 keV. The best-fit coefficients obtained by a piece wise interpolation method were used to find the effective atomic number and electron density of the compounds. These values are found to be in good agreement with the theoretical values calculated based on XCOM data.

  2. Evaluation of global onshore wind energy potential and generation costs.

    Science.gov (United States)

    Zhou, Yuyu; Luckow, Patrick; Smith, Steven J; Clarke, Leon

    2012-07-17

    In this study, we develop an updated global estimate of onshore wind energy potential using reanalysis wind speed data, along with updated wind turbine technology performance, land suitability factors, cost assumptions, and explicit consideration of transmission distance in the calculation of transmission costs. We find that wind has the potential to supply a significant portion of the world energy needs, although this potential varies substantially by region and with assumptions such as on what types of land can be used to site wind farms. Total global economic wind potential under central assumptions, that is, intermediate between optimistic and pessimistic, is estimated to be approximately 119.5 petawatt hours per year (13.6 TW) at less than 9 cents/kWh. A sensitivity analysis of eight key parameters is presented. Wind potential is sensitive to a number of input parameters, particularly wind speed (varying by -70% to +450% at less than 9 cents/kWh), land suitability (by -55% to +25%), turbine density (by -60% to +80%), and cost and financing options (by -20% to +200%), many of which have important policy implications. As a result of sensitivities studied here we suggest that further research intended to inform wind supply curve development focus not purely on physical science, such as better resolved wind maps, but also on these less well-defined factors, such as land-suitability, that will also have an impact on the long-term role of wind power.

  3. Inhibitory control and visuo-spatial reversibility in Piaget’s seminal number conservation task: A high-density ERP study.

    Directory of Open Access Journals (Sweden)

    Gregoire eBorst

    2013-12-01

    Full Text Available The present high-density ERP study on 13 adults aimed to determine whether number conservation relies on the ability to inhibit the overlearned length-equals-number strategy and then imagine the shortening of the row that was lengthened. Participants performed the number-conservation task and, after the EEG session, the mental imagery task. In the number-conservation task, first two rows with the same number of tokens and the same length were presented on a computer screen (COV condition and then, the tokens in one of the two rows were spread apart (INT condition. Participants were instructed to determine whether the two rows had an identical number of tokens. In the mental imagery task, two rows with different lengths but the same number of tokens were presented and participants were instructed to imagine the tokens in the longer row aligning with the tokens in the shorter row. In the number-conservation task, we found that the amplitudes of the centro-parietal N2 and fronto-central P3 were higher in the INT than in the COV conditions. In addition, the differences in response times between the two conditions were correlated with the differences in the amplitudes of the fronto-central P3. In light of previous results reported on the number-conservation task in adults, the present results suggest that inhibition might be necessary to succeed the number-conservation task in adults even when the transformation of the length of one of the row is displayed. Finally, we also reported correlations between the speed at which participants could imagine the shortening of one of the row in the mental imagery task, the speed at which participants could determine that the two rows had the same number of tokens after the tokens in one of the row were spread apart and the latency of the late positive parietal component in the number-conservation task. Therefore, performing the number-conservation task might involve mental transformation processes in adults.

  4. Wind Power in Electrical Distribution Systems

    DEFF Research Database (Denmark)

    Chen, Zhe

    2013-01-01

    Recent years, wind power is experiencing a rapid growth, large number of wind turbines/wind farms have been installed and connected to power systems. In addition to the large centralised wind farms connected to transmission grids, many distributed wind turbines and wind farms are operated as dist...

  5. Wind Energy Resource Atlas of Armenia

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, D.; Schwartz, M.; Scott, G.; Haymes, S.; Heimiller, D.; George, R.

    2003-07-01

    This wind energy resource atlas identifies the wind characteristics and distribution of the wind resource in the country of Armenia. The detailed wind resource maps and other information contained in the atlas facilitate the identification of prospective areas for use of wind energy technologies for utility-scale power generation and off-grid wind energy applications. The maps portray the wind resource with high-resolution (1-km2) grids of wind power density at 50-m above ground. The wind maps were created at the National Renewable Energy Laboratory (NREL) using a computerized wind mapping system that uses Geographic Information System (GIS) software.

  6. Wind energy

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    This chapter discusses the role wind energy may have in the energy future of the US. The topics discussed in the chapter include historical aspects of wind energy use, the wind energy resource, wind energy technology including intermediate-size and small wind turbines and intermittency of wind power, public attitudes toward wind power, and environmental, siting and land use issues

  7. Flight and wind-tunnel calibrations of a flush airdata sensor at high angles of attack and sideslip and at supersonic Mach numbers

    Science.gov (United States)

    Moes, Timothy R.; Whitmore, Stephen A.; Jordan, Frank L., Jr.

    1993-01-01

    A nonintrusive airdata-sensing system was calibrated in flight and wind-tunnel experiments to an angle of attack of 70 deg and to angles of sideslip of +/- 15 deg. Flight-calibration data have also been obtained to Mach 1.2. The sensor, known as the flush airdata sensor, was installed on the nosecap of an F-18 aircraft for flight tests and on a full-scale F-18 forebody for wind-tunnel tests. Flight tests occurred at the NASA Dryden Flight Research Facility, Edwards, California, using the F-18 High Alpha Research Vehicle. Wind-tunnel tests were conducted in the 30- by 60-ft wind tunnel at the NASA LaRC, Hampton, Virginia. The sensor consisted of 23 flush-mounted pressure ports arranged in concentric circles and located within 1.75 in. of the tip of the nosecap. An overdetermined mathematical model was used to relate the pressure measurements to the local airdata quantities. The mathematical model was based on potential flow over a sphere and was empirically adjusted based on flight and wind-tunnel data. For quasi-steady maneuvering, the mathematical model worked well throughout the subsonic, transonic, and low supersonic flight regimes. The model also worked well throughout the angle-of-attack and sideslip regions studied.

  8. On the truncation of the number of excited states in density functional theory sum-over-states calculations of indirect spin spin coupling constants

    International Nuclear Information System (INIS)

    Zarycz, M. Natalia C.; Provasi, Patricio F.; Sauer, Stephan P. A.

    2015-01-01

    It is investigated, whether the number of excited (pseudo)states can be truncated in the sum-over-states expression for indirect spin-spin coupling constants (SSCCs), which is used in the Contributions from Localized Orbitals within the Polarization Propagator Approach and Inner Projections of the Polarization Propagator (IPPP-CLOPPA) approach to analyzing SSCCs in terms of localized orbitals. As a test set we have studied the nine simple compounds, CH 4 , NH 3 , H 2 O, SiH 4 , PH 3 , SH 2 , C 2 H 2 , C 2 H 4 , and C 2 H 6 . The excited (pseudo)states were obtained from time-dependent density functional theory (TD-DFT) calculations with the B3LYP exchange-correlation functional and the specialized core-property basis set, aug-cc-pVTZ-J. We investigated both how the calculated coupling constants depend on the number of (pseudo)states included in the summation and whether the summation can be truncated in a systematic way at a smaller number of states and extrapolated to the total number of (pseudo)states for the given one-electron basis set. We find that this is possible and that for some of the couplings it is sufficient to include only about 30% of the excited (pseudo)states

  9. On the truncation of the number of excited states in density functional theory sum-over-states calculations of indirect spin spin coupling constants

    Energy Technology Data Exchange (ETDEWEB)

    Zarycz, M. Natalia C., E-mail: mnzarycz@gmail.com; Provasi, Patricio F., E-mail: patricio@unne.edu.ar [Department of Physics, University of Northeastern - CONICET, Av. Libertad 5500, Corrientes W3404AAS (Argentina); Sauer, Stephan P. A., E-mail: sauer@kiku.dk [Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø (Denmark)

    2015-12-28

    It is investigated, whether the number of excited (pseudo)states can be truncated in the sum-over-states expression for indirect spin-spin coupling constants (SSCCs), which is used in the Contributions from Localized Orbitals within the Polarization Propagator Approach and Inner Projections of the Polarization Propagator (IPPP-CLOPPA) approach to analyzing SSCCs in terms of localized orbitals. As a test set we have studied the nine simple compounds, CH{sub 4}, NH{sub 3}, H{sub 2}O, SiH{sub 4}, PH{sub 3}, SH{sub 2}, C{sub 2}H{sub 2}, C{sub 2}H{sub 4}, and C{sub 2}H{sub 6}. The excited (pseudo)states were obtained from time-dependent density functional theory (TD-DFT) calculations with the B3LYP exchange-correlation functional and the specialized core-property basis set, aug-cc-pVTZ-J. We investigated both how the calculated coupling constants depend on the number of (pseudo)states included in the summation and whether the summation can be truncated in a systematic way at a smaller number of states and extrapolated to the total number of (pseudo)states for the given one-electron basis set. We find that this is possible and that for some of the couplings it is sufficient to include only about 30% of the excited (pseudo)states.

  10. Wind Resource Assessment of Gujarat (India)

    Energy Technology Data Exchange (ETDEWEB)

    Draxl, C.; Purkayastha, A.; Parker, Z.

    2014-07-01

    India is one of the largest wind energy markets in the world. In 1986 Gujarat was the first Indian state to install a wind power project. In February 2013, the installed wind capacity in Gujarat was 3,093 MW. Due to the uncertainty around existing wind energy assessments in India, this analysis uses the Weather Research and Forecasting (WRF) model to simulate the wind at current hub heights for one year to provide more precise estimates of wind resources in Gujarat. The WRF model allows for accurate simulations of winds near the surface and at heights important for wind energy purposes. While previous resource assessments published wind power density, we focus on average wind speeds, which can be converted to wind power densities by the user with methods of their choice. The wind resource estimates in this study show regions with average annual wind speeds of more than 8 m/s.

  11. Heat-flux gage measurements on a flat plate at a Mach number of 4.6 in the VSD high speed wind tunnel, a feasibility test (LA28). [wind tunnel tests of measuring instruments for boundary layer flow

    Science.gov (United States)

    1975-01-01

    The feasibility of employing thin-film heat-flux gages was studied as a method of defining boundary layer characteristics at supersonic speeds in a high speed blowdown wind tunnel. Flow visualization techniques (using oil) were employed. Tabulated data (computer printouts), a test facility description, and photographs of test equipment are given.

  12. Calibration of megavoltage cone-beam CT for radiotherapy dose calculations: Correction of cupping artifacts and conversion of CT numbers to electron density

    International Nuclear Information System (INIS)

    Petit, Steven F.; Elmpt, Wouter J. C. van; Nijsten, Sebastiaan M. J. J. G.; Lambin, Philippe; Dekker, Andre L. A. J.

    2008-01-01

    Megavoltage cone-beam CT (MV CBCT) is used for three-dimensional imaging of the patient anatomy on the treatment table prior to or just after radiotherapy treatment. To use MV CBCT images for radiotherapy dose calculation purposes, reliable electron density (ED) distributions are needed. Patient scatter, beam hardening and softening effects result in cupping artifacts in MV CBCT images and distort the CT number to ED conversion. A method based on transmission images is presented to correct for these effects without using prior knowledge of the object's geometry. The scatter distribution originating from the patient is calculated with pencil beam scatter kernels that are fitted based on transmission measurements. The radiological thickness is extracted from the scatter subtracted transmission images and is then converted to the primary transmission used in the cone-beam reconstruction. These corrections are performed in an iterative manner, without using prior knowledge regarding the geometry and composition of the object. The method was tested using various homogeneous and inhomogeneous phantoms with varying shapes and compositions, including a phantom with different electron density inserts, phantoms with large density variations, and an anthropomorphic head phantom. For all phantoms, the cupping artifact was substantially removed from the images and a linear relation between the CT number and electron density was found. After correction the deviations in reconstructed ED from the true values were reduced from up to 0.30 ED units to 0.03 for the majority of the phantoms; the residual difference is equal to the amount of noise in the images. The ED distributions were evaluated in terms of absolute dose calculation accuracy for homogeneous cylinders of different size; errors decreased from 7% to below 1% in the center of the objects for the uncorrected and corrected images, respectively, and maximum differences were reduced from 17% to 2%, respectively. The

  13. Evaluation model of wind energy resources and utilization efficiency of wind farm

    Science.gov (United States)

    Ma, Jie

    2018-04-01

    Due to the large amount of abandoned winds in wind farms, the establishment of a wind farm evaluation model is particularly important for the future development of wind farms In this essay, consider the wind farm's wind energy situation, Wind Energy Resource Model (WERM) and Wind Energy Utilization Efficiency Model(WEUEM) are established to conduct a comprehensive assessment of the wind farm. Wind Energy Resource Model (WERM) contains average wind speed, average wind power density and turbulence intensity, which assessed wind energy resources together. Based on our model, combined with the actual measurement data of a wind farm, calculate the indicators using the model, and the results are in line with the actual situation. We can plan the future development of the wind farm based on this result. Thus, the proposed establishment approach of wind farm assessment model has application value.

  14. Influence of number of deliveries and total breast-feeding time on bone mineral density in premenopausal and young postmenopausal women.

    Science.gov (United States)

    Tsvetov, Gloria; Levy, Sigal; Benbassat, Carlos; Shraga-Slutzky, Ilana; Hirsch, Dania

    2014-03-01

    Pregnancy and lactation have been associated with decline in bone mineral density (BMD). It is not clear if there is a full recovery of BMD to baseline. This study sought to determine if pregnancy or breast-feeding or both have a cumulative effect on BMD in premenopausal and early postmenopausal women. We performed single-center cohort analysis. Five hundred women aged 35-55 years underwent routine BMD screening from February to July 2011 at a tertiary medical center. Patients were questioned about number of total full-term deliveries and duration of breast-feeding and completed a background questionnaire on menarche and menopause, smoking, dairy product consumption, and weekly physical exercise. Weight and height were measured. Dual-energy X-ray absorptiometry was used to measure spinal, dual femoral neck, and total hip BMD. Associations between background characteristics and BMD values were analyzed. Sixty percent of the women were premenopausal. Mean number of deliveries was 2.5 and mean duration of breast-feeding was 9.12 months. On univariate analysis, BMD values were negatively correlated with patient age (p=0.006) and number of births (p=0.013), and positively correlated with body mass index (posteoporosis later in life. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  15. Implication of nonintegral occupation number and Fermi-Dirac statistics in the local-spin-density approximation applied to finite systems

    International Nuclear Information System (INIS)

    Dhar, S.

    1989-01-01

    In electronic-structure calculations for finite systems using the local-spin-density (LSD) approximation, it is assumed that the eigenvalues of the Kohn-Sham equation should obey Fermi-Dirac (FD) statistics. In order to comply with this assumption for some of the transition-metal atoms, a nonintegral occupation number is used which also minimizes the total energy. It is shown here that for finite systems it is not necessary that the eigenvalues of the Kohn-Sham equation obey FD statistics. It is also shown that the Kohn-Sham exchange potential used in all LSD models is correct only for integer occupation number. With a noninteger occupation number the LSD exchange potential will be smaller than that given by the Kohn-Sham potential. Ab initio self-consistent spin-polarized calculations have been performed numerically for the total energy of an iron atom. It is found that the ground state belongs to the 3d 6 4s 2 configuration. The ionization potentials of all the Fe/sup n/ + ions are reported and are in agreement with experiment

  16. Calculation of depleted wind resources near wind farms

    DEFF Research Database (Denmark)

    Nielsen, Morten

    2015-01-01

    Traditional wind resource maps include wind distribution, energy density and potential power production without wake effects. Adding wake effect to such maps is feasible by means of a new method based on Fourier transformation,and the extra computational work is comparable to that of the basic wind...

  17. Comparison of SAR Wind Speed Retrieval Algorithms for Evaluating Offshore Wind Energy Resources

    DEFF Research Database (Denmark)

    Kozai, K.; Ohsawa, T.; Takeyama, Y.

    2010-01-01

    Envisat/ASAR-derived offshore wind speeds and energy densities based on 4 different SAR wind speed retrieval algorithms (CMOD4, CMOD-IFR2, CMOD5, CMOD5.N) are compared with observed wind speeds and energy densities for evaluating offshore wind energy resources. CMOD4 ignores effects of atmospheri...

  18. The influence of the number of activation detectors on the Seibersdorf - Milano intercomparison of neutron flux density spectra by WINDOWS code

    International Nuclear Information System (INIS)

    Ertek, C.

    1981-02-01

    This work is a continuation of the work performed within the IAEA programme on standardization of reactor radiation measurements, one of the important objectives of which is the assistance to laboratories in Member States to implement or intercompare the multiple foil activation techniques for different neutron field measurements. The importance of these techniques is well recognized. In CESNEF-FERMI Politecnico di Milano, Italy, they have installed near the core of a water boiler of 50kW, a neutron filter made of B 4 C in order to obtain a neutron flux density spectrum that could be of utility in intercalibration problems connected with irradiation in fast assemblies. Dr. V. Sangiust from CESNEF kindly sent the input guess neutron flux density spectrum and a series of measured reaction rates to be treated by the IAEA Seibersdorf laboratory using the SAND-II and the WINDOWS unfolding codes. The meaningful comparison using partly the same ENDF/B IV cross section data is performed. In the present work we extended the investiga tion using WINDOWS unfolding code for different numbers of activation fo ils or reaction rates

  19. Studies on effective atomic numbers for photon energy absorption and electron density of some narcotic drugs in the energy range 1 keV-20 MeV

    Science.gov (United States)

    Gounhalli, Shivraj G.; Shantappa, Anil; Hanagodimath, S. M.

    2013-04-01

    Effective atomic numbers for photon energy absorption ZPEA,eff, photon interaction ZPI,eff and for electron density Nel, have been calculated by a direct method in the photon-energy region from 1 keV to 20 MeV for narcotic drugs, such as Heroin (H), Cocaine (CO), Caffeine (CA), Tetrahydrocannabinol (THC), Cannabinol (CBD), Tetrahydrocannabivarin (THCV). The ZPEA,eff, ZPI,eff and Nel values have been found to change with energy and composition of the narcotic drugs. The energy dependence ZPEA,eff, ZPI,eff and Nel is shown graphically. The maximum difference between the values of ZPEA,eff, and ZPI,eff occurs at 30 keV and the significant difference of 2 to 33% for the energy region 5-100 keV for all drugs. The reason for these differences is discussed.

  20. Effective atomic numbers and electron densities of bacteriorhodopsin and its comprising amino acids in the energy range 1 keV–100 GeV

    Energy Technology Data Exchange (ETDEWEB)

    Ahmadi, Morteza; Lunscher, Nolan [Waterloo Institute for Nanotechnology and Department of Systems Design Engineering, University of Waterloo, 200 University Ave., W., Waterloo, Ontario, Canada N2L 3G1 (Canada); Yeow, John T.W., E-mail: jyeow@uwaterloo.ca [Waterloo Institute for Nanotechnology and Department of Systems Design Engineering, University of Waterloo, 200 University Ave., W., Waterloo, Ontario, Canada N2L 3G1 (Canada)

    2013-04-01

    Recently, there has been an interest in fabrication of X-ray sensors based on bacteriorhodopsin, a proton pump protein in cell membrane of Halobacterium salinarium. Therefore, a better understanding of interaction of X-ray photons with bacteriorhodopsin is required. We use WinXCom program to calculate the mass attenuation coefficient of bacteriorhodopsin and its comprising amino acids for photon energies from 1 keV to 100 GeV. These amino acids include alanine, arginine, asparagine, aspartic acid, glutamine, glutamic acid, glycine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, valine, Asx1, Asx2, Glx1 and Glx2. We then use that data to calculate effective atomic number and electron densities for the same range of energy. We also emphasize on two ranges of energies (10–200 keV and 1–20 MeV) in which X-ray imaging and radiotherapy machines work.

  1. Visualization of wind farms

    International Nuclear Information System (INIS)

    Pahlke, T.

    1994-01-01

    With the increasing number of wind energy installations the visual impact of single wind turbines or wind parks is a growing problem for landscape preservation, leading to resistance of local authorities and nearby residents against wind energy projects. To increase acceptance and to form a basis for planning considerations, it is necessary to develop instruments for the visualization of planned wind parks, showing their integration in the landscape. Photorealistic montages and computer animation including video sequences may be helpful in 'getting the picture'. (orig.)

  2. Effect of pulse repetition rate and number of pulses in the analysis of polypropylene and high density polyethylene by nanosecond infrared laser induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Leme, Flavio O. [Laboratorio de Quimica Analitica ' Henrique Bergamin Filho' , Centro de Energia Nuclear na Agricultura, Universidade de Sao Paulo, Av. Centenario 303, 13416-000 Piracicaba, SP (Brazil); Godoi, Quienly [Laboratorio de Quimica Analitica ' Henrique Bergamin Filho' , Centro de Energia Nuclear na Agricultura, Universidade de Sao Paulo, Av. Centenario 303, 13416-000 Piracicaba, SP (Brazil); Departamento de Quimica, Universidade Federal de Sao Carlos, Rod. Washington Luis, km 235, 13565-905 Sao Carlos, SP (Brazil); Kiyataka, Paulo H.M. [Centro de Tecnologia de Embalagens, Instituto de Tecnologia de Alimentos, Av. Brasil 2880, 13070-178 Campinas, SP (Brazil); Santos, Dario [Departamento de Ciencias Exatas e da Terra, Universidade Federal de Sao Paulo, Rua Prof. Artur Riedel 275, 09972-270 Diadema, SP (Brazil); Agnelli, Jose A.M. [Departamento de Engenharia de Materiais, Universidade Federal de Sao Carlos, Rod. Washington Luis, km 235, 13565-905 Sao Carlos, SP (Brazil); and others

    2012-02-01

    Pulse repetition rates and the number of laser pulses are among the most important parameters that do affect the analysis of solid materials by laser induced breakdown spectroscopy, and the knowledge of their effects is of fundamental importance for suggesting analytical strategies when dealing with laser ablation processes of polymers. In this contribution, the influence of these parameters in the ablated mass and in the features of craters was evaluated in polypropylene and high density polyethylene plates containing pigment-based PbCrO{sub 4}. Surface characterization and craters profile were carried out by perfilometry and scanning electron microscopy. Area, volume and profile of craters were obtained using Taylor Map software. A laser induced breakdown spectroscopy system consisted of a Q-Switched Nd:YAG laser (1064 nm, 5 ns) and an Echelle spectrometer equipped with ICCD detector were used. The evaluated operating conditions consisted of 10, 25 and 50 laser pulses at 1, 5 and 10 Hz, 250 mJ/pulse (85 J cm{sup -2}), 2 {mu}s delay time and 6 {mu}s integration time gate. Differences in the topographical features among craters of both polymers were observed. The decrease in the repetition rate resulted in irregular craters and formation of edges, especially in polypropylene sample. The differences in the topographical features and ablated masses were attributed to the influence of the degree of crystallinity, crystalline melting temperature and glass transition temperature in the ablation process of the high density polyethylene and polypropylene. It was also observed that the intensities of chromium and lead emission signals obtained at 10 Hz were two times higher than at 5 Hz by keeping the number of laser pulses constant.

  3. Results of flutter test OS7 obtained using the 0.14-scale space shuttle orbiter fin/rudder model number 55-0 in the NASA LaRC 16-foot transonic dynamics wind tunnel

    Science.gov (United States)

    Berthold, C. L.

    1977-01-01

    A 0.14-scale dynamically scaled model of the space shuttle orbiter vertical tail was tested in a 16-foot transonic dynamic wind tunnel to determine flutter, buffet, and rudder buzz boundaries. Mach numbers between .5 and 1.11 were investigated. Rockwell shuttle model 55-0 was used for this investigation. A description of the test procedure, hardware, and results of this test is presented.

  4. Association of Air Pollution Exposures With High-Density Lipoprotein Cholesterol and Particle Number: The Multi-Ethnic Study of Atherosclerosis.

    Science.gov (United States)

    Bell, Griffith; Mora, Samia; Greenland, Philip; Tsai, Michael; Gill, Ed; Kaufman, Joel D

    2017-05-01

    The relationship between air pollution and cardiovascular disease may be explained by changes in high-density lipoprotein (HDL). We examined the cross-sectional relationship between air pollution and both HDL cholesterol and HDL particle number in the MESA Air study (Multi-Ethnic Study of Atherosclerosis Air Pollution). Study participants were 6654 white, black, Hispanic, and Chinese men and women aged 45 to 84 years. We estimated individual residential ambient fine particulate pollution exposure (PM 2.5 ) and black carbon concentrations using a fine-scale likelihood-based spatiotemporal model and cohort-specific monitoring. Exposure periods were averaged to 12 months, 3 months, and 2 weeks prior to examination. HDL cholesterol and HDL particle number were measured in the year 2000 using the cholesterol oxidase method and nuclear magnetic resonance spectroscopy, respectively. We used multivariable linear regression to examine the relationship between air pollution exposure and HDL measures. A 0.7×10 - 6 m - 1 higher exposure to black carbon (a marker of traffic-related pollution) averaged over a 1-year period was significantly associated with a lower HDL cholesterol (-1.68 mg/dL; 95% confidence interval, -2.86 to -0.50) and approached significance with HDL particle number (-0.55 mg/dL; 95% confidence interval, -1.13 to 0.03). In the 3-month averaging time period, a 5 μg/m 3 higher PM 2.5 was associated with lower HDL particle number (-0.64 μmol/L; 95% confidence interval, -1.01 to -0.26), but not HDL cholesterol (-0.05 mg/dL; 95% confidence interval, -0.82 to 0.71). These data are consistent with the hypothesis that exposure to air pollution is adversely associated with measures of HDL. © 2017 American Heart Association, Inc.

  5. 14821AT LANCE, Missile Number 2419, Round Number 349APT, 12 May 1980.

    Science.gov (United States)

    1980-05-01

    WSTRUCTIONUREPOT DCUMNTAIONPAG EPORE COMPLEMON PORN REPORT NUMBER 2GOTACCESSION NO S. RECIPIENT’S CATALOG NUMBER TDR 1148 __7 0_____T___ ~. *.~----...,S. TYPE OF...Data at 0815 MDT ---------- 4 4. White Sands Desert Site (WSD) Significant Level Data at 0815 MDT ------------------------------------ 5 5. WSD Upper...humidity, dew point (0 C), density (gm/n,3), Wind direction and speed, and cloud cover were made at the LC-39 Met Site at T-0 minutes. (2) Monitor of

  6. A simple formulation for deriving effective atomic numbers via electron density calibration from dual-energy CT data in the human body.

    Science.gov (United States)

    Saito, Masatoshi; Sagara, Shota

    2017-06-01

    The main objective of this study is to propose a simple formulation (which we called DEEDZ) for deriving effective atomic numbers (Z eff ) via electron density (ρ e ) calibration from dual-energy (DE) CT data. We carried out numerical analysis of this DEEDZ method for a large variety of materials with known elemental compositions and mass densities using an available photon cross sections database. The new conversion approach was also applied to previously published experimental DECT data to validate its practical feasibility. We performed numerical analysis of the DEEDZ conversion method for tissue surrogates that have the same chemical compositions and mass densities as a commercial tissue-characterization phantom in order to determine the parameters necessary for the ρ e and Z eff calibrations in the DEEDZ conversion. These parameters were then applied to the human-body-equivalent tissues of ICRU Report 46 as objects of interest with unknown ρ e and Z eff . The attenuation coefficients of these materials were calculated using the XCOM photon cross sections database. We also applied the DEEDZ conversion to experimental DECT data available in the literature, which was measured for two commercial phantoms of different shapes and sizes using a dual-source CT scanner at 80 kV and 140 kV/Sn. The simulated Z eff 's were in excellent agreement with the reference values for almost all of the ICRU-46 human tissues over the Z eff range from 5.83 (gallstones-cholesterol) to 16.11 (bone mineral-hydroxyapatite). The relative deviations from the reference Z eff were within ± 0.3% for all materials, except for one outlier that presented a -3.1% deviation, namely, the thyroid. The reason for this discrepancy is that the thyroid contains a small amount of iodine, an element with a large atomic number (Z = 53). In the experimental case, we confirmed that the simple formulation with less fit parameters enable to calibrate Z eff as accurately as the existing calibration

  7. Wind: new wind markets

    International Nuclear Information System (INIS)

    Cameron, A.

    2005-01-01

    The June 2005 edition of 'Wind Force 12' suggests that wind could generate 12% of global electricity requirements by 2020. But what moves a potential market into an emerging one? Geographical factors include a good wind resource, plenty of open space and the ability to get the generated electricity to end-users. A country's political framework is equally important, with fixed price systems, renewable quota systems and political will all playing a part. Some potential wind markets around the world are thought to have the conditions necessary to become key players in the wind industry. The emerging markets in countries such as Australia, Brazil, Canada, France, Japan and the Philippines are highlighted as examples

  8. A robust variant of block Jacobi-Davidson for extracting a large number of eigenpairs: Application to grid-based real-space density functional theory

    Science.gov (United States)

    Lee, M.; Leiter, K.; Eisner, C.; Breuer, A.; Wang, X.

    2017-09-01

    In this work, we investigate a block Jacobi-Davidson (J-D) variant suitable for sparse symmetric eigenproblems where a substantial number of extremal eigenvalues are desired (e.g., ground-state real-space quantum chemistry). Most J-D algorithm variations tend to slow down as the number of desired eigenpairs increases due to frequent orthogonalization against a growing list of solved eigenvectors. In our specification of block J-D, all of the steps of the algorithm are performed in clusters, including the linear solves, which allows us to greatly reduce computational effort with blocked matrix-vector multiplies. In addition, we move orthogonalization against locked eigenvectors and working eigenvectors outside of the inner loop but retain the single Ritz vector projection corresponding to the index of the correction vector. Furthermore, we minimize the computational effort by constraining the working subspace to the current vectors being updated and the latest set of corresponding correction vectors. Finally, we incorporate accuracy thresholds based on the precision required by the Fermi-Dirac distribution. The net result is a significant reduction in the computational effort against most previous block J-D implementations, especially as the number of wanted eigenpairs grows. We compare our approach with another robust implementation of block J-D (JDQMR) and the state-of-the-art Chebyshev filter subspace (CheFSI) method for various real-space density functional theory systems. Versus CheFSI, for first-row elements, our method yields competitive timings for valence-only systems and 4-6× speedups for all-electron systems with up to 10× reduced matrix-vector multiplies. For all-electron calculations on larger elements (e.g., gold) where the wanted spectrum is quite narrow compared to the full spectrum, we observe 60× speedup with 200× fewer matrix-vector multiples vs. CheFSI.

  9. Wind Atlas of Bay of Bengal with Satellite Wind Measurement

    DEFF Research Database (Denmark)

    Nadi, Navila Rahman

    footstep towards offshore wind energy analysis for this region. Generally, it is difficult to find offshore wind data relative to the wind turbine hub heights, therefore a starting point is necessary to identify the possible wind power density of the region. In such scenario, Synthetic aperture radars (SAR......The objective of this study is to obtain appropriate offshore location in the Bay of Bengal, Bangladesh for further development of wind energy. Through analyzing the previous published works, no offshore wind energy estimation has been found here. That is why, this study can be claimed as the first......) have proven useful. In this study, SAR based dataset- ENVISAT ASAR has been used for Wind Atlas generation. Furthermore, a comparative study has been performed with Global Wind Atlas (GWA) to determine a potential offshore wind farm. Additionally, the annual energy production of that offshore windfarm...

  10. Effective atomic numbers and electron densities of some biologically important compounds containing H, C, N and O in the energy range 145-1330 keV

    International Nuclear Information System (INIS)

    Manjunathaguru, V; Umesh, T K

    2006-01-01

    A semi-empirical relation which can be used to determine the total attenuation cross sections of samples containing H, C, N and O in the energy range 145-1332 keV has been derived based on the total attenuation cross sections of several sugars, amino acids and fatty acids. The cross sections have been measured by performing transmission experiments in a narrow beam good geometry set-up by employing a high-resolution hyperpure germanium detector at seven energies of biological importance such as 145.4 keV, 279.2 keV, 514 keV, 661.6 keV, 1115.5 keV, 1173.2 keV and 1332.1 keV. The semi-empirical relation can reproduce the experimental values within 1-2%. The total attenuation cross sections of five elements carbon, aluminium, titanium, copper and zirconium measured in the same experimental set-up at the energies mentioned above have been used in a new matrix method to evaluate the effective atomic numbers and the effective electron densities of samples such as cholesterol, fatty acids, sugars and amino acids containing H, C, N and O atoms from their effective atomic cross sections. The effective atomic cross sections are the total attenuation cross sections divided by the total number of atoms of all types in a particular sample. Further, a quantity called the effective atomic weight was defined as the ratio of the molecular weight of a sample to the total number of atoms of all types in it. The variation of the effective atomic number was systematically studied with respect to the effective atomic weight and a new semi-empirical relation for Z eff has been evolved. It is felt that this relation can be very useful to determine the effective atomic number of any sample having H, C, N and O atoms in the energy range 145-1332 keV irrespective of its chemical structure

  11. An experimental observation of the different behavior of ionic and neutral lines of iron as a function of number density in a binary carbon–iron mixture

    International Nuclear Information System (INIS)

    Sivakumar, P.; Taleh, L.; Markushin, Y.; Melikechi, N.; Lasue, J.

    2013-01-01

    We report on the dependence of the intensities of atomic and ionic lines emitted by a nanosecond laser-induced plasma on the atomic number densities of the constituents of a binary mixture formed of carbon and iron. We show that the packing density of the sample greatly affects the relative standard deviation of the emission lines. Furthermore, we show that the variation of the intensities of the C and Fe emission lines depends in a non-trivial way on the relative C–Fe concentration. The intensities of Fe neutral atomic lines behave differently than those of the ionic ones particularly at and above concentrations of 75%–80% Fe embedded in a carbon matrix. Unlike the emission from neutral Fe, those from ionic Fe yield a very sharp decrease followed by an equally strong increase of the emission lines over a relatively small range of relative concentration of C and Fe. To better investigate this effect, we have compared the results obtained with nanosecond-LIBS to those with femtosecond-LIBS and found that this phenomenon disappears. The physical interpretation of the sharp decrease followed by an equally sharp increase in the emission intensities from Fe ions as the concentration of Fe is increased requires more studies. - Highlights: ► The effects of the size of the particles on the fluctuations of the LIBS signals ► The variation of LIBS signals with the concentrations of Fe embedded in C is nontrivial. ► The intensities of neutral atomic lines can behave differently than those of ions

  12. Wind energy development: Danish experiences and international options

    International Nuclear Information System (INIS)

    Frandsen, S.; Hasted, F.; Josephsen, L.; Nielson, J.H.

    1989-01-01

    In Denmark, wind energy makes a visible contribution to energy planning. Since 1976, over 1,800 wind turbine units have been installed in Denmark, representing a capacity of ca 140 MW out of a grid capacity of 8,000 MW. These units are all grid-connected and the unit sizes range from 55 kW to 400 kW. The installed wind energy capacity represents a substantial development of technologies for wind energy utilization during the last 15 years, involving participation from research institutes, electric utilities, private industry, and the national energy administration. A considerable improvement of the technical and economic performance of wind turbines, along with increased reliability and durability, has been strongly supported by comprehensive government programs. In 1985, another large construction program was initiated which will add 100 MW wind power capacity by the end of 1990. Parallel with commercial development, Danish utilities have developed and constructed a number of megawatt-size wind turbines on a pilot basis. In general terms the wind energy resources in Denmark are rather good, and many suitable sites exist, but installed wind energy capacity is limited by the high population density. Consequently, research is being conducted on the feasibility of offshore wind turbines. In other countries, wind energy developments similar to those in Denmark are taking place. In communities with no connection to the national grid, special attention should be paid to hybrid systems such as wind-diesel and hydro-wind systems. A substantial transfer of technology is required for facilitating significant development of hybrid systems in developing countries. 11 refs., 7 figs., 2 tabs

  13. Initial implementation of the conversion from the energy-subtracted CT number to electron density in tissue inhomogeneity corrections: An anthropomorphic phantom study of radiotherapy treatment planning

    Energy Technology Data Exchange (ETDEWEB)

    Tsukihara, Masayoshi [Division of Radiological Technology, Graduate School of Health Sciences, Niigata University, Niigata 951-8518 (Japan); Noto, Yoshiyuki [Department of Radiology, Niigata University Medical and Dental Hospital, Niigata 951-8520 (Japan); Sasamoto, Ryuta; Hayakawa, Takahide; Saito, Masatoshi, E-mail: masaito@clg.niigata-u.ac.jp [Department of Radiological Technology, School of Health Sciences, Faculty of Medicine, Niigata University, Niigata 951-8518 (Japan)

    2015-03-15

    Purpose: To achieve accurate tissue inhomogeneity corrections in radiotherapy treatment planning, the authors had previously proposed a novel conversion of the energy-subtracted computed tomography (CT) number to an electron density (ΔHU–ρ{sub e} conversion), which provides a single linear relationship between ΔHU and ρ{sub e} over a wide range of ρ{sub e}. The purpose of this study is to present an initial implementation of the ΔHU–ρ{sub e} conversion method for a treatment planning system (TPS). In this paper, two example radiotherapy plans are used to evaluate the reliability of dose calculations in the ΔHU–ρ{sub e} conversion method. Methods: CT images were acquired using a clinical dual-source CT (DSCT) scanner operated in the dual-energy mode with two tube potential pairs and an additional tin (Sn) filter for the high-kV tube (80–140 kV/Sn and 100–140 kV/Sn). Single-energy CT using the same DSCT scanner was also performed at 120 kV to compare the ΔHU–ρ{sub e} conversion method with a conventional conversion from a CT number to ρ{sub e} (Hounsfield units, HU–ρ{sub e} conversion). Lookup tables for ρ{sub e} calibration were obtained from the CT image acquisitions for tissue substitutes in an electron density phantom (EDP). To investigate the beam-hardening effect on dosimetric uncertainties, two EDPs with different sizes (a body EDP and a head EDP) were used for the ρ{sub e} calibration. Each acquired lookup table was applied to two radiotherapy plans designed using the XiO TPS with the superposition algorithm for an anthropomorphic phantom. The first radiotherapy plan was for an oral cavity tumor and the second was for a lung tumor. Results: In both treatment plans, the performance of the ΔHU–ρ{sub e} conversion was superior to that of the conventional HU–ρ{sub e} conversion in terms of the reliability of dose calculations. Especially, for the oral tumor plan, which dealt with dentition and bony structures, treatment

  14. Reproductive success of Horned Lark and McCown's Longspur in relation to wind energy infrastructure

    Science.gov (United States)

    Mahoney, Anika; Chalfoun, Anna D.

    2016-01-01

    Wind energy is a rapidly expanding industry with potential indirect effects to wildlife populations that are largely unexplored. In 2011 and 2012, we monitored 211 nests of 2 grassland songbirds, Horned Lark (Eremophila alpestris) and McCown's Longspur (Rhynchophanes mccownii), at 3 wind farms and 2 undeveloped reference sites in Wyoming, USA. We evaluated several indices of reproductive investment and success: clutch size, size-adjusted nestling mass, daily nest survival rate, and number of fledglings. We compared reproductive success between wind farms and undeveloped sites and modeled reproductive success within wind farms as a function of wind energy infrastructure and habitat. Size-adjusted nestling mass of Horned Lark was weakly negatively related to turbine density. In 2011, nest survival of Horned Lark decreased 55% as turbine density increased from 10 to 39 within 2 km of the nest. In 2012, however, nest survival of Horned Lark was best predicted by the combination of vegetation height, distance to shrub edge, and turbine density, with survival increasing weakly with increasing vegetation height. McCown's Longspur nest survival was weakly positively related to vegetation density at the nest site when considered with the amount of grassland habitat in the neighborhood and turbine density within 1 km of the nest. Habitat and distance to infrastructure did not explain clutch size or number of fledglings for either species, or size-adjusted nestling mass for McCown's Longspur. Our results suggest that the influence of wind energy infrastructure varies temporally and by species, even among species using similar habitats. Turbine density was repeatedly the most informative measure of wind energy development. Turbine density could influence wildlife responses to wind energy production and may become increasingly important to consider as development continues in areas with high-quality wind resources.

  15. Effects of gradient encoding and number of signal averages on fractional anisotropy and fiber density index in vivo at 1.5 tesla.

    Science.gov (United States)

    Widjaja, E; Mahmoodabadi, S Z; Rea, D; Moineddin, R; Vidarsson, L; Nilsson, D

    2009-01-01

    Tensor estimation can be improved by increasing the number of gradient directions (NGD) or increasing the number of signal averages (NSA), but at a cost of increased scan time. To evaluate the effects of NGD and NSA on fractional anisotropy (FA) and fiber density index (FDI) in vivo. Ten healthy adults were scanned on a 1.5T system using nine different diffusion tensor sequences. Combinations of 7 NGD, 15 NGD, and 25 NGD with 1 NSA, 2 NSA, and 3 NSA were used, with scan times varying from 2 to 18 min. Regions of interest (ROIs) were placed in the internal capsules, middle cerebellar peduncles, and splenium of the corpus callosum, and FA and FDI were calculated. Analysis of variance was used to assess whether there was a difference in FA and FDI of different combinations of NGD and NSA. There was no significant difference in FA of different combinations of NGD and NSA of the ROIs (P>0.005). There was a significant difference in FDI between 7 NGD/1 NSA and 25 NGD/3 NSA in all three ROIs (PNSA, 25 NGD/1 NSA, and 25 NGD/2 NSA and 25 NGD/3 NSA in all ROIs (P>0.005). We have not found any significant difference in FA with varying NGD and NSA in vivo in areas with relatively high anisotropy. However, lower NGD resulted in reduced FDI in vivo. With larger NGD, NSA has less influence on FDI. The optimal sequence among the nine sequences tested with the shortest scan time was 25 NGD/1 NSA.

  16. Wind energy in Europe

    International Nuclear Information System (INIS)

    Evans, L.C.

    1992-01-01

    Wind energy should be an important part of the energy supply mix, both at home and abroad, to provide cleaner air and a more stable fuel supply. Not only can wind energy contribute to solving complex global issues, it also can provide a large market for American technological leadership. Even though utilities are paying more attention to wind in a number of states, there are no plans for major installations of wind power plants in the United States. At the same time, European nations have developed aggressive wind energy development programs, including both ambitious research and development efforts and market incentives. Many countries recognize the importance of the clean energy provided by wind technology and are taking steps to promote their fledgling domestic industries. The emphasis on market incentives is starting to pay off. In 1991, European utilities and developers installed nearly twice as much wind capacity as Americans did. In 1992 the gap will be even greater. This article reviews aggressive incentives offered by European governments to boost their domestic wind industries at home and abroad in this almost $1 billion per year market. By offering substantial incentives - considerably more than the American Wind Energy Association (AWEA) is proposing - European nations are ensuring dramatic near-term wind energy development and are taking a major step toward dominating the international wind industry of the 21st century

  17. A method to determine exactly the effective atomic number, electron density and absorbtion coefficient of materials from two Computer-Tomography measurement

    International Nuclear Information System (INIS)

    Christ, G.

    1981-01-01

    By the method of computer tomography, which is in use since about 10 years, X-ray images of a layer of interest can be produced without interference from the material present above this layer. An integral measurement of the attenuation of continuous X-radiation is sufficient to record the different attenuation behaviour in a layer for the purpose of image formation. For more information, however, can be obtained by taking into account the spectral distribution of the X-ray source and the energy dependence of the attenuation, which varies for different materials. In the experimental part of this work the measurement of the spectral distribution is described together with the necessary corrections, and the possible application of the cross sections for the relevant interaction processes, which are known from the literature is studied. As shown in the theoretical part, the attenuation coefficient can be described by an effective atomic number and the electron density of the absorber in the case of an arbitrary mixture of absorbing materials and a continuous X-ray spectrum. These two unknown material parameters can be determined by a method based on the measurement of two spectra with different spectral distribution. This is demonstrated by a one-dimensional and a two-dimensional computer simulation. (orig./WU) [de

  18. Chemical composition, effective atomic number and electron density study of trommel sieve waste (TSW), Portland cement, lime, pointing and their admixtures with TSW in different proportions

    International Nuclear Information System (INIS)

    Kurudirek, Murat; Aygun, Murat; Erzeneoglu, Salih Zeki

    2010-01-01

    The trommel sieve waste (TSW) which forms during the boron ore production is considered to be a promising building material with its use as an admixture with Portland cement and is considered to be an alternative radiation shielding material, also. Thus, having knowledge on the chemical composition and radiation interaction properties of TSW as compared to other building materials is of importance. In the present study, chemical compositions of the materials used have been determined using a wavelength dispersive X-ray fluorescence spectrometer (WDXRFS). Also, TSW, some commonly used building materials (Portland cement, lime and pointing) and their admixtures with TSW have been investigated in terms of total mass attenuation coefficients (μ/ρ), photon interaction cross sections (σ t ), effective atomic numbers (Z eff ) and effective electron densities (N e ) by using X-rays at 22.1, 25 keV and γ-rays at 88 keV photon energies. Possible conclusions were drawn with respect to the variations in photon energy and chemical composition.

  19. An appraisal of wind speed distribution prediction by soft computing methodologies: A comparative study

    International Nuclear Information System (INIS)

    Petković, Dalibor; Shamshirband, Shahaboddin; Anuar, Nor Badrul; Saboohi, Hadi; Abdul Wahab, Ainuddin Wahid; Protić, Milan; Zalnezhad, Erfan; Mirhashemi, Seyed Mohammad Amin

    2014-01-01

    Highlights: • Probabilistic distribution functions of wind speed. • Two parameter Weibull probability distribution. • To build an effective prediction model of distribution of wind speed. • Support vector regression application as probability function for wind speed. - Abstract: The probabilistic distribution of wind speed is among the more significant wind characteristics in examining wind energy potential and the performance of wind energy conversion systems. When the wind speed probability distribution is known, the wind energy distribution can be easily obtained. Therefore, the probability distribution of wind speed is a very important piece of information required in assessing wind energy potential. For this reason, a large number of studies have been established concerning the use of a variety of probability density functions to describe wind speed frequency distributions. Although the two-parameter Weibull distribution comprises a widely used and accepted method, solving the function is very challenging. In this study, the polynomial and radial basis functions (RBF) are applied as the kernel function of support vector regression (SVR) to estimate two parameters of the Weibull distribution function according to previously established analytical methods. Rather than minimizing the observed training error, SVR p oly and SVR r bf attempt to minimize the generalization error bound, so as to achieve generalized performance. According to the experimental results, enhanced predictive accuracy and capability of generalization can be achieved using the SVR approach compared to other soft computing methodologies

  20. Low Reynolds Number Vehicles

    Science.gov (United States)

    1985-02-01

    of the blade. The Darrieus VAWT has more complex aerodynamics. This type of wind turbine produces power as a result of the tangential thrust as...Horizontal Axis Propeller-Type b) Verticle Axis Darrieus -Type Figure 78. Wind Turbine Configurations 0 6 Q K [_ 2 -, C 4 UJ UJ...Sailplanes 23 5.2 Wind Turbines 23 6. CONCLUDING REMARKS 24 7. RECOMMENDATIONS FOR FUTURE RESEARCH 24 REFERENCES 25 FIGURES 32 yv/ LOW REYNOLDS NUMBER

  1. The potential of wind farms

    Energy Technology Data Exchange (ETDEWEB)

    1992-01-01

    Summaries of papers presented at the European wind energy conference on the potential of wind farms are presented. It is stated that in Denmark today, wind energy provides about 3% to the Danish electricity consumption and the wind power capacity is, according to Danish wind energy policy, expected to increase substantially in the years to come. A number of countries in Europe and elsewhere are making significant progress in this repect. Descriptions of performance are given in relation to some individual wind farms. The subjects covered concern surveys of national planning and policies regarding wind utilization and national and global development of wind turbine arrays. Papers also deal with utility and project planning, wind prediction and certification, wind loads and fatigue, wakes, noise and control. (AB).

  2. Potential power density and power generation of wind parks. Share of regional wind power generation in consumption for a ''2% scenario''; Potenzielle Leistungsdichte und Stromerzeugung von Windparks. Anteil der regionalen Windstromerzeugung am Verbrauch fuer ein ''2 %-Szenario''

    Energy Technology Data Exchange (ETDEWEB)

    Konetschny, Claudia; Schmid, Tobias; Jetter, Fabian [Forschungsstelle fuer Energiewirtschaft (FfE) e.V., Muenchen (Germany)

    2017-05-15

    Targets for wind energy use are given in different units. In addition to the number of plants, the power and the annual electricity generation, an information of a surface to be used for the use of wind power has become increasingly established. However, the relationships between area consumption, installed power and generated current are not approximately linear. On the basis of a small-scale modeling of the addition of wind energy installations using the wind resource tools WiSTl developed by the Research Center for Energy Economics (FfE), the article provides recommendations for the conversion of the area identified. In addition, the share of electricity generation based on a 2% scenario of power generation from wind power plants of the electricity consumption will be determined for each Federal State. [German] Ziele zur Windenergienutzung werden in verschiedenen Einheiten angegeben. Neben der Anzahl an Anlagen, der Leistung und der jaehrlichen Stromerzeugung hat sich zunehmend die Angabe einer fuer die Windkraftnutzung auszuweisenden Flaeche etabliert. Die Zusammenhaenge zwischen Flaechenverbrauch, installierter Leistung und erzeugter Strommenge sind jedoch nicht annaehernd linear. Anhand einer kleinteiligen Modeliierung des Zubaus von Windenergieanlagen mithilfe des von der Forschungsstelle fuer Energiewirtschaft (FfE) entwickelten Windszenario-Tools WiSTl gibt der Artikel Empfehlungen zur Umrechnung der ausgewiesenen Flaeche. Zusaetzlich wird basierend auf einem 2 %-Szenario der Anteil der Stromerzeugung aus Windenergieanlagen am Stromverbrauch je Bundesland bestimmt.

  3. A modified model of axial flux permanent magnet generator for wind turbine applications

    International Nuclear Information System (INIS)

    Ashraf, M.M.

    2014-01-01

    The Axial Flux Permanent Magnet Generators (AFPMGs) are gaining immense attention in the modern era. The single stage AFPMG topology consists of one stator disc which is held stationery between two revolving rotor discs attached with a common shaft. The number of poles of AFPMG depends on the winding pattern in which the coils are connected in series within stator disc. Connecting the coils in begin-to-end winding pattern, doubles the number of poles which also increases the active mass of AFPMG. The AFPMG considering begin-to-end winding pattern, can be operated at half shaft speed. This AFPMG is also having greater air gap flux density which, ultimately, improves the power density parameter of AFPMG. In this paper, a modified AFPMG has been proposed which is designed by considering begin-to-end winding pattern. A 380W single phase, single stage prototype model has been developed and tested. The test results show that power density of designed AFPMG with begin-to-end winding pattern has been improved by 32% as compared to AFPMG with begin-to-begin winding pattern. The proposed low speed and high power density AFPMG model can be actively deployed for wind turbine applications. (author)

  4. Wind Energy

    International Nuclear Information System (INIS)

    Rodriguez D, J.M.

    1998-01-01

    The general theory of the wind energy conversion systems is presented. The availability of the wind resource in Colombia and the ranges of the speed of the wind in those which is possible economically to use the wind turbines are described. It is continued with a description of the principal technological characteristics of the wind turbines and are split into wind power and wind-powered pumps; and its use in large quantities grouped in wind farms or in autonomous systems. Finally, its costs and its environmental impact are presented

  5. Wind energy statistics

    International Nuclear Information System (INIS)

    Holttinen, H.; Tammelin, B.; Hyvoenen, R.

    1997-01-01

    The recording, analyzing and publishing of statistics of wind energy production has been reorganized in cooperation of VTT Energy, Finnish Meteorological (FMI Energy) and Finnish Wind Energy Association (STY) and supported by the Ministry of Trade and Industry (KTM). VTT Energy has developed a database that contains both monthly data and information on the wind turbines, sites and operators involved. The monthly production figures together with component failure statistics are collected from the operators by VTT Energy, who produces the final wind energy statistics to be published in Tuulensilmae and reported to energy statistics in Finland and abroad (Statistics Finland, Eurostat, IEA). To be able to verify the annual and monthly wind energy potential with average wind energy climate a production index in adopted. The index gives the expected wind energy production at various areas in Finland calculated using real wind speed observations, air density and a power curve for a typical 500 kW-wind turbine. FMI Energy has produced the average figures for four weather stations using the data from 1985-1996, and produces the monthly figures. (orig.)

  6. Subtidal hydrodynamics in a tropical lagoon: A dimensionless numbers approach

    Science.gov (United States)

    Tenorio-Fernandez, L.; Valle-Levinson, A.; Gomez-Valdes, J.

    2018-01-01

    Observations in a tropical lagoon of the Yucatan peninsula motivated a non-dimensional number analysis to examine the relative influence of tidal stress, density gradients and wind stress on subtidal hydrodynamics. A two-month observation period in Chelem Lagoon covered the transition from the dry to the wet season. Chelem Lagoon is influenced by groundwater inputs and exhibits a main sub-basin (central sub-basin), a west sub-basin and an east sub-basin. Subtidal hydrodynamics were associated with horizontal density gradients that were modified seasonally by evaporation, precipitation, and groundwater discharge. A tidal Froude number (Fr0), a Wedderburn number (W), and a Stress ratio (S0) were used to diagnose the relative importance of dominant subtidal driving forces. The Froude number (Fr0) compares tidal forcing and baroclinic forcing through the ratio of tidal stress to longitudinal baroclinic pressure gradient. The Wedderburn number (W) relates wind stress to baroclinicity. The stress ratio (S0) sizes tidal stress and wind stress. S0 is a new diagnostic tool for systems influenced by tides and winds, and represents the main contribution of this research. Results show that spring-tide subtidal flows in the tropical lagoon had log(Fr0) ≫ 0 and log(S0) > 0 , i.e., driven mainly by tidal stresses (advective accelerations). Neap tides showed log(Fr0) ≪ 0 and log(S0) < 0) , i.e., flows driven by baroclinicity, especially at the lagoon heads of the east and west sub-basins. However, when the wind stress intensified over the lagoon, the relative importance of baroclinicity decreased and the wind stress controlled the dynamics (log(W) ≫ 0). Each sub-basin exhibited a different subtidal response, according to the dimensionless numbers. The response depended on the fortnightly tidal cycle, the location and magnitude of groundwater input, and the direction and magnitude of the wind stress.

  7. Wind energy potential in India

    International Nuclear Information System (INIS)

    Rangarajan, S.

    1995-01-01

    Though located in the tropics, India is endowed with substantial wind resources because of its unique geographical location which gets fully exposed to both the south-west and north-east monsoon winds. The westerly winds of the south-west monsoons provide bulk of the wind potential. Areas with mean annual wind speed exceeding 18 k mph and areas with mean annual power density greater than 140 W/m 2 have been identified using the wind data collected by the wind monitoring project funded by the Ministry of Non-conventional Energy Sources (MNES). Seasonal variations in wind speed at selected locations are discussed as also the frequency distribution of hourly wind speed. Annual capacity factors for 250 kW wind electric generators have been calculated for several typical locations. A good linear correlation has been found between mean annual wind speed and mean annual capacity factor. A method is described for assessing wind potential over an extended region where adequate data is available. It is shown that the combined wind energy potential over five selected areas of limited extent in Gujarat, Andhra Pradesh and Tamil Nadu alone amounts to 22,000 MW under the assumption of 20 per cent land availability for installing wind farms. For a higher percentage of land availability, the potential will be correspondingly higher. (author). 12 refs., 6 figs., 3 tabs

  8. SMES for wind energy systems

    Science.gov (United States)

    Paul Antony, Anish

    Renewable energy sources are ubiquitous, wind energy in particular is one of the fastest growing forms of renewable energy, yet the stochastic nature of wind creates fluctuations that threaten the stability of the electrical grid. In addition to stability with increased wind energy, the need for additional load following capability is a major concern hindering increased wind energy penetration. Improvements in power electronics are required to increase wind energy penetration, but these improvements are hindered by a number of limitations. Changes in physical weather conditions, insufficient capacity of the transmission line and inaccurate wind forecasting greatly stymie their effect and ultimately lead to equipment damage. With this background, the overall goal of this research effort is to pitch a case for superconducting magnetic energy storage (SMES) by (1) optimally designing the SMES to be coupled with wind turbines thus reducing wind integration challenges and (2) to help influence decision makers in either increasing superconducting wire length/fill factor or improving superconducting splice technology thereby increasing the storage capacity of the SMES. Chapter 1 outlines the scope of this thesis by answering the following questions (1) why focus on wind energy? (2) What are the problems associated with increasing wind energy on the electric grid? (3) What are the current solutions related to wind integration challenges and (4) why SMES? Chapter 2, presents a detailed report on the study performed on categorizing the challenges associated with integrating wind energy into the electric grid. The conditions under which wind energy affected the electric grid are identified both in terms of voltage stability and excess wind generation. Chapter 3, details a comprehensive literature review on the different superconducting wires. A technology assessment of the five selected superconductors: [Niobium Titanium (NbTi), Niobium Tin (Nb3Sn), Bismuth strontium calcium

  9. Stability investigation of a high number density Pt1/Fe2O3 single-atom catalyst under different gas environments by HAADF-STEM

    Science.gov (United States)

    Duan, Sibin; Wang, Rongming; Liu, Jingyue

    2018-05-01

    Catalysis by supported single metal atoms has demonstrated tremendous potential for practical applications due to their unique catalytic properties. Unless they are strongly anchored to the support surfaces, supported single atoms, however, are thermodynamically unstable, which poses a major obstacle for broad applications of single-atom catalysts (SACs). In order to develop strategies to improve the stability of SACs, we need to understand the intrinsic nature of the sintering processes of supported single metal atoms, especially under various gas environments that are relevant to important catalytic reactions. We report on the synthesis of high number density Pt1/Fe2O3 SACs using a facial strong adsorption method and the study of the mobility of these supported Pt single atoms at 250 °C under various gas environments that are relevant to CO oxidation, water–gas shift, and hydrogenation reactions. Under the oxidative gas environment, Fe2O3 supported Pt single atoms are stable even at high temperatures. The presence of either CO or H2 molecules in the gas environment, however, facilitates the movement of the Pt atoms. The strong interaction between CO and Pt weakens the binding between the Pt atoms and the support, facilitating the movement of the Pt single atoms. The dissociation of H2 molecules on the Pt atoms and their subsequent interaction with the oxygen species of the support surfaces dislodge the surface oxygen anchored Pt atoms, resulting in the formation of Pt clusters. The addition of H2O molecules to the CO or H2 significantly accelerates the sintering of the Fe2O3 supported Pt single atoms. An anchoring-site determined sintering mechanism is further proposed, which is related to the metal–support interaction.

  10. Increasing the number of unloading/reambulation cycles does not adversely impact body composition and lumbar bone mineral density but reduces tissue sensitivity

    Science.gov (United States)

    Gupta, Shikha; Manske, Sarah L.; Judex, Stefan

    2013-11-01

    A single exposure to hindlimb unloading leads to changes in body mass, body composition and bone, but the consequences of multiple exposures are not yet understood. Within a 18 week period, adult C57BL/6 male mice were exposed to 1 (1x-HLU), 2 (2x-HLU) or 3 (3x-HLU) cycles of 2 weeks of hindlimb unloading (HLU) followed by 4 weeks of reambulation (RA), or served as ambulatory age-matched controls. In vivo μCT longitudinally tracked changes in abdominal adipose and lean tissues, lumbar vertebral apparent volumetric bone mineral density (vBMD) and upper hindlimb muscle cross-sectional area before and after the final HLU and RA cycle. During the final HLU cycle, significant decreases in total adipose tissue and vertebral vBMD in the three experimental groups occurred such that there were no significant between-group differences at the beginning of the final RA cycle. However, the magnitude of the HLU induced losses diminished in mice undergoing their 2nd or 3rd HLU cycle. Irrespective of the number of HLU/RA cycles, total adipose tissue and vertebral vBMD recovered and were no different from age-matched controls after the final RA period. In contrast, upper hindlimb muscle cross-sectional area was significantly lower than controls in all unloaded groups after the final RA period. These results suggest that tissues in the abdominal region are more resilient to multiple bouts of unloading and more amenable to recovery during reambulation than the peripheral musculoskeletal system.

  11. Calculation of effective atomic number and electron density of essential biomolecules for electron, proton, alpha particle and multi-energetic photon interactions

    Science.gov (United States)

    Kurudirek, Murat; Onaran, Tayfur

    2015-07-01

    Effective atomic numbers (Zeff) and electron densities (Ne) of some essential biomolecules have been calculated for total electron interaction, total proton interaction and total alpha particle interaction using an interpolation method in the energy region 10 keV-1 GeV. Also, the spectrum weighted Zeff for multi-energetic photons has been calculated using Auto-Zeff program. Biomolecules consist of fatty acids, amino acids, carbohydrates and basic nucleotides of DNA and RNA. Variations of Zeff and Ne with kinetic energy of ionizing charged particles and effective photon energies of heterogeneous sources have been studied for the given materials. Significant variations in Zeff and Ne have been observed through the entire energy region for electron, proton and alpha particle interactions. Non-uniform variation has been observed for protons and alpha particles in low and intermediate energy regions, respectively. The maximum values of Zeff have found to be in higher energies for total electron interaction whereas maximum values have found to be in relatively low energies for total proton and total alpha particle interactions. When it comes to the multi-energetic photon sources, it has to be noted that the highest Zeff values were found at low energy region where photoelectric absorption is the pre-dominant interaction process. The lowest values of Zeff have been shown in biomolecules such as stearic acid, leucine, mannitol and thymine, which have highest H content in their groups. Variation in Ne seems to be more or less the same with the variation in Zeff for the given materials as expected.

  12. The Number Density Evolution of Extreme Emission Line Galaxies in 3D-HST: Results from a Novel Automated Line Search Technique for Slitless Spectroscopy

    Science.gov (United States)

    Maseda, Michael V.; van der Wel, Arjen; Rix, Hans-Walter; Momcheva, Ivelina; Brammer, Gabriel B.; Franx, Marijn; Lundgren, Britt F.; Skelton, Rosalind E.; Whitaker, Katherine E.

    2018-02-01

    The multiplexing capability of slitless spectroscopy is a powerful asset in creating large spectroscopic data sets, but issues such as spectral confusion make the interpretation of the data challenging. Here we present a new method to search for emission lines in the slitless spectroscopic data from the 3D-HST survey utilizing the Wide-Field Camera 3 on board the Hubble Space Telescope. Using a novel statistical technique, we can detect compact (extended) emission lines at 90% completeness down to fluxes of 1.5(3.0)× {10}-17 {erg} {{{s}}}-1 {{cm}}-2, close to the noise level of the grism exposures, for objects detected in the deep ancillary photometric data. Unlike previous methods, the Bayesian nature allows for probabilistic line identifications, namely redshift estimates, based on secondary emission line detections and/or photometric redshift priors. As a first application, we measure the comoving number density of Extreme Emission Line Galaxies (restframe [O III] λ5007 equivalent widths in excess of 500 Å). We find that these galaxies are nearly 10× more common above z ∼ 1.5 than at z ≲ 0.5. With upcoming large grism surveys such as Euclid and WFIRST, as well as grisms featured prominently on the NIRISS and NIRCam instruments on the James Webb Space Telescope, methods like the one presented here will be crucial for constructing emission line redshift catalogs in an automated and well-understood manner. This work is based on observations taken by the 3D-HST Treasury Program and the CANDELS Multi-Cycle Treasury Program with the NASA/ESA HST, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

  13. Wind Energy Systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Ma, Ke

    2017-01-01

    transmission networks at the scale of hundreds of megawatts. As its level of grid penetration has begun to increase dramatically, wind power is starting to have a significant impact on the operation of the modern grid system. Advanced power electronics technologies are being introduced to improve......Wind power now represents a major and growing source of renewable energy. Large wind turbines (with capacities of up to 6-8 MW) are widely installed in power distribution networks. Increasing numbers of onshore and offshore wind farms, acting as power plants, are connected directly to power...... the characteristics of the wind turbines, and make them more suitable for integration into the power grid. Meanwhile, there are some emerging challenges that still need to be addressed. This paper provides an overview and discusses some trends in the power electronics technologies used for wind power generation...

  14. Wind power in France

    International Nuclear Information System (INIS)

    Tuille, F.; Courtel, J.

    2015-01-01

    After 3 years of steady decreasing, wind power has resumed growth in 2014 in France and the preliminary figures of 2015 confirm this trend. About 1100 MW were installed in 2014 which was almost twice as much as it was installed the year before. This renaissance is mostly due to the implementation of Brottes' law that eases the installations of wind farms by suppressing the wind power development areas (that were interfering with regional wind power schemes) and by suppressing the minimum number of 5 turbines for any new wind farms. Another important incentive measure was the announcement in January 2015 of a new financial support scheme in replacement of the policy of guaranteed purchase price for the electricity produced. In 2014 the total wind power produced in mainland France reached 17 TW which represented 3.1% of the production of electricity. (A.C.)

  15. Satellite information for wind energy applications

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, M.; Astrup, P.; Bay Hasager, C.

    2004-11-01

    An introduction to satellite information relevant for wind energy applications is given. It includes digital elevation model (DEM) data based on satellite observations. The Shuttle Radar Topography Mission (SRTM) is useful for regional scale wind resource studies. Comparison results from complex terrain in Spain and flat terrain in Denmark are found to be acceptable for both sites. Also land cover type information can be retrieved from satellite observations. Land cover type maps have to be combined with roughness data from field observation or literature values. Land cover type maps constitute an aid to map larger regions within shorter time. Field site observations of obstacles and hedges are still necessary. The raster-based map information from DEM and land cover maps can be converted for use in WASP. For offshore locations it is possible to estimate the wind resources based on ocean surface wind data from several types of satellite observations. The RWT software allows an optimal calculation of SAR wind resource statistics. A tab-file with SAR-based observed wind climate (OWC) data can be obtained for 10 m above sea level and used in WASP. RWT uses a footprint averaging technique to obtain data as similar as possible to mast observations. Maximum-likelihood fitting is used to calculate the Weibull A and k parameters from the constrained data set. Satellite SAR wind maps cover the coastal zone from 3 km and offshore with very detailed information of 400 m by 400 m grid resolution. Spatial trends in mean wind, energy density, Weibull A and k and uncertainty values are provided for the area of interest. Satellite scatterometer wind observations have a spatial resolution of 25 km by 25 km. These data typically represent a site further offshore, and the tab-file statistics should be used in WASP combined with topography and roughness information to assess the coastal wind power potential. Scatterometer wind data are observed {approx} twice per day, whereas SAR only

  16. Wind turbines and idiopathic symptoms

    DEFF Research Database (Denmark)

    Blanes-Vidal, Victoria; Schwartz, Joel

    2016-01-01

    Whether or not wind turbines pose a risk to human health is a matter of heated debate. Personal reactions to other environmental exposures occurring in the same settings as wind turbines may be responsible of the reported symptoms. However, these have not been accounted for in previous studies. We...... investigated whether there is an association between residential proximity to wind turbines and idiopathic symptoms, after controlling for personal reactions to other environmental co-exposures. We assessed wind turbine exposures in 454 residences as the distance to the closest wind turbine (Dw) and number...... of wind turbines

  17. Wind power - energy from air

    International Nuclear Information System (INIS)

    Alakangas, E.

    1998-01-01

    The wind conditions for wind power generation are favourable on the coast, in the archipelagos and in the fell areas of Finland. About 7 MW of wind power has been constructed in Finland, with the investment support of the Ministry of Trade and Industry. In 1995 about 11 GWh were produced by wind energy. A number of wind power plants are under design on the coasts of the Gulf of Finland and the Gulf of Bothnia as well as on the Aaland Islands. The first arctic wind park was constructed in Lapland in September 1996

  18. Relationships of storm-time changes in thermospheric mass density with solar wind/IMF parameters and ring current index of Sym-H

    Science.gov (United States)

    Zhou, Yunliang; Ma, S. Y.; Xiong, Chao; Luehr, Hermann

    The total air mass densities at about 500 km altitude are derived using super-STAR accelerom-eter measurements onboard GRACE satellites for 25 great magnetic storms with minimum Dst less than 100 nT during 2002 to 2006 years. Taking NRLMSISE-00 model-predicted densities without active ap index input as a reference baseline of quiet-time mass density, the storm-time changes in upper thermospheric mass densities are obtained by subtraction for all the storm events and sorted into different grids of latitude by local time sector. The relationships of the storm-time density changes with various interplanetary parameters and magnetospheric ring current index of Sym-H are statistically investigated. The parameters include Akasofu energy coupling function, the merging electric field Em, the magnitude of IMF component in the GSM y-z plane etc. as calculated from OMNI data at 1 AU. It is found that the storm-time changes in the upper thermospheric mass density have the best linear correlation with the Sym-H index in general, showing nearly zero time delay at low-latitudes and a little time ahead at high-latitudes for most cases. Unexpectedly, the magnitude of IMF component in the y-z plane, Byz, shows correlation with storm-time mass density changes better and closer than Akasofu function and even Em. And, the mass density changes lag behind Byz about 1-4 hours for most cases at low-latitudes. The correlations considered above are local time dependent, showing the lowest at dusk sectors. For the largest superstorm of November 2003, the changes in mass density are correlated very closely with Byz, Em, and Sym-H index, showing correlation coefficients averaged over all latitudes in noon sector as high as 0.93, 0.91 and 0.90 separately. The physical factors controlling the lag times between the mass density changes at mid-low-latitudes and the interplanetary parameter variations are also analyzed. The results in this study may pro-vide useful suggestions for establishing

  19. Wind energy, status and opportunities

    International Nuclear Information System (INIS)

    Van Wijk, A.

    1994-01-01

    Wind energy is diffuse but was widely used before the industrial revolution. The first oil crisis triggered renewed interest in wind energy technology in remote areas. Winds develop when solar radiation reaches the earth's highly varied surface unevenly, creating temperature density and pressure differences. The earth's atmosphere has to circulate to transport heat from the tropics towards the poles. On a global scale, these atmospheric currents work as an immense energy transfer medium. Three main applications can be distinguished: wind pumps, off-grid applications and grid-connected applications. The total generating costs for wind turbine systems are determined by total investments costs, the life time, the operating and maintenance costs, the wind regime (the wind energy potential is proportional to v 3 where v is the wind speed), the efficiency and availability of the wind turbine. The main gains are achieved as a result of improved reliability. The optimum size of a wind turbine depends on the wind speed, the wind turbine costs, the construction costs, the environmental impact and the social costs. The value of wind energy depends on the application that is made of the energy generated and on the costs of alternatives, it can be calculated by the avoided costs of damage to flora, fauna and mankind due to acid rain deposition, enhancement of the greenhouse effect. The environmental aspects are bird hindrance, noise, telecommunication interference and safety. 2 tabs., 1 fig

  20. Aerodynamic interactions from reaction controls for lateral control of the M2-F2 lifting-body entry configuration at transonic and supersonic and supersonic Mach numbers. [wind tunnel tests

    Science.gov (United States)

    Bailey, R. O.; Brownson, J. J.

    1979-01-01

    Tests were conducted in the Ames 6 by 6 foot wind tunnel to determine the interaction of reaction jets for roll control on the M2-F2 lifting-body entry vehicle. Moment interactions are presented for a Mach number range of 0.6 to 1.7, a Reynolds number range of 1.2 x 10 to the 6th power to 1.6 x 10 to the 6th power (based on model reference length), an angle-of-attack range of -9 deg to 20 deg, and an angle-of-sideslip range of -6 deg to 6 deg at an angle of attack of 6 deg. The reaction jets produce roll control with small adverse yawing moment, which can be offset by horizontal thrust component of canted jets.

  1. Experimental evaluation of wall Mach number distributions of the octagonal test section proposed for NASA Lewis Research Center's altitude wind tunnel

    Science.gov (United States)

    Harrington, Douglas E.; Burley, Richard R.; Corban, Robert R.

    1986-01-01

    Wall Mach number distributions were determined over a range of test-section free-stream Mach numbers from 0.2 to 0.92. The test section was slotted and had a nominal porosity of 11 percent. Reentry flaps located at the test-section exit were varied from 0 (fully closed) to 9 (fully open) degrees. Flow was bled through the test-section slots by means of a plenum evacuation system (PES) and varied from 0 to 3 percent of tunnel flow. Variations in reentry flap angle or PES flow rate had little or no effect on the Mach number distributions in the first 70 percent of the test section. However, in the aft region of the test section, flap angle and PES flow rate had a major impact on the Mach number distributions. Optimum PES flow rates were nominally 2 to 2.5 percent wtih the flaps fully closed and less than 1 percent when the flaps were fully open. The standard deviation of the test-section wall Mach numbers at the optimum PES flow rates was 0.003 or less.

  2. Columbia Wind Farm number-sign 1 EIS: Botanical resources technical report for the Conservation and Renewable Energy System. Appendix B

    International Nuclear Information System (INIS)

    1995-01-01

    Jones and Stokes Associates conducted botanical investigations of the Conservation and Renewable Energy Systems (CARES) project site from April through July 1994. Presurvey investigations were conducted to gain information regarding potential special-status plant species and vegetation communities that might exist on the project area. Field surveys were conducted to determine the presence of special-status plant species, map and describe potential vegetation communities, and document the presence of other species onsite, including culturally important species. Field surveys also were used to identify possible mitigation measures as a means to reduce potential project impacts to botanical resources. Floristically, the project area is located in the Columbia Basin Province dominated by shrub-steppe grassland vegetation. Completion of the presurvey and field investigations documented that the project area is dominated by native bunchgrass communities. Field surveys also determined that no special-status plant species were found on the study area. Implementation of the project would result in moderately significant impacts to the vegetation resource. Impacts include the following direct impacts: removal or disturbance of approximately 38 hectares (95 acres) of vegetation, including 32 hectares (80 acres) of native, natural communities, from project construction and the initiation of development into relatively undisturbed native vegetation communities. Indirect impacts to vegetation are associated with impacts that could occur in the future. Ongoing activities that are required to maintain the site's function of producing wind power could result in vegetation trampling and removal of vegetation. This disturbance could create areas where invasive weeds could establish and provide a continual source of weed seed in the project area

  3. Wind power barometer

    International Nuclear Information System (INIS)

    2014-01-01

    The worldwide wind power increased by 12.4% in 2013 to reach 318.6 GW but the world market globally decreased by losing 10 GW: only 35.6 GW have been installed in 2013 which is even less than was installed in 2009. This activity contraction is mainly due to the collapse of the American market, American authorities having been late to decide to maintain federal incentives. The European wind power market also contracted in 2013 because of the lack of trust of the investors in the new energy policies of the European governments. In the rest of the world wind energy has kept on growing particularly in China and Canada. At the end of 2013 the cumulated wind power reached 117,73 GW in Europe. About 1.5 MW out of 10 MW of wind power installed in Europe in 2013 come from off-shore wind farms, United-Kingdom and Denmark being the most important players by totalling more than 70% of the off-shore wind power installed at the end of 2013. Various charts and tables give the figures of the wind power cumulated and installed in 2013 in different parts of the world: Europe, North America and Asia, the time evolution of the worldwide wind power since 1995, the wind power cumulated and installed in 2013 for the different countries of Europe and the ratio between the cumulated wind power and the country population. A table lists the main manufacturers of wind turbines and gives their turnover and number of employees at the end of 2013

  4. Laboratory Facility for Simulating Solar Wind Sails

    International Nuclear Information System (INIS)

    Funaki, Ikkoh; Ueno, Kazuma; Oshio, Yuya; Ayabe, Tomohiro; Horisawa, Hideyuki; Yamakawa, Hiroshi

    2008-01-01

    Magnetic sail (MagSail) is a deep space propulsion system, in which an artificial magnetic cavity captures the energy of the solar wind to propel a spacecraft in the direction leaving the sun. For a scale-model experiment of the plasma flow of MagSail, we employed a magnetoplasmadynamic arcjet as a solar wind simulator. It is observed that a plasma flow from the solar wind simulator reaches a quasi-steady state of about 0.8 ms duration after a transient phase when initiating the discharge. During this initial phase of the discharge, a blast-wave was observed to develop radially in a vacuum chamber. When a solenoidal coil (MagSail scale model) is immersed into the quasi-steady flow where the velocity is 45 km/s, and the number density is 10 19 m-3, a bow shock as well as a magnetic cavity were formed in front of the coil. As a result of the interaction between the plasma flow and the magnetic cavity, the momentum of the simulated solar wind is decreased, and it is found from the thrust measurement that the solar wind momentum is transferred to the coil simulating MagSail.

  5. In Search of the Wind Energy Potential

    DEFF Research Database (Denmark)

    Lundtang Petersen, Erik

    2017-01-01

    The worldwide advancement of wind energy is putting high demands on a number of underlying technologies such as wind turbine aerodynamics, structural dynamics, gearbox design, electrical grid connections, and so on. As wind is the only fuel for wind power plants, naturally, wind......-meteorology and wind-climatology are essential for any utilization of wind energy. This is what we are concerned about here with a view on what has happened in wind energy potential assessments in the last 25 years where the utilization of wind turbines in national power supply has accelerated and what...... is the perspective for future improvements of the assessment methods. We take as the starting point the methodology of The European Wind Atlas [I. Troen and E. L. Petersen, European Wind Atlas (Risø National Laboratory, Roskilde, Denmark, 1989)]. From there to the global wind atlas methodology [J. Badger et al...

  6. Chemistry in T Tauri winds

    Energy Technology Data Exchange (ETDEWEB)

    Rawlings, J M.C.; Williams, D A; Canto, J

    1988-02-15

    The chemistry occurring in the winds of T Tauri stars is investigated. On the assumption that the wind is dust-free, then routes to H/sub 2/ are inhibited under the conditions in the wind, and subsequent chemistry does not produce substantial molecular abundances. The major losses to the chemical network lie in the geometrical dilution and collisional dissociation rather than in chemical destruction and photodissociation. Mass loading of the wind with dust and H/sub 2/ may, however, occur. This stimulates the chemistry and may in some circumstances lead to a conversion of approx.1-10 per cent of carbon into CO. This gives a column density of CO which is marginally detectable. A positive detection of CO at high wind velocities would imply that the winds must be cool and that mixing of molecular material from a disc, which may play a role in collimating the wind, or the remnants of a disc, must occur.

  7. Obtaining the conversion curve of CT numbers to electron density from the effective energy of the CT using the dummy SEFM

    International Nuclear Information System (INIS)

    Martin-Viera Cueto, J. A.; Garcia Pareja, S.; Benitez Villegas, E. M.; Moreno Saiz, E. M.; Bodineau Gil, C.; Caudepon Moreno, F.

    2011-01-01

    The objective of this work is to obtain the conversion curve of Hounsfield units (A) versus electron densities using a mannequin with different tissue equivalent materials. This provides for the effective energy beam CT and is used to characterize the linear coefficients of absorption of different materials that comprise the dummy.

  8. Measurement of the Lyman-alpha radiation at ionization manometers for determination of the hydrogen atom number density in fusion experiments

    International Nuclear Information System (INIS)

    Loercher, M.

    1990-01-01

    Codes like DEGAS which simulate the interaction of neutral gas with plasma (e.g. in a divertor), not only deliver the global density and flux of neutral particles, but also allow one, in addition, to distinguish between atoms and molecules. Whereas the global parameters of the neutral gas in a divertor can be measured by, for example, special ion gauges like those, which are installed in the divertor chamber, there has until now been no possibility of measuring the atomic and molecular density independently. In the frame of a diploma thesis (M. Loercher) an ASDEX neutral pressure gauge was modified in such a way that it delivers not only the global density of neutral particles (molecules and atoms) by ionization, but also the density of the atoms by measurement of the Lα-radiation produced by electron impact exitation. Owing to the very weak intensity the main effort was dedicated to developing a detector-filter combination which allows the Lα-radiation to be separated from, the H 2 bands in the VUV and be measured with a time resolution of at least of few ms. Several versions were tested theoretically and practically. The best solution was found to be a combination of an O 2 filter using MgF 2 windows and a multichannel plate. The arrangement was tested and calibrated with an atomic beam of known intensity from an oven. (orig.)

  9. How supernovae launch galactic winds?

    Science.gov (United States)

    Fielding, Drummond; Quataert, Eliot; Martizzi, Davide; Faucher-Giguère, Claude-André

    2017-09-01

    We use idealized three-dimensional hydrodynamic simulations of global galactic discs to study the launching of galactic winds by supernovae (SNe). The simulations resolve the cooling radii of the majority of supernova remnants (SNRs) and thus self-consistently capture how SNe drive galactic winds. We find that SNe launch highly supersonic winds with properties that agree reasonably well with expectations from analytic models. The energy loading (η _E= \\dot{E}_wind/ \\dot{E}_SN) of the winds in our simulations are well converged with spatial resolution while the wind mass loading (η _M= \\dot{M}_wind/\\dot{M}_\\star) decreases with resolution at the resolutions we achieve. We present a simple analytic model based on the concept that SNRs with cooling radii greater than the local scaleheight break out of the disc and power the wind. This model successfully explains the dependence (or lack thereof) of ηE (and by extension ηM) on the gas surface density, star formation efficiency, disc radius and the clustering of SNe. The winds our simulations are weaker than expected in reality, likely due to the fact that we seed SNe preferentially at density peaks. Clustering SNe in time and space substantially increases the wind power.

  10. The wind power of Mexico

    International Nuclear Information System (INIS)

    Hernandez-Escobedo, Q.; Manzano-Agugliaro, F.; Zapata-Sierra, A.

    2010-01-01

    The high price of fossil fuels and the environmental damage they cause have encouraged the development of renewable energy resources, especially wind power. This work discusses the potential of wind power in Mexico, using data collected every 10 min between 2000 and 2008 at 133 automatic weather stations around the country. The wind speed, the number of hours of wind useful for generating electricity and the potential electrical power that could be generated were estimated for each year via the modelling of a wind turbine employing a logistic curve. A linear correlation of 90.3% was seen between the mean annual wind speed and the mean annual number of hours of useful wind. Maps were constructed of the country showing mean annual wind speeds, useful hours of wind, and the electrical power that could be generated. The results show that Mexico has great wind power potential with practically the entire country enjoying more than 1700 h of useful wind per year and the potential to generate over 2000 kW of electrical power per year per wind turbine installed (except for the Chiapas's State). Indeed, with the exception of six states, over 5000 kW per year could be generated by each turbine. (author)

  11. Superconducting Wind Turbine Generators

    DEFF Research Database (Denmark)

    Mijatovic, Nenad

    A HTS machine could be a way to address some of the technical barriers offshore wind energy is about to face. Due to the superior power density of HTS machines, this technology could become a milestone on which many, including the wind industry, will rely in the future. The work presented...... in this thesis is a part of a larger endeavor, the Superwind project that focused on identifying the potentials that HTS machines could offer to the wind industry and addressing some of the challenges in the process. In order to identify these challenges, I have design and constructed a HTS machine experimental...... setup which is made to serve as precursor, leading towards an optimized HTS machine concept proposed for wind turbines. In part, the work presented in this thesis will focus on the description of the experimental setup and reasoning behind the choices made during the design. The setup comprises from...

  12. Wind energy

    International Nuclear Information System (INIS)

    Kotevski, Darko

    2003-01-01

    Wind is not only free, it is inexhaustible. Wind energy has come a very long way since the prototypes of just 20 years ago. today's wind turbines are state-of-the-art technology - modular and quick to install anywhere where there is sufficient wind potential to provide secure, centralised or distributed generation. It is a global phenomenon, the world's fastest growing energy sector, a clean and effective modern technology that completely avoids pollution and thus reducing the 'green house' effect. (Original)

  13. Statement on Wind Power

    Energy Technology Data Exchange (ETDEWEB)

    2010-01-15

    Wind power will grow in importance in future electricity supply. In the next few decades it will to some degree replace fossil power but it will, at the same time also depend on fossil-b beyond, when wind power is expected to have a substantial share of the electricity market, CO{sub 2} emission-free electricity plants that are well suited for balancing the wind intermittency will be required. Predictions of the future penetration of wind power into the electricity market are critically dependent on a number of policy measures and will be especially influenced by climate driven energy policies. Very large investments will also be necessary as is shown by the lEA's Blue Map Scenario which includes 5,000 TWh wind electricity by 2050 at a cost of USD 700 billion. This implies an average 8% increase of wind electricity per year energy system, i.e. an energy system so large that it affects the entire world. The Energy Committee's scenario for electricity production in the year 2050 includes 5,000 TWh wind electricity out of a total of 45,000 TWh. Wind electricity thus has a within presently reached penetration of wind energy in a single country and within the calculated future projections of its penetration. Future large continental and intercontinental power grids may enable higher penetrations of wind energy since contributions of wind power from a larger area will tend to reduce its intermittency. Also, large-scale storage systems (thermal storage as is intermittent power systems. These alternatives have been discussed from a technical point of view [3] but for the required large-scale systems, further studies on the social, environmental and economical implications are needed

  14. Effects of power densities, continuous and pulse frequencies, and number of sessions of low-level laser therapy on intact rat brain.

    Science.gov (United States)

    Ilic, Sanja; Leichliter, Sandra; Streeter, Jackson; Oron, Amir; DeTaboada, Luis; Oron, Uri

    2006-08-01

    The aim of the present study was to investigate the possible short- and long-term adverse neurological effects of low-level laser therapy (LLLT) given at different power densities, frequencies, and modalities on the intact rat brain. LLLT has been shown to modulate biological processes depending on power density, wavelength, and frequency. To date, few well-controlled safety studies on LLLT are available. One hundred and eighteen rats were used in the study. Diode laser (808 nm, wavelength) was used to deliver power densities of 7.5, 75, and 750 mW/cm2 transcranially to the brain cortex of mature rats, in either continuous wave (CW) or pulse (Pu) modes. Multiple doses of 7.5 mW/cm2 were also applied. Standard neurological examination of the rats was performed during the follow-up periods after laser irradiation. Histology was performed at light and electron microscopy levels. Both the scores from standard neurological tests and the histopathological examination indicated that there was no long-term difference between laser-treated and control groups up to 70 days post-treatment. The only rats showing an adverse neurological effect were those in the 750 mW/cm2 (about 100-fold optimal dose), CW mode group. In Pu mode, there was much less heating, and no tissue damage was noted. Long-term safety tests lasting 30 and 70 days at optimal 10x and 100x doses, as well as at multiple doses at the same power densities, indicate that the tested laser energy doses are safe under this treatment regime. Neurological deficits and histopathological damage to 750 mW/cm2 CW laser irradiation are attributed to thermal damage and not due to tissue-photon interactions.

  15. Total, accessible and reserve wind energy resources in Bulgaria

    International Nuclear Information System (INIS)

    Ivanov, P.; Trifonova, L.

    1996-01-01

    The article is a part of the international project 'Bulgaria Country Study to Address Climate Change Inventory of the Greenhouse Gases Emission and Sinks Alternative Energy Balance and Technology Programs' sponsored by the Department of Energy, US. The 'total' average annual wind resources in Bulgaria determined on the basis wind velocity density for more than 100 meteorological stations are estimated on 125 000 TWh. For the whole territory the theoretical wind power potential is about 14200 GW. The 'accessible' wind resources are estimated on about 62000 TWh. The 'reserve' (or usable) wind resources are determined using 8 velocity intervals for WECS (Wind Energy Conversion Systems) operation, number and disposition of turbines, and the usable (3%) part of the territory. The annual reserve resources are estimated at about 21 - 33 TWh. The 'economically beneficial' wind resources (EBWR) are those part of the reserve resources which could be included in the country energy balance using specific technologies in specific time period. It is foreseen that at year 2010 the EBWR could reach 0.028 TWh. 7 refs., 2 tabs., 1 fig

  16. Sensing the wind profile

    Energy Technology Data Exchange (ETDEWEB)

    Pena, A.

    2009-03-15

    This thesis consists of two parts. The first is a synopsis of the theoretical progress of the study that is based on a number of journal papers. The papers, which constitute the second part of the report, aim to analyze, measure, and model the wind prole in and beyond the surface layer by combining observations from cup anemometers with lidars. The lidar is necessary to extend the measurements on masts at the Horns Rev offshore wind farm and over at land at Hoevsoere, Denmark. Both sensing techniques show a high degree of agreement for wind speed measurements performed at either sites. The wind speed measurements are averaged for several stability conditions and compare well with the surface-layer wind profile. At Hoevsoere, it is sufficient to scale the wind speed with the surface friction velocity, whereas at Horns Rev a new scaling is added, due to the variant roughness length. This new scaling is coupled to wind prole models derived for flow over the sea and tested against the wind proles up to 160 m at Horns Rev. The models, which account for the boundary-layer height in stable conditions, show better agreement with the measurements than compared to the traditional theory. Mixing-length parameterizations for the neutral wind prole compare well with length-scale measurements up to 300 m at Hoevsoere and 950 m at Leipzig. The mixing-length-derived wind proles strongly deviate from the logarithmic wind prole, but agree better with the wind speed measurements. The length-scale measurements are compared to the length scale derived from a spectral analysis performed up to 160 m at Hoevsoere showing high agreement. Mixing-length parameterizations are corrected to account for stability and used to derive wind prole models. These compared better to wind speed measurements up to 300 m at Hoevsoere than the surface-layer wind prole. The boundary-layer height is derived in nearneutral and stable conditions based on turbulent momentum uxes only and in unstable conditions

  17. Small Wind Turbine Technology Assessment

    International Nuclear Information System (INIS)

    Avia Aranda, F.; Cruz Cruz, I.

    1999-01-01

    The result of the study carried out under the scope of the ATYCA project Test Plant of Wind Systems for Isolated Applications, about the state of art of the small wind turbine technology (wind turbines with swept area smaller than 40 m 2 ) is presented. The study analyzes the collected information on 60 models of wind turbines from 23 manufacturers in the worldwide market. Data from Chinese manufacturers, that have a large participation in the total number of small wind turbines in operation, are not included, due to the unavailability of the technical information. (Author) 15 refs

  18. Modeling wind speed and wind power distributions in Rwanda

    Energy Technology Data Exchange (ETDEWEB)

    Safari, Bonfils [Department of Physics, National University of Rwanda, P.O. Box 117, Huye District, South Province (Rwanda)

    2011-02-15

    Utilization of wind energy as an alternative energy source may offer many environmental and economical advantages compared to fossil fuels based energy sources polluting the lower layer atmosphere. Wind energy as other forms of alternative energy may offer the promise of meeting energy demand in the direct, grid connected modes as well as stand alone and remote applications. Wind speed is the most significant parameter of the wind energy. Hence, an accurate determination of probability distribution of wind speed values is very important in estimating wind speed energy potential over a region. In the present study, parameters of five probability density distribution functions such as Weibull, Rayleigh, lognormal, normal and gamma were calculated in the light of long term hourly observed data at four meteorological stations in Rwanda for the period of the year with fairly useful wind energy potential (monthly hourly mean wind speed anti v{>=}2 m s{sup -1}). In order to select good fitting probability density distribution functions, graphical comparisons to the empirical distributions were made. In addition, RMSE and MBE have been computed for each distribution and magnitudes of errors were compared. Residuals of theoretical distributions were visually analyzed graphically. Finally, a selection of three good fitting distributions to the empirical distribution of wind speed measured data was performed with the aid of a {chi}{sup 2} goodness-of-fit test for each station. (author)

  19. Wind Structure and Wind Loading

    DEFF Research Database (Denmark)

    Brorsen, Michael

    The purpose of this note is to provide a short description of wind, i.e. of the flow in the atmosphere of the Earth and the loading caused by wind on structures. The description comprises: causes to the generation of windhe interaction between wind and the surface of the Earthhe stochastic nature...

  20. Wind power

    International Nuclear Information System (INIS)

    Gipe, P.

    2007-01-01

    This book is a translation of the edition published in the USA under the title of ''wind power: renewable energy for home, farm and business''. In the wake of mass blackouts and energy crises, wind power remains a largely untapped resource of renewable energy. It is a booming worldwide industry whose technology, under the collective wing of aficionados like author Paul Gipe, is coming of age. Wind Power guides us through the emergent, sometimes daunting discourse on wind technology, giving frank explanations of how to use wind technology wisely and sound advice on how to avoid common mistakes. Since the mid-1970's, Paul Gipe has played a part in nearly every aspect of wind energy development from installing small turbines to promoting wind energy worldwide. As an American proponent of renewable energy, Gipe has earned the acclaim and respect of European energy specialists for years, but his arguments have often fallen on deaf ears at home. Today, the topic of wind power is cropping up everywhere from the beaches of Cape Cod to the Oregon-Washington border, and one wind turbine is capable of producing enough electricity per year to run 200 average American households. Now, Paul Gipe is back to shed light on this increasingly important energy source with a revised edition of Wind Power. Over the course of his career, Paul Gipe has been a proponent, participant, observer, and critic of the wind industry. His experience with wind has given rise to two previous books on the subject, Wind Energy Basics and Wind Power for Home and Business, which have sold over 50,000 copies. Wind Power for Home and Business has become a staple for both homeowners and professionals interested in the subject, and now, with energy prices soaring, interest in wind power is hitting an all-time high. With chapters on output and economics, Wind Power discloses how much you can expect from each method of wind technology, both in terms of energy and financial savings. The book updated models

  1. Offshore wind resources at Danish measurement sites

    Energy Technology Data Exchange (ETDEWEB)

    Barthelmie, R J; Courtney, M S; Lange, B; Nielsen, M; Sempreviva, A M [Risoe National Lab., Dept. of Wind Energy and Atmospheric Physics, Roskilde (Denmark); Svenson, J; Olsen, F [SEAS, Haslev (Denmark); Christensen, T [Elsamprojekt, Fredericia (Denmark)

    1999-03-01

    In order to characterise wind and turbulence characteristics at prospective offshore wind energy sites, meteorological observations from a number of purpose-built offshore monitoring sites have been analyzed and compared with long wind speed time series. New analyses have been conducted on the data sets focussing on meteorology, turbulence, extreme winds and wind and wave interactions. Relationships between wind speed, turbulence and fetch are highly complex. Minimum turbulence intensity offshore is associated with wind speeds of about 12 m/s. At lower wind speeds, stability effects are important while at higher winds speeds wind and wave interactions appear to dominate. On average, turbulence intensity offshore at 48 m height is approximately 0.08 if no coastal effects are present. However, the effect of the coastal discontinuity persists in wind speed and turbulence characteristics for considerable distances offshore. The majority of the adjustment of appears to occur within 20 km of the coast. (au)

  2. Wind speed perception and risk.

    Directory of Open Access Journals (Sweden)

    Duzgun Agdas

    Full Text Available BACKGROUND: How accurately do people perceive extreme wind speeds and how does that perception affect the perceived risk? Prior research on human-wind interaction has focused on comfort levels in urban settings or knock-down thresholds. No systematic experimental research has attempted to assess people's ability to estimate extreme wind speeds and perceptions of their associated risks. METHOD: We exposed 76 people to 10, 20, 30, 40, 50, and 60 mph (4.5, 8.9, 13.4, 17.9, 22.3, and 26.8 m/s winds in randomized orders and asked them to estimate wind speed and the corresponding risk they felt. RESULTS: Multilevel modeling showed that people were accurate at lower wind speeds but overestimated wind speeds at higher levels. Wind speed perceptions mediated the direct relationship between actual wind speeds and perceptions of risk (i.e., the greater the perceived wind speed, the greater the perceived risk. The number of tropical cyclones people had experienced moderated the strength of the actual-perceived wind speed relationship; consequently, mediation was stronger for people who had experienced fewer storms. CONCLUSION: These findings provide a clearer understanding of wind and risk perception, which can aid development of public policy solutions toward communicating the severity and risks associated with natural disasters.

  3. Wind speed perception and risk.

    Science.gov (United States)

    Agdas, Duzgun; Webster, Gregory D; Masters, Forrest J

    2012-01-01

    How accurately do people perceive extreme wind speeds and how does that perception affect the perceived risk? Prior research on human-wind interaction has focused on comfort levels in urban settings or knock-down thresholds. No systematic experimental research has attempted to assess people's ability to estimate extreme wind speeds and perceptions of their associated risks. We exposed 76 people to 10, 20, 30, 40, 50, and 60 mph (4.5, 8.9, 13.4, 17.9, 22.3, and 26.8 m/s) winds in randomized orders and asked them to estimate wind speed and the corresponding risk they felt. Multilevel modeling showed that people were accurate at lower wind speeds but overestimated wind speeds at higher levels. Wind speed perceptions mediated the direct relationship between actual wind speeds and perceptions of risk (i.e., the greater the perceived wind speed, the greater the perceived risk). The number of tropical cyclones people had experienced moderated the strength of the actual-perceived wind speed relationship; consequently, mediation was stronger for people who had experienced fewer storms. These findings provide a clearer understanding of wind and risk perception, which can aid development of public policy solutions toward communicating the severity and risks associated with natural disasters.

  4. Wind Speed Perception and Risk

    Science.gov (United States)

    Agdas, Duzgun; Webster, Gregory D.; Masters, Forrest J.

    2012-01-01

    Background How accurately do people perceive extreme wind speeds and how does that perception affect the perceived risk? Prior research on human–wind interaction has focused on comfort levels in urban settings or knock-down thresholds. No systematic experimental research has attempted to assess people's ability to estimate extreme wind speeds and perceptions of their associated risks. Method We exposed 76 people to 10, 20, 30, 40, 50, and 60 mph (4.5, 8.9, 13.4, 17.9, 22.3, and 26.8 m/s) winds in randomized orders and asked them to estimate wind speed and the corresponding risk they felt. Results Multilevel modeling showed that people were accurate at lower wind speeds but overestimated wind speeds at higher levels. Wind speed perceptions mediated the direct relationship between actual wind speeds and perceptions of risk (i.e., the greater the perceived wind speed, the greater the perceived risk). The number of tropical cyclones people had experienced moderated the strength of the actual–perceived wind speed relationship; consequently, mediation was stronger for people who had experienced fewer storms. Conclusion These findings provide a clearer understanding of wind and risk perception, which can aid development of public policy solutions toward communicating the severity and risks associated with natural disasters. PMID:23226230

  5. An automated technique for most-probable-number (MPN) analysis of densities of phagotrophic protists with lux-AB labelled bacteria as growth medium

    DEFF Research Database (Denmark)

    Ekelund, Flemming; Christensen, Søren; Rønn, Regin

    1999-01-01

    An automated modification of the most-probable-number (MPN) technique has been developed for enumeration of phagotrophic protozoa. The method is based on detection of prey depletion in micro titre plates rather than on presence of protozoa. A transconjugant Pseudomonas fluorescens DR54 labelled w...

  6. Database on wind characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, K.S. [The Technical Univ. of Denmark (Denmark); Courtney, M.S. [Risoe National Lab., (Denmark)

    1999-08-01

    The organisations that participated in the project consists of five research organisations: MIUU (Sweden), ECN (The Netherlands), CRES (Greece), DTU (Denmark), Risoe (Denmark) and one wind turbine manufacturer: Vestas Wind System A/S (Denmark). The overall goal was to build a database consisting of a large number of wind speed time series and create tools for efficiently searching through the data to select interesting data. The project resulted in a database located at DTU, Denmark with online access through the Internet. The database contains more than 50.000 hours of measured wind speed measurements. A wide range of wind climates and terrain types are represented with significant amounts of time series. Data have been chosen selectively with a deliberate over-representation of high wind and complex terrain cases. This makes the database ideal for wind turbine design needs but completely unsuitable for resource studies. Diversity has also been an important aim and this is realised with data from a large range of terrain types; everything from offshore to mountain, from Norway to Greece. (EHS)

  7. Design considerations for permanent magnet direct drive generators for wind energy applications

    NARCIS (Netherlands)

    Jassal, A.K.; Polinder, H.; Damen, M.E.C.; Versteegh, K.

    2012-01-01

    Permanent Magnet Direct Drive (PMDD) generators offer very high force density, high efficiency and low number of components. Due to these advantages, PMDD generators are getting popular in the wind energy industry especially for offshore application. Presence of permanent magnets gives magnetic

  8. LONG-TERM TRENDS IN THE SOLAR WIND PROTON MEASUREMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, Heather A.; McComas, David J. [Southwest Research Institute, San Antonio, TX (United States); DeForest, Craig E. [Southwest Research Institute, Boulder, CO (United States)

    2016-11-20

    We examine the long-term time evolution (1965–2015) of the relationships between solar wind proton temperature ( T {sub p}) and speed ( V {sub p}) and between the proton density ( n {sub p}) and speed using OMNI solar wind observations taken near Earth. We find a long-term decrease in the proton temperature–speed ( T {sub p}– V {sub p}) slope that lasted from 1972 to 2010, but has been trending upward since 2010. Since the solar wind proton density–speed ( n {sub p}– V {sub p}) relationship is not linear like the T {sub p}– V {sub p} relationship, we perform power-law fits for n {sub p}– V {sub p}. The exponent (steepness in the n {sub p}– V {sub p} relationship) is correlated with the solar cycle. This exponent has a stronger correlation with current sheet tilt angle than with sunspot number because the sunspot number maxima vary considerably from cycle to cycle and the tilt angle maxima do not. To understand this finding, we examined the average n {sub p} for different speed ranges, and found that for the slow wind n {sub p} is highly correlated with the sunspot number, with a lag of approximately four years. The fast wind n {sub p} variation was less, but in phase with the cycle. This phase difference may contribute to the n {sub p}– V {sub p} exponent correlation with the solar cycle. These long-term trends are important since empirical formulas based on fits to T {sub p} and V {sub p} data are commonly used to identify interplanetary coronal mass ejections, but these formulas do not include any time dependence. Changes in the solar wind density over a solar cycle will create corresponding changes in the near-Earth space environment and the overall extent of the heliosphere.

  9. The effects of vision-related aspects on noise perception of wind turbines in quiet areas.

    Science.gov (United States)

    Maffei, Luigi; Iachini, Tina; Masullo, Massimiliano; Aletta, Francesco; Sorrentino, Francesco; Senese, Vincenzo Paolo; Ruotolo, Francesco

    2013-04-26

    Preserving the soundscape and geographic extension of quiet areas is a great challenge against the wide-spreading of environmental noise. The E.U. Environmental Noise Directive underlines the need to preserve quiet areas as a new aim for the management of noise in European countries. At the same time, due to their low population density, rural areas characterized by suitable wind are considered appropriate locations for installing wind farms. However, despite the fact that wind farms are represented as environmentally friendly projects, these plants are often viewed as visual and audible intruders, that spoil the landscape and generate noise. Even though the correlations are still unclear, it is obvious that visual impacts of wind farms could increase due to their size and coherence with respect to the rural/quiet environment. In this paper, by using the Immersive Virtual Reality technique, some visual and acoustical aspects of the impact of a wind farm on a sample of subjects were assessed and analyzed. The subjects were immersed in a virtual scenario that represented a situation of a typical rural outdoor scenario that they experienced at different distances from the wind turbines. The influence of the number and the colour of wind turbines on global, visual and auditory judgment were investigated. The main results showed that, regarding the number of wind turbines, the visual component has a weak effect on individual reactions, while the colour influences both visual and auditory individual reactions, although in a different way.

  10. Wind energy applications of synthetic aperture radar

    Energy Technology Data Exchange (ETDEWEB)

    Bruun Christiansen, M.

    2006-11-15

    Synthetic aperture radars (SAR), mounted on satellites or aircraft, have proven useful for ocean wind mapping. Wind speeds at the height 10 m may be retrieved from measurements of radar backscatter using empirical model functions. The resulting wind fields are valuable in offshore wind energy planning as a supplement to on site measurements, which are costly and sparse, and model wind fields, which are not fully validated. Two applications of SAR measurements in offshore wind energy planning are addressed here: the study of wind farm wake effects and the potential of using SAR winds in offshore wind resource assessment. Firstly, wind wakes behind two large offshore wind farms in Denmark Horns Rev and Nysted are identified. A region of reduced wind speed is found downstream of both wind farms from the SAR wind fields. The wake extent and magnitude depends on the wind speed, the atmospheric stability, and the fraction of turbines operating. Wind farm wake effects are detected up to 20 km downwind of the last turbine. This distance is longer than predicted by state-of-the art wake models. Wake losses are typically 10-20% near the wind farms. Secondly, the potential of using SAR wind maps in offshore wind resource assessment is investigated. The resource assessment is made through Weibull fitting to frequency observations of wind speed and requires at least 100 satellite observations per year for a given site of interest. Predictions of the energy density are very sensitive to the wind speed and the highest possible accuracy on SAR wind retrievals is therefore sought. A 1.1 m s{sup -1} deviation on the mean wind speed is found through comparison with mast measurements at Horns Rev. The accuracy on mean wind speeds and energy densities found from satellite measurements varies with different empirical model functions. Additional uncertainties are introduced by the infrequent satellite sampling at fixed times of the day. The accuracy on satellite based wind resource

  11. Kinetic Theory and Fast Wind Observations of the Electron Strahl

    Science.gov (United States)

    Horaites, Konstantinos; Boldyrev, Stanislav; Wilson, Lynn B., III; Viñas, Adolfo F.; Merka, Jan

    2018-02-01

    We develop a model for the strahl population in the solar wind - a narrow, low-density and high-energy electron beam centred on the magnetic field direction. Our model is based on the solution of the electron drift-kinetic equation at heliospheric distances where the plasma density, temperature and the magnetic field strength decline as power laws of the distance along a magnetic flux tube. Our solution for the strahl depends on a number of parameters that, in the absence of the analytic solution for the full electron velocity distribution function (eVDF), cannot be derived from the theory. We however demonstrate that these parameters can be efficiently found from matching our solution with observations of the eVDF made by the Wind satellite's SWE strahl detector. The model is successful at predicting the angular width (FWHM) of the strahl for the Wind data at 1 au, in particular by predicting how this width scales with particle energy and background density. We find that the strahl distribution is largely determined by the local temperature Knudsen number γ ∼ |T dT/dx|/n, which parametrizes solar wind collisionality. We compute averaged strahl distributions for typical Knudsen numbers observed in the solar wind, and fit our model to these data. The model can be matched quite closely to the eVDFs at 1 au; however, it then overestimates the strahl amplitude at larger heliocentric distances. This indicates that our model may be improved through the inclusion of additional physics, possibly through the introduction of 'anomalous diffusion' of the strahl electrons.

  12. Short-term wind power forecasting: probabilistic and space-time aspects

    DEFF Research Database (Denmark)

    Tastu, Julija

    work deals with the proposal and evaluation of new mathematical models and forecasting methods for short-term wind power forecasting, accounting for space-time dynamics based on geographically distributed information. Different forms of power predictions are considered, starting from traditional point...... into the corresponding models are analysed. As a final step, emphasis is placed on generating space-time trajectories: this calls for the prediction of joint multivariate predictive densities describing wind power generation at a number of distributed locations and for a number of successive lead times. In addition......Optimal integration of wind energy into power systems calls for high quality wind power predictions. State-of-the-art forecasting systems typically provide forecasts for every location individually, without taking into account information coming from the neighbouring territories. It is however...

  13. Use of low density lipoprotein particle number levels as an aid in statin treatment decisions for intermediate risk patients: a cost-effectiveness analysis.

    Science.gov (United States)

    Shiffman, Dov; Arellano, Andre R; Caulfield, Michael P; Louie, Judy Z; Bare, Lance A; Devlin, James J; Melander, Olle

    2016-12-07

    The 2013 ACC/AHA guideline recommended either no statin therapy or moderate-intensity statin therapy (MST) for intermediate risk patients-those with 5-7.5% 10-year risk and without cardiovascular disease (CVD), hypercholesterolemia or diabetes. The guideline further suggested that the therapy choice be based on patient-clinician discussions of risks and benefits. Since low-density lipoprotein particle (LDL-P) levels were reported to be associated with CVD independently of traditional risk factors in intermediate and low risk patients, we investigated the cost-effectiveness of using LDL-P levels to identify intermediate risk patients likely to benefit from initiating or intensifying statin therapy. We evaluated 5 care strategies for intermediate risk patients. These included the strategies suggested by the guideline: no-statin therapy and MST. We compared each of these strategies to a related strategy that incorporated LDL-P testing. No-statin therapy was compared with the strategy of MST for those with high LDL-P levels and no statin therapy for all other patients (test-and-MST). MST was compared with the strategy of high-intensity statin therapy (HST) for those with high LDL-P levels and MST for all other patients (test-and-HST). We also evaluated the strategy of HST for all. Costs (payer perspective) and utilities were assessed over a 5-year time horizon in a Markov model of 100,000 hypothetical intermediate risk patients. HST dominated all other strategies, costing less and-despite causing 739 more cases of diabetes than did MST-resulting in more quality adjusted life-years (QALYs). For patient-clinician discussions that would otherwise lead to the MST strategy, we found the test-and-HST strategy reduced costs by $4.67 MM and resulted in 134 fewer CVD events and 115 additional QALYs. For patient-clinician discussions that would otherwise lead to no statin therapy, we found that the test-and-MST strategy reduced costs by $3.25 MM, resulted in 97 fewer CVD events

  14. VisibleWind: wind profile measurements at low altitude

    Science.gov (United States)

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

    2009-09-01

    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

  15. Wind energy.

    Science.gov (United States)

    Leithead, W E

    2007-04-15

    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.

  16. Non-Flow and Flow studies with differential transverse momentum and number density correlations in p-Pb and Pb-Pb at LHC

    CERN Document Server

    Acharya, Shreyasi; The ALICE collaboration; Adamova, Dagmar; Adolfsson, Jonatan; Aggarwal, Madan Mohan; Aglieri Rinella, Gianluca; Agnello, Michelangelo; Agrawal, Neelima; Ahammed, Zubayer; Ahn, Sang Un; Aiola, Salvatore; Akindinov, Alexander; Al-turany, Mohammad; Alam, Sk Noor; Silva De Albuquerque, Danilo; Aleksandrov, Dmitry; Alessandro, Bruno; Alfaro Molina, Jose Ruben; Ali, Yasir; Alici, Andrea; Alkin, Anton; Alme, Johan; Alt, Torsten; Altenkamper, Lucas; Altsybeev, Igor; Anaam, Mustafa Naji; Andrei, Cristian; Andreou, Dimitra; Andrews, Harry Arthur; Andronic, Anton; Angeletti, Massimo; Anguelov, Venelin; Anson, Christopher Daniel; Anticic, Tome; Antinori, Federico; Antonioli, Pietro; Anwar, Rafay; Apadula, Nicole; Aphecetche, Laurent Bernard; Appelshaeuser, Harald; Arcelli, Silvia; Arnaldi, Roberta; Arnold, Oliver Werner; Arsene, Ionut Cristian; Arslandok, Mesut; Audurier, Benjamin; Augustinus, Andre; Averbeck, Ralf Peter; Azmi, Mohd Danish; Badala, Angela; Baek, Yong Wook; Bagnasco, Stefano; Bailhache, Raphaelle Marie; Bala, Renu; Baldisseri, Alberto; Ball, Markus; Baral, Rama Chandra; Barbano, Anastasia Maria; Barbera, Roberto; Barile, Francesco; Barioglio, Luca; Barnafoldi, Gergely Gabor; Barnby, Lee Stuart; Ramillien Barret, Valerie; Bartalini, Paolo; Barth, Klaus; Bartsch, Esther; Bastid, Nicole; Basu, Sumit; Batigne, Guillaume; Batyunya, Boris; Batzing, Paul Christoph; Bazo Alba, Jose Luis; Bearden, Ian Gardner; Beck, Hans; Bedda, Cristina; Behera, Nirbhay Kumar; Belikov, Iouri; Bellini, Francesca; Bello Martinez, Hector; Bellwied, Rene; Espinoza Beltran, Lucina Gabriela; Belyaev, Vladimir; Bencedi, Gyula; Beole, Stefania; Bercuci, Alexandru; Berdnikov, Yaroslav; Berenyi, Daniel; Bertens, Redmer Alexander; Berzano, Dario; Betev, Latchezar; Bhaduri, Partha Pratim; Bhasin, Anju; Bhat, Inayat Rasool; Bhatt, Himani; Bhattacharjee, Buddhadeb; Bhom, Jihyun; Bianchi, Antonio; Bianchi, Livio; Bianchi, Nicola; Bielcik, Jaroslav; Bielcikova, Jana; Bilandzic, Ante; Biro, Gabor; Biswas, Rathijit; Biswas, Saikat; Blair, Justin Thomas; Blau, Dmitry; Blume, Christoph; Boca, Gianluigi; Bock, Friederike; Bogdanov, Alexey; Boldizsar, Laszlo; Bombara, Marek; Bonomi, Germano; Bonora, Matthias; Borel, Herve; Borissov, Alexander; Borri, Marcello; Botta, Elena; Bourjau, Christian; Bratrud, Lars; Braun-munzinger, Peter; Bregant, Marco; Broker, Theo Alexander; Broz, Michal; Brucken, Erik Jens; Bruna, Elena; Bruno, Giuseppe Eugenio; Budnikov, Dmitry; Buesching, Henner; Bufalino, Stefania; Buhler, Paul; Buncic, Predrag; Busch, Oliver; Buthelezi, Edith Zinhle; Bashir Butt, Jamila; Buxton, Jesse Thomas; Cabala, Jan; Caffarri, Davide; Caines, Helen Louise; Caliva, Alberto; Calvo Villar, Ernesto; Soto Camacho, Rabi; Camerini, Paolo; Capon, Aaron Allan; Carena, Francesco; Carena, Wisla; Carnesecchi, Francesca; Castillo Castellanos, Javier Ernesto; Castro, Andrew John; Casula, Ester Anna Rita; Ceballos Sanchez, Cesar; Chandra, Sinjini; Chang, Beomsu; Chang, Wan; Chapeland, Sylvain; Chartier, Marielle; Chattopadhyay, Subhasis; Chattopadhyay, Sukalyan; Chauvin, Alex; Cheshkov, Cvetan Valeriev; Cheynis, Brigitte; Chibante Barroso, Vasco Miguel; Dobrigkeit Chinellato, David; Cho, Soyeon; Chochula, Peter; Chowdhury, Tasnuva; Christakoglou, Panagiotis; Christensen, Christian Holm; Christiansen, Peter; Chujo, Tatsuya; Chung, Suh-urk; Cicalo, Corrado; Cifarelli, Luisa; Cindolo, Federico; Cleymans, Jean Willy Andre; Colamaria, Fabio Filippo; Colella, Domenico; Collu, Alberto; Colocci, Manuel; Concas, Matteo; Conesa Balbastre, Gustavo; Conesa Del Valle, Zaida; Contreras Nuno, Jesus Guillermo; Cormier, Thomas Michael; Corrales Morales, Yasser; Cortese, Pietro; Cosentino, Mauro Rogerio; Costa, Filippo; Costanza, Susanna; Crkovska, Jana; Crochet, Philippe; Cuautle Flores, Eleazar; Cunqueiro Mendez, Leticia; Dahms, Torsten; Dainese, Andrea; Dani, Sanskruti; Danisch, Meike Charlotte; Danu, Andrea; Das, Debasish; Das, Indranil; Das, Supriya; Dash, Ajay Kumar; Dash, Sadhana; De, Sudipan; De Caro, Annalisa; De Cataldo, Giacinto; De Conti, Camila; De Cuveland, Jan; De Falco, Alessandro; De Gruttola, Daniele; De Marco, Nora; De Pasquale, Salvatore; Derradi De Souza, Rafael; Franz Degenhardt, Hermann; Deisting, Alexander; Deloff, Andrzej; Delsanto, Silvia; Deplano, Caterina; Dhankher, Preeti; Di Bari, Domenico; Di Mauro, Antonio; Di Ruzza, Benedetto; Arteche Diaz, Raul; Dietel, Thomas; Dillenseger, Pascal; Ding, Yanchun; Divia, Roberto; Djuvsland, Oeystein; Dobrin, Alexandru Florin; Domenicis Gimenez, Diogenes; Donigus, Benjamin; Dordic, Olja; Van Doremalen, Lennart Vincent; Dubey, Anand Kumar; Dubla, Andrea; Ducroux, Laurent; Dudi, Sandeep; Duggal, Ashpreet Kaur; Dukhishyam, Mallick; Dupieux, Pascal; Ehlers Iii, Raymond James; Elia, Domenico; Endress, Eric; Engel, Heiko; Epple, Eliane; Erazmus, Barbara Ewa; Erhardt, Filip; Ersdal, Magnus Rentsch; Espagnon, Bruno; Eulisse, Giulio; Eum, Jongsik; Evans, David; Evdokimov, Sergey; Fabbietti, Laura; Faggin, Mattia; Faivre, Julien; Fantoni, Alessandra; Fasel, Markus; Feldkamp, Linus; Feliciello, Alessandro; Feofilov, Grigorii; Fernandez Tellez, Arturo; Ferretti, Alessandro; Festanti, Andrea; Feuillard, Victor Jose Gaston; Figiel, Jan; Araujo Silva Figueredo, Marcel; Filchagin, Sergey; Finogeev, Dmitry; Fionda, Fiorella; Fiorenza, Gabriele; Flor, Fernando; Floris, Michele; Foertsch, Siegfried Valentin; Foka, Panagiota; Fokin, Sergey; Fragiacomo, Enrico; Francescon, Andrea; Francisco, Audrey; Frankenfeld, Ulrich Michael; Fronze, Gabriele Gaetano; Fuchs, Ulrich; Furget, Christophe; Furs, Artur; Fusco Girard, Mario; Gaardhoeje, Jens Joergen; Gagliardi, Martino; Gago Medina, Alberto Martin; Gajdosova, Katarina; Gallio, Mauro; Duarte Galvan, Carlos; Ganoti, Paraskevi; Garabatos Cuadrado, Jose; Garcia-solis, Edmundo Javier; Garg, Kunal; Gargiulo, Corrado; Gasik, Piotr Jan; Gauger, Erin Frances; De Leone Gay, Maria Beatriz; Germain, Marie; Ghosh, Jhuma; Ghosh, Premomoy; Ghosh, Sanjay Kumar; Gianotti, Paola; Giubellino, Paolo; Giubilato, Piero; Glassel, Peter; Gomez Coral, Diego Mauricio; Gomez Ramirez, Andres; Gonzalez, Victor; Gonzalez Zamora, Pedro; Gorbunov, Sergey; Gorlich, Lidia Maria; Gotovac, Sven; Grabski, Varlen; Graczykowski, Lukasz Kamil; Graham, Katie Leanne; Greiner, Leo Clifford; Grelli, Alessandro; Grigoras, Costin; Grigoryev, Vladislav; Grigoryan, Ara; Grigoryan, Smbat; Gronefeld, Julius Maximilian; Grosa, Fabrizio; Grosse-oetringhaus, Jan Fiete; Grosso, Raffaele; Guernane, Rachid; Guerzoni, Barbara; Guittiere, Manuel; Gulbrandsen, Kristjan Herlache; Gunji, Taku; Gupta, Anik; Gupta, Ramni; Bautista Guzman, Irais; Haake, Rudiger; Habib, Michael Karim; Hadjidakis, Cynthia Marie; Hamagaki, Hideki; Hamar, Gergoe; Hamid, Mohammed; Hamon, Julien Charles; Hannigan, Ryan; Haque, Md Rihan; Harris, John William; Harton, Austin Vincent; Hassan, Hadi; Hatzifotiadou, Despina; Hayashi, Shinichi; Heckel, Stefan Thomas; Hellbar, Ernst; Helstrup, Haavard; Herghelegiu, Andrei Ionut; Gonzalez Hernandez, Emma; Herrera Corral, Gerardo Antonio; Herrmann, Florian; Hetland, Kristin Fanebust; Hilden, Timo Eero; Hillemanns, Hartmut; Hills, Christopher; Hippolyte, Boris; Hohlweger, Bernhard; Horak, David; Hornung, Sebastian; Hosokawa, Ritsuya; Hota, Jyotishree; Hristov, Peter Zahariev; Huang, Chun-lu; Hughes, Charles; Huhn, Patrick; Humanic, Thomas; Hushnud, Hushnud; Hussain, Nur; Hussain, Tahir; Hutter, Dirk; Hwang, Dae Sung; Iddon, James Philip; Iga Buitron, Sergio Arturo; Ilkaev, Radiy; Inaba, Motoi; Ippolitov, Mikhail; Islam, Md Samsul; Ivanov, Marian; Ivanov, Vladimir; Izucheev, Vladimir; Jacak, Barbara; Jacazio, Nicolo; Jacobs, Peter Martin; Jadhav, Manoj Bhanudas; Jadlovska, Slavka; Jadlovsky, Jan; Jaelani, Syaefudin; Jahnke, Cristiane; Jakubowska, Monika Joanna; Janik, Malgorzata Anna; Jena, Chitrasen; Jercic, Marko; Jevons, Oliver; Jimenez Bustamante, Raul Tonatiuh; Jin, Muqing; Jones, Peter Graham; Jusko, Anton; Kalinak, Peter; Kalweit, Alexander Philipp; Kang, Ju Hwan; Kaplin, Vladimir; Kar, Somnath; Karasu Uysal, Ayben; Karavichev, Oleg; Karavicheva, Tatiana; Karczmarczyk, Przemyslaw; Karpechev, Evgeny; Kebschull, Udo Wolfgang; Keidel, Ralf; Keijdener, Darius Laurens; Keil, Markus; Ketzer, Bernhard Franz; Khabanova, Zhanna; Khan, Ahsan Mehmood; Khan, Shaista; Khan, Shuaib Ahmad; Khanzadeev, Alexei; Kharlov, Yury; Khatun, Anisa; Khuntia, Arvind; Kielbowicz, Miroslaw Marek; Kileng, Bjarte; Kim, Byungchul; Kim, Daehyeok; Kim, Dong Jo; Kim, Eun Joo; Kim, Hyeonjoong; Kim, Jinsook; Kim, Jiyoung; Kim, Minjung; Kim, Se Yong; Kim, Taejun; Kim, Taesoo; Kirsch, Stefan; Kisel, Ivan; Kiselev, Sergey; Kisiel, Adam Ryszard; Klay, Jennifer Lynn; Klein, Carsten; Klein, Jochen; Klein-boesing, Christian; Klewin, Sebastian; Kluge, Alexander; Knichel, Michael Linus; Knospe, Anders Garritt; Kobdaj, Chinorat; Varga-kofarago, Monika; Kohler, Markus Konrad; Kollegger, Thorsten; Kondratyeva, Natalia; Kondratyuk, Evgeny; Konevskikh, Artem; Konyushikhin, Maxim; Kovalenko, Oleksandr; Kovalenko, Vladimir; Kowalski, Marek; Kralik, Ivan; Kravcakova, Adela; Kreis, Lukas; Krivda, Marian; Krizek, Filip; Kruger, Mario; Kryshen, Evgeny; Krzewicki, Mikolaj; Kubera, Andrew Michael; Kucera, Vit; Kuhn, Christian Claude; Kuijer, Paulus Gerardus; Kumar, Jitendra; Kumar, Lokesh; Kumar, Shyam; Kundu, Sourav; Kurashvili, Podist; Kurepin, Alexander; Kurepin, Alexey; Kuryakin, Alexey; Kushpil, Svetlana; Kvapil, Jakub; Kweon, Min Jung; Kwon, Youngil; La Pointe, Sarah Louise; La Rocca, Paola; Lai, Yue Shi; Lakomov, Igor; Langoy, Rune; Lapidus, Kirill; Lardeux, Antoine Xavier; Larionov, Pavel; Laudi, Elisa; Lavicka, Roman; Lea, Ramona; Leardini, Lucia; Lee, Seongjoo; Lehas, Fatiha; Lehner, Sebastian; Lehrbach, Johannes; Lemmon, Roy Crawford; Leon Monzon, Ildefonso; Levai, Peter; Li, Xiaomei; Li, Xing Long; Lien, Jorgen Andre; Lietava, Roman; Lim, Bong-hwi; Lindal, Svein; Lindenstruth, Volker; Lindsay, Scott William; Lippmann, Christian; Lisa, Michael Annan; Litichevskyi, Vladyslav; Liu, Alwina; Ljunggren, Hans Martin; Llope, William; Lodato, Davide Francesco; Loginov, Vitaly; Loizides, Constantinos; Loncar, Petra; Lopez, Xavier Bernard; Lopez Torres, Ernesto; Lowe, Andrew John; Luettig, Philipp Johannes; Luhder, Jens Robert; Lunardon, Marcello; Luparello, Grazia; Lupi, Matteo; Maevskaya, Alla; Mager, Magnus; Mahmood, Sohail Musa; Maire, Antonin; Majka, Richard Daniel; Malaev, Mikhail; Malik, Qasim Waheed; Malinina, Liudmila; Mal'kevich, Dmitry; Malzacher, Peter; Mamonov, Alexander; Manko, Vladislav; Manso, Franck; Manzari, Vito; Mao, Yaxian; Marchisone, Massimiliano; Mares, Jiri; Margagliotti, Giacomo Vito; Margotti, Anselmo; Margutti, Jacopo; Marin, Ana Maria; Markert, Christina; Marquard, Marco; Martin, Nicole Alice; Martinengo, Paolo; Martinez, Jacobb Lee; Martinez Hernandez, Mario Ivan; Martinez-garcia, Gines; Martinez Pedreira, Miguel; Masciocchi, Silvia; Masera, Massimo; Masoni, Alberto; Massacrier, Laure Marie; Masson, Erwann; Mastroserio, Annalisa; Mathis, Andreas Michael; Toledo Matuoka, Paula Fernanda; Matyja, Adam Tomasz; Mayer, Christoph; Mazzilli, Marianna; Mazzoni, Alessandra Maria; Meddi, Franco; Melikyan, Yuri; Menchaca-rocha, Arturo Alejandro; Meninno, Elisa; Mercado-perez, Jorge; Meres, Michal; Soncco Meza, Carlos; Mhlanga, Sibaliso; Miake, Yasuo; Micheletti, Luca; Mieskolainen, Matti Mikael; Mihaylov, Dimitar Lubomirov; Mikhaylov, Konstantin; Mischke, Andre; Mishra, Aditya Nath; Miskowiec, Dariusz Czeslaw; Mitra, Jubin; Mitu, Ciprian Mihai; Mohammadi, Naghmeh; Mohanty, Auro Prasad; Mohanty, Bedangadas; Khan, Mohammed Mohisin; Moreira De Godoy, Denise Aparecida; Perez Moreno, Luis Alberto; Moretto, Sandra; Morreale, Astrid; Morsch, Andreas; Muccifora, Valeria; Mudnic, Eugen; Muhlheim, Daniel Michael; Muhuri, Sanjib; Mukherjee, Maitreyee; Mulligan, James Declan; Gameiro Munhoz, Marcelo; Munning, Konstantin; Arratia Munoz, Miguel Ignacio; Munzer, Robert Helmut; Murakami, Hikari; Murray, Sean; Musa, Luciano; Musinsky, Jan; Myers, Corey James; Myrcha, Julian Wojciech; Naik, Bharati; Nair, Rahul; Nandi, Basanta Kumar; Nania, Rosario; Nappi, Eugenio; Narayan, Amrendra; Naru, Muhammad Umair; Nassirpour, Adrian Fereydon; Ferreira Natal Da Luz, Pedro Hugo; Nattrass, Christine; Rosado Navarro, Sebastian; Nayak, Kishora; Nayak, Ranjit; Nayak, Tapan Kumar; Nazarenko, Sergey; Negrao De Oliveira, Renato Aparecido; Nellen, Lukas; Nesbo, Simon Voigt; Neskovic, Gvozden; Ng, Fabian; Nicassio, Maria; Niedziela, Jeremi; Nielsen, Borge Svane; Nikolaev, Sergey; Nikulin, Sergey; Nikulin, Vladimir; Noferini, Francesco; Nomokonov, Petr; Nooren, Gerardus; Cabanillas Noris, Juan Carlos; Norman, Jaime; Nyanin, Alexander; Nystrand, Joakim Ingemar; Oh, Hoonjung; Ohlson, Alice Elisabeth; Oleniacz, Janusz; Oliveira Da Silva, Antonio Carlos; Oliver, Michael Henry; Onderwaater, Jacobus; Oppedisano, Chiara; Orava, Risto; Oravec, Matej; Ortiz Velasquez, Antonio; Oskarsson, Anders Nils Erik; Otwinowski, Jacek Tomasz; Oyama, Ken; Pachmayer, Yvonne Chiara; Pacik, Vojtech; Pagano, Davide; Paic, Guy; Palni, Prabhakar; Pan, Jinjin; Pandey, Ashutosh Kumar; Panebianco, Stefano; Papikyan, Vardanush; Pareek, Pooja; Park, Jonghan; Parkkila, Jasper Elias; Parmar, Sonia; Passfeld, Annika; Pathak, Surya Prakash; Patra, Rajendra Nath; Paul, Biswarup; Pei, Hua; Peitzmann, Thomas; Peng, Xinye; Pereira, Luis Gustavo; Pereira Da Costa, Hugo Denis Antonio; Peresunko, Dmitry Yurevich; Perez Lezama, Edgar; Peskov, Vladimir; Pestov, Yury; Petracek, Vojtech; Petrovici, Mihai; Petta, Catia; Peretti Pezzi, Rafael; Piano, Stefano; Pikna, Miroslav; Pillot, Philippe; Ozelin De Lima Pimentel, Lais; Pinazza, Ombretta; Pinsky, Lawrence; Pisano, Silvia; Piyarathna, Danthasinghe; Ploskon, Mateusz Andrzej; Planinic, Mirko; Pliquett, Fabian; Pluta, Jan Marian; Pochybova, Sona; Podesta Lerma, Pedro Luis Manuel; Poghosyan, Martin; Polishchuk, Boris; Poljak, Nikola; Poonsawat, Wanchaloem; Pop, Amalia; Poppenborg, Hendrik; Porteboeuf, Sarah Julie; Pozdniakov, Valeriy; Prasad, Sidharth Kumar; Preghenella, Roberto; Prino, Francesco; Pruneau, Claude Andre; Pshenichnov, Igor; Puccio, Maximiliano; Punin, Valery; Putschke, Jorn Henning; Raha, Sibaji; Rajput, Sonia; Rak, Jan; Rakotozafindrabe, Andry Malala; Ramello, Luciano; Rami, Fouad; Raniwala, Rashmi; Raniwala, Sudhir; Rasanen, Sami Sakari; Rascanu, Bogdan Theodor; Ratza, Viktor; Ravasenga, Ivan; Read, Kenneth Francis; Redlich, Krzysztof; Rehman, Attiq Ur; Reichelt, Patrick Simon; Reidt, Felix; Ren, Xiaowen; Renfordt, Rainer Arno Ernst; Reshetin, Andrey; Revol, Jean-pierre; Reygers, Klaus Johannes; Riabov, Viktor; Richert, Tuva Ora Herenui; Richter, Matthias Rudolph; Riedler, Petra; Riegler, Werner; Riggi, Francesco; Ristea, Catalin-lucian; Rode, Sudhir Pandurang; Rodriguez Cahuantzi, Mario; Roeed, Ketil; Rogalev, Roman; Rogochaya, Elena; Rohr, David Michael; Roehrich, Dieter; Rokita, Przemyslaw Stefan; Ronchetti, Federico; Dominguez Rosas, Edgar; Roslon, Krystian; Rosnet, Philippe; Rossi, Andrea; Rotondi, Alberto; Roukoutakis, Filimon; Roy, Christelle Sophie; Roy, Pradip Kumar; Vazquez Rueda, Omar; Rui, Rinaldo; Rumyantsev, Boris; Rustamov, Anar; Ryabinkin, Evgeny; Ryabov, Yury; Rybicki, Andrzej; Saarinen, Sampo; Sadhu, Samrangy; Sadovskiy, Sergey; Safarik, Karel; Saha, Sumit Kumar; Sahoo, Baidyanath; Sahoo, Pragati; Sahoo, Raghunath; Sahoo, Sarita; Sahu, Pradip Kumar; Saini, Jogender; Sakai, Shingo; Saleh, Mohammad Ahmad; Sambyal, Sanjeev Singh; Samsonov, Vladimir; Sandoval, Andres; Sarkar, Amal; Sarkar, Debojit; Sarkar, Nachiketa; Sarma, Pranjal; Sas, Mike Henry Petrus; Scapparone, Eugenio; Scarlassara, Fernando; Schaefer, Brennan; Scheid, Horst Sebastian; Schiaua, Claudiu Cornel; Schicker, Rainer Martin; Schmidt, Christian Joachim; Schmidt, Hans Rudolf; Schmidt, Marten Ole; Schmidt, Martin; Schmidt, Nicolas Vincent; Schukraft, Jurgen; Schutz, Yves Roland; Schwarz, Kilian Eberhard; Schweda, Kai Oliver; Scioli, Gilda; Scomparin, Enrico; Sefcik, Michal; Seger, Janet Elizabeth; Sekiguchi, Yuko; Sekihata, Daiki; Selyuzhenkov, Ilya; Senosi, Kgotlaesele; Senyukov, Serhiy; Serradilla Rodriguez, Eulogio; Sett, Priyanka; Sevcenco, Adrian; Shabanov, Arseniy; Shabetai, Alexandre; Shahoyan, Ruben; Shaikh, Wadut; Shangaraev, Artem; Sharma, Anjali; Sharma, Ankita; Sharma, Meenakshi; Sharma, Natasha; Sheikh, Ashik Ikbal; Shigaki, Kenta; Shimomura, Maya; Shirinkin, Sergey; Shou, Qiye; Shtejer Diaz, Katherin; Sibiryak, Yury; Siddhanta, Sabyasachi; Sielewicz, Krzysztof Marek; Siemiarczuk, Teodor; Silvermyr, David Olle Rickard; Simatovic, Goran; Simonetti, Giuseppe; Singaraju, Rama Narayana; Singh, Ranbir; Singh, Randhir; Singhal, Vikas; Sarkar - Sinha, Tinku; Sitar, Branislav; Sitta, Mario; Skaali, Bernhard; Slupecki, Maciej; Smirnov, Nikolai; Snellings, Raimond; Snellman, Tomas Wilhelm; Song, Jihye; Soramel, Francesca; Sorensen, Soren Pontoppidan; Sozzi, Federica; Sputowska, Iwona Anna; Stachel, Johanna; Stan, Ionel; Stankus, Paul; Stenlund, Evert Anders; Stocco, Diego; Storetvedt, Maksim Melnik; Strmen, Peter; Alarcon Do Passo Suaide, Alexandre; Sugitate, Toru; Suire, Christophe Pierre; Suleymanov, Mais Kazim Oglu; Suljic, Miljenko; Sultanov, Rishat; Sumbera, Michal; Sumowidagdo, Suharyo; Suzuki, Ken; Swain, Sagarika; Szabo, Alexander; Szarka, Imrich; Tabassam, Uzma; Takahashi, Jun; Tambave, Ganesh Jagannath; Tanaka, Naoto; Tarhini, Mohamad; Tariq, Mohammad; Tarzila, Madalina-gabriela; Tauro, Arturo; Tejeda Munoz, Guillermo; Telesca, Adriana; Terrevoli, Cristina; Teyssier, Boris; Thakur, Dhananjaya; Thakur, Sanchari; Thomas, Deepa; Thoresen, Freja; Tieulent, Raphael Noel; Tikhonov, Anatoly; Timmins, Anthony Robert; Toia, Alberica; Topilskaya, Nataliya; Toppi, Marco; Rojas Torres, Solangel; Tripathy, Sushanta; Trogolo, Stefano; Trombetta, Giuseppe; Tropp, Lukas; Trubnikov, Victor; Trzaska, Wladyslaw Henryk; Trzcinski, Tomasz Piotr; Trzeciak, Barbara Antonina; Tsuji, Tomoya; Tumkin, Alexandr; Turrisi, Rosario; Tveter, Trine Spedstad; Ullaland, Kjetil; Umaka, Ejiro Naomi; Uras, Antonio; Usai, Gianluca; Utrobicic, Antonija; Vala, Martin; Van Hoorne, Jacobus Willem; Van Leeuwen, Marco; Vande Vyvre, Pierre; Varga, Dezso; Diozcora Vargas Trevino, Aurora; Vargyas, Marton; Varma, Raghava; Vasileiou, Maria; Vasiliev, Andrey; Vauthier, Astrid; Vazquez Doce, Oton; Vechernin, Vladimir; Veen, Annelies Marianne; Vercellin, Ermanno; Vergara Limon, Sergio; Vermunt, Luuk; Vernet, Renaud; Vertesi, Robert; Vickovic, Linda; Viinikainen, Jussi Samuli; Vilakazi, Zabulon; Villalobos Baillie, Orlando; Villatoro Tello, Abraham; Vinogradov, Alexander; Virgili, Tiziano; Vislavicius, Vytautas; Vodopyanov, Alexander; Volkl, Martin Andreas; Voloshin, Kirill; Voloshin, Sergey; Volpe, Giacomo; Von Haller, Barthelemy; Vorobyev, Ivan; Voscek, Dominik; Vranic, Danilo; Vrlakova, Janka; Wagner, Boris; Wang, Hongkai; Wang, Mengliang; Watanabe, Yosuke; Weber, Michael; Weber, Steffen Georg; Wegrzynek, Adam; Weiser, Dennis Franz; Wenzel, Sandro Christian; Wessels, Johannes Peter; Westerhoff, Uwe; Whitehead, Andile Mothegi; Wiechula, Jens; Wikne, Jon; Wilk, Grzegorz Andrzej; Wilkinson, Jeremy John; Willems, Guido Alexander; Williams, Crispin; Willsher, Emily; Windelband, Bernd Stefan; Witt, William Edward; Xu, Ran; Yalcin, Serpil; Yamakawa, Kosei; Yano, Satoshi; Yin, Zhongbao; Yokoyama, Hiroki; Yoo, In-kwon; Yoon, Jin Hee; Yurchenko, Volodymyr; Zaccolo, Valentina; Zaman, Ali; Zampolli, Chiara; Correa Zanoli, Henrique Jose; Zardoshti, Nima; Zarochentsev, Andrey; Zavada, Petr; Zavyalov, Nikolay; Zbroszczyk, Hanna Paulina; Zhalov, Mikhail; Zhang, Xiaoming; Zhang, Yonghong; Zhang, Zuman; Zhao, Chengxin; Zherebchevskii, Vladimir; Zhigareva, Natalia; Zhou, Daicui; Zhou, You; Zhou, Zhuo; Zhu, Hongsheng; Zhu, Jianhui; Zhu, Ya; Zichichi, Antonino; Zimmermann, Markus Bernhard; Zinovjev, Gennady; Zmeskal, Johann; Zou, Shuguang

    2018-01-01

    Measurements of two-particle differential number correlation functions $R_{2}$ and transverse momentum correlation functions $P_{2}$, obtained from p-Pb collisions at $\\sqrt{s_{NN}}$ = 5.02 TeV and Pb-Pb collisions at $\\sqrt{s_{NN}}$ = 2.76 TeV, are presented. Measurements are reported for charged particles in the pseudorapidity range |$\\eta$| < 1.0, and transverse momentum range 0.2 < $p_{T}$ < 2.0 GeV/$c$ as a function of pair separation in pseudorapidity, |$\\Delta\\eta$|, azimuthal angle, $\\Delta\\phi$, and for several charged-particle multiplicity classes. The correlation measurements are carried out for like-sign (LS) and unlike-sign (US) charged-particle pairs separately. The LS and US correlation functions are combined to obtain charge-independent (CI) and charge-dependent (CD) correlation functions. The correlation functions $R_{2}^{(CI)}$ and $P_{2}^{(CI)}$ both feature a prominent and relatively narrow peak centered at $\\Delta\\phi$ = 0, |$\\Delta\\eta$| = 0 (called near-side peak in the rema...

  17. Rare copy number alterations and copy-neutral loss of heterozygosity revealed in ameloblastomas by high-density whole-genome microarray analysis.

    Science.gov (United States)

    Diniz, Marina Gonçalves; Duarte, Alessandra Pires; Villacis, Rolando A; Guimarães, Bruna V A; Duarte, Luiz Cláudio Pires; Rogatto, Sílvia R; Gomez, Ricardo Santiago; Gomes, Carolina Cavaliéri

    2017-05-01

    Ameloblastoma (unicystic, UA, or multicystic, MA) is a rare tumor associated with bone destruction and facial deformity. Its malignant counterpart is the ameloblastic carcinoma (AC). The BRAFV600E mutation is highly prevalent in all these tumors subtypes and cannot account for their different clinical behaviors. We assessed copy number alterations (CNAs) and copy-neutral loss of heterozygosity (cnLOH) in UA (n = 2), MA (n = 3), and AC (n = 1) using the CytoScan HD Array (Affymetrix) and the BRAFV600E status. RT-qPCR was applied in four selected genes (B4GALT1, BAG1, PKD1L2, and PPP2R5A) covered by rare alterations, also including three MA and four normal oral tissues. Fifty-seven CNAs and cnLOH were observed in the ameloblastomas and six CNAs in the AC. Seven of the CNAs were rare (six in UA and one in MA), four of them encompassing genes (gains of 7q11.21, 1q32.3, and 9p21.1 and loss of 16q23.2). We found positive correlation between rare CNA gene dosage and the expression of B4GALT1, BAG1, PKD1L2, and PPP2R5A. The AC and 1 UA were BRAF wild-type; however, this UA showed rare genomic alterations encompassing genes associated with RAF/MAPK activation. Ameloblastomas show rare CNAs and cnLOH, presenting a specific genomic profile with no overlapping of the rare alterations among UA, MA, and AC. These genomic changes might play a role in tumor evolution and in BRAFV600E-negative tumors. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  18. Market survey China. Wind Energy

    International Nuclear Information System (INIS)

    2008-07-01

    The title survey presents an overview of the wind developments in China, an analysis of the key market players in this sector, and an assessment of the potential future market for wind-related activities in China. The survey is concluded with a number of conclusions and recommendations

  19. MCMC for Wind Power Simulation

    NARCIS (Netherlands)

    Papaefthymiou, G.; Klöckl, B.

    2008-01-01

    This paper contributes a Markov chain Monte Carlo (MCMC) method for the direct generation of synthetic time series of wind power output. It is shown that obtaining a stochastic model directly in the wind power domain leads to reduced number of states and to lower order of the Markov chain at equal

  20. Continuous supersonic plasma wind tunnel

    DEFF Research Database (Denmark)

    Andersen, S.A.; Jensen, Vagn Orla; Nielsen, P.

    1969-01-01

    The normal magnetic field configuration of a Q device has been modified to obtain a 'magnetic Laval nozzle'. Continuous supersonic plasma 'winds' are obtained with Mach numbers ~3. The magnetic nozzle appears well suited for the study of the interaction of supersonic plasma 'winds' with either...

  1. Calculation of amorphous silica solubilities at 25° to 300°C and apparent cation hydration numbers in aqueous salt solutions using the concept of effective density of water

    Science.gov (United States)

    Fournier, Robert O.; Williams, Marshall L.

    1983-01-01

    The solubility of amorphous silica in aqueous salt solutions at 25° to 300°C can be calculated using information on its solubility in pure water and a model in which the activity of water in the salt solution is defined to equal the effective density. pe, of “free” water in that solution. At temperatures of 100°C and above, pe closely equals the product of the density of the solution times the weight fraction of water in the solution. At 25°C, a correction parameter must be applied to pe that incorporates a term called the apparent cation hydration number, h. Because of the many assumptions and other uncertainties involved in determining values of h, by the model used here, the reported numbers are not necessarily real hydration numbers even though they do agree with some published values determined by activity and diffusion methods. Whether or not h is a real hydration number, it would appear to be useful in its inclusion within a more extensive activity coefficient term that describes the departure of silica solubilities in concentrated salt solutions from expected behavior according to the model presented here. Values of h can be calculated from measured amorphous silica solubilities in salt solutions at 25°C provided there is no complexing of dissolved silica with the dissolved salt, or if the degree of complexing is known. The previously postulated aqueous silica-sulfate complexing in aqueous Na2SO4 solutions is supported by results of the present effective density of water model

  2. An assessment on seasonal analysis of wind energy characteristics and wind turbine characteristics

    International Nuclear Information System (INIS)

    Akpinar, E. Kavak; Akpinar, S.

    2005-01-01

    This paper presents seasonal variations of the wind characteristics and wind turbine characteristics in the regions around Elazig, namely Maden, Agin and Keban. Mean wind speed data in measured hourly time series format is statistically analyzed for the six year period 1998-2003. The probability density distributions are derived from the time series data and their distributional parameters are identified. Two probability density functions are fitted to the measured probability distributions on a seasonal basis. The wind energy characteristics of all the regions is studied based on the Weibull and Rayleigh distributions. Energy calculations and capacity factors for the wind turbine characteristics were determined for wind machines of different sizes between 300 and 2300 kW. It was found that Maden is the best region, among the regions analyzed, for wind characteristics and wind turbine characteristics

  3. Linear wind generator

    International Nuclear Information System (INIS)

    Kozarov, A.; Petrov, O.; Antonov, J.; Sotirova, S.; Petrova, B.

    2006-01-01

    The purpose of the linear wind-power generator described in this article is to decrease the following disadvantages of the common wind-powered turbine: 1) large bending and twisting moments to the blades and the shaft, especially when strong winds and turbulence exist; 2) significant values of the natural oscillation period of the construction result in the possibility of occurrence of destroying resonance oscillations; 3) high velocity of the peripheral parts of the rotor creating a danger for birds; 4) difficulties, connected with the installation and the operation on the mountain ridges and passages where the wind energy potential is the largest. The working surfaces of the generator in questions driven by the wind are not connected with a joint shaft but each moves along a railway track with few oscillations. So the sizes of each component are small and their number can be rather large. The mechanical trajectory is not a circle but a closed outline in a vertical plain, which consists of two rectilinear sectors, one above the other, connected in their ends by semi-circumferences. The mechanical energy of each component turns into electrical on the principle of the linear electrical generator. A regulation is provided when the direction of the wind is perpendicular to the route. A possibility of effectiveness is shown through aiming of additional quantities of air to the movable components by static barriers

  4. Wind energy in South Africa

    International Nuclear Information System (INIS)

    Linde, H.A. van der

    1996-01-01

    Wind, in South Africa, has been a source of energy for many years but at the same time it is taking as much time and effort to receive the recognition it deserves as anywhere else in the world. The wind resource is comparable to a number of areas in the world wind is exploited as a grid connected source of electrical energy. Although the environmental impact of conventional sources of energy is not as widespread as most of the industrial nations some areas should be looked at critically. Wind as a bulk generator of energy is tentatively being looked at with some demonstration projects being planned. (author)

  5. Wind energy - the right approach

    International Nuclear Information System (INIS)

    Wade-Smith, R.; Pitcher, K.; British Wind Energy Association, London; European Wind Energy Association)

    1992-01-01

    The improved climate afforded by the Electricity Act 1989 and in particular the so-called non-fossil fuel obligation (NFFO) has brought about a significant number of renewable energy proposals and in particular wind power projects. The 1990 Order included nine wind projects - five windfarms ranging from four to twenty four wind turbines and four single turbine proposals. The purpose of this article is to help the reader have a greater understanding of some of the planning issues concerned with a wind power project (in the UK), and the basis upon which obstacles can be overcome on the road to achieving planning approval. (author)

  6. Next Generation Wind Turbine

    Energy Technology Data Exchange (ETDEWEB)

    Cheraghi, S. Hossein [Western New England Univ., Springfield, MA (United States); Madden, Frank [FloDesign Wind Turbine Corp., Waltham, MA (United States)

    2012-09-01

    The goal of this collaborative effort between Western New England University's College of Engineering and FloDesign Wind Turbine (FDWT) Corporation to wok on a novel areodynamic concept that could potentially lead to the next generation of wind turbines. Analytical studies and early scale model tests of FDWT's Mixer/Ejector Wind Turbine (MEWT) concept, which exploits jet-age advanced fluid dynamics, indicate that the concept has the potential to significantly reduce the cost of electricity over conventional Horizontal Axis Wind Turbines while reducing land usage. This project involved the design, fabrication, and wind tunnel testing of components of MEWT to provide the research and engineering data necessary to validate the design iterations and optimize system performance. Based on these tests, a scale model prototype called Briza was designed, fabricated, installed and tested on a portable tower to investigate and improve the design system in real world conditions. The results of these scale prototype efforts were very promising and have contributed significantly to FDWT's ongoing development of a product scale wind turbine for deployment in multiple locations around the U.S. This research was mutually beneficial to Western New England University, FDWT, and the DOE by utilizing over 30 student interns and a number of faculty in all efforts. It brought real-world wind turbine experience into the classroom to further enhance the Green Engineering Program at WNEU. It also provided on-the-job training to many students, improving their future employment opportunities, while also providing valuable information to further advance FDWT's mixer-ejector wind turbine technology, creating opportunities for future project innovation and job creation.

  7. Effect of Blade Roughness on Transition and Wind Turbine Performance.

    Energy Technology Data Exchange (ETDEWEB)

    Ehrmann, Robert S. [Texas A & M Univ., College Station, TX (United States); White, E. B. [Texas A & M Univ., College Station, TX (United States)

    2015-09-01

    The real-world effect of accumulated surface roughness on wind-turbine power production is not well understood. To isolate specific blade roughness features and test their effect, field measurements of turbine-blade roughness were made and simulated on a NACA 633-418 airfoil in a wind tunnel. Insect roughness, paint chips, and erosion were characterized then manufactured. In the tests, these roughness configurations were recreated as distributed roughness, a forward-facing step, and an eroded leading edge. Distributed roughness was tested in three heights and five densities. Chord Reynolds number was varied between 0:8 to 4:8 × 106. Measurements included lift, drag, pitching moment, and boundary-layer transition location. Results indicate minimal effect from paint-chip roughness. As distributed roughness height and density increase, the lift-curve slope, maximum lift, and lift-to-drag ratio decrease. As Reynolds number increases, natural transition is replaced by bypass transition. The critical roughness Reynolds number varies between 178 to 318, within the historical range. At a chord Reynolds number of 3:2 × 106, the maximum lift-to-drag ratio decreases 40% for 140 μm roughness, corresponding to a 2.3% loss in annual energy production. Simulated performance loss compares well to measured performance loss of an in-service wind turbine.

  8. Grid Integration of Offshore Wind | Wind | NREL

    Science.gov (United States)

    Grid Integration of Offshore Wind Grid Integration of Offshore Wind Much can be learned from the existing land-based integration research for handling the variability and uncertainty of the wind resource Arklow Bank offshore wind park consists of seven GE Wind 3.6-MW wind turbines. Integration and

  9. Assessment and analysis of wind energy generation and power ...

    African Journals Online (AJOL)

    time, a statistical analysis of wind characteristics and the extrapolation of weibull parameters are presented. Otherwise, the .... The wind speed probability density function. (PDF) can ... be adjusted using following expression [28, 30,. 31]:. (11).

  10. Wind Energy

    Energy Technology Data Exchange (ETDEWEB)

    Beurskens, H.J.M. [SET Analysis, Kievitlaan 26, 1742 AD Schagen (Netherlands); Brand, A.J. [Energy research Centre of the Netherlands ECN, Unit Wind Energy, P.O. Box 1, 1755 ZG Petten (Netherlands)

    2013-02-15

    Over the years, wind energy has become a major source of renewable energy worldwide. The present chapter addresses the wind resource, which is available for exploitation for large-scale electricity production, and its specific physical properties. Furthermore, the technical options available to convert the energy of the air flow into mechanical energy and electricity are described. Specific problems of large-scale integration of wind energy into the grid as well as the present and future market developments are described in this chapter. Finally, environmental aspects are discussed briefly.

  11. Prospects for generating electricity by large onshore and offshore wind farms

    Science.gov (United States)

    Volker, Patrick J. H.; Hahmann, Andrea N.; Badger, Jake; Jørgensen, Hans E.

    2017-03-01

    The decarbonisation of energy sources requires additional investments in renewable technologies, including the installation of onshore and offshore wind farms. For wind energy to remain competitive, wind farms must continue to provide low-cost power even when covering larger areas. Inside very large wind farms, winds can decrease considerably from their free-stream values to a point where an equilibrium wind speed is reached. The magnitude of this equilibrium wind speed is primarily dependent on the balance between turbine drag force and the downward momentum influx from above the wind farm. We have simulated for neutral atmospheric conditions, the wind speed field inside different wind farms that range from small (25 km2) to very large (105 km2) in three regions with distinct wind speed and roughness conditions. Our results show that the power density of very large wind farms depends on the local free-stream wind speed, the surface characteristics, and the turbine density. In onshore regions with moderate winds the power density of very large wind farms reaches 1 W m-2, whereas in offshore regions with very strong winds it exceeds 3 W m-2. Despite a relatively low power density, onshore regions with moderate winds offer potential locations for very large wind farms. In offshore regions, clusters of smaller wind farms are generally preferable; under very strong winds also very large offshore wind farms become efficient.

  12. Sensing the wind profile

    DEFF Research Database (Denmark)

    Pena Diaz, Alfredo

    This thesis consists of two parts. The first is a synopsis of the theoretical progress of the study that is based on a number of journal papers. The papers, which constitute the second part of the report, aim to analyze, measure, and model the wind prole in and beyond the surface layer by combini...

  13. Wind energy potential in Peshawar, Pakistan

    International Nuclear Information System (INIS)

    Nasir, S.M.; Raza, S.M.

    1994-01-01

    Hourly wind data at Peshawar airport, received from the Headquarters, Pakistan Air Force, has been used to determine the diurnal variations, speed duration and speed frequency curves. The applicability of Weibull distribution is then tested over probability density function, which shows that weibull distribution fits the wind data satisfactorily and with a good precision, provided the observations of calm spells are omitted. Our analysis shows that monthly mean wind speed and wind power varies from 0.6 to 2.0 m/s and 0.2 to 4.0 wm-2, respectively, giving fair prospects for wind owe applications over the summer months. (author)

  14. Cholesterol Efflux Capacity, High-Density Lipoprotein Particle Number, and Incident Cardiovascular Events: An Analysis From the JUPITER Trial (Justification for the Use of Statins in Prevention: An Intervention Trial Evaluating Rosuvastatin).

    Science.gov (United States)

    Khera, Amit V; Demler, Olga V; Adelman, Steven J; Collins, Heidi L; Glynn, Robert J; Ridker, Paul M; Rader, Daniel J; Mora, Samia

    2017-06-20

    Recent failures of drugs that raised high-density lipoprotein (HDL) cholesterol levels to reduce cardiovascular events in clinical trials have led to increased interest in alternative indices of HDL quality, such as cholesterol efflux capacity, and HDL quantity, such as HDL particle number. However, no studies have directly compared these metrics in a contemporary population that includes potent statin therapy and low low-density lipoprotein cholesterol. HDL cholesterol levels, apolipoprotein A-I, cholesterol efflux capacity, and HDL particle number were assessed at baseline and 12 months in a nested case-control study of the JUPITER trial (Justification for the Use of Statins in Prevention: An Intervention Trial Evaluating Rosuvastatin), a randomized primary prevention trial that compared rosuvastatin treatment to placebo in individuals with normal low-density lipoprotein cholesterol but increased C-reactive protein levels. In total, 314 cases of incident cardiovascular disease (CVD) (myocardial infarction, unstable angina, arterial revascularization, stroke, or cardiovascular death) were compared to age- and gender-matched controls. Conditional logistic regression models adjusting for risk factors evaluated associations between HDL-related biomarkers and incident CVD. Cholesterol efflux capacity was moderately correlated with HDL cholesterol, apolipoprotein A-I, and HDL particle number (Spearman r = 0.39, 0.48, and 0.39 respectively; P capacity (OR/SD, 0.89; 95% CI, 0.72-1.10; P =0.28), HDL cholesterol (OR/SD, 0.82; 95% CI, 0.66-1.02; P =0.08), or apolipoprotein A-I (OR/SD, 0.83; 95% CI, 0.67-1.03; P =0.08). Twelve months of rosuvastatin (20 mg/day) did not change cholesterol efflux capacity (average percentage change -1.5%, 95% CI, -13.3 to +10.2; P =0.80), but increased HDL cholesterol (+7.7%), apolipoprotein A-I (+4.3%), and HDL particle number (+5.2%). On-statin cholesterol efflux capacity was inversely associated with incident CVD (OR/SD, 0.62; 95% CI, 0

  15. World Wind

    Data.gov (United States)

    National Aeronautics and Space Administration — World Wind allows any user to zoom from satellite altitude into any place on Earth, leveraging high resolution LandSat imagery and SRTM elevation data to experience...

  16. Wind power

    International Nuclear Information System (INIS)

    2009-01-01

    At the end of 2008,the European wind power capacity had risen to 65,247 MW which is a 15,1% increase on 2007. The financial crisis does not appear to have any real consequences of the wind power sector's activity in 2008. At the end of 2008 the European Union accommodated 53,9% of the world's wind power capacity. The top ten countries in terms of installed wind capacities are: 1) Usa with 25,388 MW, 2) Germany with 23,903 MW, 3) Spain with 16,740 MW, 4) China with 12,200 MW, 5) India with 9,645 MW, 6) Italy with 3,736 MW, 7) France with 3,542 MW, 8) U.K. with 3,406 MW, 9) Denmark with 3,166 MW and 10) Portugal with 2,862 MW. (A.C.)

  17. FACTS Devices for Large Wind Power Plants

    DEFF Research Database (Denmark)

    Adamczyk, Andrzej Grzegorz; Teodorescu, Remus; Rodriguez, Pedro

    2010-01-01

    Growing number of wind turbines is changing electricity generation profile all over the world. However, high wind energy penetration affects power system safety and stability. For this reason transmission system operators (TSO) impose more stringent connection requirements on the wind power plant...

  18. Optimizing wind power generation while minimizing wildlife impacts in an urban area.

    Directory of Open Access Journals (Sweden)

    Gil Bohrer

    Full Text Available The location of a wind turbine is critical to its power output, which is strongly affected by the local wind field. Turbine operators typically seek locations with the best wind at the lowest level above ground since turbine height affects installation costs. In many urban applications, such as small-scale turbines owned by local communities or organizations, turbine placement is challenging because of limited available space and because the turbine often must be added without removing existing infrastructure, including buildings and trees. The need to minimize turbine hazard to wildlife compounds the challenge. We used an exclusion zone approach for turbine-placement optimization that incorporates spatially detailed maps of wind distribution and wildlife densities with power output predictions for the Ohio State University campus. We processed public GIS records and airborne lidar point-cloud data to develop a 3D map of all campus buildings and trees. High resolution large-eddy simulations and long-term wind climatology were combined to provide land-surface-affected 3D wind fields and the corresponding wind-power generation potential. This power prediction map was then combined with bird survey data. Our assessment predicts that exclusion of areas where bird numbers are highest will have modest effects on the availability of locations for power generation. The exclusion zone approach allows the incorporation of wildlife hazard in wind turbine siting and power output considerations in complex urban environments even when the quantitative interaction between wildlife behavior and turbine activity is unknown.

  19. Optimizing wind power generation while minimizing wildlife impacts in an urban area.

    Science.gov (United States)

    Bohrer, Gil; Zhu, Kunpeng; Jones, Robert L; Curtis, Peter S

    2013-01-01

    The location of a wind turbine is critical to its power output, which is strongly affected by the local wind field. Turbine operators typically seek locations with the best wind at the lowest level above ground since turbine height affects installation costs. In many urban applications, such as small-scale turbines owned by local communities or organizations, turbine placement is challenging because of limited available space and because the turbine often must be added without removing existing infrastructure, including buildings and trees. The need to minimize turbine hazard to wildlife compounds the challenge. We used an exclusion zone approach for turbine-placement optimization that incorporates spatially detailed maps of wind distribution and wildlife densities with power output predictions for the Ohio State University campus. We processed public GIS records and airborne lidar point-cloud data to develop a 3D map of all campus buildings and trees. High resolution large-eddy simulations and long-term wind climatology were combined to provide land-surface-affected 3D wind fields and the corresponding wind-power generation potential. This power prediction map was then combined with bird survey data. Our assessment predicts that exclusion of areas where bird numbers are highest will have modest effects on the availability of locations for power generation. The exclusion zone approach allows the incorporation of wildlife hazard in wind turbine siting and power output considerations in complex urban environments even when the quantitative interaction between wildlife behavior and turbine activity is unknown.

  20. Preliminary study of long-term wind characteristics of the Mexican Yucatan Peninsula

    International Nuclear Information System (INIS)

    Soler-Bientz, Rolando; Watson, Simon; Infield, David

    2009-01-01

    Mexico's Yucatan Peninsula is one of the most promising areas for wind energy development within the Latin American region but no comprehensive assessment of wind resource has been previously published. This research presents a preliminary analysis of the meteorological parameters relevant to the wind resource in order to find patterns in their long-term behaviour and to establish a foundation for subsequent research into the wind power potential of the Yucatan Peninsula. Three meteorological stations with data measured for a period between 10 and 20 years were used in this study. The monthly trends of ambient temperature, atmospheric pressure and wind speed data were identified and are discussed. The directional behaviour of the winds, their frequency distributions and the related Weibull parameters are presented. Wind power densities for the study sites have been estimated and have been shown to be relatively low (wind power class 1), though a larger number of suitable sites needs to be studied before a definitive resource evaluation can be reported.

  1. Wind power

    Energy Technology Data Exchange (ETDEWEB)

    1979-01-01

    This publication describes some of the technical, economic, safety and institutional considerations involved in the selection, installation and evaluation of a wind generation system. This information is presented, where possible, in practical, non-technical terms. The first four sections provide background information, theory, and general knowledge, while the remaining six sections are of a more specific nature to assist the prospective owner of a wind generator in his calculations and selections. Meteorological information is provided relating to the wind regime in Nova Scotia. The section on cost analysis discusses some of the factors and considerations which must be examined in order to provide a logical comparison between the alternatives of electricity produced from other sources. The final two sections are brief summaries of the regulations and hazards pertaining to the use of wind generators. The cost of wind-generated electricity is high compared to present Nova Scotia Power Corporation rates, even on Sable Island, Nova Scotia's highest wind area. However, it may be observed that Sable Island is one of the areas of Nova Scotia which is not presently supplied through the power grid and, particularly if there was a significant increase in the price of diesel oil, wind-generated electricity may well be the most economical alternative in that area. Generally speaking, however, where a consumer can purchase electricity at the normal domestic rate, wind generators are not economical, and they will not become economical unless there is a great reduction in their cost, an great increase in electricity rates, or both. Includes glossary. 23 figs., 11 tabs.

  2. Development of distributed topographical forecasting model for wind resource assessment using artificial neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Narayana, P.B. [Green Life Energy Solutions LLP, Secunderabad (India); Rao, S.S. [National Institute of Technology. Dept. of Mechanical Engineering, Warangal (India); Reddy, K.H. [JNT Univ.. Dept. of Mechanical Engineering, Anantapur (India)

    2012-07-01

    Economics of wind power projects largely depend on the availability of wind power density. Wind resource assessment is a study estimating wind speeds and wind power densities in the region under consideration. The accuracy and reliability of data sets comprising of wind speeds and wind power densities at different heights per topographic region characterized by elevation or mean sea level, is important for wind power projects. Indian Wind Resource Assessment program conducted in 80's consisted of wind data measured by monitoring stations at different topographies in order to measure wind power density values at 25 and 50 meters above the ground level. In this paper, an attempt has been made to assess wind resource at a given location using artificial neural networks. Existing wind resource data has been used to train the neural networks. Location topography (characterized by longitude, latitude and mean sea level), air density, mean annual wind speed (MAWS) are used as inputs to the neural network. Mean annual wind power density (MAWPD) in watt/m{sup 2} is predicted for a new topographic location. Simple back propagation based neural network has been found to be sufficient for predicting these values with suitable accuracy. This model is closely linked to the problem of wind energy forecasting considering the variations of specific atmospheric variables with time horizons. This model will help the wind farm developers to have an initial estimation of the wind energy potential at a particular topography. (Author)

  3. (epf) in estimating wind power density

    African Journals Online (AJOL)

    Dogara M. D et. al

    (7). ∞. 0. Energy Pattern Factor (EPF). The Energy Pattern Factor (EPF) Method, is defined by Akdag and Ali (2009) as an ... the monthly average for an eleven year period was found (table. 1). .... Edition, Mc Graw Hill Inc., New York. Walker ...

  4. Wind farm policy 1995

    International Nuclear Information System (INIS)

    Anon.

    1995-03-01

    Argyll and Bute District Council, having received a number of planning applications for the erection of wind farms, seeks, in this document, to set out its environmental policy on these installations in line with national government guidelines and those from Strathclyde Regional Council. District Council policy on thirteen environmental issues connected with wind farm construction is set out, covering issues such as environmental impacts on wild-life, noise pollution, access for construction, maintenance and decommissioning vehicles as well as planning consent issues. Recommendations are made to four interested bodies, Strathclyde Regional Council, the Forestry Authority and Scottish Natural Heritage and the Royal Society for the Protection of Birds. (UK)

  5. Aggregated wind power generation probabilistic forecasting based on particle filter

    International Nuclear Information System (INIS)

    Li, Pai; Guan, Xiaohong; Wu, Jiang

    2015-01-01

    Highlights: • A new method for probabilistic forecasting of aggregated wind power generation. • A dynamic system is established based on a numerical weather prediction model. • The new method handles the non-Gaussian and time-varying wind power uncertainties. • Particle filter is applied to forecast predictive densities of wind generation. - Abstract: Probability distribution of aggregated wind power generation in a region is one of important issues for power system daily operation. This paper presents a novel method to forecast the predictive densities of the aggregated wind power generation from several geographically distributed wind farms, considering the non-Gaussian and non-stationary characteristics in wind power uncertainties. Based on a mesoscale numerical weather prediction model, a dynamic system is established to formulate the relationship between the atmospheric and near-surface wind fields of geographically distributed wind farms. A recursively backtracking framework based on the particle filter is applied to estimate the atmospheric state with the near-surface wind power generation measurements, and to forecast the possible samples of the aggregated wind power generation. The predictive densities of the aggregated wind power generation are then estimated based on these predicted samples by a kernel density estimator. In case studies, the new method presented is tested on a 9 wind farms system in Midwestern United States. The testing results that the new method can provide competitive interval forecasts for the aggregated wind power generation with conventional statistical based models, which validates the effectiveness of the new method

  6. Evaluation of wind energy potential in the south-south geopolitical ...

    African Journals Online (AJOL)

    South geopolitical zone of Nigeria using 10 year wind data obtained at a height of 10m as a possible location for energy generation from wind. The obtained ... Keywords: Mean wind speed, Wind power density, Wind energy, Renewable energy ...

  7. Level densities

    International Nuclear Information System (INIS)

    Ignatyuk, A.V.

    1998-01-01

    For any applications of the statistical theory of nuclear reactions it is very important to obtain the parameters of the level density description from the reliable experimental data. The cumulative numbers of low-lying levels and the average spacings between neutron resonances are usually used as such data. The level density parameters fitted to such data are compiled in the RIPL Starter File for the tree models most frequently used in practical calculations: i) For the Gilber-Cameron model the parameters of the Beijing group, based on a rather recent compilations of the neutron resonance and low-lying level densities and included into the beijing-gc.dat file, are chosen as recommended. As alternative versions the parameters provided by other groups are given into the files: jaeri-gc.dat, bombay-gc.dat, obninsk-gc.dat. Additionally the iljinov-gc.dat, and mengoni-gc.dat files include sets of the level density parameters that take into account the damping of shell effects at high energies. ii) For the backed-shifted Fermi gas model the beijing-bs.dat file is selected as the recommended one. Alternative parameters of the Obninsk group are given in the obninsk-bs.dat file and those of Bombay in bombay-bs.dat. iii) For the generalized superfluid model the Obninsk group parameters included into the obninsk-bcs.dat file are chosen as recommended ones and the beijing-bcs.dat file is included as an alternative set of parameters. iv) For the microscopic approach to the level densities the files are: obninsk-micro.for -FORTRAN 77 source for the microscopical statistical level density code developed in Obninsk by Ignatyuk and coworkers, moller-levels.gz - Moeller single-particle level and ground state deformation data base, moller-levels.for -retrieval code for Moeller single-particle level scheme. (author)

  8. Do terrestrial animals avoid areas close to turbines in functioning wind farms in agricultural landscapes?

    Science.gov (United States)

    Łopucki, Rafał; Klich, Daniel; Gielarek, Sylwia

    2017-07-01

    Most studies on the effects of wind energy on animals have focused on avian and bat activity, habitat use, and mortality, whereas very few have been published on terrestrial, non-volant wildlife. In this paper, we studied the utilization of functioning wind farm areas by four terrestrial animals common to agricultural landscapes: European roe deer, European hare, red fox, and the common pheasant. Firstly, we expected that the studied animals do not avoid areas close to turbines and utilize the whole area of functioning wind farms with a frequency similar to the control areas. Secondly, we expected that there is no relation between the turbine proximity and the number of tracks of these animals. The study was conducted over two winter seasons using the snow-tracking method along 100 m linear transects. In total, 583 transects were recorded. Wind farm operations may affect terrestrial animals both in wind farm interiors and in a 700-m buffer zone around the edge of turbines. The reactions of animals were species specific. Herbivorous mammals (roe deer and European hare) avoided wind farm interiors and proximity to turbines. The common pheasant showed a positive reaction to wind turbine proximity. The red fox had the most neutral response to wind turbines. Although this species visited wind farm interiors less often than the control area, there was no relation between fox track density and turbine proximity. Greater weight should be given to the effects of wind farms on non-flying wildlife than at present. Investors and regulatory authorities should always consider the likely impacts of wind farms during environmental impact assessments and try to reduce these negative effects.

  9. Prospects for generating electricity by large onshore and offshore wind farms

    DEFF Research Database (Denmark)

    Volker, Patrick; Hahmann, Andrea N.; Badger, Jake

    2017-01-01

    large wind farms, winds can decrease considerably from their free-stream values to a point where an equilibrium wind speed is reached. The magnitude of this equilibrium wind speed is primarily dependent on the balance between turbine drag force and the downward momentum influx from above the wind farm......The decarbonisation of energy sources requires additional investments in renewable technologies, including the installation of onshore and offshore wind farms. For wind energy to remain competitive, wind farms must continue to provide low-cost power even when covering larger areas. Inside very...... on the local free-stream wind speed, the surface characteristics, and the turbine density. In onshore regions with moderate winds the power density of very large wind farms reaches 1 W m−2, whereas in offshore regions with very strong winds it exceeds 3 W m−2. Despite a relatively low power density, onshore...

  10. FINAL REPORT WIND POWER WARM SPRINGS RESERVATION TRIBAL LANDS DOE GRANT NUMBER DE-FG36-07GO17077 SUBMITTED BY WARM SPRINGS POWER & WATER ENTERPRISES A CORPORATE ENTITY OF THE CONFEDERATED TRIBES OF WARM SPRINGS WARM SPRINGS, OREGON

    Energy Technology Data Exchange (ETDEWEB)

    Jim Manion; Michael Lofting; Wil Sando; Emily Leslie; Randy Goff

    2009-03-30

    Wind Generation Feasibility Warm Springs Power and Water Enterprises (WSPWE) is a corporate entity owned by the Confederated Tribes of the Warm Springs Reservation, located in central Oregon. The organization is responsible for managing electrical power generation facilities on tribal lands and, as part of its charter, has the responsibility to evaluate and develop renewable energy resources for the Confederated Tribes of Warm Springs. WSPWE recently completed a multi-year-year wind resource assessment of tribal lands, beginning with the installation of wind monitoring towers on the Mutton Mountains site in 2003, and collection of on-site wind data is ongoing. The study identified the Mutton Mountain site on the northeastern edge of the reservation as a site with sufficient wind resources to support a commercial power project estimated to generate over 226,000 MWh per year. Initial estimates indicate that the first phase of the project would be approximately 79.5 MW of installed capacity. This Phase 2 study expands and builds on the previously conducted Phase 1 Wind Resource Assessment, dated June 30, 2007. In order to fully assess the economic benefits that may accrue to the Tribes through wind energy development at Mutton Mountain, a planning-level opinion of probable cost was performed to define the costs associated with key design and construction aspects of the proposed project. This report defines the Mutton Mountain project costs and economics in sufficient detail to allow the Tribes to either build the project themselves or contract with a developer under the most favorable terms possible for the Tribes.

  11. Depletion of solar wind plasma near a planetary boundary

    International Nuclear Information System (INIS)

    Zwan, B.J.; Wolf, R.A.

    1976-01-01

    A mathematical model is presented that describes the squeezing of solar wind plasma out along interplanetary magnetic field lines in the region between the bow shock and the effective planetary boundary (in the case of the earth, the magnetopause). In the absence of local magnetic merging the squeezing process should create a 'depletion layer,' a region of very low plasma density just outside the magnetopause. Numerical solutions are obtained for the dimensionless magnetohydrodynamic equations describing this depletion process for the case where the solar wind magnetic field is perpendicular to the solar wind flow direction. For the case of the earth with a magnetopause standoff distance of 10 R/subE/, the theory predicts that the density should be reduced by a factor > or =2 in a layer about 700--1300 km thick if M/subA/, the Alfven Mach number in the solar wind, is equal to 8. The layer thickness should vary as M/subA/ -2 and should be approximately uniform for a large area of the magnetopause around the subsolar point. Computed layer thicknesses are somewhat smaller than those derived from Lees' axisymmetric model. Depletion layers should develop fully only where magnetic merging is locally unimportant. Scaling of the model calculations to Venus and Mars suggest layer thicknesses about 1/10 and 1/15 those of the earth, respectively, neglecting diffusion and ionospheric effects

  12. Wind Powering America

    Energy Technology Data Exchange (ETDEWEB)

    Flowers, L. (NREL); Dougherty, P. J. (DOE)

    2001-07-07

    At the June 1999 Windpower Conference, the Secretary of Energy launched the Office of Energy Efficiency and Renewable Energy's Wind Powering America (WPA) initiative. The goals of the initiative are to meet 5% of the nation's energy needs with wind energy by 2020 (i.e., 80,000 megawatts installed), to double the number of states that have more than 20 megawatts (MW) of wind capacity to 16 by 2005 and triple it to 24 by 2010, and to increase wind's contribution to Federal electricity use to 5% by 2010. To achieve the Federal government's goal, DOE would take the leadership position and work with its Federal partners. Subsequently, the Secretary accelerated the DOE 5% commitment to 2005. Achieving the 80,000 MW goal would result in approximately $60 billion investment and $1.5 billion of economic development in our rural areas (where the wind resources are the greatest). The purpose of this paper is to provide an update on DOE's strategy for achieving its goals and the activities it has undertaken since the initiative was announced.

  13. Wind energy and Turkey.

    Science.gov (United States)

    Coskun, Aynur Aydin; Türker, Yavuz Özhan

    2012-03-01

    The global energy requirement for sustaining economic activities, meeting social needs and social development is increasing daily. Environmentally friendly, renewable energy resources are an alternative to the primary non-renewable energy resources, which devastate ecosystems in order to meet increasing demand. Among renewable energy sources such as hydropower, biopower, geothermal power and solar power, wind power offers distinct advantages to Turkey. There is an increasing tendency toward wind globally and the European Union adjusted its legal regulations in this regard. As a potential EU Member state, Turkey is going through a similar process. The number of institutional and legal regulations concerning wind power has increased in recent years; technical infrastructure studies were completed, and some important steps were taken in this regard. This study examines the way in which Turkey has developed support for wind power, presents a SWOT analysis of the wind power sector in Turkey and a projection was made for the concrete success expected to be accomplished in the future.

  14. Wind Powering America

    International Nuclear Information System (INIS)

    Flowers, L.; Dougherty, P. J.

    2001-01-01

    At the June 1999 Windpower Conference, the Secretary of Energy launched the Office of Energy Efficiency and Renewable Energy's Wind Powering America (WPA) initiative. The goals of the initiative are to meet 5% of the nation's energy needs with wind energy by 2020 (i.e., 80,000 megawatts installed), to double the number of states that have more than 20 megawatts (MW) of wind capacity to 16 by 2005 and triple it to 24 by 2010, and to increase wind's contribution to Federal electricity use to 5% by 2010. To achieve the Federal government's goal, DOE would take the leadership position and work with its Federal partners. Subsequently, the Secretary accelerated the DOE 5% commitment to 2005. Achieving the 80,000 MW goal would result in approximately$60 billion investment and$1.5 billion of economic development in our rural areas (where the wind resources are the greatest). The purpose of this paper is to provide an update on DOE's strategy for achieving its goals and the activities it has undertaken since the initiative was announced

  15. The steady and vibrating statuses of tulip tree leaves in wind

    Directory of Open Access Journals (Sweden)

    Yuanyuan Zhu

    2017-01-01

    Full Text Available The study of tree leaf aerodynamics is useful to tree protection, solar panel design and development of new power generation technology. 73 tulip leaves were tested in suspended condition and with front as well as back surface of the lamina facing wind. Three types of vibrating statuses, two types of steady statuses, and five critical wind speeds were observed. The existence probabilities of the statuses and criticals, the probability density distribution of every critical over the range of wind speed 0–27 m/s, and the expected values of the criticals were obtained by statistics. The critical Reynolds number, defined by critical wind speed and lamina length, shows an increasing trend with increasing the lamina area or length to width ratio of the lamina, but it shows no trend of increase or decrease with increasing the length ratio of petiole to lamina.

  16. Interspecific Interactions and the Scope for Parent-Offspring Conflict: High Mite Density Temporarily Changes the Trade-Off between Offspring Size and Number in the Burying Beetle, Nicrophorus vespilloides.

    Directory of Open Access Journals (Sweden)

    Ornela De Gasperin

    Full Text Available Parents have a limited amount of resources to invest in reproduction and commonly trade-off how much they invest in offspring size (or quality versus brood size. A negative relationship between offspring size and number has been shown in numerous taxa and it underpins evolutionary conflicts of interest between parents and their young. For example, previous work on vertebrates shows that selection favours mothers that produce more offspring, at the expense of individual offspring size, yet favours offspring that have relatively few siblings and therefore attain a greater size at independence. Here we analyse how this trade-off is temporarily affected by stochastic variation in the intensity of interspecific interactions. We examined the effect of the mite Poecilochirus carabi on the relationship between offspring size and number in the burying beetle, Nicrophorus vespilloides. We manipulated the initial number of mites in the reproductive event (by introducing either no mites, 4 mites, 10 mites, or 16 mites, and assessed the effect on the brood. We found a similar trade-off between offspring size and number in all treatments, except in the '16 mite' treatment where the correlation between offspring number and size flattened considerably. This effect arose because larvae in small broods failed to attain a high mass by dispersal. Our results show that variation in the intensity of interspecific interactions can temporarily change the strength of the trade-off between offspring size and number. In this study, high densities of mites prevented individual offspring from attaining their optimal weight, thus potentially temporarily biasing the outcome of parent-offspring conflict in favour of parents.

  17. Interspecific Interactions and the Scope for Parent-Offspring Conflict: High Mite Density Temporarily Changes the Trade-Off between Offspring Size and Number in the Burying Beetle, Nicrophorus vespilloides.

    Science.gov (United States)

    De Gasperin, Ornela; Kilner, Rebecca M

    2016-01-01

    Parents have a limited amount of resources to invest in reproduction and commonly trade-off how much they invest in offspring size (or quality) versus brood size. A negative relationship between offspring size and number has been shown in numerous taxa and it underpins evolutionary conflicts of interest between parents and their young. For example, previous work on vertebrates shows that selection favours mothers that produce more offspring, at the expense of individual offspring size, yet favours offspring that have relatively few siblings and therefore attain a greater size at independence. Here we analyse how this trade-off is temporarily affected by stochastic variation in the intensity of interspecific interactions. We examined the effect of the mite Poecilochirus carabi on the relationship between offspring size and number in the burying beetle, Nicrophorus vespilloides. We manipulated the initial number of mites in the reproductive event (by introducing either no mites, 4 mites, 10 mites, or 16 mites), and assessed the effect on the brood. We found a similar trade-off between offspring size and number in all treatments, except in the '16 mite' treatment where the correlation between offspring number and size flattened considerably. This effect arose because larvae in small broods failed to attain a high mass by dispersal. Our results show that variation in the intensity of interspecific interactions can temporarily change the strength of the trade-off between offspring size and number. In this study, high densities of mites prevented individual offspring from attaining their optimal weight, thus potentially temporarily biasing the outcome of parent-offspring conflict in favour of parents.

  18. Autocorrelation Study of Solar Wind Plasma and IMF Properties as Measured by the MAVEN Spacecraft

    Science.gov (United States)

    Marquette, Melissa L.; Lillis, Robert J.; Halekas, J. S.; Luhmann, J. G.; Gruesbeck, J. R.; Espley, J. R.

    2018-04-01

    It has long been a goal of the heliophysics community to understand solar wind variability at heliocentric distances other than 1 AU, especially at ˜1.5 AU due to not only the steepening of solar wind stream interactions outside 1 AU but also the number of missions available there to measure it. In this study, we use 35 months of solar wind and interplanetary magnetic field (IMF) data taken at Mars by the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft to conduct an autocorrelation analysis of the solar wind speed, density, and dynamic pressure, which is derived from the speed and density, as well as the IMF strength and orientation. We found that the solar wind speed is coherent, that is, has an autocorrelation coefficient above 1/e, over roughly 56 hr, while the density and pressure are coherent over smaller intervals of roughly 25 and 20 hr, respectively, and that the IMF strength is coherent over time intervals of approximately 20 hr, while the cone and clock angles are considerably less steady but still somewhat coherent up to time lags of roughly 16 hr. We also found that when the speed, density, pressure, or IMF strength is higher than average, the solar wind or IMF becomes uncorrelated more quickly, while when they are below average, it tends to be steadier. This analysis allows us to make estimates of the values of solar wind plasma and IMF parameters when they are not directly measured and provide an approximation of the error associated with that estimate.

  19. Applying Nyquist's method for stability determination to solar wind observations

    Science.gov (United States)

    Klein, Kristopher G.; Kasper, Justin C.; Korreck, K. E.; Stevens, Michael L.

    2017-10-01

    The role instabilities play in governing the evolution of solar and astrophysical plasmas is a matter of considerable scientific interest. The large number of sources of free energy accessible to such nearly collisionless plasmas makes general modeling of unstable behavior, accounting for the temperatures, densities, anisotropies, and relative drifts of a large number of populations, analytically difficult. We therefore seek a general method of stability determination that may be automated for future analysis of solar wind observations. This work describes an efficient application of the Nyquist instability method to the Vlasov dispersion relation appropriate for hot, collisionless, magnetized plasmas, including the solar wind. The algorithm recovers the familiar proton temperature anisotropy instabilities, as well as instabilities that had been previously identified using fits extracted from in situ observations in Gary et al. (2016). Future proposed applications of this method are discussed.

  20. Wind Generators

    Science.gov (United States)

    1989-01-01

    When Enerpro, Inc. president, Frank J. Bourbeau, attempted to file a patent on a system for synchronizing a wind generator to the electric utility grid, he discovered Marshall Space Flight Center's Frank Nola's power factor controller. Bourbeau advanced the technology and received a NASA license and a patent for his Auto Synchronous Controller (ASC). The ASC reduces generator "inrush current," which occurs when large generators are abruptly brought on line. It controls voltage so the generator is smoothly connected to the utility grid when it reaches its synchronous speed, protecting the components from inrush current damage. Generator efficiency is also increased in light winds by applying lower than rated voltage. Wind energy is utilized to drive turbines to generate electricity for utility companies.

  1. Wind turbine

    Science.gov (United States)

    Cheney, Jr., Marvin C.

    1982-01-01

    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.

  2. Autonomous Aerial Sensors for Wind Power Meteorology

    DEFF Research Database (Denmark)

    Giebel, Gregor; Schmidt Paulsen, Uwe; Reuder, Joachim

    2011-01-01

    , UAVs could be quite cost-effective. In order to test this assumption and to test the limits of UAVs for wind power meteorology, this project assembles four different UAVs from four participating groups. Risø has built a lighter-than-air kite with a long tether, Bergen University flies a derivative......This paper describes a new approach for measurements in wind power meteorology using small unmanned flying platforms. Large-scale wind farms, especially offshore, need an optimisation between installed wind power density and the losses in the wind farm due to wake effects between the turbines. Good...... movement. In any case, a good LIDAR or SODAR will cost many tenthousands of euros. Another current problem in wind energy is the coming generation of wind turbines in the 10-12MW class, with tip heights of over 200m. Very few measurement masts exist to verify our knowledge of atmospheric physics, and most...

  3. 78 FR 29364 - Exelon Corporation, Exelon Wind 1, LLC, Exelon Wind 2, LLC, Exelon Wind 3, LLC, Exelon Wind 4...

    Science.gov (United States)

    2013-05-20

    ...-005, QF07-55-005, QF07-56-005, QF07-257-004] Exelon Corporation, Exelon Wind 1, LLC, Exelon Wind 2, LLC, Exelon Wind 3, LLC, Exelon Wind 4, LLC, Exelon Wind 5, LLC, Exelon Wind 6, LLC, Exelon Wind 7, LLC, Exelon Wind 8, LLC, Exelon Wind 9, LLC, Exelon Wind 10, LLC, Exelon Wind 11, LLC, High Plains...

  4. Power Electronics Converters for Wind Turbine Systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Liserre, Marco; Ma, Ke

    2012-01-01

    The steady growth of installed wind power together with the upscaling of the single wind turbine power capability has pushed the research and development of power converters toward full-scale power conversion, lowered cost pr kW, increased power density, and also the need for higher reliability. ...

  5. 3D WindScanner lidar measurements of wind and turbulence around wind turbines, buildings and bridges

    Science.gov (United States)

    Mikkelsen, T.; Sjöholm, M.; Angelou, N.; Mann, J.

    2017-12-01

    WindScanner is a distributed research infrastructure developed at DTU with the participation of a number of European countries. The research infrastructure consists of a mobile technically advanced facility for remote measurement of wind and turbulence in 3D. The WindScanners provide coordinated measurements of the entire wind and turbulence fields, of all three wind components scanned in 3D space. Although primarily developed for research related to on- and offshore wind turbines and wind farms, the facility is also well suited for scanning turbulent wind fields around buildings, bridges, aviation structures and of flow in urban environments. The mobile WindScanner facility enables 3D scanning of wind and turbulence fields in full scale within the atmospheric boundary layer at ranges from 10 meters to 5 (10) kilometers. Measurements of turbulent coherent structures are applied for investigation of flow pattern and dynamical loads from turbines, building structures and bridges and in relation to optimization of the location of, for example, wind farms and suspension bridges. This paper presents our achievements to date and reviews briefly the state-of-the-art of the WindScanner measurement technology with examples of uses for wind engineering applications.

  6. Path-integral computation of superfluid densities

    International Nuclear Information System (INIS)

    Pollock, E.L.; Ceperley, D.M.

    1987-01-01

    The normal and superfluid densities are defined by the response of a liquid to sample boundary motion. The free-energy change due to uniform boundary motion can be calculated by path-integral methods from the distribution of the winding number of the paths around a periodic cell. This provides a conceptually and computationally simple way of calculating the superfluid density for any Bose system. The linear-response formulation relates the superfluid density to the momentum-density correlation function, which has a short-ranged part related to the normal density and, in the case of a superfluid, a long-ranged part whose strength is proportional to the superfluid density. These facts are discussed in the context of path-integral computations and demonstrated for liquid 4 He along the saturated vapor-pressure curve. Below the experimental superfluid transition temperature the computed superfluid fractions agree with the experimental values to within the statistical uncertainties of a few percent in the computations. The computed transition is broadened by finite-sample-size effects

  7. Investigation of wind characteristics and wind energy assessment in Sao Joao do Cariri (SJC) - Paraiba, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Laerte; Filho, Celso

    2010-09-15

    In this study wind characterization and wind energy assessment of the Sao Joao do Cariri (SJC) in Paraiba state situated in Brazilian northeast. The average wind speed and temperature for 25 and 50 m were found 4,74m/s, 24,46C and 5,31m/s 24,25C with wind speed predominate direction of SSE (165 degrees). Weibull shape, scale ,Weibull fit wind speed and Power wind density found 2,54, 5,4m/s, 4,76m/s and 103W/m2 for 25m wind height measurements and 2,59, 6,0m/s, 5,36m/s and 145W/m2 for 50m wind height measurements.

  8. Status of the French wind energy fleet - December 2010

    International Nuclear Information System (INIS)

    2010-12-01

    Maps, tables and graphs indicate the installed wind energy power in France at 1 October 2010, the evolution of the installed power and number of wind turbines, the distribution of installed power at the region and district levels, wind energy production in October 2010, and market shares of wind turbine manufacturers in France

  9. Management of moderate wind energy coastal resources

    International Nuclear Information System (INIS)

    Karamanis, D.

    2011-01-01

    Research highlights: → Life cycle analysis reveals the viability of moderate wind fields utilization. → Wind turbine is the greenest electricity generator at a touristic site. → Wind parks should be collective applications of small hotel-apartments owners. -- Abstract: The feasibility of wind energy utilization at moderate wind fields was investigated for a typical touristic coastal site in Western Greece. Initially, the wind speed and direction as well as its availability, duration and diurnal variation were assessed. For an analysis period of eight years, the mean wind speed at ten meters was determined as 3.8 m s -1 with a small variation in monthly average wind speeds between 3.0 (January) and 4.4 m s -1 (October). The mean wind power density was less than 200 W m -2 at 10 m indicating the limiting suitability of the site for the usual renewable energy applications. However, life cycle analysis for wind turbine generators with lower cut-in, cut-out, and rated speeds revealed that the energy yield ratio can reach a value of six for a service life of 20 years while the energy pay-back period can be 3 years with 33 kt CO 2 -e of avoided greenhouse emissions. Therefore, the recent technological turbine improvements make wind power viable even at moderate wind fields. Moreover, the study of electricity supply of typical small hotel-apartments in the region of Western Greece indicated that the installation of 300 wind turbine generators in these moderate wind fields would cover the total consumption during the open touristic period with profits during the rest of the year. According to these results, wind turbine generators are the 'greenest' way of generating electricity in touristic coastal sites, even of moderate wind speeds.

  10. Remote Sensing Wind and Wind Shear System.

    Science.gov (United States)

    Contents: Remote sensing of wind shear and the theory and development of acoustic doppler; Wind studies; A comparison of methods for the remote detection of winds in the airport environment; Acoustic doppler system development; System calibration; Airport operational tests.

  11. Wind energy in the agricultural sector. Tailwind or head wind?

    International Nuclear Information System (INIS)

    Van der Knijff, A.

    1999-06-01

    The state of the art in the use of wind energy in the agricultural sector in the Netherlands is given in order to map opportunities. Obstacles to expansion of wind capacity in that sector in the short term are described, as well as the most important developments with respect to wind energy. An estimated 275 wind turbines with a capacity of 50 MW are in use in the Netherlands. This means that the agricultural sector accounts for approximately 14% of the total wind capacity in the Netherlands (363 MW in 1998). Most of the agricultural businesses supply all the electricity generated to the public networks. Only a small number of farmers use some of the generated electricity themselves. The most important obstacles for the agrarian sector are the proposed policies of provinces and municipalities, the limited capacity of the public electricity network, and the lack of clarity regarding the liberalisation of the electricity market. In particular, provincial and municipal policies (solitary wind turbines versus wind farms) will determine the prospects for the future of wind energy in the agrarian sector. Despite possible adversities, there are good prospects for the future for the sector because farmers own land in windy locations. 33 refs

  12. Wind and IMP 8 Solar Wind, Magnetosheath and Shock Data

    Science.gov (United States)

    2004-01-01

    The purpose of this project was to provide the community access to magnetosheath data near Earth. We provided 27 years of IMP 8 magnetosheath proton velocities, densities, and temperatures with our best (usually 1-min.) time resolution. IMP 8 crosses the magnetosheath twice each 125 day orbit, and we provided magnetosheath data for the roughly 27 years of data for which magnetometer data are also available (which are needed to reliably pick boundaries). We provided this 27 years of IMP 8 magnetosheath data to the NSSDC; this data is now integrated with the IMP 8 solar wind data with flags indicating whether each data point is in the solar wind, magnetosheath, or at the boundary between the two regions. The plasma speed, density, and temperature are provided for each magnetosheath point. These data are also available on the MIT web site ftp://space .mit.edu/pub/plasma/imp/www/imp.html. We provide ASCII time-ordered rows of data giving the observation time, the spacecraft position in GSE, the velocity is GSE, the density and temperature for protons. We also have analyzed and archived on our web site the Wind magnetosheath plasma parameters. These consist of ascii files of the proton and alpha densities, speeds, and thermal speeds. These data are available at ftp://space.mit.edu/pub/plasma/wind/sheath These are the two products promised in the work statement and they have been completed in full.

  13. Physics-based Tests to Identify the Accuracy of Solar Wind Ion Measurements: A Case Study with the Wind Faraday Cups

    Science.gov (United States)

    Kasper, J. C.; Lazarus, A. J.; Steinberg, J. T.; Ogilvie, K. W.; Szabo, A.

    2006-01-01

    We present techniques for comparing measurements of velocity, temperature, and density with constraints imposed by the plasma physics of magnetized bi-Maxwellian ions. Deviations from these physics-based constraints are interpreted as arising from measurement errors. Two million ion spectra from the Solar Wind Experiment Faraday Cup instruments on the Wind spacecraft are used as a case study. The accuracy of velocity measurements is determined by the fact that differential flow between hydrogen and helium should be aligned with the ambient magnetic field. Modeling the breakdown of field alignment suggests velocity uncertainties are less than 0.16% in magnitude and 3deg in direction. Temperature uncertainty is found by examining the distribution of observed temperature anisotropies in high-beta solar wind intervals where the firehose, mirror, and cyclotron microinstabilities should drive the distribution to isotropy. The presence of a finite anisotropy at high beta suggests overall temperature uncertainties of 8%. Hydrogen and helium number densities are compared with the electron density inferred from observations of the local electron plasma frequency as a function of solar wind speed and year. We find that after accounting for the contribution of minor ions, the results are consistent with a systematic offset between the two instruments of 34%. The temperature and density methods are sensitive to non-Maxwellian features such as heat flux and proton beams and as a result are more suited to slow solar wind where these features are rare. These procedures are of general use in identifying the accuracy of observations from any solar wind ion instrument.

  14. Wind Turbine Generator System Power Performance Test Report for the ARE442 Wind Turbine

    Energy Technology Data Exchange (ETDEWEB)

    van Dam, J.; Jager, D.

    2010-02-01

    This report summarizes the results of a power performance test that NREL conducted on the ARE 442 wind turbine. This test was conducted in accordance with the International Electrotechnical Commission's (IEC) standard, Wind Turbine Generator Systems Part 12: Power Performance Measurements of Electricity Producing Wind Turbines, IEC 61400-12-1 Ed.1.0, 2005-12. However, because the ARE 442 is a small turbine as defined by IEC, NREL also followed Annex H that applies to small wind turbines. In these summary results, wind speed is normalized to sea-level air density.

  15. Wind model for low frequency power fluctuations in offshore wind farms

    DEFF Research Database (Denmark)

    Vigueras-Rodríguez, A.; Sørensen, Poul Ejnar; Cutululis, Nicolaos Antonio

    2010-01-01

    of hours, taking into account the spectral correlation between different wind turbines. The modelling is supported by measurements from two large wind farms, namely Nysted and Horns Rev. Measurements from individual wind turbines and meteorological masts are used. Finally, the models are integrated......This paper investigates the correlation between the frequency components of the wind speed Power Spectral Density. The results extend an already existing power fluctuation model that can simulate power fluctuations of wind power on areas up to several kilometers and for time scales up to a couple...

  16. Wind energy

    International Nuclear Information System (INIS)

    Portilla S, L.A.

    1995-01-01

    The wind energy or eolic energy is a consequence of solar energy, the one which is absorbed by the atmosphere and is transformed into energy of movement of large bulks of air. In this process the atmosphere acts as the filter to the solar radiation and demotes the ultraviolet beams that result fatal to life in the Earth. The ionosphere is the most external cap and this is ionized by means of absorption process of ultraviolet radiation arising to the Sun. The atmosphere also acts as a trap to the infrared radiation, it that results from the continual process of energetic degradation. In this way, the interaction between Earth - Atmospheres, is behaved as a great greenhouse, maintaining the constant temperatures, including in the dark nights. Processes as the natural convection (that occur by the thermodynamic phenomenon), equatorial calmness, trade winds and against trade winds and global distribution of the air currents are described. The other hand, techniques as the transformation of the wind into energy and its parameters also are shown

  17. Wind power

    International Nuclear Information System (INIS)

    2006-06-01

    This road-map proposes by the Group Total aims to inform the public on the wind power. It presents the principles, the technology takes off, its applications and technology focus, the global market trends and the outlooks and Total commitments in the domain. (A.L.B.)

  18. Influence of housing density on the number of road containers for selective collection. Methodology and analysis of the results; Influenza della densita' abitativa sul numero dei contenitori stradali per la raccolta differenziata: metodologia e analisi dei risultati

    Energy Technology Data Exchange (ETDEWEB)

    Florio, G. [Calabria Univ., Arcavata di rende, RC (Italy). Dipt. di Meccanica; Greco, G. [MI.GA. S.r.l., Rende, CS (Italy); Giordano, R.

    1999-10-01

    In planning the network of road bins for selective collection, housing density or the relationship between built-up area and population living, is significant. The influence of the above parameter on planning the system is formalised in this work and an evaluation method valid for the number of bins required for a generic material is developed. Application to a real case has enable the obtainable results with the proposed procedure to be indicate. [Italian] Nel presente lavoro viene formalizzata l'influenza del parametro sul dimensionamento del sistema della raccolta differenziata e viene presentato un metodo divalutazione del numero di contenitori valido per un generico materiale. Un'applicazione ad un caso reale ha permesso di evidenziare i risultati ottenuti con la procedura proposta.

  19. Wind Energy Japan

    Energy Technology Data Exchange (ETDEWEB)

    Komatsubara, Kazuyo [Embassy of the Kingdom of the Netherlands, Tokyo (Japan)

    2012-06-15

    An overview is given of wind energy in Japan: Background; Wind Energy in Japan; Japanese Wind Energy Industry; Government Supports; Useful Links; Major Japanese Companies; Profiles of Major Japanese Companies; Major Wind Energy Projects in Japan.

  20. Wind energy systems

    Science.gov (United States)

    Stewart, H. J.

    1978-01-01

    A discussion on wind energy systems involved with the DOE wind energy program is presented. Some of the problems associated with wind energy systems are discussed. The cost, efficiency, and structural design of wind energy systems are analyzed.

  1. Solar Wind 0.1-1 keV Electrons in the Corotating Interaction Regions

    Science.gov (United States)

    Wang, L.; Tao, J.; Li, G.; Wimmer-Schweingruber, R. F.; Jian, L. K.; He, J.; Tu, C.; Tian, H.; Bale, S. D.

    2017-12-01

    Here we present a statistical study of the 0.1-1 keV suprathermal electrons in the undisturbed and compressed slow/fast solar wind, for the 71 corotating interaction regions (CIRs) with good measurements from the WIND 3DP and MFI instruments from 1995 to 1997. For each of these CIRs, we separate the strahl and halo electrons based on their different behaviors in pitch angle distributions in the undisturbed and compressed solar wind. We fit both the strahl and halo energy spectra to a kappa function with an index κ index and effective temperature Teff, and calculate the pitch-angle width at half-maximum (PAHM) of the strahl population. We also integrate the electron measurements between 0.1 and 1.0 keV to obtain the number density n and average energy Eavg for the strahl and halo populations. We find that for both the strahl and halo populations within and around these CIRs, the fitted κ index strongly correlates with Teff, similar to the quiet-time solar wind (Tao et al., ApJ, 2016). The number density of both the strahl and halo shows a strong positive correlation with the electron core temperature. The strahl number density ns is correlated with the magnitude of interplanetary magnetic field, and the strahl PAHM width is anti-correlated with the solar wind speed. These results suggest that the origin of strahl electrons from the solar corona is likely related to the electron core temperature and magnetic field strength, while the production of halo electrons in the interplanetary medium could depend on the solar wind velocity.

  2. 3D WindScanner lidar measurements of wind and turbulence around wind turbines, buildings and bridges

    DEFF Research Database (Denmark)

    Mikkelsen, Torben Krogh; Sjöholm, Mikael; Angelou, Nikolas

    2017-01-01

    WindScanner is a distributed research infrastructure developed at DTU with the participation of a number of European countries. The research infrastructure consists of a mobile technically advanced facility for remote measurement of wind and turbulence in 3D. The WindScanners provide coordinated...... structures and of flow in urban environments. The mobile WindScanner facility enables 3D scanning of wind and turbulence fields in full scale within the atmospheric boundary layer at ranges from 10 meters to 5 (10) kilometers. Measurements of turbulent coherent structures are applied for investigation...

  3. Wind around the world

    International Nuclear Information System (INIS)

    Rackstraw, K.

    1998-01-01

    A combination of cost reductions and progressive policies in key markets kept the world wind market percolating in 1997 with a record 1510 MW of new wind capacity installed, representing annual sales of more than $1.5 billion. This new record surpasses last year''s total by 24 percent, about the average annual rate of growth for the last three years. Worldwide utility-scale wind installations at the end of 1997 totaled 7763 MW. Most activity occurred in Europe, which accounted for over 75 percent of 1997 installations. Germany was again the world''s leading single market, this time by quite a large margin, accounting for more than one-third of the annual total by itself at 532 MW in 1997. The end of 1997 also marked the time at which Germany officially passed the US as the largest total single market with over 2079 MW in total installations versus about 1805 MW for the US, although the US had actually lost the lead by mid-year. Spain is the new addition to the top echelon of world wind markets, installing 215 MW in 1997 that more than doubles their total installed capacity over the previous year and ranks them number three in the world for the year. Denmark''s 1997 total of 300 MW is also a record, although this estimate could go up as the official count is finalized. India, the second largest wind market in 1995 and 1996, slipped several notches because of a variety of factors, including a change in government and a slowdown in the economy. The US wind market continues to stagnate as it has for the last several years, largely because of the uncertainty surrounding restructuring of US electric utilities. The US market is poised for a big comeback in 1998, however

  4. An optimal design of coreless direct-drive axial flux permanent magnet generator for wind turbine

    International Nuclear Information System (INIS)

    Ahmed, D; Ahmad, A

    2013-01-01

    Different types of generators are currently being used in wind power technology. The commonly used are induction generator (IG), doubly-fed induction generator (DFIG), electrically excited synchronous generator (EESG) and permanent magnet synchronous generator (PMSG). However, the use of PMSG is rapidly increasing because of advantages such as higher power density, better controllability and higher reliability. This paper presents an innovative design of a low-speed modular, direct-drive axial flux permanent magnet (AFPM) generator with coreless stator and rotor for a wind turbine power generation system that is developed using mathematical and analytical methods. This innovative design is implemented in MATLAB / Simulink environment using dynamic modelling techniques. The main focus of this research is to improve efficiency of the wind power generation system by investigating electromagnetic and structural features of AFPM generator during its operation in wind turbine. The design is validated by comparing its performance with standard models of existing wind power generators. The comparison results demonstrate that the proposed model for the wind power generator exhibits number of advantages such as improved efficiency with variable speed operation, higher energy yield, lighter weight and better wind power utilization.

  5. An optimal design of coreless direct-drive axial flux permanent magnet generator for wind turbine

    Science.gov (United States)

    Ahmed, D.; Ahmad, A.

    2013-06-01

    Different types of generators are currently being used in wind power technology. The commonly used are induction generator (IG), doubly-fed induction generator (DFIG), electrically excited synchronous generator (EESG) and permanent magnet synchronous generator (PMSG). However, the use of PMSG is rapidly increasing because of advantages such as higher power density, better controllability and higher reliability. This paper presents an innovative design of a low-speed modular, direct-drive axial flux permanent magnet (AFPM) generator with coreless stator and rotor for a wind turbine power generation system that is developed using mathematical and analytical methods. This innovative design is implemented in MATLAB / Simulink environment using dynamic modelling techniques. The main focus of this research is to improve efficiency of the wind power generation system by investigating electromagnetic and structural features of AFPM generator during its operation in wind turbine. The design is validated by comparing its performance with standard models of existing wind power generators. The comparison results demonstrate that the proposed model for the wind power generator exhibits number of advantages such as improved efficiency with variable speed operation, higher energy yield, lighter weight and better wind power utilization.

  6. First and second order Markov chain models for synthetic generation of wind speed time series

    International Nuclear Information System (INIS)

    Shamshad, A.; Bawadi, M.A.; Wan Hussin, W.M.A.; Majid, T.A.; Sanusi, S.A.M.

    2005-01-01

    Hourly wind speed time series data of two meteorological stations in Malaysia have been used for stochastic generation of wind speed data using the transition matrix approach of the Markov chain process. The transition probability matrices have been formed using two different approaches: the first approach involves the use of the first order transition probability matrix of a Markov chain, and the second involves the use of a second order transition probability matrix that uses the current and preceding values to describe the next wind speed value. The algorithm to generate the wind speed time series from the transition probability matrices is described. Uniform random number generators have been used for transition between successive time states and within state wind speed values. The ability of each approach to retain the statistical properties of the generated speed is compared with the observed ones. The main statistical properties used for this purpose are mean, standard deviation, median, percentiles, Weibull distribution parameters, autocorrelations and spectral density of wind speed values. The comparison of the observed wind speed and the synthetically generated ones shows that the statistical characteristics are satisfactorily preserved

  7. Density measures and additive property

    OpenAIRE

    Kunisada, Ryoichi

    2015-01-01

    We deal with finitely additive measures defined on all subsets of natural numbers which extend the asymptotic density (density measures). We consider a class of density measures which are constructed from free ultrafilters on natural numbers and study a certain additivity property of such density measures.

  8. Wind energy and aviation interests - interim guidelines

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-07-01

    The impact on aviation of increasing the number of wind farms in the United Kingdom is discussed by the Wind Energy, Defence and Civil Aviation Interests Working Group, comprising the Department of Trade and Industry, the Civil Aviation Authority, the Ministry of Defence, and the British Wind Energy Association. The report offers guidance to wind farm developers, local authorities and statutory consultees within the aviation community: the main thrust of the guidelines is to support the UK Government's wind energy targets. Although the document does not contain in-depth technical discussions, it does provide references to such information.

  9. Conditional prediction intervals of wind power generation

    DEFF Research Database (Denmark)

    Pinson, Pierre; Kariniotakis, Georges

    2010-01-01

    A generic method for the providing of prediction intervals of wind power generation is described. Prediction intervals complement the more common wind power point forecasts, by giving a range of potential outcomes for a given probability, their so-called nominal coverage rate. Ideally they inform...... on the characteristics of prediction errors for providing conditional interval forecasts. By simultaneously generating prediction intervals with various nominal coverage rates, one obtains full predictive distributions of wind generation. Adapted resampling is applied here to the case of an onshore Danish wind farm...... to the case of a large number of wind farms in Europe and Australia among others is finally discussed....

  10. Extreme Response for Wind Turbines

    DEFF Research Database (Denmark)

    Toft, Henrik Stensgaard; Sørensen, John Dalsgaard

    2009-01-01

    The characteristic load on wind turbines during operation are among others dependent on the mean wind speed, the turbulence intensity and type and settings of the control system. The characteristic load during operation is normally estimated by statistical extrapolation of a limited number...... of simulated 10min time series of the response according to the wind turbine standard IEC 61400-1. However, this method assumes that the individual 10min time series and the extracted peaks from the time series are independent. In the present paper is this assumption investigated based on field measurements...

  11. Space-time trajectories of wind power generation: Parameterized precision matrices under a Gaussian copula approach

    DEFF Research Database (Denmark)

    Tastu, Julija; Pinson, Pierre; Madsen, Henrik

    2015-01-01

    -correlations. Estimation is performed in a maximum likelihood framework. Based on a test case application in Denmark, with spatial dependencies over 15 areas and temporal ones for 43 hourly lead times (hence, for a dimension of n = 645), it is shown that accounting for space-time effects is crucial for generating skilful......Emphasis is placed on generating space-time trajectories of wind power generation, consisting of paths sampled from high-dimensional joint predictive densities, describing wind power generation at a number of contiguous locations and successive lead times. A modelling approach taking advantage...

  12. Three-component model of solar wind--interstellar medium interaction: some numerical results

    International Nuclear Information System (INIS)

    Baranov, V.; Ermakov, M.; Lebedev, M.

    1981-01-01

    A three-component (electrons, protons, H atoms) model for the interaction between the local interstellar medium and the solar wind is considered. A numerical analysis has been performed to determine how resonance charge exchange in interstellar H atoms that have penetrated the solar wind would affect the two-shock model developed previously by Baranov et al. In particular, if n/sub Hinfinity//n/sub e/infinity>10 (n/sub Hinfinity/, n/sub e/infinity denote the number density of H atoms and electrons in the local ISM) the inner shock may approach the sun as closely as the outer planetary orbits

  13. Relationship of {sup 99m}Tc-HYNIC annexin V uptake to microvessel density, FasL and MMP-9 expression, and the number of tumour-infiltrating lymphocytes in head and neck carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Vermeersch, Hubert; Loose, David [Department of Head and Neck Surgery, University Hospital Ghent (Belgium); Mervillie, Kris; Cuvelier, Claude [Department of Pathology, University Hospital Ghent (Belgium); Lahorte, Christophe; Slegers, Guido [Department of Radiopharmacy, Ghent University (Belgium); Dierck, Rudi Andre; Van de Wiele, Christophe [Division of Nuclear Medicine, University Hospital Ghent, De Pintelaan 185B, 9000, Ghent (Belgium); Steinmetz, Neil [Theseus Imaging Corporation, Cambridge, Massachusetts (United States)

    2004-07-01

    This study reports on the relationship between quantitative {sup 99m}Tc-HYNIC radiolabelled annexin V tumour uptake measurements, Fas ligand (FasL) expression, matrix metalloproteinase-9 (MMP-9) expression, microvessel density (MVD) and the number of tumour-infiltrating lymphocytes in squamous cell carcinoma of the head and neck (SCCHN) patients. Twenty-eight patients (24 men and 4 women; mean age 59 years, range 43-83 years) suffering from a primary (n, number of patients=22) or locally recurrent (n=6) SCCHN were studied. All patients underwent a spiral CT scan, allowing estimation of lesion size in three dimensions, and {sup 99m}Tc-HYNIC annexin V scintigraphy within 1 week of each other. Biopsies or resection of the suspected primary tumour or local recurrence for histopathological analysis were performed on all patients within a period of 10 days following {sup 99m}Tc-HYNIC annexin V scintigraphy. The percentage uptake of the injected dose of {sup 99m}Tc-HYNIC annexin V in visible tumour lesions on scintigrams divided by the tumour volume, derived from CT, was related to MVD and to histological score (HSCORE) values for MMP-9 and FasL expression as well as to the number of tumour-infiltrating lymphocytes (CD45 staining). Median percentage absolute tumour uptake of the injected dose/cm{sup 3} tumour volume derived from tomographic images was 0.0001% (SD 0.0001%) at 5-6 h p.i. (range: 0.000007-0.0003%). Mean HSCORE for MMP-9 tumour staining was 2.1 (SD 0.84). Mean HSCORE for FasL tumour staining was 2.49 (SD 0.92). At the sites of tumour containing the highest number of vessels, the mean MVD was 20 vessels/field at the hot spot (range 1-73). The median number of tumour-infiltrating lymphocytes was 500 (range 100-5,000). The percentage absolute tumour uptake of the injected dose/cm{sup 3} tumour volume derived from tomographic images correlated linearly with FasL HSCORES(r=0.47, P=0.02). No correlation was found between the percentage absolute tumour uptake of the

  14. Relationship of 99mTc-HYNIC annexin V uptake to microvessel density, FasL and MMP-9 expression, and the number of tumour-infiltrating lymphocytes in head and neck carcinoma

    International Nuclear Information System (INIS)

    Vermeersch, Hubert; Loose, David; Mervillie, Kris; Cuvelier, Claude; Lahorte, Christophe; Slegers, Guido; Dierck, Rudi Andre; Van de Wiele, Christophe; Steinmetz, Neil

    2004-01-01

    This study reports on the relationship between quantitative 99m Tc-HYNIC radiolabelled annexin V tumour uptake measurements, Fas ligand (FasL) expression, matrix metalloproteinase-9 (MMP-9) expression, microvessel density (MVD) and the number of tumour-infiltrating lymphocytes in squamous cell carcinoma of the head and neck (SCCHN) patients. Twenty-eight patients (24 men and 4 women; mean age 59 years, range 43-83 years) suffering from a primary (n, number of patients=22) or locally recurrent (n=6) SCCHN were studied. All patients underwent a spiral CT scan, allowing estimation of lesion size in three dimensions, and 99m Tc-HYNIC annexin V scintigraphy within 1 week of each other. Biopsies or resection of the suspected primary tumour or local recurrence for histopathological analysis were performed on all patients within a period of 10 days following 99m Tc-HYNIC annexin V scintigraphy. The percentage uptake of the injected dose of 99m Tc-HYNIC annexin V in visible tumour lesions on scintigrams divided by the tumour volume, derived from CT, was related to MVD and to histological score (HSCORE) values for MMP-9 and FasL expression as well as to the number of tumour-infiltrating lymphocytes (CD45 staining). Median percentage absolute tumour uptake of the injected dose/cm 3 tumour volume derived from tomographic images was 0.0001% (SD 0.0001%) at 5-6 h p.i. (range: 0.000007-0.0003%). Mean HSCORE for MMP-9 tumour staining was 2.1 (SD 0.84). Mean HSCORE for FasL tumour staining was 2.49 (SD 0.92). At the sites of tumour containing the highest number of vessels, the mean MVD was 20 vessels/field at the hot spot (range 1-73). The median number of tumour-infiltrating lymphocytes was 500 (range 100-5,000). The percentage absolute tumour uptake of the injected dose/cm 3 tumour volume derived from tomographic images correlated linearly with FasL HSCORES(r=0.47, P=0.02). No correlation was found between the percentage absolute tumour uptake of the injected dose/cm 3 tumour

  15. The Wind Energy Potential of Kurdistan, Iran

    Science.gov (United States)

    Arefi, Farzad; Moshtagh, Jamal; Moradi, Mohammad

    2014-01-01

    In the current work by using statistical methods and available software, the wind energy assessment of prone regions for installation of wind turbines in, Qorveh, has been investigated. Information was obtained from weather stations of Baneh, Bijar, Zarina, Saqez, Sanandaj, Qorveh, and Marivan. The monthly average and maximum of wind speed were investigated between the years 2000–2010 and the related curves were drawn. The Golobad curve (direction and percentage of dominant wind and calm wind as monthly rate) between the years 1997–2000 was analyzed and drawn with plot software. The ten-minute speed (at 10, 30, and 60 m height) and direction (at 37.5 and 10 m height) wind data were collected from weather stations of Iranian new energy organization. The wind speed distribution during one year was evaluated by using Weibull probability density function (two-parametrical), and the Weibull curve histograms were drawn by MATLAB software. According to the average wind speed of stations and technical specifications of the types of turbines, the suitable wind turbine for the station was selected. Finally, the Divandareh and Qorveh sites with favorable potential were considered for installation of wind turbines and construction of wind farms. PMID:27355042

  16. Applications of wind turbines in Canada

    Energy Technology Data Exchange (ETDEWEB)

    South, P; Rangi, R S; Templin, R J

    1977-01-01

    There are differing views as to the role of wind energy in the overall requirements. While some people tend to ignore it there are others who think that wind could be a major source of energy. In this paper an effort has been made to determine the wind power potential and also the amount that is economically usable. From the existing wind data a map showing the distribution of wind power density has been prepared. This map shows that the maritime provinces and the west coast of Hudson Bay have high wind power potential. These figures show that the wind power potential is of the same order as the installed electrical generating capacity in Canada (58 x 10/sup 6/kW in 1974). However, in order to determine how much of this power is usable the economics of adding wind energy to an existing system must be considered. A computer program has been developed at NRC to analyze the coupling of wind turbines with mixed power systems. Using this program and making certain assumptions about the cost of WECS and fuel the maximum amount of usable wind energy has been calculated. It is shown that if an installed capacity of 420 megawatts of wind power was added to the existing diesel capacity it would result in a savings of 60,000,000 gallons of fuel oil per year. On the other hand it is shown that if the existing installed hydro electric capacity of 37,000 megawatts (1976) was increased to 60,000 megawatts without increasing the average water flow rate, an installed capacity of 60,000 megawatts of wind power could be added to the system. This would result in an average of 14,000 megawatts from the wind. Using projected manufacturing costs for vertical axis wind turbines, the average cost of wind energy could be in the range of 1.4 cents/kwh to 3.6 cents/kwh.

  17. Wind Loads on Structures

    DEFF Research Database (Denmark)

    Dyrbye, Claes; Hansen, Svend Ole

    Wind loads have to be taken into account when designing civil engineering structures. The wind load on structures can be systematised by means of the wind load chain: wind climate (global), terrain (wind at low height), aerodynamic response (wind load to pressure), mechanical response (wind...... pressure to structural response) and design criteria. Starting with an introduction of the wind load chain, the book moves on to meteorological considerations, atmospheric boundary layer, static wind load, dynamic wind load and scaling laws used in wind-tunnel tests. The dynamic wind load covers vibrations...... induced by wind turbulence, vortex shedding, flutter and galloping. The book gives a comprehensive treatment of wind effects on structures and it will be useful for consulting engineers designing wind-sensitive structures. It will also be valuable for students of civil engineering as textbook...

  18. Panorama 2013 - Offshore wind power

    International Nuclear Information System (INIS)

    Vinot, Simon

    2012-10-01

    While onshore wind power is already a well-developed global industry, offshore wind power is still in the consolidation and globalization phase. The most mature of marine renewable energies is beginning to venture off the European coast and even to other continents, driven by public policies and the ever increasing number of players joining this promising market, which should evolve into deeper waters thanks to floating structures. (author)

  19. Stellar winds

    International Nuclear Information System (INIS)

    Weymann, R.J.

    1978-01-01

    It is known that a steady outflow of material at comparable rates of mass loss but vastly different speeds is now known to be ubiquitous phenomenon among both the luminous hot stars and the luminous but cool red giants. The flows are probably massive enough in both cases to give rise to significant effects on stellar evolution and the mass balance between stars and the interstellar medium. The possible mechanisms for these phenomena as well as the methods of observation used are described. In particular, the mass-loss processes in stars other than the sun that also involve a steady flow of matter are considered. The evidence for their existence is described, and then the question of whether the process thought to produce the solar wind is also responsible for producing these stellar winds is explored

  20. Investigation of wind characteristics and assessment of wind energy potential for Waterloo region, Canada

    International Nuclear Information System (INIS)

    Li Meishen; Li Xianguo

    2005-01-01

    Wind energy becomes more and more attractive as one of the clean renewable energy resources. Knowledge of the wind characteristics is of great importance in the exploitation of wind energy resources for a site. It is essential in designing or selecting a wind energy conversion system for any application. This study examines the wind characteristics for the Waterloo region in Canada based on a data source measured at an elevation 10 m above the ground level over a 5-year period (1999-2003) with the emphasis on the suitability for wind energy technology applications. Characteristics such as annual, seasonal, monthly and diurnal wind speed variations and wind direction variations are examined. Wind speed data reveal that the windy months in Waterloo are from November to April, defined as the Cold Season in this study, with February being the windiest month. It is helpful that the high heating demand in the Cold Season coincides with the windy season. Analysis shows that the day time is the windy time, with 2 p.m. in the afternoon being the windiest moment. Moreover, a model derived from the maximum entropy principle (MEP) is applied to determine the diurnal, monthly, seasonal and yearly wind speed frequency distributions, and the corresponding Lagrangian parameters are determined. Based on these wind speed distributions, this study quantifies the available wind energy potential to provide practical information for the application of wind energy in this area. The yearly average wind power density is 105 W/m 2 . The day and night time wind power density in the Cold Season is 180 and 111 W/m 2 , respectively

  1. Using Satellite SAR to Characterize the Wind Flow around Offshore Wind Farms

    Directory of Open Access Journals (Sweden)

    Charlotte Bay Hasager

    2015-06-01

    Full Text Available Offshore wind farm cluster effects between neighboring wind farms increase rapidly with the large-scale deployment of offshore wind turbines. The wind farm wakes observed from Synthetic Aperture Radar (SAR are sometimes visible and atmospheric and wake models are here shown to convincingly reproduce the observed very long wind farm wakes. The present study mainly focuses on wind farm wake climatology based on Envisat ASAR. The available SAR data archive covering the large offshore wind farms at Horns Rev has been used for geo-located wind farm wake studies. However, the results are difficult to interpret due to mainly three issues: the limited number of samples per wind directional sector, the coastal wind speed gradient, and oceanic bathymetry effects in the SAR retrievals. A new methodology is developed and presented. This method overcomes effectively the first issue and in most cases, but not always, the second. In the new method all wind field maps are rotated such that the wind is always coming from the same relative direction. By applying the new method to the SAR wind maps, mesoscale and microscale model wake aggregated wind-fields results are compared. The SAR-based findings strongly support the model results at Horns Rev 1.

  2. Wind resource assessment: A three year experience

    Energy Technology Data Exchange (ETDEWEB)

    Al-Abbadi, N.M.; Alawaji, S.H.; Eugenio, N.N. [Energy Research Institute (ERI), Riyadh (Saudi Arabia)

    1997-12-31

    This paper presents the results of data collected from three different sites located in the central, northern and eastern region of Saudi Arabia. Each site is geographically and climatologically different from the others. Statistical moments and frequency distributions were generated for the wind speed and direction parameters to analyse the wind energy characteristics and its availability. The results of these statistical operations present the wind power and energy density estimates of the three sites. The data analysis presented a prospect of wind energy conversion and utilization. The annual extractable energy density is 488, 890, 599 kWh/m{sup 2} for the central, northern and eastern sites respectively. Also, the paper demonstrates the lessons learned from operating wind assessment stations installed in remote areas having different environmental characteristics.

  3. Wind conditions for wind turbine design

    Energy Technology Data Exchange (ETDEWEB)

    Maribo Pedersen, B.

    1999-04-01

    Delegates from Europe and USA attended the meeting and discussed general aspects of wind conditions for wind turbine design. The subjects and the presented papers covered a very broad range of aspects of wind conditions and related influence on the wind turbine. (EHS)

  4. An evaluation of wind energy potential at Kati Bandar, Pakistan

    Energy Technology Data Exchange (ETDEWEB)

    Ullah, Irfan [Department of Mechanical Engineering, NWFP University of Engineering and Technology, Peshawar (Pakistan); Chaudhry, Qamar-uz-Zaman [Pakistan Meteorological Department, Sector H-8/2, Islamabad (Pakistan); Chipperfield, Andrew J. [Computational Engineering and Design Group, School of Engineering Sciences, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom)

    2010-02-15

    As a developing nation of energy-starved people, Pakistan urgently needs new sources of affordable, clean energy. Wind energy is potentially attractive because of its low environmental impact and sustainability. This work aims to investigate the wind power production potential of sites in south-eastern Pakistan. Wind speed data measured over a one-year period at a typical site on the south-east coast of Pakistan are presented. Frequency distributions of wind speed and wind power densities at three heights, seasonal variations of speed, and estimates of power likely to be produced by commercial turbines are included. The site investigated is found to be a class 4 wind power site with annual average wind speed of 7.16 m/s and power density of 414 W/m{sup 2} at 50 m height. The site is, therefore, likely to be suitable for wind farms as well as small, stand-alone systems. (author)

  5. On wind speed pattern and energy potential in Nigeria

    International Nuclear Information System (INIS)

    Adaramola, M.S.; Oyewola, O.M.

    2011-01-01

    The aim of this paper is to review wind speed distribution and wind energy availability in Nigeria and discuss the potential of using this resource for generation of wind power in the country. The power output from a wind turbine is strongly dependent on the wind speed and accurate information about the wind data in a targeted location is essential. The annual mean wind speeds in Nigeria range from about 2 to 9.5 m/s and the annual power density range between 3.40 and 520 kW/m 2 based on recent reported data. The trend shows that wind speeds are low in the south and gradually increases to relatively high speeds in the north. The areas that are suitable for exploitation of wind energy for electricity generation as well as for water pumping were identified. Also some of the challenges facing the development of wind energy and suggested solutions were presented. - Research Highlights: → Review of wind speed distribution and wind energy availability in Nigeria in presented. → The annual mean wind speeds in Nigeria range from about 2 to 9.5 m/s and the annual power density range between 3.40 and 520 kW/m 2 based on recent reported data. → The areas that are suitable for exploitation of wind energy for electricity generation as well as for water pumping were identified.

  6. Economic feasibility of developing wind turbines in Aligoodarz, Iran

    International Nuclear Information System (INIS)

    Mohammadi, Kasra; Mostafaeipour, Ali

    2013-01-01

    Highlights: • Three hourly long term measured wind speed data from 2005 to 2009 for city of Aligoodarz in Iran was analyzed. • Wind power density and wind energy density of the region were estimated using Weibull distribution. • Performance of six different wind turbine models were analyzed. • Economic evaluation was performed and installing of E-3120 (50 kW) model turbine was suggested. - Abstract: This study evaluates the economic feasibility of electricity generation using wind turbines in city of Aligoodarz situated in the west part of Iran. For this purpose, the wind energy potential and its characteristics were assessed in terms of diurnal, monthly and annual analysis using five years measured wind speed data from 2005 to 2009 at 10 m height. The analysis results specified a nearly stable wind pattern in different hours and months of the year which demonstrated more suitability of the region for wind energy harnessing to meet the electricity demand in all time intervals throughout the year. According to Pacific Northwest Laboratory (PNL) wind power classification, the wind resource in Aligoodarz falls in class 3 and the location was recognized as a moderate location for wind energy development. The economic feasibility of six different wind turbines with rated powers ranging from 20 to 150 kW was evaluated. Among all turbines examined, the E-3120 wind turbine was introduced as the most attractive option for installation

  7. Wind potential assessment of Quebec Province

    International Nuclear Information System (INIS)

    Ilinca, A.; Chaumel, J.-L.; Retiveau, J.-L.

    2003-01-01

    The paper presents the development of a comprehensive wind atlas of the Province of Quebec. This study differs from previous studies by 1) use of a standard classification index to categorize the wind resource, 2) extensive review of surface and upper air data available for the Province to define the wind resource, and 3) integration of available wind data with the topography of the Province. The wind resource in the Province of Quebec is classified using the scheme proposed by Battelle-Pacific Northwest Laboratory (PNL). The Battelle-PNL classification is a numerical one which includes rankings from Wind Power Class 1 (lowest) to Wind Power Class 7 (highest). Associated with each numerical classification is a range of wind power and associated mean wind speed at 10 m and 50 m above ground level. For this study, a classification for 30 m above ground level was interpolated and used. A significant amount of wind data was gathered for the Province. These data were obtained from Atmospheric Environment Service (AES), Canada, from wind project developers, and from climatological summaries of surface and upper air data. A total of 35 primary data sites were selected in the Province. Although a number of wind data sites in the Province were identified and used in the analysis, large areas of the Province lacked any specific wind information. The Province was divided into grid blocks having dimensions of 1/4 o latitude by 1/3 o longitude. Each grid block is assigned a numerical Wind Power Class value ranging from 1 to 7. This value is based on the integration of the available wind data and the topography within the square. The majority of the Province was classified as 1 or 2. Coastal locations and topographic features in the interior of the Province typically have Wind Power Class 3 or higher. (author)

  8. Global wind power development: Economics and policies

    International Nuclear Information System (INIS)

    Timilsina, Govinda R.; Cornelis van Kooten, G.; Narbel, Patrick A.

    2013-01-01

    Existing literature indicates that theoretically, the earth's wind energy supply potential significantly exceeds global energy demand. Yet, only 2–3% of global electricity demand is currently derived from wind power despite 27% annual growth in wind generating capacity over the last 17 years. More than 95% of total current wind power capacity is installed in the developed countries plus China and India. Our analysis shows that the economic competitiveness of wind power varies at wider range across countries or locations. A climate change damage cost of US$20/tCO 2 imposed to fossil fuels would make onshore wind competitive to all fossil fuels for power generation; however, the same would not happen to offshore wind, with few exceptions, even if the damage cost is increased to US$100/tCO 2 . To overcome a large number of technical, financial, institutional, market and other barriers to wind power, many countries have employed various policy instruments, including capital subsidies, tax incentives, tradable energy certificates, feed-in tariffs, grid access guarantees and mandatory standards. Besides, climate change mitigation policies, such as the Clean Development Mechanism, have played a pivotal role in promoting wind power. Despite these policies, intermittency, the main technical constraint, could remain as the major challenge to the future growth of wind power. - Highlights: • Global wind energy potential is enormous, yet the wind energy contribution is very small. • Existing policies are boosting development of wind power. • Costs of wind energy are higher than cost of fossil-based energies. • Reasonable premiums for climate change mitigation substantially promote wind power. • Intermittency is the key challenge to future development of wind power

  9. Validation of satellite SAR offshore wind speed maps to in-situ data, microscala and mesoscale model results

    Energy Technology Data Exchange (ETDEWEB)

    Hasager, C B; Astrup, P; Barthelmie, R; Dellwik, E; Hoffmann Joergensen, B; Gylling Mortensen, N; Nielsen, M; Pryor, S; Rathmann, O

    2002-05-01

    captured the local wind speeds very well especially near the coast and up to around 5 km offshore. Further offshore the KAMM2 model results seemed more reliable than the WAsP model. This is likely due to the effect of high orography of the island Corsica located North of the study area. The mountains were included in the KAMM2 model domain but not in the WAsP model domain. The mountains had a significant impact on the wind field far offshore. In the Gulf of Suez the winds are very strong but there exists large spatial wind speed gradients and this makes the site challenging for SAR wind speed validation studies. Only three cases were analyzed for the Gulf of Suez in Egypt. A study on how many wind speed maps would be needed for wind resource estimation showed that around 60-70 randomly selected satellite images are required to characterize the mean wind speed and Weibull c parameter, while of the order of 150 images are required to obtain a variance estimate, and nearly 2000 are needed to obtain a robust estimate of energy density (or Weibull k). This is under the assumption of no error in the SAR wind speed maps and for an uncertainty of {+-} 10% at a confidence level of 90%. Around 100 satellite SAR scenes may be available for some sites on Earth but far few at other sites. Currently the number of available satellite SAR scenes is increasing rapidly with ERS-2, RADARSAT-1 and ENVISAT in orbit. Hence the technique holds promise for future utilization in offshore wind resource assessment. (au)

  10. Absolute number density and kinetic analysis of CF, CF{sub 2} and C{sub 2}F{sub 4} molecules in pulsed CF{sub 4}/H{sub 2} rf plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Stepanov, Sergey

    2010-04-26

    Tunable Diode Laser Absorption Spectroscopy in the mid InfraRed spectral range (IR-TDLAS) has been applied to investigate the behaviour of CF, CF{sub 2} and C{sub 2}F{sub 4} species produced in pulsed CF{sub 4}/H{sub 2} capacitively coupled radio frequency plasmas (13.56 MHz CCP). This experimental technique was shown to be suitable for temporally resolved measurements of the absolute number density of the target molecules in the studied fluorocarbon discharges. The temporal resolution of about 20..40 ms typically achieved in the standard data acquisition mode (''stream mode'') was sufficient for the real-time measurements of CF{sub 2} and C{sub 2}F{sub 4}, but not of CF whose kinetics was observed to be much faster. Therefore, a more sophisticated approach (''burst mode'') providing a temporal resolution of 0.94 ms was established and successfully applied to CF density measurements. In order to enable the TDLAS measurements of the target species, preliminary investigations on their spectroscopic data had been carried out. In particular, pure C{sub 2}F{sub 4} has been produced in laboratory by means of vacuum thermal decomposition (pyrolysis) of polytetrafluoroethylene and used as a reference gas. Therefore, an absorption structure consisting of several overlapping C{sub 2}F{sub 4} lines around 1337.11 cm{sup -1} was selected and carefully calibrated, which provided the first absolute measurements of the species by means of the applied experimental technique. The absolute number density traces measured for CF, CF{sub 2} and C{sub 2}F{sub 4} in the studied pulsed plasmas were then analysed, in which two differential balance equations were proposed for each of the species to describe their behaviour during both ''plasma on'' and ''plasma off'' phases. Analytical solutions of the balance equations were used to fit the experimental data and hence to deduce important information on the

  11. Absolute number density and kinetic analysis of CF, CF{sub 2} and C{sub 2}F{sub 4} molecules in pulsed CF{sub 4}/H{sub 2} rf plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Stepanov, Sergey

    2010-04-26

    Tunable Diode Laser Absorption Spectroscopy in the mid InfraRed spectral range (IR-TDLAS) has been applied to investigate the behaviour of CF, CF{sub 2} and C{sub 2}F{sub 4} species produced in pulsed CF{sub 4}/H{sub 2} capacitively coupled radio frequency plasmas (13.56 MHz CCP). This experimental technique was shown to be suitable for temporally resolved measurements of the absolute number density of the target molecules in the studied fluorocarbon discharges. The temporal resolution of about 20..40 ms typically achieved in the standard data acquisition mode (''stream mode'') was sufficient for the real-time measurements of CF{sub 2} and C{sub 2}F{sub 4}, but not of CF whose kinetics was observed to be much faster. Therefore, a more sophisticated approach (''burst mode'') providing a temporal resolution of 0.94 ms was established and successfully applied to CF density measurements. In order to enable the TDLAS measurements of the target species, preliminary investigations on their spectroscopic data had been carried out. In particular, pure C{sub 2}F{sub 4} has been produced in laboratory by means of vacuum thermal decomposition (pyrolysis) of polytetrafluoroethylene and used as a reference gas. Therefore, an absorption structure consisting of several overlapping C{sub 2}F{sub 4} lines around 1337.11 cm{sup -1} was selected and carefully calibrated, which provided the first absolute measurements of the species by means of the applied experimental technique. The absolute number density traces measured for CF, CF{sub 2} and C{sub 2}F{sub 4} in the studied pulsed plasmas were then analysed, in which two differential balance equations were proposed for each of the species to describe their behaviour during both ''plasma on'' and ''plasma off'' phases. Analytical solutions of the balance equations were used to fit the experimental data and hence to deduce important information on the kinetics of the studied molecules. In particular, during the ''plasma off'' phase

  12. Wind energy assessment and wind farm simulation in Triunfo - Pernambuco, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Laerte; Filho, Celso

    2010-09-15

    The Triunfo wind's characterization, in Pernambuco state, situated in Brazilian northeast, and wind power potential assessment study shows a average wind speed of 11.27 m / s, predominant Southeast wind direction, average wind power density of 1672 W/m2 and Weibull parameters shape and scale equal to 2,0 and 12,7 m/s. The wind farm was simulated by using 850kW wind turbines (total of 20MW). The simulated shows AEP of 111,4 GWh, Cf of 62% and 5462 hours of operation by year. The economical simulated results, shows Pay-back of 3 years, TIR = 47% and VAN = 85.506kEuro booths @ 20 years time period.

  13. Optimal wind energy penetration in power systems: An approach based on spatial distribution of wind speed

    International Nuclear Information System (INIS)

    Zolfaghari, Saeed; Riahy, Gholam H.; Abedi, Mehrdad; Golshannavaz, Sajjad

    2016-01-01

    Highlights: • Chronological wind speeds at distinct locations of the wind farm are not the same. • Spatial distribution of wind speed affects wind farm’s output power expectation. • Neglecting wind speed’s spatial doubt leads to mistake in wind energy penetration. • Scenario-based method can be used for effective wind capacity penetration level. - Abstract: Contributing in power system expansions, the present study establishes an efficient scheme for optimal integration of wind energy resources. The proposed approach highly concerns the spatial distribution of wind speed at different points of a wind farm. In mathematical statements, a suitable probability distribution function (PDF) is well-designed for representing such uncertainties. In such conditions, it is likely to have dissimilar output powers for individual and identical wind turbines. Thus, the overall aggregated PDF of a wind farm remarkably influences the critical parameters including the expected power and energy, capacity factor, and the reliability metrics such as loss of load expectation (LOLE) and expected energy not supplied (EENS). Furthermore, the proposed approach is deployed for optimal allocation of wind energy in bulk power systems. Hence, two typical test systems are numerically analyzed to interrogate the performance of the proposed approach. The conducted survey discloses an over/underestimation of harvestable wind energy in the case of overlooking spatial distributions. Thus, inaccurate amounts of wind farm’s capacity factor, output power, energy and reliability indices might be estimated. Meanwhile, the number of wind turbines may be misjudged to be installed. However, the proposed approach yields in a fair judgment regarding the overall performance of the wind farm. Consequently, a reliable penetration level of wind energy to the power system is assured. Extra discussions are provided to deeply assess the promising merits of the founded approach.

  14. Class Generation for Numerical Wind Atlases

    DEFF Research Database (Denmark)

    Cutler, N.J.; Jørgensen, B.H.; Ersbøll, Bjarne Kjær

    2006-01-01

    A new optimised clustering method is presented for generating wind classes for mesoscale modelling to produce numerical wind atlases. It is compared with the existing method of dividing the data in 12 to 16 sectors, 3 to 7 wind-speed bins and dividing again according to the stability...... of the atmosphere. Wind atlases are typically produced using many years of on-site wind observations at many locations. Numerical wind atlases are the result of mesoscale model integrations based on synoptic scale wind climates and can be produced in a number of hours of computation. 40 years of twice daily NCEP...... adapting to the local topography. The purpose of forming classes is to minimise the computational time for the mesoscale model while still representing the synoptic climate features. Only tried briefly in the past, clustering has traits that can be used to improve the existing class generation method...

  15. Wind Statistics Offshore based on Satellite Images

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay; Mouche, Alexis; Badger, Merete

    2009-01-01

    -based observations become available. At present preliminary results are obtained using the routine methods. The first step in the process is to retrieve raw SAR data, calibrate the images and use a priori wind direction as input to the geophysical model function. From this process the wind speed maps are produced....... The wind maps are geo-referenced. The second process is the analysis of a series of geo-referenced SAR-based wind maps. Previous research has shown that a relatively large number of images are needed for achieving certain accuracies on mean wind speed, Weibull A and k (scale and shape parameters......Ocean wind maps from satellites are routinely processed both at Risø DTU and CLS based on the European Space Agency Envisat ASAR data. At Risø the a priori wind direction is taken from the atmospheric model NOGAPS (Navel Operational Global Atmospheric Prediction System) provided by the U.S. Navy...

  16. Draft-circular on wind turbines. Concept-circulaire wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    1983-01-01

    Criteria for providing licenses to build and operate a wind turbine are surveyed. Factors to consider are: characteristics of the landscape, density of population, town and country planning, environmental aspects (birds), safety and nuisance. National regulations for wind turbines will simplify licensing procedures and improve legal security.

  17. Wind effects on RVACS performance

    International Nuclear Information System (INIS)

    Tzanos, C.

    1995-01-01

    The reactor vessel auxillary cooling system (RVACS) is a passive liquid-metal reactor decay-heat removal system. The RVACS performance is a function of the pressure difference between air flow inlet and outlet, of the air inlet temperature, of the air density variation along the flow path, and of the pressure loss characteristics of the path. The pressure difference can be affected by wind speed and direction. The objective of this project was to investigate the effects of wind on the performance of the RVACS, specifically, the heat release through the stacks, of a liquid-metal reactor

  18. Reduction of the Random Variables of the Turbulent Wind Field

    DEFF Research Database (Denmark)

    Sichani, Mahdi Teimouri; Nielsen, Søren R.K.

    2012-01-01

    .e. Importance Sampling (IS) or Subset Simulation (SS), will be deteriorated on problems with many random variables. The problem with PDEM is that a multidimensional integral has to be carried out over the space defined by the random variables of the system. The numerical procedure requires discretization......Applicability of the Probability Density Evolution Method (PDEM) for realizing evolution of the probability density for the wind turbines has rather strict bounds on the basic number of the random variables involved in the model. The efficiency of most of the Advanced Monte Carlo (AMC) methods, i...... of the integral domain; this becomes increasingly difficult as the dimensions of the integral domain increase. On the other hand efficiency of the AMC methods is closely dependent on the design points of the problem. Presence of many random variables may increase the number of the design points, hence affects...

  19. Nearly incompressible MHD turbulence in the solar wind

    International Nuclear Information System (INIS)

    Matthaeus, W.H.; Zhou, Y.

    1989-01-01

    Observational studies indicate that solar wind plasma and magnetic field fluctuations may be meaningfully viewed as an example of magnetohydrodynamic turbulence. This paper presents a brief summary of some relevant results of turbulence theory and reviews a turbulence style description of 'typical' solar wind conditions. Recent results, particularly those regarding the radial evolution of inertial range cross helicity, support the viewpoint that interplanetary turbulence is active and evolving with heliocentric distance. A number of observed properties can be understood by appeal to incompressible turbulence mechanisms. This connection may be understood by appeal to incompressible turbulence mechanisms. This connection may be understood in terms of theories of pseudosound density fluctuations and nearly incompressible magnetohydrodynamics, which are also reviewed here. Finally, we summarize a recent two-scale dynamical theory of the radial and temporal evolution of the turbulence, which may provide an additional framework for understanding the observations. (author). 49 refs

  20. Spatial and temporal patterns of global onshore wind speed distribution

    International Nuclear Information System (INIS)

    Zhou, Yuyu; Smith, Steven J

    2013-01-01

    Wind power, a renewable energy source, can play an important role in electrical energy generation. Information regarding wind energy potential is important both for energy related modeling and for decision-making in the policy community. While wind speed datasets with high spatial and temporal resolution are often ultimately used for detailed planning, simpler assumptions are often used in analysis work. An accurate representation of the wind speed frequency distribution is needed in order to properly characterize wind energy potential. Using a power density method, this study estimated global variation in wind parameters as fitted to a Weibull density function using NCEP/climate forecast system reanalysis (CFSR) data over land areas. The Weibull distribution performs well in fitting the time series wind speed data at most locations according to R 2 , root mean square error, and power density error. The wind speed frequency distribution, as represented by the Weibull k parameter, exhibits a large amount of spatial variation, a regionally varying amount of seasonal variation, and relatively low decadal variation. We also analyzed the potential error in wind power estimation when a commonly assumed Rayleigh distribution (Weibull k = 2) is used. We find that the assumption of the same Weibull parameter across large regions can result in non-negligible errors. While large-scale wind speed data are often presented in the form of mean wind speeds, these results highlight the need to also provide information on the wind speed frequency distribution. (letter)

  1. Probability density function of the number of embryos collected from superovulated Nelore breed donors Função de densidade de probabilidade do número de embriões produzidos por doadoras da raça Nelore

    Directory of Open Access Journals (Sweden)

    Renato Travassos Beltrame

    2009-08-01

    Full Text Available Several models have been developed to evaluate reproductive status of cows through concentration of progesterone in milk, the effect of sex selection in the commercial production of herds and bioeconomic performance of the multiple ovulation and embryo transfer system in select herds. However, models describing the production of embryos in superovulated females have yet to be developed. A probability density function of the number of embryos collected by donors of the Nelore breed was determined. Records of 61,928 embryo collections from 26,767 donors from 1991 to 2005 were analyzed. Data were provided by the Brazilian Association of Creators of Zebu and Controlmax Consultoria e Sistemas Ltda. The probability density function of the number of viable embryos was modeled using exponential and gamma distributions. Parameter fitting was carried out for maximum likelihood using a non-linear gradient method. Both distributions presented similar level of precision: root mean square error (RMSE = 0.0072 and 0.0071 for the exponential and gamma distributions, respectively; both distributions are thus deemed suitable for representing the probability density function of embryo production by Nelore females.Diversos modelos têm sido desenvolvidos para avaliar o estado reprodutivo de vacas por meio da concentração de progesterona no leite, o efeito da seleção do sexo na produção comercial de rebanhos e o desempenho bioeconômico da ovulação múltipla e transferência de embriões em rebanhos selecionados. No entanto, modelos que descrevem a produção de embriões em fêmeas superovulados ainda têm de ser desenvolvidos. Uma função de densidade probabilidade para o número de embriões viáveis recuperados de doadoras da raça Nelore foi determinada. Dados de 61.928 coletas de 26.767 doadoras entre 1991 e 2005 foram analisados. Os resultados foram fornecidos pela Associação Brasileira de Criadores de Zebu (ABCZ e pela empresa Controlmax

  2. Distributed Wind Competitiveness Improvement Project

    Energy Technology Data Exchange (ETDEWEB)

    2018-02-27

    The Competitiveness Improvement Project (CIP) is a periodic solicitation through the U.S. Department of Energy and its National Renewable Energy Laboratory. The Competitiveness Improvement Project (CIP) is a periodic solicitation through the U.S. Department of Energy and its National Renewable Energy Laboratory. Manufacturers of small and medium wind turbines are awarded cost-shared grants via a competitive process to optimize their designs, develop advanced manufacturing processes, and perform turbine testing. The goals of the CIP are to make wind energy cost competitive with other distributed generation technology and increase the number of wind turbine designs certified to national testing standards. This fact sheet describes the CIP and funding awarded as part of the project.ufacturers of small and medium wind turbines are awarded cost-shared grants via a competitive process to optimize their designs, develop advanced manufacturing processes, and perform turbine testing. The goals of the CIP are to make wind energy cost competitive with other distributed generation technology and increase the number of wind turbine designs certified to national testing standards. This fact sheet describes the CIP and funding awarded as part of the project.

  3. Wind Power Meteorology

    DEFF Research Database (Denmark)

    Lundtang Petersen, Erik; Mortensen, Niels Gylling; Landberg, Lars

    Wind power meteorology has evolved as an applied science, firmly founded on boundary-layer meteorology, but with strong links to climatology and geography. It concerns itself with three main areas: siting of wind turbines, regional wind resource assessment, and short-term prediction of the wind...... resource. The history, status and perspectives of wind power meteorology are presented, with emphasis on physical considerations and on its practical application. Following a global view of the wind resource, the elements of boundary layer meteorology which are most important for wind energy are reviewed......: wind profiles and shear, turbulence and gust, and extreme winds. The data used in wind power meteorology stem mainly from three sources: onsite wind measurements, the synoptic networks, and the re-analysis projects. Wind climate analysis, wind resource estimation and siting further require a detailed...

  4. Density functional theory studies on the solvent effects in Al(H2O)63+ water-exchange reactions: the number and arrangement of outer-sphere water molecules.

    Science.gov (United States)

    Liu, Li; Zhang, Jing; Dong, Shaonan; Zhang, Fuping; Wang, Ye; Bi, Shuping

    2018-03-07

    Density functional theory (DFT) calculations combined with cluster models are performed at the B3LYP/6-311+G(d,p) level for investigating the solvent effects in Al(H 2 O) 6 3+ water-exchange reactions. A "One-by-one" method is proposed to obtain the most representative number and arrangement of explicit H 2 Os in the second hydration sphere. First, all the possible ways to locate one explicit H 2 O in second sphere (N m ' = 1) based on the gas phase structure (N m ' = 0) are examined, and the optimal pathway (with the lowest energy barrier) for N m ' = 1 is determined. Next, more explicit H 2 Os are added one by one until the inner-sphere is fully hydrogen bonded. Finally, the optimal pathways with N m ' = 0-7 are obtained. The structural and energetic parameters as well as the lifetimes of the transition states are compared with the results obtained with the "Independent-minimum" method and the "Independent-average" method, and all three methods show that the pathway with N m ' = 6 may be representative. Our results give a new idea for finding the representative pathway for water-exchange reactions in other hydrated metal ion systems.

  5. Wind Energy Basics | NREL

    Science.gov (United States)

    Wind Energy Basics Wind Energy Basics We have been harnessing the wind's energy for hundreds of grinding grain. Today, the windmill's modern equivalent-a wind turbine can use the wind's energy to most energy. At 100 feet (30 meters) or more aboveground, they can take advantage of the faster and

  6. Prospecting for Wind

    Science.gov (United States)

    Swapp, Andy; Schreuders, Paul; Reeve, Edward

    2011-01-01

    Many people use wind to help meet their needs. Over the years, people have been able to harness or capture the wind in many different ways. More recently, people have seen the rebirth of electricity-generating wind turbines. Thus, the age-old argument about technology being either good or bad can also be applied to the wind. The wind can be a…

  7. Careers in Wind Energy

    Science.gov (United States)

    Liming, Drew; Hamilton, James

    2011-01-01

    As a common form of renewable energy, wind power is generating more than just electricity. It is increasingly generating jobs for workers in many different occupations. Many workers are employed on wind farms: areas where groups of wind turbines produce electricity from wind power. Wind farms are frequently located in the midwestern, western, and…

  8. Theoretical models for MHD turbulence in the solar wind

    International Nuclear Information System (INIS)

    Veltri, P.; Malara, F.

    1997-01-01

    The in situ measurements of velocity, magnetic field, density and temperature fluctuations performed in the solar wind have greatly improved our knowledge of MDH turbulence not only from the point of view of space physics but also from the more general point of view of plasma physics. These fluctuations which extend over a wide range of frequencies (about 5 decades), a fact which seems to be the signature of turbulent nonlinear energy cascade, display, mainly in the trailing edge of high-speed streams, a number of features characteristic of a self-organized situation: i) a high degree of correlation between magnetic and velocity field fluctuations, ii) a very low level of fluctuations in mass density and magnetic-field intensity, iii) a considerable anisotropy revealed by minimum variance analysis of the magnetic-field correlation tensor. Many fundamental processes in plasma physics, which were largely unknown or not understood before their observations in the solar wind, have been explained, by building up analytical models or performing numerical simulations. We discuss the most recent analytical theories and numerical simulations and outline the limits implicit in any analysis which consider the low-frequency solar-wind fluctuations as a superposition of linear modes. The characterization of low-frequency fluctuations during Alfvenic periods, which results from the models discussed, is finally presented

  9. WIND SPEED Monitoring in Northern Eurasia

    Science.gov (United States)

    Bulygina, O.; Korshunova, N. N.; Razuvaev, V. N.; Groisman, P. Y.

    2016-12-01

    The wind regime of Russia varies a great deal due to the large size of the country's territory and variety of climate and terrain conditions. Changes in the regime of surface wind are of great practical importance. They can affect heat and water balance. Strong wind is one of the most hazardous meteorological event for various sectors of economy and for infrastructure. The main objective of this research is to monitoring wind speed change in Northern Eurasia At meteorological stations wind speed and wind direction are measured at the height of 10-12 meters over the land surface with the help of wind meters or wind wanes. Calculations were made on the basis of data for the period of 1980-2015. It allowed the massive scale disruption of homogeneity to be eliminated and sufficient period needed to obtain sustainable statistic characteristics to be retained. Data on average and maximum wind speed measured at 1457 stations of Russia were used. The analysis of changes in wind characteristics was made on the basis of point data and series of average characteristics obtained for 18 quasi-homogeneous climatic regions. Statistical characteristics (average and maximum values of wind speed, prevailing wind direction, values of the boundary of the 90%, 95% and 99%-confidence interval in the distribution of maximum wind speed) were obtained for all seasons and for the year as a whole. Values of boundaries of the 95% and 99%-confidence interval in the distribution of maximum wind speed were considered as indicators of extremeness of the wind regime. The trend of changes in average and maximum wind speed was assessed with a linear trend coefficient. A special attention was paid to wind changes in the Arctic where dramatic changes in surface air temperature and sea ice extent and density have been observed during the past decade. The analysis of the results allowed seasonal and regional features of changes in the wind regime on the territory of the northern part of Eurasia to be

  10. Global wind energy outlook 2006

    International Nuclear Information System (INIS)

    2006-09-01

    The global market for wind power has been expanding faster than any other source of renewable energy. From just 4,800 MW in 1995 the world total has multiplied more than twelve-fold to reach over 59,000 MW at the end of 2005. The international market is expected to have an annual turnover in 2006 of more than euro 13 billion, with an estimated 150,000 people employed around the world. The success of the industry has attracted investors from the mainstream finance and traditional energy sectors. In a number of countries the proportion of electricity generated by wind power is now challenging conventional fuels. The Global Wind Energy Outlook 2006 reports that over a third of the world's electricity - crucially including that required by industry - can realistically be supplied by wind energy by the middle of the century. The report provides an industry blueprint that explains how wind power could supply 34% of the world's electricity by 2050. Most importantly, it concludes that if wind turbine capacity implemented on this scale it would save 113 billion tonnes of CO2 from entering the atmosphere by 2050. This places wind power as one of the world's most important energy sources for the 21st century. The 'Global Wind Energy Outlook 2006' runs three different scenarios for wind power - a Reference scenario based on figures from the International Energy Agency (IEA); a Moderate version which assumes that current targets for renewable energy are successful; and an advanced version assuming that all policy options in favour of renewables have been adopted. These are then set against two scenarios for global energy demand. Under the Reference scenario, growth in demand is again based on IEA projections; under the High Energy Efficiency version, a range of energy efficiency measures result in a substantial reduction in demand

  11. Validation of Power Output for the WIND Toolkit

    Energy Technology Data Exchange (ETDEWEB)

    King, J.; Clifton, A.; Hodge, B. M.

    2014-09-01

    Renewable energy integration studies require wind data sets of high quality with realistic representations of the variability, ramping characteristics, and forecast performance for current wind power plants. The Wind Integration National Data Set (WIND) Toolkit is meant to be an update for and expansion of the original data sets created for the weather years from 2004 through 2006 during the Western Wind and Solar Integration Study and the Eastern Wind Integration Study. The WIND Toolkit expands these data sets to include the entire continental United States, increasing the total number of sites represented, and it includes the weather years from 2007 through 2012. In addition, the WIND Toolkit has a finer resolution for both the temporal and geographic dimensions. Three separate data sets will be created: a meteorological data set, a wind power data set, and a forecast data set. This report describes the validation of the wind power data set.

  12. Generating wind fluctuations for Large Eddy Simulation inflow boundary condition

    International Nuclear Information System (INIS)

    Bekele, S.A.; Hangan, H.

    2004-01-01

    Large Eddy Simulation (LES) studies of flows over bluff bodies immersed in a boundary layer wind environment require instantaneous wind characteristics. The influences of the wind environment on the building pressure distribution are a well-established fact in the experimental study of wind engineering. Measured wind data of full or model scale are available only at a limited number of points. A method of obtaining instantaneous wind data at all mesh points of the inlet boundary for LES computation is necessary. Herein previous and new wind inflow generation techniques are presented. The generated wind data is then applied to a LES computation of a channel flow. The characteristics of the generated wind fluctuations in comparison to the measured data and the properties of the flow field computed from these two wind data are discussed. (author)

  13. The use of energy pattern factor (EPF) in estimating wind power ...

    African Journals Online (AJOL)

    The Energy Pattern Factor (EPF) method is a less computational method of estimating the available wind power density of an area and wind speed variation account for the energy power density throughout a given period. Using the Average daily wind speed data for an 11 year period (2004-2014) obtained from the ...

  14. Wind energy program overview

    International Nuclear Information System (INIS)

    1992-02-01

    This overview emphasizes the amount of electric power that could be provided by wind power rather than traditional fossil fuels. New wind power markets, advances in technology, technology transfer, and wind resources are some topics covered in this publication

  15. Hupa Numbers.

    Science.gov (United States)

    Bennett, Ruth, Ed.; And Others

    An introduction to the Hupa number system is provided in this workbook, one in a series of numerous materials developed to promote the use of the Hupa language. The book is written in English with Hupa terms used only for the names of numbers. The opening pages present the numbers from 1-10, giving the numeral, the Hupa word, the English word, and…

  16. Triangular Numbers

    Indian Academy of Sciences (India)

    Admin

    Triangular number, figurate num- ber, rangoli, Brahmagupta–Pell equation, Jacobi triple product identity. Figure 1. The first four triangular numbers. Left: Anuradha S Garge completed her PhD from. Pune University in 2008 under the supervision of Prof. S A Katre. Her research interests include K-theory and number theory.

  17. Proth Numbers

    Directory of Open Access Journals (Sweden)

    Schwarzweller Christoph

    2015-02-01

    Full Text Available In this article we introduce Proth numbers and prove two theorems on such numbers being prime [3]. We also give revised versions of Pocklington’s theorem and of the Legendre symbol. Finally, we prove Pepin’s theorem and that the fifth Fermat number is not prime.

  18. A ``Cyber Wind Facility'' for HPC Wind Turbine Field Experiments

    Science.gov (United States)

    Brasseur, James; Paterson, Eric; Schmitz, Sven; Campbell, Robert; Vijayakumar, Ganesh; Lavely, Adam; Jayaraman, Balaji; Nandi, Tarak; Jha, Pankaj; Dunbar, Alex; Motta-Mena, Javier; Craven, Brent; Haupt, Sue

    2013-03-01

    The Penn State ``Cyber Wind Facility'' (CWF) is a high-fidelity multi-scale high performance computing (HPC) environment in which ``cyber field experiments'' are designed and ``cyber data'' collected from wind turbines operating within the atmospheric boundary layer (ABL) environment. Conceptually the ``facility'' is akin to a high-tech wind tunnel with controlled physical environment, but unlike a wind tunnel it replicates commercial-scale wind turbines operating in the field and forced by true atmospheric turbulence with controlled stability state. The CWF is created from state-of-the-art high-accuracy technology geometry and grid design and numerical methods, and with high-resolution simulation strategies that blend unsteady RANS near the surface with high fidelity large-eddy simulation (LES) in separated boundary layer, blade and rotor wake regions, embedded within high-resolution LES of the ABL. CWF experiments complement physical field facility experiments that can capture wider ranges of meteorological events, but with minimal control over the environment and with very small numbers of sensors at low spatial resolution. I shall report on the first CWF experiments aimed at dynamical interactions between ABL turbulence and space-time wind turbine loadings. Supported by DOE and NSF.

  19. Modelling Wind for Wind Farm Layout Optimization Using Joint Distribution of Wind Speed and Wind Direction

    OpenAIRE

    Ju Feng; Wen Zhong Shen

    2015-01-01

    Reliable wind modelling is of crucial importance for wind farm development. The common practice of using sector-wise Weibull distributions has been found inappropriate for wind farm layout optimization. In this study, we propose a simple and easily implementable method to construct joint distributions of wind speed and wind direction, which is based on the parameters of sector-wise Weibull distributions and interpolations between direction sectors. It is applied to the wind measurement data a...

  20. Sagan numbers

    OpenAIRE

    Mendonça, J. Ricardo G.

    2012-01-01

    We define a new class of numbers based on the first occurrence of certain patterns of zeros and ones in the expansion of irracional numbers in a given basis and call them Sagan numbers, since they were first mentioned, in a special case, by the North-american astronomer Carl E. Sagan in his science-fiction novel "Contact." Sagan numbers hold connections with a wealth of mathematical ideas. We describe some properties of the newly defined numbers and indicate directions for further amusement.

  1. Preliminary evaluation of wind power potential in Bangladesh

    International Nuclear Information System (INIS)

    Rahman, M.M.; Azam, M.M.; Choudhury, M.G.M.

    1998-01-01

    Available wind speed data for six locations of Bangladesh have been analyzed with a view to assess the wind power potential of these locations. Regions having high wind potential are identified for the generation of electric energy by wind energy conversion systems (WECS). The wind power density varies from 12 to 650 W/m/sup 2/ in Bangladesh depending on the location and time of year. Among the six locations, Chittagang, a coastal station in the southeastern region of the country, possesses the maximum wind power density (1670650 W/m/sup 2/) and seems to be the most suitable location for establishing WECS. This study could be considered as the basis for further research and development effort on wind power application in Bangladesh. (authors)

  2. Wind farm project economics : value of wind

    Energy Technology Data Exchange (ETDEWEB)

    Bills-Everett, T. [Mainstream Renewable Power, Toronto, ON (Canada)

    2010-07-01

    This PowerPoint presentation discussed methods of increasing the value of wind power projects. Appropriate turbine selection and layout is needed to ensure that wind resources are fully developed. Construction costs have a significant impact on project costs. The world turbine price index has not significantly fluctuated since 2006. Operating costs, and the value of wind power projects, are linked with OPEX fluctuations. Wind power projects can significantly reduce greenhouse gas (GHG) emissions. An increase in wind power capacity will reduce the overall cost of energy produced from wind power. Countries can use wind power as part of a renewable energy portfolio designed to reduce risks related to diminishing petroleum supplies. Wind power will help to ensure a global transition to renewable energy use. tabs., figs.

  3. Wind turbines, is it just wind?

    International Nuclear Information System (INIS)

    Boiteux, M.

    2012-01-01

    The author first outlines that wind energy is not only random, but almost absent in extreme situations when it would be needed (for example and notably, very cold weather without wind). He suggests the association of a gas turbine to each wind turbine, so that the gas turbine will replace non operating wind turbines. He notices that wind turbines are not proximity energy as they were said to be, and that profitability in fact requires tens of grouped giant wind turbines. He also outlines the high cost of construction of grids for the connection of these wind turbines. Thus, he states that wind energy is far from being profitable in the present conditions of electricity tariffs in France

  4. Wind energy potential assessment of Cameroon's coastal regions for the installation of an onshore wind farm.

    Science.gov (United States)

    Arreyndip, Nkongho Ayuketang; Joseph, Ebobenow; David, Afungchui

    2016-11-01

    For the future installation of a wind farm in Cameroon, the wind energy potentials of three of Cameroon's coastal cities (Kribi, Douala and Limbe) are assessed using NASA average monthly wind data for 31 years (1983-2013) and compared through Weibull statistics. The Weibull parameters are estimated by the method of maximum likelihood, the mean power densities, the maximum energy carrying wind speeds and the most probable wind speeds are also calculated and compared over these three cities. Finally, the cumulative wind speed distributions over the wet and dry seasons are also analyzed. The results show that the shape and scale parameters for Kribi, Douala and Limbe are 2.9 and 2.8, 3.9 and 1.8 and 3.08 and 2.58, respectively. The mean power densities through Weibull analysis for Kribi, Douala and Limbe are 33.7 W/m2, 8.0 W/m2 and 25.42 W/m2, respectively. Kribi's most probable wind speed and maximum energy carrying wind speed was found to be 2.42 m/s and 3.35 m/s, 2.27 m/s and 3.03 m/s for Limbe and 1.67 m/s and 2.0 m/s for Douala, respectively. Analysis of the wind speed and hence power distribution over the wet and dry seasons shows that in the wet season, August is the windiest month for Douala and Limbe while September is the windiest month for Kribi while in the dry season, March is the windiest month for Douala and Limbe while February is the windiest month for Kribi. In terms of mean power density, most probable wind speed and wind speed carrying maximum energy, Kribi shows to be the best site for the installation of a wind farm. Generally, the wind speeds at all three locations seem quite low, average wind speeds of all the three studied locations fall below 4.0m/s which is far below the cut-in wind speed of many modern wind turbines. However we recommend the use of low cut-in speed wind turbines like the Savonius for stand alone low energy needs.

  5. Solar wind/local interstellar medium interaction including charge exchange with neural hydrogen

    Science.gov (United States)

    Pauls, H. Louis; Zank, Gary P.

    1995-01-01

    We present results from a hydrodynamic model of the interaction of the solar wind with the local interstellar medium (LISM), self-consistently taking into account the effects of charge exchange between the plasma component and the interstellar neutrals. The simulation is fully time dependent, and is carried out in two or three dimensions, depending on whether the helio-latitudinal dependence of the solar wind speed and number density (both giving rise to three dimensional effects) are included. As a first approximation it is assumed that the neutral component of the flow can be described by a single, isotropic fluid. Clearly, this is not the actual situation, since charge exchange with the supersonic solar wind plasma in the region of the nose results in a 'second' neutral fluid propagating in the opposite direction as that of the LISM neutrals.