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1

Towers for Offshore Wind Turbines  

NASA Astrophysics Data System (ADS)

Increasing energy demand coupled with pollution free production of energy has found a viable solution in wind energy. Land based windmills have been utilized for power generation for more than two thousand years. In modern times wind generated power has become popular in many countries. Offshore wind turbines are being used in a number of countries to tap the energy from wind over the oceans and convert to electric energy. The advantages of offshore wind turbines as compared to land are that offshore winds flow at higher speed than onshore winds and the more available space. In some land based settings, for better efficiency, turbines are separated as much as 10 rotor diameters from each other. In offshore applications where only two wind directions are likely to predominate, the distances between the turbines arranged in a line can be shortened to as little as two or four rotor diameters. Today, more than a dozen offshore European wind facilities with turbine ratings of 450 kw to 3.6 MW exist offshore in very shallow waters of 5 to 12 m. Compared to onshore wind turbines, offshore wind turbines are bigger and the tower height in offshore are in the range of 60 to 80 m. The water depths in oceans where offshore turbines can be located are within 30 m. However as the distance from land increases, the costs of building and maintaining the turbines and transmitting the power back to shore also increase sharply. The objective of this paper is to review the parameters of design for the maximum efficiency of offshore wind turbines and to develop types offshore towers to support the wind turbines. The methodology of design of offshore towers to support the wind turbine would be given and the environmental loads for the design of the towers would be calculated for specific cases. The marine corrosion on the towers and the methods to control the corrosion also would be briefly presented. As the wind speeds tend to increase with distance from the shore, turbines build father offshore will be able to capture more wind energy. Currently two types of towers are considered. Cylindrical tubular structures and truss type structures. But truss type structures have less weight and flexibility in design. The construction of the offshore towers to harness the wind energy is also presented. The results will include the calculation of wind and wave forces on the tower and the design details for the tower.

Kurian, V. J.; Narayanan, S. P.; Ganapathy, C.

2010-06-01

2

Hydrogen Storage in Wind Turbine Towers  

SciTech Connect

Low-cost hydrogen storage is recognized as a cornerstone of a renewables-hydrogen economy. Modern utility-scale wind turbine towers are typically conical steel structures that, in addition to supporting the rotor, could be used to store hydrogen. This study has three objectives: (1) Identify the paramount considerations associated with using a wind turbine tower for hydrogen storage; (2)Propose and analyze a cost-effective design for a hydrogen-storing tower; and (3) Compare the cost of storage in hydrogen towers to the cost of storage in conventional pressure vessels. The paramount considerations associated with a hydrogen tower are corrosion (in the form of hydrogen embrittlement) and structural failure (through bursting or fatigue life degradation). Although hydrogen embrittlement (HE) requires more research, it does not appear to prohibit the use of turbine towers for hydrogen storage. Furthermore, the structural modifications required to store hydrogen in a tower are not cost prohibitive.

Kottenstette, R.; Cotrell, J.

2003-09-01

3

Motion responsive wind turbine tower damping  

Microsoft Academic Search

An accelerometer disposed on the support tower of a wind turbine electric generating system in the vicinity of the rotor thereof provides a signal indicative of acceleration of the tower in the direction of the rotor rotational axis. The signal is passed through a band-pass filter for summation with a torque\\/power controlled blade pitch angle reference rate signal the integral

J. M. Kos; K. I. Harner; J. P. Patrick

1983-01-01

4

Towers for Offshore Wind Turbines  

Microsoft Academic Search

Increasing energy demand coupled with pollution free production of energy has found a viable solution in wind energy. Land based windmills have been utilized for power generation for more than two thousand years. In modern times wind generated power has become popular in many countries. Offshore wind turbines are being used in a number of countries to tap the energy

V. J. Kurian; S. P. Narayanan; C. Ganapathy

2010-01-01

5

Vertical wind turbine power generating tower  

SciTech Connect

The tower comprises a base supported on a framework which mounts a wind powered turbine having a vertical axis of rotation. Air is channeled to the turbine rotor to cause counterclockwise rotation thereof by upper and lower wind deflectors. The wind deflectors include channels which cause the oncoming air to swirl in a counterclockwise motion into the rotor transmitting energy thereto. The vertical struts of the framework are also configured so as to deflect the oncoming air into the rotor in a counterclockwise direction. The rotor itself comprises columns of vertically spaced, radially extending scoops and radially extending curved blades to ensure highly efficient energy conversion. The rotor is formed with no center shaft to allow free flow of air therethrough.

Retz, P.

1982-12-28

6

Predicted motion wind turbine tower damping  

SciTech Connect

Damping of the primary bending mode of a tower (12) mounting a wind turbine having a control (36) for providing a pitch blade angle reference signal (40) to modulate the pitch of the turbine blades (1) through a pitch change mechanism (38) for constant power is provided by generating the pitch blade angle reference signal as the integral (104) of the summation (266) of a torque/power controlling blade pitch angle reference rate signal (98) with an estimated acceleration signal (255) generated by filtering (250, 252, 254) the blade pitch angle reference signal (40) with the following transfer function

Harner, K. I.; Kos, J. M.; Patrick, J. P.

1984-03-06

7

Wind Turbine Tower Optimization Method Using a Genetic Algorithm  

Microsoft Academic Search

A wind turbine tower optimization program was developed, using a genetic algorithm. This allowed a rational analysis to reduce the mass of turbine tower, by considering, for example, the distributions of diameter and wall thickness, and the positions of flanges and access ports to navigation lights. Both extreme and fatigue loads were calculated, based on wind turbine design requirements and

Shigeo Yoshida

2006-01-01

8

Wind Shear Characteristics at Central Plains Tall Towers (presentation)  

SciTech Connect

The objectives of this report are: (1) Analyze wind shear characteristics at tall tower sites for diverse areas in the central plains (Texas to North Dakota)--Turbines hub heights are now 70-100 m above ground and Wind measurements at 70-100+ m have been rare. (2) Present conclusions about wind shear characteristics for prime wind energy development regions.

Schwartz, M.; Elliott, D.

2006-06-05

9

Wind tunnel test method to study out-of-service tower crane behaviour in storm winds  

Microsoft Academic Search

An experimental method used to study the behaviour of tower cranes in strong winds exposed to the disturbed shear flow induced by the surrounding built environment is proposed. Wind tunnel tests on a tower crane model are described, the tower crane is considered as a rigid body slender structure equipped with a single degree of freedom part: the crane mobile

D. Voisin; G. Grillaud; C. Solliec; A. Beley-Sayettat; J.-L. Berlaud; A. Miton

2004-01-01

10

Modeling and Control of Wind Turbine Tower Vibrations  

NASA Astrophysics Data System (ADS)

Developed is a model for studying the vibrations of a wind turbine tower subjected to random wind loadings. The tower is modeled as an elastic Euler-Bernoulli beam, viscously damped and fixed at the bottom. The concentrated mass of the turbine is located at the top of the tower where also the wind loading is applied as a step function. The partial differential equation of the model is managed by the method of separation of variables and along with the applied modal analysis produces an efficient numerical-analytic solution algorithm. Demonstrated is the ability for dissipating the vibrations through a properly designed controller. Numerical results are provided.

Genov, J.; Gilev, B.; Slavchev, Y.; Venkov, G.

2010-10-01

11

Double hinged articulated tower interaction with wind and waves  

Microsoft Academic Search

Articulated offshore towers are highly flexible against rotation at the hinges and derive their stability by means of inherently large buoyancy forces. The displacement response of such towers is mainly governed by the rigid body mode of vibration which has a very low frequency. Since the fluctuating wind velocity spectrum has high energy content in the low frequency region, therefore,

Nazrul Islam; Mohd Moonis Zaheer; Suhail Ahmed

2009-01-01

12

Comparison of Second Wind Triton Data with Meteorological Tower Measurements  

SciTech Connect

With the increased interest in remote sensing of wind information in recent years, it is important to determine the reliability and accuracy of new wind measurement technologies if they are to replace or supplement conventional tower-based measurements. In this study, we present the results of an analysis characterizing the measurement performance of a state-of-the-art SOund Detection And Ranging (sodar) device when compared to a high-quality tower measurement program. Second Wind Inc. (Somerville, MA, USA) provided NREL with more than six months of data from a measurement program conducted near an operating wind farm in western Texas.

Scott, G.; Elliott, D.; Schwartz, M.

2010-02-01

13

Wind Shear Characteristics at Central Plains Tall Towers  

Microsoft Academic Search

The object of this study is to analyze wind shear characteristics at tall tower sites in the Central Plains of the United States. The hub heights of modern turbines used for wind farm projects are now 70 meters (m) to 100 m above ground and some advanced turbines under development for deployment during the second half of this decade are

M. Schwartz; D. Elliott

2006-01-01

14

Automatically controlled wind propeller and tower shadow eliminator  

SciTech Connect

A propeller hub carries pivotally-mounted blades that are linked to a spring-loaded collar on the propeller shaft for automatic coning and feathering under predetermined high velocity movement along the propeller shaft to change the blade pitch angle during low wind velocity conditions. An airfoil support mounts a propeller shaft and turns therewith to reduce tower shadow effects. This is called a ''down-wind system'' meaning the propeller is behind the tower and causes the assembly to rotate into the wind without a tail vane.

Randolph, A.J.

1982-01-12

15

Average wind statistics for SRP area meteorological towers.  

National Technical Information Service (NTIS)

A quality assured set of average wind Statistics for the seven SRP area meteorological towers has been calculated for the five-year period 1982--1986 at the request of DOE/SR. A Similar set of statistics was previously compiled for the years 1975-- 1979. ...

J. E. Laurinat

1987-01-01

16

A high resolution tower shadow model for downwind wind turbines  

Microsoft Academic Search

A high resolution model for tower shadow effects on horizontal axis wind turbines has been developed which involves the use of a prescribed wake vortex model and an efficient near wake dynamic model of the vorticity trailed from the blade. The prescribed wake model is applied at first stage of the modelling strategy to provide basic information on blade aerodynamics.

Tongguang Wang; Frank N. Coton

2001-01-01

17

Simulation model of wind turbine 3p torque oscillations due to wind shear and tower shadow  

Microsoft Academic Search

To determine the control structures and possible power quality issues, the dynamic torque generated by the blades of a wind turbine must be represented. This paper presents an analytical formulation of the generated aerodynamic torque of a three-bladed wind turbine including the effects of wind shear and tower shadow. The comprehensive model includes turbine-specific parameters such as radius, height, and

Dale S. L. Dolan; Peter W. Lehn

2006-01-01

18

Performance prediction of a cooling tower using artificial neural network  

Microsoft Academic Search

This paper describes an application of artificial neural networks (ANNs) to predict the performance of a cooling tower under a broad range of operating conditions. In order to gather data for training and testing the proposed ANN model, an experimental counter flow cooling tower was operated at steady state conditions while varying the dry bulb temperature and relative humidity of

M. Hosoz; H. M. Ertunc; H. Bulgurcu

2007-01-01

19

Performance prediction of a multi-stage wind tower for indoor cooling  

NASA Astrophysics Data System (ADS)

A theoretical model is developed to establish an in-depth understanding of the performance of a three-stage wind tower with a bypass system for indoor cooling in rural dry and hot climates. Model simulations are presented for a wide range of ambient conditions that include inlet wind speed, inlet temperature and relative humidity. Simulation results provide an insight into the desirable water flow rates and air-to-water loadings for comfort zone temperatures and relative humidity levels at the exit of the wind tower. Simulations show wind towers with variable cross-sections provide an increase in the cooling power for the same inlet wind speed, inlet air temperature and relative humidity when compared to wind towers with a constant cross-section. The study shall lead to a better understanding to designing wind towers that are both environmentally friendly and energy efficient.

Issa, Roy J.; Chang, Byungik

2012-08-01

20

Wind Climate Analyses for a 61-M Tower in the Southeast  

Microsoft Academic Search

The Savannah River Technology Center's (SRTC) Atmospheric Technologies Group (ATG) has operated nine 61-m tower sites including the Central Climatology (CC) tower which is located near the center of the Savannah River Site (SRS) since 1985. Data from the weather instruments on this tower have provided answers to questions involving risk analyses, dose studies, forecast verifications, and wind\\/temperature conditions during

2003-01-01

21

Wind Dependence on the Flow Rate in a Natural Draught Cooling Tower.  

National Technical Information Service (NTIS)

The efficiency of a natural draught cooling tower depends, among other things, on the effect of the wind on the flow in the tower stack. Determinations were made on a natural draught wet cooling tower 100 metres high, for the purpose of studying this effe...

E. Baer G. Ernst D. Wurz

1981-01-01

22

Wind Speeds as Measured by Cup and Sonic Anemometers and Influenced by Tower Structure  

Microsoft Academic Search

Wind tunnel and field experiments have shown that the fast-response three-component sonic anemometer is a highly accurate wind speed sensor. When sonic anemometers were used as reference sensors for wind speed, slower response cup anemometers were found to consistently overestimate the wind speed. Despite measures taken during a field program in Kansas to minimize tower influence on wind measurements, the

Yutaka Izumi; Morton L. Barad

1970-01-01

23

Modelling of tornado and microburst-induced wind loading and failure of a lattice transmission tower  

Microsoft Academic Search

Many transmission line and tower failures worldwide are attributed to high intensity winds (HIW) associated with tornadoes and microbursts. This paper describes models for the wind velocity time–histories of transient tornado and microburst events and the resulting loading on a lattice tower. A dynamic structural analysis has been undertaken for two HIW events, predicting a tornado-induced shear failure, as observed

Eric Savory; Gerard A. R. Parke; Mostafa Zeinoddini; Norman Toy; Peter Disney

2001-01-01

24

Modified shape of the Eiffel Tower determined for an atmospheric boundary-layer wind profile  

NASA Astrophysics Data System (ADS)

The design and construction of the Eiffel Tower was based, in part, on a uniform horizontal wind model giving 300 kg m-2 kinematic pressure acting on the surface of the tower. Eiffel received a patent for his method of construction that eliminates the need for diagonal trellis bars used to resist the moment of an oncoming wind. At the end of the 19th century boundary-layer theory, laminar or turbulent, was nonexistent. Now, however, models for atmospheric flow over rough landscapes are available, the simplest being a power-law distribution of velocity with height. In this paper we deduce the shape of the tower had Eiffel incorporated this information into the design and construction of his world famous tower. Moreover, we prove Eiffel's observation that the tower profile conforms to the moment distribution wrought by the wind.

Weidman, P. D.

2009-06-01

25

Hydrogen Storage in Wind Turbine Towers: Design Considerations; Preprint  

SciTech Connect

The paramount considerations associated with a hydrogen tower are corrosion (in the form of hydrogen embrittlement) and structural failure (through bursting or fatigue life degradation). Although hydrogen embrittlement (HE) requires more research and experimentation, it does not appear to prohibit the use of turbine towers for hydrogen storage. Furthermore, the structural modifications required to store hydrogen in a tower are technically feasible. We discovered that hydrogen towers have a''crossover pressure'' at which their critical mode of failure crosses over from fatigue to bursting. The crossover pressure for many turbine towers is between 10 and 15 atm. The cost of hydrogen storage per unit of storage capacity is lowest near the crossover pressure. Above the crossover pressure, however, storage costs rise quickly.

Kottenstette, R.; Cotrell, J.

2003-09-01

26

Wind and Temperature Profile Characteristics from Observations on a 1400 ft Tower  

Microsoft Academic Search

Profiles of mean wind speed obtained from a 1420-ft tower are analyzed on the basis of similarity theory to determine the relationship of profile shape to lapse rate structure. A total of 274 profiles representing four observation times (0600, 1000, 1400, and 1800 CST) are used in the analysis. Thirty minute averages of the wind speed are taken at eleven

R. H. Thuillier; U. O. Lappe

1964-01-01

27

Optimization research on the structure of horizontally-arranged indirect air-cooling tower under strong wind condition  

NASA Astrophysics Data System (ADS)

Strong wind has a significant impact on the heat radiation of the air-cooling system. In this research, a numerical calculation model of 2×1000MW horizontally arranged air-cooling tower is established to simulate the flow distribution and heat exchanging capability of three different structures-horizontally-arranged indirect air-cooling tower, tower with guide wall outside, and tower with a cross wall inside-under high-speed wind and extreme-speed wind conditions. The result reveals that the structure with the guide wall outside the tower only works under strong wind condition while the structure with cross wall inside shows the anti-wind capability under both high-speed wind and extreme-speed wind conditions.

Chen, Guoyong; Gu, Hongfang; Wang, Haijun; Qin, Yongbo

2013-07-01

28

Wind Climate Analyses for a 61-M Tower in the Southeast  

SciTech Connect

The Savannah River Technology Center's (SRTC) Atmospheric Technologies Group (ATG) has operated nine 61-m tower sites including the Central Climatology (CC) tower which is located near the center of the Savannah River Site (SRS) since 1985. Data from the weather instruments on this tower have provided answers to questions involving risk analyses, dose studies, forecast verifications, and wind/temperature conditions during extreme events and planned tests. Most recently, data from these towers are being used for initial and boundary conditions for computationally intensive numerical simulations using mesoscale forecasting models that are run on a three-hourly basis by ATG for SRS and the surrounding vicinity. We found that a series of wind roses based on relatively short time scales (from two weeks to one hour) were a convenient method to depict the predominant wind speeds and directions at anemometer sites in the Southeast operated by the NWS. That report also revealed some interesting spatial and temporal relationships among thirteen NWS stations in the Carolinas, Georgia, and Florida. Our study here will focus on the CC tower to show changes in the wind speed and direction distributions with height during diurnal and annual cycles. This study will concentrate on mean wind speed and direction statistics.

Weber, A.H.

2003-11-24

29

Tracking of smokestack and cooling tower plumes using wind measurements at different levels  

SciTech Connect

Relationships between cooling tower and smokestack plumes at the Bowen Electric Generating Plant in northwestern Georgia and wind direction measurements at levels from the surface at 850 mb (approx. 1.5 km) are examined. The wind measurements play an important role in estimating plume directions which in turn are utilized to establish control and target (upwind and downwind) areas for a study of plant-induced precipitation modification. Fifty-two plume observations were made during a three week period in December 1979. Results indicate that a windset (4.5 km from the plant) mounted at a level approximating that of the cooling tower plume is a better predictor of plume direction than surface windsets (1.0 km from the plant) or 850 mb level winds. However, an apparent topographical influence on the wind direction measurements at the plume-level windset site somewhat limits its plume tracking capability, at least for ambient winds from the SW quadrant.

Miller, R.L.; Patrinos, A.A.N.

1980-08-01

30

Influence of Tower Shadow and Wind Turbulence on the Performance of Power System Stabilizers for DFIG-Based Wind Farms  

Microsoft Academic Search

The aim of the paper is to demonstrate the way in which mechanical power variations, due to tower shadow and wind turbulence, influence control performance of power system stabilizer (PSS) loops for doubly-fed induction generators (DFIGs). The PSS auxiliary loops are applied on a specific DFIG control scheme, the flux magnitude and angle controller (FMAC). However, since the PSS signal

F. Michael Hughes; Olimpo Anaya-Lara; G. Ramtharan; Nicholas Jenkins; Goran Strbac

2008-01-01

31

Effects of a vibration mass damper in a wind turbine tower.  

National Technical Information Service (NTIS)

In this paper the problem of reducing the dynamical response and hereby the fatigue load on a wind turbine tower is treated. The fatigue load is reduced by introduction of a mass damper. The investigations are performed on a pitch regulated 3-blade horizo...

I. Enevoldsen K. J. Moerk

1993-01-01

32

Continuous sliding mode control of a TV transmission tower under stochastic wind  

Microsoft Academic Search

An active mass damper has been designed to be installed on the upper observation deck of the 310 m Nanjing TV transmission tower in China in order to reduce the acceleration response under strong wind gusts. In this paper, we present a continuous sliding mode control (CSMC) strategy using dynamic output feedback for application to the active mass damper system

J. C. Wu; J. N. Yang

1997-01-01

33

The influence of the design methodology in the response of transmission towers to wind loading  

Microsoft Academic Search

From a theoretical approach, the design procedure for the establishment of wind loading on transmission towers was reviewed and current procedures, such as Davenport's gust response factor (GRF), were compared with the statistical method using influence lines (SIL), which is considered more realistic. This latter approach can account for unbalanced loading effects, shear and axial loads and the effects of

A. M. Loredo-Souza; A. G. Davenport

2003-01-01

34

NREL National Wind Technology Center (NWTC): M2 Tower; Boulder, Colorado (Data)  

SciTech Connect

The National Wind Technology Center (NWTC), located at the foot of the Rocky Mountains near Boulder, Colorado, is a world-class research facility managed by NREL for the U.S. Department of Energy. NWTC researchers work with members of the wind energy industry to advance wind power technologies that lower the cost of wind energy through research and development of state-of-the-art wind turbine designs. NREL's Measurement and Instrument Data Center provides data from NWTC's M2 tower which are derived from instruments mounted on or near an 82 meter (270 foot) meteorological tower located at the western edge of the NWTC site and about 11 km (7 miles) west of Broomfield, and approximately 8 km (5 miles) south of Boulder, Colorado. The data represent the mean value of readings taken every two seconds and averaged over one minute. The wind speed and direction are measured at six heights on the tower and air temperature is measured at three heights. The dew point temperature, relative humidity, barometric pressure, totalized liquid precipitation, and global solar radiation are also available.

Jager, D.; Andreas, A.

1996-09-24

35

Recent Results From the NOAA/ESRL GMD Tall Tower Network  

NASA Astrophysics Data System (ADS)

We will present a summary of new results from NOAA Earth System Research Laboratory`s Tall Tower greenhouse gas monitoring network. The tower network is operated by the Global Monitoring Division, which also maintains the global Cooperative Air Sampling network and a network of aircraft profiling sites over North America. Tall tower CO2 mixing ratio measurements are sensitive to upwind fluxes over scales of hundreds of kilometers, and the primary objective of the tower network is to obtain regionally representative carbon flux estimates for the North American continent. Mixing ratios of CO2 and CO are measured semi-continuously at the towers, and the KWKT-TV tower site near Moody, TX has recently also been equipped with sensors to measure radon and O3. Daily flask samples are collected at the KWKT tower and analyzed for CO2, CO, CH4, SF6, N2O, H2, stable isotopes of CO2 and CH4, COS, and a variety of halocarbon and hydrocarbon species. Daily flask sampling will be implemented at all tower sites within the next few years. We have used the Stochastic Time Inverted Lagrangian Transport (STILT) model to investigate upwind influences on the tower observations. CO measurements provide an indicator of polluted air masses, and we will present a summary of the frequency and origin of pollution events observed at the towers. We will present an analysis of the primary factors contributing to observed CO2 variability along with average seasonal and diurnal cycles of CO2 at the tower sites. Tower measurements are being used to evaluate atmospheric transport models in the context of the Transcom Continuous experiment and are an important constraint for CO2 data assimilation systems that produce regional to global carbon flux estimates with up to weekly resolution.

Andrews, A. E.; Tans, P. P.; Peters, W.; Hirsch, A.; Sweeney, C.; Petron, G.; Kofler, J.; Zhao, C.; Masarie, K.; Wofsy, S. C.; Matross, D. M.; Mahadevan, P.; Longo, M.; Gerbig, C.; Lin, J. C.

2006-12-01

36

Numerical simulation of fluid flow and thermal performance of a dry-cooling tower under cross wind condition  

Microsoft Academic Search

Using the finite volume method (FVM), the fluid flow and temperature distribution around and in a dry-cooling tower under cross wind are simulated numerically. Since the flow is turbulent, the k–? turbulence model is used. The numerical results are used to estimate the heat transfer between radiators of the tower and air around it. The numerical results are also compared

M. D. Su; G. F. Tang; S. Fu

1999-01-01

37

Vibration Based Wind Turbine Tower Foundation Design Utilizing Soil-Foundation-Structure Interaction  

NASA Astrophysics Data System (ADS)

Wind turbines have been used to generate electricity as an alternative energy source to conventional fossil fuels. This case study is for multiple wind towers located at different villages in Alaska where severe arctic weather conditions exist. The towers are supported by two different types of foundations; large mat or deep piles foundations. Initially, a Reinforced Concrete (RC) mat foundation was utilized to provide the system with vertical and lateral support. Where soil conditions required it, a pile foundation solution was devised utilizing a 30'' thick RC mat containing an embedded steel grillage of W18 beams supported by 20''-24'' grouted or un-grouted piles. The mixing and casting of concrete in-situ has become the major source of cost and difficulty of construction at these remote Alaska sites. An all-steel foundation was proposed for faster installation and lower cost, but was found to impact the natural frequencies of the structural system by significantly softening the foundation system. The tower-foundation support structure thus became near-resonant with the operational frequencies of the wind turbine leading to a likelihood of structural instability or even collapse. A detailed 3D Finite-Element model of the original tower-foundation-pile system with RC foundation was created using SAP2000. Soil springs were included in the model based on soil properties obtained from the geotechnical consultant. The natural frequency from the model was verified against the tower manufacturer analytical and the experimental values. Where piles were used, numerous iterations were carried out to eliminate the need for the RC and optimize the design. An optimized design was achieved with enough separation between the natural and operational frequencies to prevent damage to the structural system eliminating the need for any RC encasement to the steel foundation or grouting to the piles.

Al Satari, P. E. Mohamed

2008-07-01

38

The IAUC Urban Flux Network - An international network of micrometeorological flux towers in urban ecosystems  

NASA Astrophysics Data System (ADS)

Throughout the past decade, numerous research groups have put significant effort into setting up new infrastructure to directly measure fluxes between various urban ecosystems and the atmosphere using micrometeorological methods - mainly eddy covariance of energy, water vapour, carbon dioxide, and aerosols. More and more long-term sites are installed in areas considered ‘typical’ for selected urban developments to quantify the impact of urban form and management on energy and greenhouse gas exchange and to support the biogeochemical modeling of urban ecosystem. Only few tall towers in urban areas are included in the FLUXNET database (http:// www.fluxnet.ornl.gov/). Most urban sites are not suitable for FLUXNET as virtually no urban site is focusing on the quantification of annual net ecosystem exchange (NEE). Urban flux-tower projects rather focus on urban-specific processes such as the role of managed urban vegetation, modified soils, urban water use, fossil-fuel emissions, the release of air pollutants, and/or anthropogenic heat fluxes. Therefore the International Association on Urban Climate (IAUC) has established the “Urban Flux Network” with the goal to network research groups and activities in the international urban flux community. The IAUC provides a simple, geographical database (http://www.urban-climate.org/) with the objective to collect and share information about ongoing and discontinued micrometeorological tower sites located in urban environments. Currently the database hosts over 30 towers from 5 continents. Example data from selected towers will demonstrate the potential of using data from a variety of urban ecosystems to quantify density effects, or the role of vegetation structure and irrigation management on the exchange of primarily energy and carbon dioxide.

Christen, A.; Grimmond, S.; Roth, M.; Pardyjak, E.

2009-12-01

39

Wind shear for large wind turbine generators at selected tall tower sites  

SciTech Connect

The objective of the study described in this report is to examine the nature of wind shear profiles and their variability over the height of large horizontal-axis wind turbines and to provide information on wind shear relevant to the design and opertion of large wind turbines. Wind turbine fatigue life and power quality are related through the forcing functions on the blade to the shapes of the wind shear profiles and their fluctuations over the disk of rotation.

Elliott, D.L.

1984-04-01

40

The Effect of Wind Speed at the Top of the Tower on the Performance and Energy Generated from _THERMOSYPHON Solar Turbine  

NASA Astrophysics Data System (ADS)

Energy generated from wind turbine depends to a great extent on the wind speed at its inlet. The use of thermosyphon solar tower is an attempt to increase the air velocity at inlet of the wind turbine and of course to increase its power. The wind speed in a certain location changes always with time and with the height above ground surface. In this work, the effect of wind speed at the top of the tower on the performance as well as on the energy generated from thermosyphon solar turbine was studied theoretically. One location in Egypt was chosen for this study. The calculations were achieved mainly with the solar turbine located at tower bottom. For the purpose of comparison, the energy generated from the solar turbine was compared with that generated from free wind turbine at tower height with the absence of solar tower. It was found that, the wind speed at the top of the tower results in a pressure drop which affects the performance of the thermosyphon solar turbine. This pressure drop increases with the rise in wind speed and will be zero only when the wind speed at the top of the tower reaches zero. It was found also that, there is an increase in friction losses through the tower and a decrease in both temperature difference between inlet and outlet of the tower and in heat losses from tower walls with the rise in wind speed in location. The inlet air velocity to the solar turbine and consequently its specific power were found to be increased with the increase in wind speed at the top of the tower. Therefore, the effect of wind speed at the top of the tower must be taken into account during thermosyphon solar tower calculations. By comparing the performance of solar turbine and the free wind turbine located at tower height with the absence of thermosyphon solar tower, it was found that the mean inlet air velocity to the solar turbine located at tower bottom and consequently its specific power are higher than these values for free wind turbine. The mean inlet air velocity to the solar turbine is found to be 117% of its value for a free wind turbine. The yearly specific energy generated from solar turbine is expected to be 157% of its value for free wind turbine.

El-Haroun, A. A.

2002-01-01

41

Space-time VMS computation of wind-turbine rotor and tower aerodynamics  

NASA Astrophysics Data System (ADS)

We present the space-time variational multiscale (ST-VMS) computation of wind-turbine rotor and tower aerodynamics. The rotor geometry is that of the NREL 5MW offshore baseline wind turbine. We compute with a given wind speed and a specified rotor speed. The computation is challenging because of the large Reynolds numbers and rotating turbulent flows, and computing the correct torque requires an accurate and meticulous numerical approach. The presence of the tower increases the computational challenge because of the fast, rotational relative motion between the rotor and tower. The ST-VMS method is the residual-based VMS version of the Deforming-Spatial-Domain/Stabilized ST (DSD/SST) method, and is also called "DSD/SST-VMST" method (i.e., the version with the VMS turbulence model). In calculating the stabilization parameters embedded in the method, we are using a new element length definition for the diffusion-dominated limit. The DSD/SST method, which was introduced as a general-purpose moving-mesh method for computation of flows with moving interfaces, requires a mesh update method. Mesh update typically consists of moving the mesh for as long as possible and remeshing as needed. In the computations reported here, NURBS basis functions are used for the temporal representation of the rotor motion, enabling us to represent the circular paths associated with that motion exactly and specify a constant angular velocity corresponding to the invariant speeds along those paths. In addition, temporal NURBS basis functions are used in representation of the motion and deformation of the volume meshes computed and also in remeshing. We name this "ST/NURBS Mesh Update Method (STNMUM)." The STNMUM increases computational efficiency in terms of computer time and storage, and computational flexibility in terms of being able to change the time-step size of the computation. We use layers of thin elements near the blade surfaces, which undergo rigid-body motion with the rotor. We compare the results from computations with and without tower, and we also compare using NURBS and linear finite element basis functions in temporal representation of the mesh motion.

Takizawa, Kenji; Tezduyar, Tayfun E.; McIntyre, Spenser; Kostov, Nikolay; Kolesar, Ryan; Habluetzel, Casey

2013-07-01

42

Windmill tower  

SciTech Connect

A windmill tower supports a propeller and a platform that in turn supports a propeller feather control system and a generator system. The entire tower rotates at its base under changes in wind direction so the rotating propeller is constantly maintained upwind of the tower. The tower is a rigid structure that withstands cyclic thrust and torque loading sufficiently to reduce resonant vibrations of the tower as the propeller rotates under the influence of the wind. The resonant frequency of the tower can be higher than the passing frequency of the rotating propeller blades. The tower includes a pair of generally upright fore legs that converge upwardly toward a first apex on the propeller axis of rotation near the front of the platform immediately behind the propeller hub. A diagonal bracing strut extends downwardly from the first apex away from the plane of the fore legs and toward the rear of the tower. The bottoms of the fore legs and the diagonal bracing strut are rigidly interconnected by base plane truss members. A pair of upwardly converging aft legs extend diagonally upwardly from the bottoms of the fore legs toward a second apex aft of the first apex at the rear of the platform. At regular vertical intervals, stiffening trusses add rigidity to the main upright members of the tower structure. The natural frequency of the tower is raised by the fore legs and the diagonal bracing strut being interconnected in a rigid base plane truss. The diagonal bracing strut resists thrust loading on the tower, and the fore legs and aft legs resist torsional forces produced at the top of the tower.

Schachle, C.; Schachle, E.C.; Schachle, J.R.; Schachle, P.J.

1982-04-06

43

The PNL single-tower measurement model of rotationally sampled turbulent wind, with user's guide for STRS2PC  

SciTech Connect

This report describes a single-tower rotationally sampled wind model, STRS-2, that approximates a set of time series of turbulent wind experienced by individual points rotating in circles in a crosswind plane using measurements from anemometers arrayed vertically along a single line. The purposes of the model are (1) to use turbulence measurements made economically from conventional single-tower arrays of anemometers, (2) to incorporate measures characteristics of the wind at specific sites under consideration for operation of wind turbines, spanning the height range if interest, and (3) to estimate the unmeasured turbulence characteristics in the crosswind plane that spans the disk of the rotor blades. 17 refs., 15 figs., 5 tabs.

Connell, J.R.; Morris, V.R.; Powell, D.C.; Gower, G.L.

1988-06-01

44

Feasibility of in situ blade deflection monitoring of a wind turbine using a laser displacement sensor within the tower  

NASA Astrophysics Data System (ADS)

With the potential of commercially viable global wind power, the use of wind energy is expected to rise further, along with related problems. One issue is collision of the wind turbine blades with the tower during operation. Structural health monitoring is required to improve operational safety, minimize the risk of sudden failure or total breakdown, ensure reliable power generation, and reduce wind turbine life cycle costs. To this end, large numbers of sensors such as fiber Bragg grating and piezoelectric devices have been attached to the structure, which is uneconomical and impractical for large wind turbines. This study proposes a single laser displacement sensor (LDS) system in which all of the rotating blades can be cost-effectively evaluated. In contrast to the approach of blade sensor installation, the LDS system is installed in the tower to enable noncontact blade displacement monitoring. The concept of a noncontact sensor and actuator and their energy delivery device installed in the tower will enable various approaches for wind turbine structural health monitoring. Blade bolt loosening can cause deflection in an affected blade. Similarly, nacelle tilt or mass loss damage in a blade can result in changes in blade deflection, but the proposed system can detect such problems early on.

Lee, Jung-Ryul; Kim, Hyeong-Cheol

2013-02-01

45

Does the European eddy flux tower network represent the climatic and ecophysiological diversity of Europe?  

NASA Astrophysics Data System (ADS)

In analyzing the increase of greenhouse gas concentration in terrestrial atmosphere, the studies about the role of vegetation in the carbon exchange regulation are relevant. In this respect, a network using the eddy covariance technique to measure CO2 and H2O exchanges between terrestrial ecosystems and atmosphere, has been established. When the network was established, 16 towers all located in forest ecosystems were maintained. In the past 15 years, the network grew and the current Carboeurope-IP monitoring network consists of more than 100 flux towers (www.carboaurope.org) located all over Europe aiming to represent the diversified of geographic regions, climatic and vegetation characteristics (Plant Functional Types). Because the growth of the network was driven by funding and administrative issues rather than scientific needs, we evaluated, in retrospective, the representativeness of the current network based on climatic and ecophysiological characteristics of the sites and the European territory. We used a cluster approach based on the distance matrix of Self Organizing Maps (SOM) (Kohonen 2001), where the SOM was trained with 21 variables describing main meteorological and productivity characteristics and their inter-annual and seasonal variability of the European territory. A separate SOM was trained for each PFT and the representativeness of eddy towers sites has been evaluated on the basis of their positions on the SOM clusters map (i.e. the 21-D variable-space). The main underlying assumption was that the number of clusters within each PFT was similar to the current number of towers. The analysis showed that the current network is representing the European domain quite well in respect to the variables considered, although North-Eastern and South-Eastern climatic and ecosphysiological conditions are poorly sampled for several PFT. The same approach was used to propose a new tower arrangement that maximizes the network representativeness. Further, our results shown that use of data-driven clustering techniques like SOM can contribute to the evaluation of network representativeness with important impact in network design and analysis of model simulations based on the data derived from this monitoring network. Kohonen T (2001) Self-Organizing Maps. Springer-Verlag, Berlin.

Canfora, E.; Papale, D.; Luyssaert, S.; Sulkava, M.

2009-04-01

46

Bird Strikes and Electrocutions at Power Lines, Communication Towers, and Wind Turbines: State of the Art and State of the Science - Next Steps Toward Mitigation1  

Microsoft Academic Search

Migratory birds suffer considerable human-caused mortality from structures built to provide public serv- ices and amenities. Three such entities are increasing nationwide: communication towers, power lines, and wind turbines. Communication towers have been grow- ing at an exponential rate over at least the past 6 years. The U.S. Fish and Wildlife Service is especially con- cerned about growing impacts to

Albert M. Manville

2005-01-01

47

Bestimmung von Boeen Gemessen an Einem 130M-Mast bei Wilhelmshaven (Shape of Wind Gusts at a 130M Tower at Wilhelmshaven (Germany)).  

National Technical Information Service (NTIS)

A tower equipped with wind sensors at different levels above the ground is described. The tower had a triangular cross section with a side length of 1 m; the length of the sensor carrying booms was slightly more than 3 m, thus minimizing the wake effects ...

G. Tetzlaff K. Schreiber M. Kotzian J. Rissmann E. Hollwurtel

1992-01-01

48

Mapping the network for planning: a correlational PET activation study with the Tower of London task  

Microsoft Academic Search

Summary We used the Tower of London task (TOL) and H215O- PET to map the network of brain structures involved in planning. Six healthy right-handed subjects had 12 measurements of relative regional cerebral blood flow (rrCBF) during six conditions, each performed twice. There was one rest condition, and five sets of TOL problems at different complexity levels, performed on a

Alain Dagher; Adrian M. Owen; Henning Boecker; David J. Brooks

1999-01-01

49

Atmospheric CO2 and CH4 Measurement Network on Towers in Siberia  

NASA Astrophysics Data System (ADS)

In order to estimate CO2 and CH4 fluxes at regional to sub-continental scale by an inverse model, a network of tall towers for atmospheric CO2 and CH4 measurements has been established over a region of thousand square kilometers in west Siberia. In-situ continuous measurements have been conducted at 6 stations: Berezorechka (56.17N, 84.33E) since 2002, Parabel (58.25N, 82.40E) and Igrim (63.20N, 64.48E) since 2004, Demyanskoe (59.78N, 70.87E) and Noyabrsk (63.43N, 76.76E) since 2005, and Yakutsk (62.83N, 129.35E) in east Siberia since 2005. Over next two years, installations of 4 more stations are planned. This study provides some results of observation from this network. Seasonal cycles of CO2 showed quite similar trends in growing season (May to September) among the west Siberian sites. The remarkable decrease of CO2 concentration occurred in early May and the seasonal minimum was observed between July and August. On the other hand, the short-term (from several days to week) variations in CO2 concentrations were quite different among the sites, particularly during the growing season. Rather large variation of more than 25 ppm within a week was observed during winter. The changes in CO2 concentrations at the nearby sites were almost identical. Monthly mean values of CO2 during the growing season were relatively higher at the northern sites than at southern sites. These observational results evidentially reflected the regional characteristics of CO2 flux variation, transportation, and mixing process. Daily cycles of CH4 in summer showed nocturnal increase and diurnal decrease which was due to emission of CH4 from wetland accumulated over night, and diurnal convective mixing. Relatively high concentrations of CH4 were observed in winter and summer. Because there is one of the world's vastest wetland in western Siberia, the peak of CH4 in summer implies the significant role of CH4 emissions from the west Siberian wetland to the atmosphere. On the other hand, an exceptionally high concentration of CH4 of more than 3 ppm was observed in several sites. It occurred irrespective of time of a day but was associated with the definite wind direction. This may be linked to a strong point source of CH4 such as the leakage of natural-gas from pipeline or compressor station located near the observation sites. Thus, the data presented in this study can contribute to the future effort to detect the leakage point in the pipeline using satellite data.

Shimoyama, K.; Machida, T.; Shinohara, A.; Maksyutov, S.; Arshinov, M.; Davydov, D.; Fofonov, A.; Krasnov, O.; Fedoseev, N.; Belan, B.; Belan, H.; Inoue, G.

2006-12-01

50

Report on a wind-energy applications network for Hawaii  

Microsoft Academic Search

A wind energy applications network (WEAN) for Hawaii is proposed to coordinate the various activities in wind conversion. The network includes an infrastructure of people, programs, and governmental agencies working together to solve problems of wind energy conversion with a common goal of securing optimum utilization of Hawaii's wind energy potential. The network concept has a wind energy development objective

D. R. Neill; P. K. Takahashi

1978-01-01

51

Finite Element Analysis of a Wind Turbine Response when the Tower and the Blades are Modeled as Distributed Parameter Systems  

NASA Astrophysics Data System (ADS)

Finite element (FE) model of a wind turbine (WT) system is constructed where the tower and the blades are assumed as distributed parameter systems, the nacelle--as a concentrated mass and the wind loading is generated from fluid simulations. The system response is simulated by a program implementation of the model and the results obtained are compared to the results from ANSYS 3-D simulations. The constructed WT model could be utilized for identification and optimization of the system parameters as well as for defining modal characteristics and generating reduced models based on the first several natural frequencies and modal shapes.

Pasheva, V.; Slavchev, Y.; Venkov, G.

2011-12-01

52

A virtual tall tower network for understanding continental sources and sinks of CO2  

SciTech Connect

Our understanding of the North American terrestrial carbon cycle is limited by both a lack of continental atmospheric CO2 data, and by a need for methods to interpret these and other continental data with confidence. In response to this challenge a rapid expansion of the N. American carbon cycle observational network is underway. This expansion includes a network of continuous, continental CO2 mixing ratio observations being collected at a subset of AmeriFlux towers. Progress in developing this resource includes instrument development, site installation, calibration and intercalibration efforts, and initiation of a uniform data product. Progess in applying these data include proposed methods for interpreting surface layer measurements in atmospheric inversions (the virtual tall towers approach), examination of coherence patterns in continental mixing ratios in response to weather and climate, and application of these mixing ratio measurements in formal atmospheric inversions. Future work will merge these methods with interpretation of flux towers observations of terrestrial carbon fluxes in an effort to create a single coherent diagnosis of North American terrestrial carbon fluxes over a multi-year period.

Davis, K.J.; Richardson, S.J.; Miles, N.L.

2007-03-09

53

Wind energy harvesting control for green cellphone towers with dSPACE implementation  

Microsoft Academic Search

Abundance of renewable energy sources at the location of cellphone antennas and the high cost of grid expansion to remote areas provide economic incentives for development of green cellphone towers. At the height of 15–60 meter, these towers experience a semi steady flow of air suitable to generate electric power. However, some technical challenges and sizing procedures need to be

Afshin Izadian; Heng Yang; Nathaniel Girrens

2011-01-01

54

On comparing three artificial neural networks for wind speed forecasting  

Microsoft Academic Search

Wind speed forecasting is critical for wind energy conversion systems since it greatly influences the issues such as the scheduling of a power system, and the dynamic control of the wind turbine. In this paper, we present a comprehensive comparison study on the application of different artificial neural networks in 1-h-ahead wind speed forecasting. Three types of typical neural networks,

Gong Li; Jing Shi

2010-01-01

55

WIND SPEED AND POWER PREDICTION USING ARTIFICIAL NEURAL NETWORKS  

Microsoft Academic Search

Short-term wind prediction over different time steps is vital for wind farms in operation for various applications. Considering the complexity of atmospheric processes governing wind, time series models are preferred over physical models for wind prediction. Artificial neural networks (ANNs), which perform a non-linear mapping between inputs and outputs, provide an alternative approach for wind prediction. Two popular ANN types,

S. Jayaraj; K. Padmakumari; E. Sreevalsan; Arun P

56

Dopamine modulates default mode network deactivation in elderly individuals during the Tower of London task.  

PubMed

Task-induced deactivation is frequently reported in the ventro-medial prefrontal cortex (vmPFC) and posterior cingulate cortex (PCC), regions considered to belong to the default mode network. To investigate the effect of dopamine on task-induced deactivation, we used positron emission tomography to measure cerebral blood flow during performance of the Tower of London task before and after administration of the dopamine receptor agonist apomorphine in six healthy volunteers (49-66 years old) and six Parkinson disease patients (52-69 years old). Although task-induced deactivation was observed in the vmPFC and PCC in both groups and in both conditions, an inverse correlation between activation and problem complexity was observed in the vmPFC only in the apomorphine condition. PMID:19442867

Nagano-Saito, Atsuko; Liu, Jiaqiang; Doyon, Julien; Dagher, Alain

2009-04-15

57

Analysis of Wind Characteristics at United States Tall Tower Measurement Sites  

Microsoft Academic Search

A major initiative of the U.S. Department of Energy (DOE) is to ensure that 20% of the country's electricity is produced by wind energy by the year 2030. An understanding of the boundary layer characteristics, especially at elevated heights greater than 80 meters (m) above the surface is a key factor for wind turbine design, wind plant layout, and identifying

D. Elliott; M. Schwartz; G. Scott; S. Haymes

2008-01-01

58

Fatality Assessment and Control Evaluation (FACE) Report: Railcar Worker Dies After Being Crushed by a Reach Stacker Lifting a Wind Tower Section in Colorado.  

National Technical Information Service (NTIS)

On October 27, 2010, a 21-year-old worker died after being crushed between the tire of a reach stacker (powered industrial truck) and a railcar. Wind turbine tower sections weighing up to 54 tons each were being loaded onto railcars by the use of two reac...

E. Reyes J. Helmkamp M. Kiefer P. Moore

2011-01-01

59

Wind tunnel experiments of cooling-tower plumes in the presence of cross flow  

NASA Astrophysics Data System (ADS)

Measurements of velocity and temperature field and flow visualization results are reported for an ideal case of a cooling-tower plume in the presence of cross flow for various velocity ratios, densimetric Froude numbers, and Reynolds numbers. Coherent structures in the form of jet-like, wake-like or mushroom type of vortices have been observed. The type of the structures depends primarily on the velocity ratio. As the Reynolds number increases turbulent structures appear which carry vorticity of the same sign as the partner vortices in the low Reynolds number case. The measurements showed that there is a strong interaction between the bending over plume or jet and the wake of the cooling tower which is basically responsible for the downwash effect, which generally is quite strong at low velocity ratios and high Reynolds numbers. High turbulence intensities are produced on the wake of the tower for about 6 to 8 diameters. The plume is diluted faster as the velocity ratio and buoyancy increase.

Andreopoulos, J.

60

Wind tunnel experiments on cooling tower plumes part I: In uniform cross flow  

SciTech Connect

Measurements of velocity and temperature field and flow visualization results are reported for an ideal case of a cooling-tower plume in the presence of a uniform cross flow for various velocity ratios, densimetric Froude numbers, and Reynolds numbers. Coherent structures in the form of jet-like, wake-like or mushroom type of vortices have been observed. The type of the structures depends primarily on the velocity ratio. As the Reynolds number increases turbulent structures appear, which carry vorticity of the same sign as the partner vortices in the low Reynolds number case. The measurements showed that there is a strong interaction between the bending over plume or jet and the wake of the cooling tower which is basically responsible for the downwash effect. The latter is generally quite strong at low velocity ratios and high Reynolds numbers. High turbulence intensities are produced in the wake of the tower for a distance 6 to 8 diameters. The plume is diluted faster as the velocity ratio increases and buoyancy decreases. In the wake region of the stack dilution increased with buoyancy.

Andreopoulos, J.

1987-01-01

61

Wind Power Plant Prediction by Using Neural Networks: Preprint  

SciTech Connect

This paper introduces a method of short-term wind power prediction for a wind power plant by training neural networks based on historical data of wind speed and wind direction. The model proposed is shown to achieve a high accuracy with respect to the measured data.

Liu, Z.; Gao, W.; Wan, Y. H.; Muljadi, E.

2012-08-01

62

Nonlinear model identification of wind turbine with a neural network  

Microsoft Academic Search

A nonlinear model of wind turbine based on a neural network (NN) is described for the estimation of wind turbine output power. The proposed nonlinear model uses the wind speed average, the standard deviation and the past output power as input data. An anemometer with a sampling rate of one second provides the wind speed data. The NN identification process

Sousso Kélouwani; Kodjo Agbossou

2004-01-01

63

Wind wave directions determined form synthetic aperture radar imagery and from a tower in Lake Michigan  

NASA Astrophysics Data System (ADS)

Directional wave spectra calculated from digitized synthetic aperture radar (SAR) images of waves on Lake Michigan are compared to a wave directional spectrum determined from measurements taken at a tower and to a one-dimensional spectrum determined from a Waverider buoy. The comparison is within one frequency band for peak energy frequency and within 20° for direction, but the SAR image intensity spectrum does not have the same shape as a wave height spectrum. Wave refraction directions observed in the SAR spectra are within 10° of classical wave refraction calculations.

Schwab, David J.; Schuchman, Robert A.; Liu, Paul C.

1981-03-01

64

Assessing and improving the representativeness of monitoring networks: The European flux tower network example  

NASA Astrophysics Data System (ADS)

It is estimated that more than 500 eddy covariance sites are operated globally, providing unique information about carbon and energy exchanges between terrestrial ecosystems and the atmosphere. These sites are often organized in regional networks like CarboEurope-IP, which has evolved over the last 15 years without following a predefined network design. Data collected by these networks are used for a wide range of applications. In this context, the representativeness of the current network is an important aspect to consider in order to correctly interpret the results and to quantify uncertainty. This paper proposes a cluster-based tool for quantitative network design, which was developed in order to suggest the best network for a defined number of sites or to assess the representativeness of an existing network to address the scientific question of interest. The paper illustrates how the tool can be used to assess the performance of the current CarboEurope-IP network and to improve its design. The tool was tested and validated with modeled European GPP data as the target variable and by using an empirical upscaling method (Artificial Neural Network (ANN)) to assess the improvements in the ANN prediction with different design scenarios and for different scientific questions, ranging from a simple average GPP of Europe to spatial, temporal, and spatiotemporal variability. The results show how quantitative network design could improve the predictive capacity of the ANN. However, the analysis also reveals a fundamental shortcoming of optimized networks, namely their poor capacity to represent the spatial variability of the fluxes.

Sulkava, Mika; Luyssaert, Sebastiaan; Zaehle, SöNke; Papale, Dario

2011-09-01

65

Distribution of GHG over West Siberia: airborne and tower network observations.  

NASA Astrophysics Data System (ADS)

In spite of high confidence level in understanding of greenhouse effect on climate change there is a lack of measurement data over significant part of the Northern Hemisphere. Taking into account the importance of the global climate changes and international cooperation in this field, NIES (National Institute for Environmental Studies) and IAO (Institute of Atmospheric Optics) combined their efforts in the framework of Joint Japanese-Russian Project on GHG monitoring to fill up this gap at least over West Siberia, which occupies a significant part of Northern Eurasia. This monitoring consists of airborne and tower network observations. Airborne study of vertical distribution of greenhouse gases nearby Novosibirsk (between 54°05'N-81°50'E and 54°35'N-82°40'E) has been started on July 1997. Monthly flight observation have been conducted at an altitude from 500 to 7000 km. The 11-year airborne study nearby Novosibirsk has revealed a positive trend in CO2 mixing ratio (>15 ppm) and the absence of a definite trend for CH4. Minimum of CO2 concentration is typically observed at the end of July. Highest annual amplitudes of CO2 mixing ratio (up to 40 ppm) are observed in the atmospheric boundary layer. During recent years a tower network (8 towers) for carbon dioxide and methane monitoring was established in West Siberia. This network covers several climatic zones from steppes in the south to northern taiga in the north (51°N to 63°N and 62°E to 82°E). In this paper we present the first results of the diurnal, seasonal, and annual behavior of these greenhouse gases in the surface atmospheric layer over West Siberia Diurnal behavior of CO2 mixing ratio showed its maximum amplitude in July and its minimum amplitude in January. Concentration gradient between northern and southern regions remains during the whole year. Carbon dioxide mixing ratio has a pronounced annual behavior with a maximum in December and a minimum in July-August. It starts to decrease on March, and this process becomes more intensive from May until July. Since the beginning of September and until December intensity of CO2 sink is smaller than the rate of its emission. Diurnal behavior of the CH4 mixing ratio is mainly neutral during the year except for the late spring and beginning of the summer when a significant one is observed. There is a CH4 concentration gradient directed from south to north with a difference in concentration from 100 to 340 ppb. In the annual behavior of CH4 concentration two maxima and two minima are observed in the center of the region under study (maxima: July and December-January; minima: April-May and October). At northern sites the main maximum is also observed in winter with one-month lag with respect to central regions. Summer maximum over southern regions is not so intensive and observed in August. Amplitude of annual behavior at northern sites is 200 ppb, and 100-120 ppb at southern. The most interannual variability is 150 ppb and observed during main and secondary maxima.

Arshinov, M. Yu.; Machida, T.; Inoue, G.; Belan, B. D.; Maksyutov, Sh.; Sasakawa, M.; Watai, T.; Shimoyama, K.; Sutoh, H.; Davydov, D. K.

2009-04-01

66

The effect of the heat exchanger arrangement and wind-break walls on the performance of natural draft dry-cooling towers subjected to cross-winds  

Microsoft Academic Search

In most full scale dry-cooling towers rectangular heat exchanger bundles are arranged either vertically around the circumference of the tower or horizontally in the inlet cross-section of the tower. A numerical procedure is used in the present paper to investigate the influence of the particular arrangement on the performance of a tower in windy conditions with the results being verified

A. F. du Preez; D. G. Kröger

1995-01-01

67

Half-hourly atmospheric 13CO2 observed by cavity ring-down spectroscopy analyzer in the USDA Forest Service Climate Tower Network  

NASA Astrophysics Data System (ADS)

Network-wide measurements of atmospheric 13CO2 enable the partitioning of global CO2 into oceanic and terrestrial sources and sinks by a 'double-deconvolution' approach. The approach is sensitive to small changes in the13C/12C signatures associated with terrestrial photosynthesis (?) and respiration (?13CR). Flask-based measurements have provided robust estimates of terrestrial 13C discrimination at seasonal time scales. These canopy-level 13C observations were in general agreement with our leaf-level understanding of physiological responses to environmental variation, though many relationships remain empirical. An improved temporal resolution of 13C measurements in stress-sensitive ecosystems by a coordinated network would strategically provide much-needed data to further develop mechanistic models for the assessment of continental-scale carbon budget. Here we present high-precision, continuous 13CO2 measurements made by Picarro cavity ring-down spectroscopy instrument at a subset of AmeriFlux towers (Wind River, GLEES, Howland, Silas Little, and Coweeta) in the new USDA Forest Service Climate Tower Network. Most of these sites have long eddy flux and meteorological records and a history of participating in syntheses. Half-hourly average CO2, H2O and 13CO2 mixing ratios have been recorded at 3 canopy heights (1m aboveground, mid- and above-canopy) since 2010. Analyzer-dependent sensitivity to temperature fluctuation, water vapor concentration, and CO2 concentration were carefully evaluated and their performances were compared between the 5 Picarro analyzers. We also compared the self-generated calibration functions with manufacturer specifications. Large discrepancies were noted in some cases, suggesting the need to independently evaluate these still-evolving spectroscopy analyzers by the users. Upon careful calibration, these analyzers were capable of producing continuous 13CO2 data that gave good agreement when compared to flask measurements. Diurnal and vertical profiles of atmospheric 13CO2 measured in the 5 USFS-managed forests are presented and discussed.

Lai, C.; Hollinger, D. Y.; Massman, W. J.; Clark, K. L.; Bible, K.; Vose, J.; Desai, A. R.; Kolka, R.; Richardson, A. D.; Hom, J. L.; Evans, R.; Forest Service Climate Tower Network

2011-12-01

68

A Global Network of Eddy-Covariance Flux Towers to Study Ecosystem Dynamics, Enhance Models, and Validate Remote Sensing Products  

NASA Astrophysics Data System (ADS)

Long-term measurements of carbon dioxide, water vapor, and energy fluxes are integral to quantifying seasonal and spatial patterns and understanding biological and climatic processes that control the canopy-scale exchanges of carbon and water with the atmosphere. Currently there is a global network of over 140 eddy-correlation flux-tower systems, with most flux towers operating continuously for 3 years or longer. Towers are located in temperate conifer and broadleaf forests, tropical and boreal forests, crops, grasslands, chaperral, wetlands, and tundra on five continents. A global database, called FLUXNET (http://daac.ornl.gov/fluxnet/), provides consistent and complete flux data to support global carbon cycle science. FLUXNET contains carbon, water vapor, sensible heat, momentum, and radiation flux measurements with associated ancillary and value-added data products. Gaps in the measurement record are filled using robust methods to provide daily, monthly, and annual estimates. Flux data are being used to validate ecosystem model outputs and provide scientific information to improve underlying model algorithms. By examining fluxes from a variety of climatic conditions and ecosystems represented across the network, important controls on fluxes have been identified including plant functional type, stand age, light, cloud cover, temperature, humidity deficits and water use, length of growing season in temperate broad-leaved forests, and landscape heterogeneity. An overarching goal of FLUXNET is to provide information for validating remote sensing based products such as net primary productivity and energy absorption.

Olson, R. J.; Falge, E.; Baldocchi, D.; Gu, L.; Holladay, S.; Cook, R. B.

2001-05-01

69

Windmill tower shadow eliminator  

SciTech Connect

In a wind driven propeller system an airfoil support for the shaft of a propeller having an even number of blades extends above and below the shaft a distance at least equal to the blade length and pivots with the propeller into the wind for substantially eliminating tower shadow effects on the propeller.

Randolph, A.J.

1984-04-17

70

Using neural networks to estimate wind turbine power generation  

Microsoft Academic Search

This paper uses data collected at Central and South West Services Fort Davis wind farm (USA) to develop a neural network based prediction of power produced by each turbine. The power generated by electric wind turbines changes rapidly because of the continuous fluctuation of wind speed and direction. It is important for the power industry to have the capability to

Shuhui Li; Donald C. Wunsch; Edgar A. O'Hair; Michael G. Giesselmann

2001-01-01

71

Wind-induced Dynamics Of A Deep Space Network Antenna  

Microsoft Academic Search

Accurate spacecraft tracking by the NASA Deep Space Network (DSN) antennas must be assured during changing weather conditions. Wind disturbances are the main source of antenna vibrations, and consequently tracking errors. A wind force model is developed, and simulation results of wind-induced vibrations and pointing errors of the DSN antennas are presented. The antenna model includes the antenna structure, the

W. Gawronski; B. Bienkiewicz; R. E. Hill

1994-01-01

72

Optimization of Wind Turbine Performance With Data-Driven Models  

Microsoft Academic Search

This paper presents a multiobjective optimization model of wind turbine performance. Three different objectives, wind power output, vibration of drive train, and vibration of tower, are used to evaluate the wind turbine performance. Neural network models are developed to capture dynamic equations modeling wind turbine performance. Due to the complexity and nonlinearity of these models, an evolutionary strategy algorithm is

Andrew Kusiak; Zijun Zhang; Mingyang Li

2010-01-01

73

Dynamics of Wind Generators on Electric Utility Networks  

Microsoft Academic Search

Dynamic interaction of wind-turbine-driven generators on electric utility networks was studied by computer simulation. Nonlinear representations of wind-turbine and various drive train elements and Park equation representations of synchronous and induction generators were implemented. An infinite capacity network was assumed. Time history responses for various system configurations were computed using as the input function severe wind gust data added to

CRAIGC. JOHNSON; RICHARDT. SMITH

1976-01-01

74

An Atmospheric Solitary Gust Observed with a Doppler Radar, a Tall Tower and a Surface Network  

Microsoft Academic Search

Doppler radar and a 444 m tall instrumented tower provide a detailed view of the kinematic and thermodynamic structure of a solitary gust. A study of the data fields, and comparison with theoretical and laboratory work leads to the conclusion that the gust is an internal solitary wave of permanent form launched by a thunderstorm outflow onto an inversion layer

Richard J. Doviak; Runsheng Ge

1984-01-01

75

Towers for Antarctic Telescopes  

NASA Astrophysics Data System (ADS)

To take advantage of the exceptional seeing above the boundary layer on Antarctic sites, a high-resolution telescope must be mounted on a support tower. An open transparent tower of framework minimizes the upward temperature-disturbed airflow. A typical minimum height is 30m. The tower platform has to be extremely stable against wind-induced rotational motions, which have to be less than fractions of an arc second, unusually small from a mechanical engineering viewpoint. In a traditional structure, structural deflections result in angular deflections of the telescope platform, which introduce tip and tilt motions in the telescope. However, a structure that is designed to deflect with parallel motion relative to the horizontal plane will undergo solely translation deflections in the telescope platform and thus will not degrade the image. The use of a parallel motion structure has been effectively demonstrated in the design of the 15-m tower for the Dutch Open Telescope (DOT) on La Palma. Special framework geometries are developed, which make it possible to construct high towers in stories having platforms with extreme stability against wind-induced tilt. These geometric solutions lead to constructions, being no more massive than a normal steel framework carrying the same load. Consequently, these lightweight towers are well suited to difficult sites as on Antarctica. A geometry with 4 stories has been worked out.

Hammerschlag, R. H.; Bettonvil, F. C. M.; Jägers, A. P. L.; Nielsen, G.

76

Convection towers  

DOEpatents

Convection towers which are capable of cleaning the pollution from large quantities of air, of generating electricity, and of producing fresh water utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity, and condensers produce fresh water. 6 figs.

Prueitt, M.L.

1996-01-16

77

Convection towers  

DOEpatents

Convection towers which are capable of cleaning the pollution from large quantities of air and of generating electricity utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity. Other embodiments may also provide fresh water, and operate in an updraft mode.

Prueitt, Melvin L. (Los Alamos, NM)

1994-01-01

78

Radar Wind Profilers in the Colorado Network.  

National Technical Information Service (NTIS)

Radar systems used to measure vertical profiles of the horizontal wind in nearly all weather conditions can use frequencies between about 40 and 1000 MHz. This report describes three radar systems that measure wind profiles continuously and automatically....

R. G. Strauch D. A. Merritt K. P. Moran

1985-01-01

79

Impact of assimilating met-tower, turbine nacelle anemometer and other intensified wind farm observation systems on 0 - 12h wind energy prediction using the NCAR WRF-RTFDDA model  

NASA Astrophysics Data System (ADS)

In collaboration with Xcel Energy and Vasaila Inc., the National Center for Atmospheric Research (NCAR) conducts modeling study to evaluate the existing and the enhanced intensive observation systems for wind power nowcasting and short-range forecasting at a northern Colorado wind farm. The NCAR WRF (Weather Research and Forecasting model) based Real-Time Four-Dimensional Data Assimilation (RTFDDA) and forecasting system, which has been employed to support Xcel Energy operational wind forecast, was used in this study. The observational data include ten met-towers, a 915Hz wind profiler, a sodar and a Windcube Doppler lidar, besides the in-farm met-towers and wind speed and power reports from more than 300 of wind turbines. The WRF-RTFDDA 4-dimensioanl data assimilation algorithm allows to spread and propagate observation information in the WRF model space (x, y, z and time) with weighting functions built according to the observation location and time. The WRF-RTFDDA was set up to run with four nested domains with grid increments of 30, 10, 3.333 and 1.111km respectively. The standard and diverse non-conventional observations are assimilated on coarse grid domains along with the special wind farm observations. In this study, we investigate a) spread of surface observations in PBL according to PBL depth and regimes, b) optimization of horizontal influence radii and steep-terrain adjustment, and c) impact of different observation platforms and data types on 0 - 12 h wind prediction . It is found that PBL mixing and thermodynamic structures are greatly influenced by the PBL parameterization formulation. The range of the data assimilation effect on forecasts relies on weather and PBL regimes. In most cases, assimilation of in-farm and near-farm observations improves up to 12-hour wind power prediction and assimilation of in-farm data can significantly improves 0 - 6 hour forecasts.

Liu, Y.; Cheng, W.; Liu, Y. W.; Wiener, G.; Frehlich, R.; Mahoney, W.; Warner, T.; Himelic, J.; Parks, K.; Early, S.

2010-09-01

80

Evaluation of remote sensing based terrestrial productivity from MODIS using regional tower eddy flux network observations  

Microsoft Academic Search

The Moderate Resolution Spectroradiometer (MODIS) sensor has provided near real-time estimates of gross primary production (GPP) since March 2000. We compare four years (2000 to 2003) of satellite-based calculations of GPP with tower eddy CO2 flux-based estimates across diverse land cover types and climate regimes. We examine the potential error contributions from meteorology, leaf area index (LAI)\\/fPAR, and land cover.

Faith Ann Heinsch; Maosheng Zhao; Steven W. Running; John S. Kimball; Ramakrishna R. Nemani; Kenneth J. Davis; Paul V. Bolstad; Bruce D. Cook; Ankur R. Desai; Daniel M. Ricciuto; Beverly E. Law; Walter C. Oechel; Hyojung Kwon; Hongyan Luo; Steven C. Wofsy; Allison L. Dunn; J. William Munger; Dennis D. Baldocchi; Liukang Xu; David Y. Hollinger; Andrew D. Richardson; Paul C. Stoy; Mario B. S. Siqueira; Russell K. Monson; Sean P. Burns; Lawrence B. Flanagan

2006-01-01

81

Variation in bat and bird fatalities at wind energy facilities: assessing the effects of rotor size and tower height  

Microsoft Academic Search

Wind energy is a rapidly growing sector of the alternative energy industry in North America, and larger, more productive turbines are being installed. However, there are concerns regarding bird and bat fatalities at wind turbines. To assess the influence of turbine size on bird and bat fatalities, we analyzed data from North American wind energy facili- ties. Diameter of the

Robert M. R. Barclay; E. F. Baerwald; J. C. Gruver

2007-01-01

82

Mobile WiMAX-based communication network planning in Seribu Island by utilizing existing towers  

Microsoft Academic Search

An archipelago consisting of number of islands is relying on the broadband wireless technology to facilitate its telecommunication service. Mobile WiMAX (Worldwide Interoperability Mobile Access), as one of the broadband wireless technologies, is proposed to be applied as the network deployment in this paper. The network planning is designed based on cellular communication systems using hexagonal cells model. Five islands

Hardi Nusantara; Zaki Mujahid; Achmad Munir

2011-01-01

83

Investigating of wind turbines affects on recloser operation in distribution networks  

Microsoft Academic Search

Wind turbines are normally installed on distribution networks and reclosers are one of the main parts of that. Recloser operations are well known in traditional network, but they need more investigations when wind turbines are connected on the other side of the recloser. Existences of wind turbines produce mal-functions of reclosers. In this paper, the affects of the wind turbines

H. Kazemi Karegar; S. Saberi

2010-01-01

84

Autonomous dual-mode CAES systems for maximum wind energy contribution in remote island networks  

Microsoft Academic Search

Wind parks operating in autonomous island networks with limited capacity of wind energy absorption are faced with considerable energy curtailments. To encounter the existing situation, the concept of wind energy storage suggests an alternative worth investigating. On the other hand, the expansion of natural gas networks in big islands, where remarkable wind potential may be met as well, questions the

D. Zafirakis; J. K. Kaldellis

2010-01-01

85

Estimating missing data of wind speeds using neural network  

Microsoft Academic Search

In a lake system, wind data is important for hydrodynamics and sediment transport modeling. However, there exists missing data caused by instrumental failure due to birds, thunderstorms, or other unexpected events. Missing data will degrade the performance of modeling approach and accuracy of model results. In order to overcome this problem, we have developed a neural network model that attempts

Punnee Siripitayananon; Hui-Chuan Chen; Kang-Ren Jin

2002-01-01

86

Wind power forecasting using advanced neural networks models  

Microsoft Academic Search

In this paper, an advanced model, based on recurrent high order neural networks, is developed for the prediction of the power output profile of a wind park. This model outperforms simple methods like persistence, as well as classical methods in the literature. The architecture of a forecasting model is optimised automatically by a new algorithm, that substitutes the usually applied

G. N. Kariniotakis; G. S. Stavrakakis; E. F. Nogaret

1996-01-01

87

Balsa Towers  

NSDL National Science Digital Library

Learners work in groups to design and build a tower out of balsa wood. As a motivator, they can compete to build a tower with the highest strength-to-weight ratio. Learners draw structurally sound 2D designs in the first part of the activity, then use those designs to construct the 3D structure. This activity is best used as a part of a larger lesson or after other building activities. Time for activity can be split over multiple meetings.

Devereaux, Kelly; Burnham, Benjamin

2004-01-01

88

Network Wind Power Over the Pacific Northwest. Progress Report, October 1979-September 1980.  

SciTech Connect

The research in FY80 is composed of six primary tasks. These tasks include data collection and analysis, wind flow studies around an operational wind turbine generator (WTG), kite anemometer calibration, wind flow analysis and prediction, the Klickitat County small wind energy conversion system (SWECS) program, and network wind power analysis. The data collection and analysis task consists of four sections, three of which deal with wind flow site surveys and the fourth with collecting and analyzing wind data from existing data stations. This report also includes an appendix which contains mean monthly wind speed data summaries, wind spectrum summaries, time series analysis plots, and high wind summaries.

Baker, Robert W.; Hewson, E. Wendell

1980-10-01

89

Solar wind outflow and the chromospheric magnetic network  

PubMed

Observations of outflow velocities in coronal holes (regions of open coronal magnetic field) have recently been obtained with the Solar and Heliospheric Observatory (SOHO) spacecraft. Velocity maps of Ne7+ from its bright resonance line at 770 angstroms, formed at the base of the corona, show a relationship between outflow velocity and chromospheric magnetic network structure, suggesting that the solar wind is rooted at its base to this structure, emanating from localized regions along boundaries and boundary intersections of magnetic network cells. This apparent relation to the chromospheric magnetic network and the relatively large outflow velocity signatures will improve understanding of the complex structure and dynamics at the base of the corona and the source region of the solar wind. PMID:9933156

Hassler; Dammasch; Lemaire; Brekke; Curdt; Mason; Vial; Wilhelm

1999-02-01

90

Upward lightning observations from towers in Rapid City, South Dakota and comparison with National Lightning Detection Network data, 2004-2010  

NASA Astrophysics Data System (ADS)

We report on upward lightning observations from ten tall towers (91-191 m) in Rapid City, South Dakota, USA and compare with National Lightning Detection Network (NLDN) data. A total of 81 upward flashes were observed from 2004-2010 using GPS time-stamped optical sensors, and in all but one case, visible flash activity preceded the development of the upward leaders. Time-correlated analysis showed that the NLDN recorded an event within 50 km of towers and within 500 ms prior to upward leader development from the tower(s) for 83% (67/81) of the upward flashes. A preceding positive cloud-to-ground stroke (+CG) was detected in 57% (46/81) of the cases, and a preceding positive intracloud flash (+IC) in 23% (19/81) of the cases. However, 8 of the 19 NLDN-indicated +IC events were actually +CG strokes based on optical observations. Preceding negative intracloud flashes (-IC) were recorded for 2% (2/81) of the cases. Analysis also showed that for 44% (36/81) of the upward flashes, the NLDN reported subsequent negative cloud-to-ground (-CG) strokes and/or -IC events at one or more tower locations. Of the 151 subsequent events, 70% (105/151) were -CG reports and 30% (46/151) were listed as -IC events. The geometric mean/median location accuracy and peak current for subsequent events were 194 m/206 m and -12.9 kA/-12.4 kA respectively. These correlated observations suggest that a majority of the upward lightning flashes were triggered by a preceding flash with the dominant triggering type being the +CG flash.

Warner, Tom A.; Cummins, Kenneth L.; Orville, Richard E.

2012-10-01

91

Strategies to design and place towers for long-term ecological observations at continental scale  

NASA Astrophysics Data System (ADS)

There are numerous tower-based measurements applied in ecological science worldwide. National Ecological Observatory Network (NEON) is designing a tower-based method at 60 sites continental wide to measure abiotic drivers of ecological change, carbon and energy fluxes, and to specifically provide ecological connectively to measurements of organism ecology and connectively to remote sensed data products. Several issues come to bear when designing an infrastructure that has to accommodate different suites of measurements that have various requirements, i.e., micrometeorological, scalar flux measurements, atmospheric chemistry and boundary layer properties, and have to be objectively placed across the entire range of climate and ecosystem structures found in North America. Here, we present a comprehensive strategy that combines wind roses, footprint models, ecosystem structure, vegetation and soil maps, as well as ‘eyes on’ site visits to design and place a tower. This methodology is being used to examine the 60 preliminary tower designs in the largest ecological observatory in the world today to optimize the long-term representative measurements over the ecosystems of interests. We found that some preliminary site designs do not meet our tower science requirements due to an inadequate fetch for prevailing wind directions, extent of ecosystems boundaries, or concerns of edge effects. In these cases, the tower location shall be either micro-sited at the current locale, or moved and relocated to a different site altogether. After site specific characterization, we also found that some designed tower heights could not access the well mixed surface layer above canopy and had to be extended in design. Because wind comes from all direction at some sites, presents a particular challenge to orient a square tower. In all cases, we optimized the tower orientation to acquire the most amounts of valid data. To avoid the effects of flow distortion on measurements, the boom length (for sensor mounts) is determined to be 2-3 times of the face width of the tower on the windward side of tower. The measurement levels and heights on a tower are determined by the ecosystem type, canopy and strata. At least 4 measurement levels are expected for short statue ecosystem like grasslands, agricultural land, and prairies, whereas, 6-8 levels are expected for tall forest ecosystems.

Luo, H.; Loescher, H. W.; Ayres, E.; Clement, R.

2010-12-01

92

Analysis of wind energy time series with kernel methods and neural networks  

Microsoft Academic Search

Wind energy has an important part to play as renewable energy resource in a sustainable world. For a reliable integration of wind energy the volatile nature of wind has to be understood. This article shows how kernel methods and neural networks can serve as modeling, forecasting and monitoring techniques, and, how they contribute to a successful integration of wind into

Oliver Kramer; Fabian Gieseke

2011-01-01

93

Aerodynamic tower shake force analysis for VAWT  

Microsoft Academic Search

Vertical axis wind turbines (VAWT) are subjected to blade lift forces which vary continuously in both magnitude and direction. These blade lift forces are transmitted via the blade support arms to the tower. The resulting tower force vector is a composite of: a downwind and a crosswind average force component, rotating force vectors, and force vectors oscillating in the crosswind

J. L. Loth

1985-01-01

94

Rapunzel's Tower  

ERIC Educational Resources Information Center

|Children's literature often inspires the author's lessons, and reading to her primary students motivates their participation. In this article, the author presents and describes her lesson which is based on the book "Falling for Rapunzel" by Leah Wilcox. Students created a fairy tale tower in this lesson, which took place over three class periods.…

Depp, Sheryl

2007-01-01

95

Tricky Tower  

NSDL National Science Digital Library

In this classic brain teaser, learners use logic and strategy to move a tower of discs from one peg to another peg without breaking a set of rules. This lesson introduces learners to higher level thinking skills and provides practice of processes and tools used in problem solving.

Houston, Children'S M.

2008-01-01

96

Two Towers  

NSDL National Science Digital Library

The Two Towers is the only full featured LP Mud based upon the works of J.R.R Tolkien. It is dedicated to a exciting and challenging role-playing experience for the discriminating mudder and Tolkien aficionado. See the snazzy intro to the Web page and a full-screen map of Middle Earth. Connections to Tolkien information pages are also provided.

97

Geomagnetic storm predictions from solar wind data with the use of dynamic neural networks  

Microsoft Academic Search

Dynamic neural networks have been shown as an encouraging alternative to traditional approaches for nonlinear temporal predictions. We use partially recurrent neural networks to study solar wind-magnetosphere coupling by predicting geomagnetic storms. The solar wind and Dst data used in this study are selected from the period 1963 to 1992. Statistical cross-correlation analyses and neural networks are applied to finding

Jian-Guo Wu; Henrik Lundstedt

1997-01-01

98

Occupational exposure to radiofrequency fields in antenna towers.  

PubMed

Exposure of workers to radiofrequency fields was assessed in two medium-sized antenna towers. Towers had transmitting antennas from different networks, e.g. mobile phone networks, radio and digital TV sub-stations and amateur radio. The levels of radiofrequency fields were measured close to the ladders of the towers. All measured values were below ICNIRP occupational reference levels. PMID:17166878

Alanko, T; Hietanen, M

2006-12-13

99

Performance of cool towers under various climates in Jordan  

Microsoft Academic Search

The concept of cool towers, which is a modern version of the historical wind catchers was re-visited. In contrast with the expression of cooling towers, which usually refers to equipment used to cool the water in power stations, air conditioning plants etc., cool towers are used to cool the air to provide comfort conditions for occupants. The main driving force

Ali A Badran

2003-01-01

100

Virtual Tower  

SciTech Connect

The primary responsibility of an intrusion detection system (IDS) operator is to monitor the system, assess alarms, and summon and coordinate the response team when a threat is acknowledged. The tools currently provided to the operator are somewhat limited: monitors must be switched, keystrokes must be entered to call up intrusion sensor data, and communication with the response force must be maintained. The Virtual tower is an operator interface assembled from low-cost commercial-off-the-shelf hardware and software; it enables large amounts of data to be displayed in a virtual manner that provides instant recognition for the operator and increases assessment accuracy in alarm annunciator and control systems. This is accomplished by correlating and fusing the data into a 360-degree visual representation that employs color, auxiliary attributes, video, and directional audio to prompt the operator. The Virtual Tower would be a valuable low-cost enhancement to existing systems.

Wayne, R.A. [Sandia National Labs., Albuquerque, NM (United States). Security Engineering Dept.

1997-08-01

101

Surface and Tower Meteorological Instrumentation at NSA Handbook - January 2006  

SciTech Connect

The Surface and Tower Meteorological Instrumentation at Atqasuk (METTWR2H) uses mainly conventional in situ sensors to measure wind speed, wind direction, air temperature, dew point and humidity mounted on a 10-m tower. It also obtains barometric pressure, visibility, and precipitation data from sensors at or near the base of the tower. In addition, a Chilled Mirror Hygrometer is located at 1 m for comparison purposes. Temperature and relative humidity probes are mounted at 2 m and 5 m on the tower. For more information, see the Surface and Tower Meteorological Instrumentation at Atqasuk Handbook.

MT Ritsche

2006-01-30

102

Nocturnal wind direction shear and its potential impact on pollutant transport  

SciTech Connect

The estimation of transport and diffusion of airborne pollutants during the nighttime is challenging, especially over complex terrain where gravity driven drainage flows may be overlain with wind from a different direction. This study investigates the character of wind direction shear in the lowest 100 m using tower measurements from a complex, semi-arid site where local thermally-driven flows are common. The effects of wind direction shear on plume transport are studied by simulating a hypothetical elevated term release. This is accomplished by first simulating transport and dispersion using wind measurements from only the 12-m level from a network of towers. This case represents the approach commonly taken at many facilities where a network of short towers is available. Then the release is modeled using wind measurements made at four levels in the lowest 100 m. The differences between the two simulations are significant and would lead to very different responses in an emergency situation.

Bowen, B.M. [Lawrence Livermore National Lab., CA (United States); Baars, J.A.; Stone, G.L. [Los Alamos National Lab., NM (United States)

1998-12-31

103

76 FR 10328 - Grant of Authority for Subzone Status; Vestas Nacelles America, Inc. (Wind Turbine Nacelles, Hubs...  

Federal Register 2010, 2011, 2012, 2013

...Vestas Nacelles America, Inc. (Wind Turbine Nacelles, Hubs, Blades and Towers...special-purpose subzone at the wind turbine nacelle, hub, blade and tower manufacturing...manufacturing and warehousing of wind turbine nacelles, hubs, blades and towers...

2011-02-24

104

Evaluation of Wind Vectors Measured by a Bistatic Doppler Radar Network  

Microsoft Academic Search

By installing and linking additional receivers to a monostatic Doppler radar, several wind components can be measured and combined into a wind vector field. Such a bistatic Doppler radar network was developed in 1993 by the National Center for Atmospheric Research and has been in operation at different research departments. Since then, the accuracy of wind vectors has been investigated

Katja Friedrich; Martin Hagen

2004-01-01

105

Estimation of Energy Yield From Wind Farms Using Artificial Neural Networks  

Microsoft Academic Search

This paper uses the data from seven wind farms at Muppandal, Tamil Nadu, India, collected for three years from April 2002 to March 2005 for the estimation of energy yield from wind farms. The model is developed with the help of neural network methodology, and it involves three input variables-wind speed, relative humidity, and generation hours-and one output variable, which

M. Carolin Mabel; E. Fernandez

2009-01-01

106

Customer Security Assessment in Distribution Networks With High Penetration of Wind Power  

Microsoft Academic Search

A novel methodology is proposed for the customer security assessment with high penetration of wind power in modern distribution networks. The customer security is quantified through customer damage costs by operating wind farms without standing reserve, which causes an inadequate supply of power to meet loads at some operating conditions. Necessary reserve to mitigate intermittency of wind is quantified through

Dilan Jayaweera; Graeme Burt; James R. McDonald

2007-01-01

107

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

Microsoft Academic Search

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

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

2011-01-01

108

Large-scale wind power integration and voltage stability limits in regional networks  

Microsoft Academic Search

When planning and developing large-scale wind power plants in areas distant from the main power transmission system, voltage control assessments and reactive power compensation are increasingly important. Voltage stability of the regional network may be a main limitation with respect to maximum rating and operation of the wind power plant Technical constraints in relation to wind power integration in weak

M. P. Palsson; T. Toftevaag; K. Uhlen; J. O. G. Tande

2002-01-01

109

Effectiveness of tuned liquid column dampers for vibration control of towers  

Microsoft Academic Search

The effectiveness of tuned liquid column dampers (TLCD) in controlling the wind-induced vibration of towers is studied. The nonlinear governing equation of the TLCD is linearized to obtain the stochastic response of the towers due to along-wind turbulence. Through parametric studies, the optimum parameters for maximum reduction in acceleration and displacement are presented for a wide range of towers. It

T. Balendra; C. M. Wang; H. F. Cheong

1995-01-01

110

Use of Bayesian networks classifiers for long-term mean wind turbine energy output estimation at a potential wind energy conversion site  

Microsoft Academic Search

Due to the interannual variability of wind speed a feasibility analysis for the installation of a Wind Energy Conversion System at a particular site requires estimation of the long-term mean wind turbine energy output. A method is proposed in this paper which, based on probabilistic Bayesian networks (BNs), enables estimation of the long-term mean wind speed histogram for a site

José A. Carta; Sergio Velázquez; J. M. Matías

2011-01-01

111

Solar thermal and wind energy power source  

Microsoft Academic Search

A transparent panel enclosed tower provides a confined space for solar heating air. An upright wind turbine, mounted on the tower top, communicates with the tower enclosed space. As the solar heated air expands and becomes lighter it is displaced by cooler atmospheric air at the bottom of the tower creating a turbine driving thermal updraft in combination with wind

Argo

1980-01-01

112

Solar power towers  

Microsoft Academic Search

Components of solar power towers include a heliostat array, a central receiver, a thermodynamic conversion system, and a thermal storage unit. A 1-MW solar power tower prototype which has 17,500 sq m of mirror surface and a tower 90 m in elevation is currently under development in France. A joint European project to develop another 1-MW solar power tower is

M. Bignon

1979-01-01

113

WindTalker: A P2P-Based Low-Latency Anonymous Communication Network  

NASA Astrophysics Data System (ADS)

Compared with traditional static anonymous communication networks, the P2P architecture can provide higher anonymity in communication. However, the P2P architecture also leads to more challenges, such as route, stability, trust and so on. In this paper, we present WindTalker, a P2P-based low-latency anonymous communication network. It is a pure decentralized mix network and can provide low-latency services which help users hide their real identity in communication. In order to ensure stability and reliability, WindTalker imports “seed nodes” to help a peer join in the P2P network and the peer nodes can use gossip-based protocol to exchange active information. Moreover, WindTalker uses layer encryption to ensure the information of relayed messages cannot be leaked. In addition, malicious nodes in the network are the major threat to anonymity of P2P anonymous communication, so WindTalker imports a trust mechanism which can help the P2P network exclude malicious nodes and optimize the strategy of peer discovery, tunnel construction, and relaying etc. in anonymous communications. We deploy peer nodes of WindTalker in our campus network to test reliability and analyze anonymity in theory. The network measurement and simulation analysis shows that WindTalker can provide low-latency and reliable anonymous communication services.

Zhang, Jia; Duan, Haixin; Liu, Wu; Wu, Jianping

114

Optimal control of wind turbine using neural networks  

Microsoft Academic Search

Variable-speed, fixed-pitch wind turbines are required to optimize power output performance without the aerodynamic controls. In steady-state, a wind turbine generator system is operated such that the optimum points of wind rotor curve and electrical generator curve coincide. In order to obtain maximum power output of a wind turbine generator system, it is necessary to drive the wind turbine at

Mahinsasa Narayana; Ghanim Putrus

2010-01-01

115

Climate and vegetation controls on the surface water balance: Synthesis of evapotranspiration measured across a global network of flux towers  

NASA Astrophysics Data System (ADS)

The Budyko framework elegantly reduces the complex spatial patterns of actual evapotranspiration and runoff to a general function of two variables: mean annual precipitation (MAP) and net radiation. While the methodology has first-order skill, departures from a globally averaged curve can be significant and may be usefully attributed to additional controls such as vegetation type. This paper explores the magnitude of such departures as detected from flux tower measurements of ecosystem-scale evapotranspiration, and investigates their attribution to site characteristics (biome, seasonal rainfall distribution, and frozen precipitation). The global synthesis (based on 167 sites with 764 tower-years) shows smooth transition from water-limited to energy-limited control, broadly consistent with catchment-scale relations and explaining 62% of the across site variation in evaporative index (the fraction of MAP consumed by evapotranspiration). Climate and vegetation types act as additional controls, combining to explain an additional 13% of the variation in evaporative index. Warm temperate winter wet sites (Mediterranean) exhibit a reduced evaporative index, 9% lower than the average value expected based on dryness index, implying elevated runoff. Seasonal hydrologic surplus explains a small but significant fraction of variance in departures of evaporative index from that expected for a given dryness index. Surprisingly, grasslands on average have a higher evaporative index than forested landscapes, with 9% more annual precipitation consumed by annual evapotranspiration compared to forests. In sum, the simple framework of supply- or demand-limited evapotranspiration is supported by global FLUXNET observations but climate type and vegetation type are seen to exert sizeable additional controls.

Williams, Christopher A.; Reichstein, Markus; Buchmann, Nina; Baldocchi, Dennis; Beer, Christian; Schwalm, Christopher; Wohlfahrt, Georg; Hasler, Natalia; Bernhofer, Christian; Foken, Thomas; Papale, Dario; Schymanski, Stan; Schaefer, Kevin

2012-06-01

116

LWST Phase I Project Conceptual Design Study: Evaluation of Design and Construction Approaches for Economical Hybrid Steel\\/Concrete Wind Turbine Towers; June 28, 2002 -- July 31, 2004  

Microsoft Academic Search

The United States Department of Energy (DOE) Wind Energy Research Program has begun a new effort to partner with U.S. industry to develop wind technology that will allow wind systems to compete in regions of low wind speed. The Class 4 and 5 sites targeted by this effort have annual average wind speeds of 5.8 m\\/s (13 mph), measured at

LaNier

2005-01-01

117

A neural network based wind speed estimator for a wind turbine control  

Microsoft Academic Search

Variable speed wind generation systems are more attractive than fixed-speed systems because of the more efficient energy production improved power quality, and improved dynamic performance during grid disturbances. In this sense, to implement maximum wind power extraction, most controller designs of the variable-speed wind turbine generators employ anemometers to measure wind speed in order to derive the desired optimal shaft

Oscar Barambones; Jose Maria Gonzalez de Durana; Enrique Kremers

2010-01-01

118

Software Development for Analysis of Solar-Wind Hybrid Systems Supplying Local Distribution Networks  

Microsoft Academic Search

This paper deals with the modelling of an electrical local network supplied with energy provided by renewable resources. Its purpose is to implement and develop a software application to analyse and simulate a real hybrid solar-wind system connected to a local grid using Matlab Simulink environment. Blocks like wind model, solar model, local grid model are implemented and the results

Adrian Gligor

119

A new approach to improve voltage stability in a network with fixed speed wind turbines  

Microsoft Academic Search

In this paper, fixed speed wind turbines problems has been studied from the short term voltage stability point of view and a new approach is presented to improve voltage stability of networks with this kind of turbines without using of FACTS devices. A full converter wind turbine next to the induction generators can inject reactive power, to improve their transient

Yasser Ashkhane

2011-01-01

120

Wind energy prediction using a two-hidden layer neural network  

Microsoft Academic Search

The power generated by wind turbines changes rapidly because of the continuous fluctuation of wind speed and air density. As a consequence, it can be important to predict the energy production, starting from some basic input parameters. The aim of this paper is to show that a two-hidden layer neural network can represent a useful tool to carefully predict the

Giuseppe Grassi; Pietro Vecchio

2010-01-01

121

Typical Mid Tower Elevation & Section, Typical Mid Tower Footing ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Typical Mid Tower Elevation & Section, Typical Mid Tower Footing Section & Elevation, South Tower Section & Elevation, and North Tower Sections & Elevation - Cape Arago Light Station Footbridge, Gregory Point, Charleston, Coos County, OR

122

Experimental study of effects of separation distance between twin high-rise tower models on gaseous diffusion behind the downwind tower model  

Microsoft Academic Search

Twin high-structures give rise to the additional complexity of a nearby structure. The separation distances between twin high-rise towers have especially large effects on the flow and the concentration fields around them. Wind tunnel experiments have shown that the primary effect of the upwind tower is to retard the flow separation on the top and sides of the downwind tower,

Masaaki Ohba

1998-01-01

123

Fault analysis of distribution network with wind turbines of DFIG  

Microsoft Academic Search

With high penetrations of wind energy, different types of wind farm generators do not have the same fault transient characteristics that can complicate the selection and configuration of wind farm grid protection equipment. Incorrect selection of protection equipment will affect the stability and of the power systems. This paper investigates and analyzes the transient characteristics of doubly-fed induction generator (DFIG)

Yang Beige; Xue Hui; Bai Dandan; Hu Wei; He Jinghan

2011-01-01

124

Optimising the Design of Offshore Wind Farm Collection Networks  

Microsoft Academic Search

Wind turbines have reached a stage of maturity such that their use in offshore applications is becoming common. A principal objective of the offshore wind farm developer is to implement the wind farm to give the lowest cost of energy over the lifetime of the project, thus ensuring the greatest return on investment. Economic performance of the turbines is paramount,

P. D. Hopewell; F. Castro-Sayas; D. I. Bailey

2006-01-01

125

Economic evaluation of the dual mode CAES solution for increased wind energy contribution in autonomous island networks  

Microsoft Academic Search

Wind parks operating in autonomous island grids, such as those encountered in the Aegean Archipelago, face considerable wind energy curtailments, owed to the inability of local electricity networks to absorb the entire wind energy production. On the other hand, plans promoting the natural gas-based electricity generation in big islands (such as Crete) question the future of wind energy. To recover

D. Zafirakis; J. K. Kaldellis

2009-01-01

126

Cellular Phone Towers  

MedlinePLUS

... the call. How are people exposed to the energy from cellular phone towers? As people use cell ... where people can be exposed to them. The energy from a cellular phone tower antenna, like that ...

127

Aerodynamic tower shake force analysis for VAWT  

SciTech Connect

Vertical axis wind turbines (VAWT) are subjected to blade lift forces which vary continuously in both magnitude and direction. These blade lift forces are transmitted via the blade support arms to the tower. The resulting tower force vector is a composite of: a downwind and a crosswind average force component, rotating force vectors, and force vectors oscillating in the crosswind direction. The frequency of the rotating and oscillating forces are multiples of the product of Bw, where B is the number of blades used and ..omega.. is the rotor angular velocity. The magnitude of the largest tower shake force vector is of the same order as the average downwind force component, and may represent a serious design constraint in the calculation of the required tower stiffness. A closed-form solution for the tower force vectors has been derived, by introducing a suitable wind interference model. It shows that the magnitude of the largest tower shake force vector, using a threebladed rotor, is four times smaller than a two-bladed rotor. The Betz limit and the optimum tip speed ratio as a function of solidity has been derived by comparison with two semicylindrical actuators in series.

Loth, J.L.

1985-02-01

128

A robust wind turbine control using a Neural Network based wind speed estimator  

Microsoft Academic Search

Modern wind turbines are capable to work in variable speed operations. These wind turbines are provided with adjustable speed generators, like the double feed induction generator. One of the main advantage of adjustable speed generators is that they improve the system efficiency compared to fixed speed generators because turbine speed is adjusted as a function of wind speed to maximize

Oscar Barambones

2010-01-01

129

A numerical study of interacting buoyant cooling-tower plumes  

Microsoft Academic Search

The compact design of mechanical cooling towers necessitates that the plumes are issued into the cross-wind in close proximity. An improved understanding of the interaction of adjacent plumes is therefore required for better design of such cooling towers, which may lead to a reduction in their environmental impact. This paper presents the results of a numerical investigation into the interaction

R. B. Bornoff; M. R. Mokhtarzadeh-Dehghan

2001-01-01

130

Wind energy prediction using a two-hidden layer neural network  

NASA Astrophysics Data System (ADS)

The power generated by wind turbines changes rapidly because of the continuous fluctuation of wind speed and air density. As a consequence, it can be important to predict the energy production, starting from some basic input parameters. The aim of this paper is to show that a two-hidden layer neural network can represent a useful tool to carefully predict the wind energy output. By using proper experimental data (collected from three wind farm in Southern Italy) in combination with a back propagation learning algorithm, a suitable neural architecture is found, characterized by the hyperbolic tangent transfer function in the first hidden layer and the logarithmic sigmoid transfer function in the second hidden layer. Simulation results are reported, showing that the estimated wind energy values (predicted by the proposed network) are in good agreement with the experimental measured values.

Grassi, Giuseppe; Vecchio, Pietro

2010-09-01

131

Plant Vogtle cooling tower studies  

SciTech Connect

Intensive ground-based field studies of plumes from two large, natural-draft cooling towers were conducted in support of the MTI modeling effort. Panchromatic imagery, IR imagery, meteorological data, internal tower temperatures and plant power data were collected during the field studies. These data were used to evaluate plume simulations, plume radioactive transfer calculations and plume volume estimation algorithms used for power estimation. Results from six field studies indicate that a 3-D atmospheric model at sufficient spatial resolution can effectively simulate a cooling tower plume if the plume is of sufficient size and the ambient meteorology is known and steady. Small plumes and gusty wind conditions degrade the agreement between the simulated and observed plumes. Thermal radiance calculations based on the simulated plumes produced maximum IR temperatures (near tower exit) which were in good agreement with measured IR temperatures for the larger plumes. For the smaller plumes, the calculated IR temperature was lower than the measured temperature by several degrees. Variations in maximum IR plume temperature with decreasing power (one reactor was undergoing a shutdown process), were clearly observed in the IR imagery and seen in the simulations. These temperature changes agreed with those calculated from an overall tower energy and momentum balance. Plume volume estimates based on camcorder images at three look angles were typically 20--30 percent larger than the plume volumes derived from the simulations, although one estimate was twice the simulated volume. Volume overestimation is expected and will have to be accounted for to some degree if plume volume is to be a useful diagnostic quantity in power estimation. Volume estimation with MTI imagery will require a large, stable plume and two looks in the visible bands (5m GSD) along with a solar shadow.

O'Steen, L.

2000-01-26

132

Tower of London test: a comparison between conventional statistic approach and modelling based on artificial neural network in differentiating fronto-temporal dementia from Alzheimer's disease.  

PubMed

The early differentiation of Alzheimer's disease (AD) from frontotemporal dementia (FTD) may be difficult. The Tower of London (ToL), thought to assess executive functions such as planning and visuo-spatial working memory, could help in this purpose. Twentytwo Dementia Centers consecutively recruited patients with early FTD or AD. ToL performances of these groups were analyzed using both the conventional statistical approaches and the Artificial Neural Networks (ANNs) modelling. Ninety-four non aphasic FTD and 160 AD patients were recruited. ToL Accuracy Score (AS) significantly (p < 0.05) differentiated FTD from AD patients. However, the discriminant validity of AS checked by ROC curve analysis, yielded no significant results in terms of sensitivity and specificity (AUC 0.63). The performances of the 12 Success Subscores (SS) together with age, gender and schooling years were entered into advanced ANNs developed by Semeion Institute. The best ANNs were selected and submitted to ROC curves. The non-linear model was able to discriminate FTD from AD with an average AUC for 7 independent trials of 0.82. The use of hidden information contained in the different items of ToL and the non linear processing of the data through ANNs allows a high discrimination between FTD and AD in individual patients. PMID:21606576

Franceschi, Massimo; Caffarra, Paolo; Savarè, Rita; Cerutti, Renata; Grossi, Enzo

2011-01-01

133

Progress on Deriving National Emission Estimates of Climate-Active and Ozone-Depleting Halocarbons: Observational Constraints From Ongoing Aircraft and Tall Tower Air Sampling Networks  

NASA Astrophysics Data System (ADS)

In addition to NOAA's global air sampling network, two additional air sampling programs have been built recently to allow ongoing measurements of greenhouse-active and ozone-depleting gases in non-remote areas across North America. In one, flasks are collected approximately daily at nine tall towers in non-remote areas of the US. In a second involving aircraft, 8-12 flasks are collected at altitudes up to 8 km asl above 20 sites every 1-4 weeks. Measurements of approximately 50 gases are made from each of these samples and provide a rich dataset of chemical markers related to urban, industrial, oceanic, biomass burning, fossil-fuel burning, atmospheric mixing, photosynthesis, and soil influences. Emission signals are readily apparent in the halocarbon and hydrocarbon data, upon which this talk will focus. Correlations between different halocarbons show variations as a function of season and region and likely are related to emissions variations over space and time. Multiple approaches are being explored to derive absolute emission rates for these ozone-depleting and climate active chemicals that are representative of the entire U.S. These approaches include correlating enhancements in halocarbon mixing ratios above background levels with those observed for trace gases having better quantified emissions, such as CO, CO2, and 14CO2. Different modeling approaches should also prove useful, and are being explored.

Montzka, S.; Miller, L.; Miller, B.; Sweeney, C.; Andrews, A.; Karion, A.; Miller, J. B.; Jacobson, A.; Lehman, S.; Turnbull, J.

2008-12-01

134

Neural Network Based Interpolation of Wind Tunnel Test Data  

Microsoft Academic Search

The main objective of this research is to design a generalized framework for knowledge based management system (KBMS). This proposed system captures the knowledge of experts and the knowledge acquired is used for designing new systems. Wind Tunnel Test data of missiles has been taken into consideration for knowledge management in this research work and the interpolation of wind tunnel

S. Thamarai Selvi; S. Rama; E. Mahendran

2007-01-01

135

Keynote: Of towers, tunnels, animals, and wireless sensor networks: From research to the real world — And back  

Microsoft Academic Search

Wireless sensor networks (WSNs) have been around for more than a decade. Although the research community has become increasingly aware of the importance of real-world deployments, however, the latter represent a tiny fraction of the literature on WSNs. Moreover, of these few real-world experiences, those reporting about long-term, operational systems are themselves a small fraction of the total. In this

Gian Pietro Picco

2012-01-01

136

Technical Status Report for US Wind Farmers Network  

SciTech Connect

The theme of the work in this quarter was community-based wind and locally owned wind projects. The work Windustry has done is just beginning to touch the heart of the matter for a hugely interested audience of rural landowners and rural communities. We revised and published a Windustry Newsletter on two farmer owned wind projects called Minwind I and Minwind II. This article was largely researched and written last quarter but the principal individuals that organized the wind projects didn't want any more farmers calling them up than they already had, so they urged us to put a hold on the article or not publish it. This presented a unique problem for Windustry. Up to this point, we had not dealt with generating too much attention for a wind energy project. The story of a group of farmers and individuals pooling their resources for two locally owned commercial-scale wind projects is very compelling and the organizers of the projects were getting a great deal of attention from other farmers that want more details on the project. However, the organizers committed a large amount of their own resources toward the set up of this project which took many hours with their legal counsel and they did not have the capacity or the desire to provide answers for all the other farmers and individuals who were requesting information. Windustry worked with the business entity and did not publish the newsletter until we resolved some of the problems with the high level of interest in this project. Windustry resolved to address this issue by creating a custom track in the state and regional wind energy conference held in Minneapolis, November 21-22, 2002. There were a few sessions in the Landowner and Citizen Workshops track that were specifically created to talk about the ''how-to's for rural landowners to put together their own projects. Also, the conference's Community-Based Wind track addressed what makes a good project and what moneylenders are looking for when they evaluate wind projects. All of this contributed to the general knowledge base for other farmers to understand what it takes to put together their own wind energy enterprise. In a limited way, Windustry is beginning to define, differentiate and explore new types of wind energy business models. A good initial step is defining community-based wind as projects that are publicly owned--by a municipality, a rural electric coop, a county, or public entity like a school system, or hospital or jail. Ultimately, this work will lead to new materials on wind energy business models for rural landowners and communities.

Daniels, Lisa

2003-02-19

137

Development of a Nonlinear Soft-Sensor Using a GMDH Network for a Refinery Crude Distillation Tower  

NASA Astrophysics Data System (ADS)

In atmospheric distillation processes, the stabilization of processes is required in order to optimize the crude-oil composition that corresponds to product market conditions. However, the process control systems sometimes fall into unstable states in the case where unexpected disturbances are introduced, and these unusual phenomena have had an undesirable affect on certain products. Furthermore, a useful chemical engineering model has not yet been established for these phenomena. This remains a serious problem in the atmospheric distillation process. This paper describes a new modeling scheme to predict unusual phenomena in the atmospheric distillation process using the GMDH (Group Method of Data Handling) network which is one type of network model. According to the GMDH network, the model structure can be determined systematically. However, the least squares method has been commonly utilized in determining weight coefficients (model parameters). Estimation accuracy is not entirely expected, because the sum of squared errors between the measured values and estimates is evaluated. Therefore, instead of evaluating the sum of squared errors, the sum of absolute value of errors is introduced and the Levenberg-Marquardt method is employed in order to determine model parameters. The effectiveness of the proposed method is evaluated by the foaming prediction in the crude oil switching operation in the atmospheric distillation process.

Fujii, Kenzo; Yamamoto, Toru

138

LWST Phase I Project Conceptual Design Study: Evaluation of Design and Construction Approaches for Economical Hybrid Steel/Concrete Wind Turbine Towers; June 28, 2002 -- July 31, 2004  

SciTech Connect

The United States Department of Energy (DOE) Wind Energy Research Program has begun a new effort to partner with U.S. industry to develop wind technology that will allow wind systems to compete in regions of low wind speed. The Class 4 and 5 sites targeted by this effort have annual average wind speeds of 5.8 m/s (13 mph), measured at 10 m (33 ft) height. Such sites are abundant in the United States and would increase the land area available for wind energy production twenty-fold. The new program is targeting a levelized cost of energy of 3 cents/kWh at these sites by 2010. A three-element approach has been initiated. These efforts are concept design, component development, and system development. This work builds on previous activities under the WindPACT program and the Next Generation Turbine program. If successful, DOE estimates that his new technology could result in 35 to 45 gigawatts of additional wind capacity being installed by 2020.

LaNier, M. W.

2005-01-01

139

Wind power forecasting using fuzzy neural networks enhanced with on-line prediction risk assessment  

Microsoft Academic Search

The paper presents an advanced wind forecasting system that uses on-line SCADA measurements, as well as numerical weather predictions (NWP) as input, to predict the power production of wind parks 48 hours ahead. The prediction system integrates models based on adaptive fuzzy-neural networks configured either for short-term (1-10 hours) or long-term (1-48 hours) forecasting. The paper presents detailed one-year evaluation

P. Pinson; G. N. Kariniotakis

2003-01-01

140

Lower tropospheric horizontal wind over Indonesia: A comparison of wind profiler network observations with global reanalyses  

NASA Astrophysics Data System (ADS)

Horizontal wind data over Indonesia obtained by global reanalyses were compared with wind-profiling radar (WPR) observations in Indonesia at Kototabang (100.32°E, 0.20°S), Pontianak (109.37°E, 0.00°S), Manado (124.92°E, 1.55°N), and Biak (136.10°E, 1.18°S). The global-reanalysis data were 850- and 700-hPa horizontal winds for 2007 and 2008. These data were obtained from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) Reanalysis (R1), the NCEP-Department of Energy (DOE) Atmospheric Model Intercomparison Project (AMIP-II) Reanalysis (R2), the Japan Meteorological Agency Climate Data Assimilation System (JCDAS), the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis-interim (ERA-Interim). All the four reanalyses showed good agreement with the WPR zonal and meridional wind data (correlation coefficient >0.7 in most cases). Of the four reanalyses, ERA-Interim had the highest correlation coefficient with the WPR winds in both zonal (correlation coefficient 0.89) and meridional (0.77) components. It can be explained that ERA-Interim used four-dimensional variational analysis (4D-var) for data assimilation, whereas the other reanalyses used three-dimensional variational analysis (3D-var). The zonal winds of the four reanalyses had smaller (78-87%) amplitudes than did the WPR winds. Further comparison of the zonal winds between the global reanalyses and operational radiosondes indicated that global-reanalysis zonal winds with smaller amplitudes are common in and around Indonesia.

Tabata, Yoshikazu; Hashiguchi, Hiroyuki; Yamamoto, Masayuki K.; Yamamoto, Mamoru; Yamanaka, Manabu D.; Mori, Shuichi; Syamsudin, Fadli; Manik, Timbul

2011-06-01

141

Artificial neural network-based maximum power point tracking control for variable speed wind energy conversion systems  

Microsoft Academic Search

A new maximum power point tracking (MPPT) controller using artificial neural networks (ANN) for variable speed wind energy conversion system (WECS) is proposed. The algorithm uses Jordan recurrent ANN and is trained online using back propagation. The inputs to the networks are the instantaneous output power, maximum output power, rotor speed and wind speed, and the output is the rotor

J. S. Thongam; P. Bouchard; H. Ezzaidi; M. Ouhrouche

2009-01-01

142

Surface and Tower Meteorological Instrumentation at Atqasuk (METTWR2H) Handbook  

SciTech Connect

The Atqasuk meteorology station (AMET) uses mainly conventional in situ sensors to measure wind speed, wind direction, air temperature, dew point, and humidity mounted on a 10-m tower. It also obtains barometric pressure, visibility and precipitation data from sensors at or near the base of the tower. In addition, a chilled mirror hygrometer (CMH) is located at 1 m for comparison purposes. Temperature and relative humidity (RH) probes are mounted at 2 m and 5 m on the tower.

Ritsche, MT

2006-01-01

143

A Study of the Solar Wind-Magnetosphere Coupling Using Neural Networks  

NASA Astrophysics Data System (ADS)

The interaction between solar wind plasma and interplanetary magnetic field (IMF) and Earth's magnetosphere induces geomagnetic activity. Geomagnetic storms can cause many adverse effects on technical systems in space and on the Earth. It is therefore of great significance to accurately predict geomagnetic activity so as to minimize the amount of disruption to these operational systems and to allow them to work as efficiently as possible. Dynamic neural networks are powerful in modeling the dynamics encoded in time series of data. In this study, we use partially recurrent neural networks to study the solar wind-magnetosphere coupling by predicting geomagnetic storms (as measured by the Dstindex) from solar wind measurements. The solar wind, the IMF and the geomagnetic index Dst data are hourly averaged and read from the National Space Science Data Center's OMNI database. We selected these data from the period 1963 to 1992, which cover 10552h and contain storm time periods 9552h and quiet time periods 1000h. The data are then categorized into three data sets: a training set (6634h), across-validation set (1962h), and a test set (1956h). The validation set is used to determine where the training should be stopped whereas the test set is used for neural networks to get the generalization capability (the out-of-sample performance). Based on the correlation analysis between the Dst index and various solar wind parameters (including various combinations of solar wind parameters), the best coupling functions can be found from the out-of-sample performance of trained neural networks. The coupling functions found are then used to forecast geomagnetic storms one to several hours in advance. The comparisons are made on iterating the single-step prediction several times and on making a non iterated, direct prediction. Thus, we will present the best solar wind-magnetosphere coupling functions and the corresponding prediction results. Interesting Links: Lund Space Weather and AI Center

Wu, Jian-Guo; Lundstedt, Henrik

1996-12-01

144

Vector Winds from a Single-Transmitter Bistatic Dual-Doppler Radar Network  

Microsoft Academic Search

A bistatic dual-Doppler weather radar network consisting of only one transmitter and a nontransmitting, nonscanning, low-cost bistatic receiver was deployed in the Boulder, Colorado, area during 1993.The Boulder network took data in a variety of weather situations, including low-reflectivity stratiform snowfall, several convective cells, and a hailstorm. Dual-Doppler vector wind fields were retrieved and compared to those from a traditional,

Joshua Wurman

1994-01-01

145

FLYWHEEL ENERGY STORAGE SYSTEM TO IMPROVE THE INTEGRATION OF WIND GENERATORS INTO A NETWORK  

Microsoft Academic Search

The association of a Variable-Speed Wind Generator (VSWG) and a Flywheel Energy Storage System (FESS) with the aim to improve the integration of such generators in a network is studied. A resonant controller-based network connection and a fuzzy-logic supervisory are proposed. A 3 kW test bench is described, and a first experiment which validates the principle of the FESS is

Ludovic Leclercq; Christophe Saudemont; Benoît Robyns; Gabriel Cimuca; Mircea M. Radulescu

2003-01-01

146

Optimization of a wind-power fuel-cell hybrid system in an autonomous electrical network environment  

Microsoft Academic Search

Stability considerations associated with intermittency prevent high wind energy penetration in small electrical networks. The case of the islands of the Aegean is presented. [Ntziachristos L, Kouridis C, Samaras Z, Pattas K. A wind-power fuel-cell hybrid system study on the non-interconnected Aegean islands grid. Renewable Energy 2005;30(10):1471–1487] proposed a wind turbine(WT)–fuel-cell hybrid as a means to store wind energy and

Emmanuel Kasseris; Zissis Samaras; Dimitrios Zafeiris

2007-01-01

147

Twin Towers of Hanoi  

Microsoft Academic Search

In the Twin Towers of Hanoi version of the well known Towers of Hanoi Problem there are two coupled sets of pegs. In each move, one chooses a pair of pegs in one of the sets and performs the only possible legal transfer of a disk between the chosen pegs (the smallest disk from one of the pegs is moved

Zoran Sunic

2011-01-01

148

Statue Display Tower  

NSDL National Science Digital Library

In this activity, learners design, build, test and redesign a display tower that will meet a specific set of criteria and constraints. Learners apply the engineering design process to solve the Golden Book design challenge to make a low cost display tower that can hold a statue and can be taken apart and reassembled easily for transporting from one library to another.

Ieee

2013-07-08

149

Lost Subways: Tower Hill  

NSDL National Science Digital Library

This interesting website reviews "lost subways," including photos, articles, and other historical information. The Tower Hill Subway was England's first tube railway under the Thames which was open for public use from 1870-1896. This page offers an overview, timeline, history, description of the tunnel (in French), a bibliography, and a list of online resources about the Tower Hill Subway.

Delaitre, Frederic

2008-02-12

150

Mechanical Stresses in Fixed-Speed Wind Turbines Due to Network Disturbances  

Microsoft Academic Search

Electrical faults and other network disturbances generate transients of the generator electromagnetic torque, which result in significant stresses for the wind turbine (WT) mechanical system and may also have a detrimental effect on the fatigue life of important drive train components, such as the gearbox. In this paper the effect of faults and other disturbances, common in rural medium voltage

S. A. Papathanassiou; M. P. Papadopoulous

2001-01-01

151

Mechanical stresses in fixed-speed wind turbines due to network disturbances  

Microsoft Academic Search

Electrical faults and other network disturbances generate transients of the generator electromagnetic torque which result in significant stresses for the wind turbine (WT) mechanical system and may also have a detrimental effect on the fatigue life of important drive train components, such as the gearbox. In this paper, the effect of faults and other disturbances, common in rural medium voltage

Stavros A. Papathanassiou; Michael P. Papadopoulos

2001-01-01

152

Dynamic Modeling and Control of DFIG-Based Wind Turbines Under Unbalanced Network Conditions  

Microsoft Academic Search

This paper presents an analysis and control design of a doubly-fed induction generator (DFIG)-based wind generation system operating under unbalanced network conditions. A DFIG system model in the positive and negative synchronous reference frames is presented. Variations of stator active and reactive powers and generator torque are fully defined in the presence of negative sequence voltage and current. Alternative DFIG

Lie Xu; Yi Wang

2007-01-01

153

Neural network controller for a permanent magnet generator applied in a wind energy conversion system  

Microsoft Academic Search

In this paper a neural network controller for achieving maximum power tracking as well as output voltage regulation, for a wind energy conversion system (WECS) employing a permanent magnet synchronous generator, is proposed. The permanent magnet generator (PMG) supplies a DC load via a bridge rectifier and two buck–boost converters. Adjusting the switching frequency of the first buck–boost converter achieves

Mona N. Eskander

2002-01-01

154

Impact of wind turbine generators on network resonance and harmonic distortion  

Microsoft Academic Search

Distributed generators (DGs) are being increasingly connected at medium voltage level distribution networks. It is likely that different types of DGs, i.e. wind turbine generators (WTGs), photovoltaic solar systems, etc, may be connected on the same feeder. Most of the modern DGs are equipped with power electronic converters at their terminals, which act as sources of harmonic injection into the

Dhaval Patel; Rajiv K. Varma; Ravi Seethapathy; Michael Dang

2010-01-01

155

Higher Order Wavelet Neural Networks with Kalman learning for wind speed forecasting  

Microsoft Academic Search

In this paper, a Higher Order Wavelet Neural Net- work (HOWNN) trained with an Extended Kalman Filter (EKF) is implemented to solve the wind forecasting problem. The Neural Network based scheme is composed of high order terms in the input layer, two hidden layers, one incorporating radial wavelets as activation functions and the other using classical logistic sigmoid, and an

Luis J. Ricalde; Glendy A. Catzin; Alma Y. Alanis; Edgar N. Sanchez

2011-01-01

156

Wind  

NSDL National Science Digital Library

This document examine wind power as an energy resource. The reading will define wind and discuss topics such as (1) The history of wind machines, (2) Today's windmills, and (3) Types of wind machines. This resource is structured as an informational handout to supplement your energy activities or to generate discussion questions. Copyright 2005 International Technology Education Association

National Energy Education Development (NEED) Project

2003-01-01

157

Cooling tower waste reduction  

SciTech Connect

At Lawrence Livermore National Laboratory (LLNL), the two main cooling tower systems (central and northwest) were upgraded during the summer of 1997 to reduce the generation of hazardous waste. In 1996, these two tower systems generated approximately 135,400 lbs (61,400 kg) of hazardous sludge, which is more than 90 percent of the hazardous waste for the site annually. At both, wet decks (cascade reservoirs) were covered to block sunlight. Covering the cascade reservoirs reduced the amount of chemical conditioners (e.g. algaecide and biocide), required and in turn the amount of waste generated was reduced. Additionally, at the northwest cooling tower system, a sand filtration system was installed to allow cyclical filtering and backflushing, and new pumps, piping, and spray nozzles were installed to increase agitation. the appurtenance upgrade increased the efficiency of the cooling towers. The sand filtration system at the northwest cooling tower system enables operators to continuously maintain the cooling tower water quality without taking the towers out of service. Operational costs (including waste handling and disposal) and maintenance activities are compared for the cooling towers before and after upgrades. Additionally, the effectiveness of the sand filter system in conjunction with the wet deck covers (northwest cooling tower system), versus the cascade reservoir covers alone (south cooling tower south) is discussed. the overall expected return on investment is calculated to be in excess of 250 percent. this upgrade has been incorporated into the 1998 DOE complex-wide water conservation project being led by Sandia National Laboratory/Albuquerque.

Coleman, S.J.; Celeste, J.; Chine, R.; Scott, C.

1998-05-01

158

FIELD INVESTIGATION OF COOLING TOWER AND COOLING POND PLUMES  

EPA Science Inventory

Measurements were made relating to the behavior of water-vapor plumes from forced-draft cooling towers and from cooling ponds. There were three categories of measurements. (1) Ambient weather data including temperature, humidity, wind speed and wind direction. These measurements ...

159

Wind data requirements for wind turbine generator design  

Microsoft Academic Search

The statistical methods of wind modeling for the design of tall masts, buildings, towers, and bridges are shown to be effective for the analysis of wind loads on wind turbine generators (WTG). The wind velocity profile and turbulence is defined as the instantaneous deviations from the short term mean wind speed, and is capable of reducing the fatigue life of

U. Hassan

1980-01-01

160

Tower Camera Handbook  

SciTech Connect

The tower camera in Barrow provides hourly images of ground surrounding the tower. These images may be used to determine fractional snow cover as winter arrives, for comparison with the albedo that can be calculated from downward-looking radiometers, as well as some indication of present weather. Similarly, during spring time, the camera images show the changes in the ground albedo as the snow melts. The tower images are saved in hourly intervals. In addition, two other cameras, the skydeck camera in Barrow and the piling camera in Atqasuk, show the current conditions at those sites.

Moudry, D

2005-01-01

161

DETAIL VIEW OF AERIAL TRAM SUPPORT TOWER SIX WITH TOWERS ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

DETAIL VIEW OF AERIAL TRAM SUPPORT TOWER SIX WITH TOWERS SEVEN, EIGHT, NINE, TEN, AND BREAK OVER TOWER IN DISTANCE, LOOKING NORTH. TOWER SIX IS THE LAST BEFORE A DEEP CHASM, AS IS SEEN BY THE DISTANCE BETWEEN TOWERS SIX AND SEVEN. SEE CA-291-21 FOR IDENTICAL B&W NEGATIVE. - Keane Wonder Mine, Park Route 4 (Daylight Pass Cutoff), Death Valley Junction, Inyo County, CA

162

DETAIL VIEW OF AERIAL TRAM SUPPORT TOWER SIX WITH TOWERS ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

DETAIL VIEW OF AERIAL TRAM SUPPORT TOWER SIX WITH TOWERS SEVEN,EIGHT, NINE, TEN, AND BREAK OVER TOWER IN DISTANCE, LOOKING NORTH. TOWER SIX IS THE LAST BEFORE A DEEP CHASM, AS IS SEEN BY THE DISTANCE BETWEEN TOWERS SIX AND SEVEN. SEE CA-291-48 (CT) FOR IDENTICAL COLOR TRANSPARENCY. - Keane Wonder Mine, Park Route 4 (Daylight Pass Cutoff), Death Valley Junction, Inyo County, CA

163

Tower Investigation and the Egg  

NSDL National Science Digital Library

Towers have been a part of developed society for centuries, serving a variety of purposes, from watch towers to modern cell towers. In this activity, student groups design and build three types of towers, engineering them to meet the requirements that they hold an egg one foot high for 15 seconds.

Center For Engineering Educational Outreach

164

Cooling Tower Plume Model.  

National Technical Information Service (NTIS)

A review of recently reported cooling tower plume models yields none that is universally accepted. The entrainment and drag mechanisms and the effect of moisture on the plume trajectory are phenomena which are treated differently by various investigators....

L. D. Winiarski W. E. Frick

1976-01-01

165

On the aerodynamic and aeroelastic response of a bridge tower  

Microsoft Academic Search

This work is concerned with the aerodynamic characterization of a cable-stayed bridge tower in free-standing configuration; experimental tests were performed at Politecnico di Milano Wind Tunnel under smooth and turbulent flow conditions. The aerodynamic behavior of the tower was investigated through static and dynamic tests on a 1:30 scale sectional model; the whole structure response has been studied using a

Marco Belloli; Fabio Fossati; Stefano Giappino; Sara Muggiasca; Marco Villani

2011-01-01

166

Hurricane Frances Rain Towers  

NSDL National Science Digital Library

NASAs TRMM spacecraft allows us to look under Hurricane Frances clouds to see the rain structure. Spikes in the rain structure known as "Hot Towers" indicate storm intensity. The "hot towers" which refers to the tall cumulonimbus, has been seen as one of the mechanisms by which the intensity of a tropical cyclone is maintained. Because of the size (1-5 km) and short duration (30 minute to 2 hours) of these hot towers, studies of these events have been limited to descriptive studies from aircraft observations, although a few have attempted to use the presence of hot towers in a predictive capacity. Before TRMM, no data set exists that can show globally and definitively the presence of these hot towers in cyclone systems. Aircraft radar studies of individual storms lack global coverage. Global microwave or Infrared sensor observations do not provide the needed spatial resolution. With a ground resolution of 5 km, the TRMM Precipitation Radar provided the needed data set for examining the predictive value of hot towers in cyclone intensification.

Perkins, Lori; Halverson, Jeff

2005-04-11

167

Surface and Tower Meteorological Instrumentation at Barrow (METTWR4H) Handbook  

SciTech Connect

The Barrow meteorology station (BMET) uses mainly conventional in situ sensors mounted at four different heights (2m, 10m, 20m and 40m) on a 40 m tower to obtain profiles of wind speed, wind direction, air temperature, dew point and humidity. It also obtains barometric pressure, visibility and precipitation data from sensors at the base of the tower. Additionally, a Chilled Mirror Hygrometer and an Ultrasonic wind speed sensor are located near the 2m level for comparison purposes.

Ritsche, MT

2008-04-01

168

Impact of assimilating met-tower, turbine nacelle anemometer and other intensified wind farm observation systems on 0 - 12h wind energy prediction using the NCAR WRF-RTFDDA model  

Microsoft Academic Search

In collaboration with Xcel Energy and Vasaila Inc., the National Center for Atmospheric Research (NCAR) conducts modeling study to evaluate the existing and the enhanced intensive observation systems for wind power nowcasting and short-range forecasting at a northern Colorado wind farm. The NCAR WRF (Weather Research and Forecasting model) based Real-Time Four-Dimensional Data Assimilation (RTFDDA) and forecasting system, which has

Y. Liu; W. Cheng; G. Wiener; R. Frehlich; W. Mahoney; T. Warner; J. Himelic; K. Parks; S. Early

2010-01-01

169

STATISTICAL CORRELATIONS OF SURFACE WIND DATA: A COMPARISON BETWEEN A NATIONAL WEATHER SERVICE STATION AND A NEARBY AEROMETRIC MONITORING NETWORK  

EPA Science Inventory

This report presents a statistical analysis of wind data collected at a network of stations in the Southeast Ohio River Valley. The purpose of this study is to determine the extent to which wind measurements made by the National Weather Service (NWS) station at the Tri-State Airp...

170

MPPT control strategy for wind energy conversion system based on RBF network  

Microsoft Academic Search

This paper presents maximum-power-point-tracking (MPPT) based control algorithms for optimal wind energy capture using radial basis function network (RBFN) and a proposed torque observer MPPT algorithm. The design of a high-performance on-line training RBFN using back-propagation learning algorithm regulating controller for the sensorless control of a permanent magnet synchronous generator (PMSG). The PMSG is controlled by the loss-minimization control with

Whei-Min Lin; Chih-Ming Hong; Fu-Sheng Cheng; Kai Hung Lu

2011-01-01

171

Ride-Through Analysis of Doubly Fed Induction Wind-Power Generator Under Unsymmetrical Network Disturbance  

Microsoft Academic Search

This paper presents a ride-through simulation study of a 2-MW wind-power doubly fed induction generator (DFIG) under a short-term unsymmetrical network disturbance. The DFIG is represented by an analytical two-axis model with constant lumped parameters and by a finite element method (FEM)-based model. The model of the DFIG is coupled with the model of the active crowbar protected and direct

Slavomir Seman; Jouko Niiranen; Antero Arkkio

2006-01-01

172

3. VIEW NORTHWEST, height finder radar towers, and radar tower ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. VIEW NORTHWEST, height finder radar towers, and radar tower (unknown function) - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

173

Session: What have studies of communications towers suggested regarding the impact of guy wires and lights on birds and bats  

Microsoft Academic Search

This session at the Wind Energy and Birds\\/Bats workshop consisted of one presentation followed by a discussion\\/question and answer period. The paper ''Wind turbines and Avian Risk: Lessons from Communications Towers'' was given by Paul Kerlinger. The presenter outlined lessons that have been learned from research on communications (not cell) towers and about the impacts of guy wires and lights

Kerlinger

2004-01-01

174

Solar power towers  

SciTech Connect

The high desert near Barstow, California, has witnessed the development of this country`s first two solar power towers. Solar One operated successfully from 1982 to 1988 and proved that power towers work efficiently to produce utility-scale power from sunlight. Solar Two was connected to the utility grid in 1996 and is operating today. Like its predecessor, Solar Two is rated at 10 megawatts. An upgrade of the Solar One plant, Solar Two demonstrates how solar energy can be stored in the form of heat in molten salt for power generation on demand. The experience gained with these two pilot power towers has established a foundation on which industry can develop its first commercial plants. These systems produce electricity on a large scale. They are unique among solar technologies because they can store energy efficiently and cost effectively. They can operate whenever the customer needs power, even after dark or during cloudy weather.

Not Available

1998-04-01

175

Solar power towers  

SciTech Connect

The high desert near Barstow, California, has witnessed the development of this country's first two solar power towers. Solar One operated successfully from 1982 to 1988 and proved that power towers work efficiently to produce utility-scale power from sunlight. Solar Two was connected to the utility grid in 1996 and is operating today. Like its predecessor, Solar Two is rated at 10 megawatts. An upgrade of the Solar One plant, Solar Two demonstrates how solar energy can be stored in the form of heat in molten salt for power generation on demand. The experience gained with these two pilot power towers has established a foundation on which industry can develop its first commercial plants. These systems produce electricity on a large scale. They are unique among solar technologies because they can store energy efficiently and cost effectively. They can operate whenever the customer needs power, even after dark or during cloudy weather.

NONE

1998-04-01

176

Solar thermal power towers  

NASA Astrophysics Data System (ADS)

The solar thermal central receiver technology, known as solar power towers, is rapidly evolving to a state of near-term energy availability for electrical power generation and industrial process heat applications. The systems consist of field arrays of heliostat reflectors, a central receiver boiler, short term thermal storage devices, and either turbine-generators or heat exchangers. Fluid temperatures up to 550 C are currently achievable, and technology developments are underway to reach 1100 C. Six solar power towers are now under construction or in test operation in five countries around the world.

Kreith, F.; Meyer, R. T.

1984-07-01

177

A Towering Achievement  

NSDL National Science Digital Library

In this experience, learners use the internet to research physical details about Chihuly's Fireworks of Glass "Tower" and "Ceiling" and consider the decisions Chihuly had to make as he was planning the sculpture. As part of the activity, learners practice their measuring skills to estimate the height of Chihuly's "Tower." Learners also consider the roles and responsibilities of team members and other workers and why teamwork is important in constructing a large sculpture. This activity is featured on pp.45-48 of the "Fireworks of Glass: The Art of Dale Chihuly" unit of study for grades 3-5.

Indianapolis, The C.

2006-01-01

178

5. VIEW EAST, height finder radar towers, radar tower (unknown ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. VIEW EAST, height finder radar towers, radar tower (unknown function), prime search radar tower, operations building, and central heating plant - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

179

Standardized Calculation of Cooling Towers.  

National Technical Information Service (NTIS)

For a standardized calculation and assessment of the basic cooling tower types, methods are given for calculating the evaporation characteristics as a characteristic cooling tower value for counterflow and crossflow systems. For the crossflow cooling towe...

P. E. Harting

1977-01-01

180

Thermal Characteristics of Heating Towers  

NASA Astrophysics Data System (ADS)

Thermal characteristics of heating towers for air-source heat pumps are studied in terms of the overall enthalpy-transfer coefficient. Ka. First. the method of counter-flow calculation is presented taking physical properties of ethylene glycol solutions into account. Next, both cooling-tower and heating-tower experiments are carried out in a small, induced-draft. counterflow tower packed with tubes of a staggerd arrangement. using water and commercial ethylene glycol solutions. The coefficient Ka measured in the heating-tower experiment shows a trend similar to that in the cooling-tower experiment. So. the data on cooling towers will be helpful to the thermal design of heating towers.

Fujita, Toshihiko; Kametani, Shigeki

181

Observations of wind turbine wakes and surface roughness effects on wind flow variability  

Microsoft Academic Search

Wind data collected at nine meteorological towers at the Goodnoe Hills MOD-2 wind turbine site were analyzed to characterize the wind flow over the site both in the absence and presence of wind turbine wakes. Free-flow characteristics examined were the variability of wind speed and turbulence intensity across the site as a function of wind direction and surface roughness. The

D. L. Elliott; J. C. Barnard

1990-01-01

182

Solar thermal power towers  

Microsoft Academic Search

The solar thermal central receiver technology, known as solar power towers, is rapidly evolving to a state of near-term energy availability for electrical power generation and industrial process heat applications. The systems consist of field arrays of heliostat reflectors, a central receiver boiler, short term thermal storage devices, and either turbine-generators or heat exchangers. Fluid temperatures up to 550 C

FRANK KREITH; RICHARD T. MEYER

1984-01-01

183

Cell Towers and Songbirds  

ERIC Educational Resources Information Center

|This article describes how our common addiction to cell phones was used to launch a discussion about their use, impacts on the environment, and connections to issues of civic concern. By encouraging middle school science students to adopt the perspectives of special-interest groups debating communication tower restrictions designed to protect…

Klosterman, Michelle; Mesa, Jennifer; Milton, Katie

2009-01-01

184

Investigation of Excitation Control for Wind-Turbine Generator Stability.  

National Technical Information Service (NTIS)

High speed horizontal axis wind turbine generators with blades on the downwind side of the support tower require special design considerations to handle disturbances introduced by the flow wake behind the tower. Experiments and analytical analyses were ma...

V. D. Gebben

1977-01-01

185

Plan now for cold-weather operation of cooling towers  

SciTech Connect

This article describes what a midwestern utility has done to keep natural-draft towers running when faced with long bouts of high winds and single-digit temperatures. Severe ice buildup is the biggest threat. American Electric Power Co. (AEP) has six crossflow and eight counterflow natural-draft hyperbolic cooling towers in operation today. In the crossflow designs, subject of this discussion, the fill sections are more exposed to wind and cold. Their design circulating-water flow rates range from 220,000 to 600,000 gal/min; they serve 600-, 800-, and 1,300-MW coal-fired generating units. The towers are located in the Midwest and experience long periods of sub-freezing conditions during the winter months. High winds accompanied by single-digit temperatures often prevail for days at a time. During the record cold spell in January 1994, average temperatures as low as {minus}20 F occurred throughout AEP`s service area. Fill bypass systems have been incorporated into the design of AEP`s natural-draft cooling towers, and can pass between 25 and 50% of full-rated circulating-water flow. These systems prevent ice formation within the fill sections (heat-transfer media) by recirculating water directly to the tower cold-water basin during winter startup, when heat content of the circulating water is relatively low.

Michell, F.L.; Drew, D.H.

1996-06-01

186

Scanning Doppler Lidar Measurements for Wind Energy Applications  

Microsoft Academic Search

The development of wind energy has increased rapidly along with the size and capacity of wind turbines. These larger machines require detailed wind resource measurements at higher and higher altitudes. Accurate wind speed, wind direction, and turbulence statistics are required for wind resource assessment and efficient wind farm operation. Tower measurements are limited in coverage and do not provide the

R. Frehlich; N. Kelley

2008-01-01

187

GUST BUFFETING AND AEROELASTIC BEHAVIOUR OF POLES AND MONOTUBULAR TOWERS  

Microsoft Academic Search

The evolution in the constructional field and the realization of ever more slender and light structures have emphasized the increasing difficulty of properly evaluating the actions and effects of wind on poles and monotubular towers. Faced with this situation the Italian constructors, united in a consortium coordinated by ACS ACAI Servizi, entrusted the Department of Structural and Geotechnical Engineering of

G. Solari; L. C. PAGNINI

1999-01-01

188

New Scientist: Construction of Worlds Largest Tower to Begin  

NSDL National Science Digital Library

This article from the New Scientist talks about the building of the world's tallest building in Dubai, United Arab Emirates. The tower construction will be completed in 2008 and will result in a structure 800 meters tall. The article discusses how the building has been designed to address a primary concern for buildings of this height--wind.

189

Federal Building and Fire Safety Investigation of the World Trade Center Disaster: Reference Structural Models and Baseline Performance Analysis of the World Trade Center Towers. NIST NCSTAR 1-2A.  

National Technical Information Service (NTIS)

This report establishes the baseline performance of the North and South World Trade Center Towers (WTC 1 and WTC 2) under design gravity and wind loading conditions. Baseline performance results include basic information about the towers behavior under de...

R. B. Garlock W. J. Faschan

2005-01-01

190

Direct adaptive control of wind energy conversion systems using Gaussian networks.  

PubMed

Grid connected wind energy conversion systems (WECS) present interesting control demands, due to the intrinsic nonlinear characteristics of windmills and electric generators. In this paper a direct adaptive control strategy for WECS control is proposed. It is based on the combination of two control actions: a radial basis zfunction network-based adaptive controller, which drives the tracking error to zero with user specified dynamics, and a supervisory controller, based on crude bounds of the system's nonlinearities. The supervisory controller fires when the finite neural-network approximation properties cannot be guaranteed. The form of the supervisor control and the adaptation law for the neural controller are derived from a Lyapunov analysis of stability. The results are applied to a typical turbine/generator pair, showing the feasibility of the proposed solution. PMID:18252585

Mayosky, M A; Cancelo, I E

1999-01-01

191

Grid integration of wind energy: A case study on a typical sub-transmission network in Namibia  

Microsoft Academic Search

This paper presents a case study on the transient performance of a typical sub-transmission network in Namibia in relation to grid integration of wind energy. The authors focus on the relative impact of two wind generator technologies, viz. direct-driven synchronous generator (DDSG) and doubly-fed induction generator (DFIG). Important aspects investigated are the impacts of penetration levels (generation capacity) of the

A. I. Elombo; S. P. Chowdhury; H. J. Vermeulen

2010-01-01

192

Relative importance of parameters affecting wind speed prediction using artificial neural networks  

NASA Astrophysics Data System (ADS)

In traditional artificial neural networks (ANN) models, the relative importance of the individual meteorological input variables is often overlooked. A case study is presented in this paper to model monthly wind speed values using meteorological data (air pressure, air temperature, relative humidity, and precipitation), where the study also includes an estimate of the relative importance of these variables. Recorded monthly mean data are available at a gauging site in Tabriz, Azerbaijan, Iran, for the period from 2000 to 2005, gauged in the city at the outskirt of alluvial funneling mountains with an established microclimatic conditions and a diurnal wind regime. This provides a sufficiently severe test for the ANN model with a good predictive capability of 1 year of lead time but without any direct approach to refer the predicted results to local microclimatic conditions. A method is used in this paper to calculate the relative importance of each meteorological input parameters affecting wind speed, showing that air pressure and precipitation are the most and least influential parameters with approximate values of 40 and 10 %, respectively. This gained knowledge corresponds to the local knowledge of the microclimatic and geomorphologic conditions surrounding Tabriz.

Ghorbani, M. A.; Khatibi, R.; Hosseini, B.; Bilgili, M.

2013-10-01

193

Relative importance of parameters affecting wind speed prediction using artificial neural networks  

NASA Astrophysics Data System (ADS)

In traditional artificial neural networks (ANN) models, the relative importance of the individual meteorological input variables is often overlooked. A case study is presented in this paper to model monthly wind speed values using meteorological data (air pressure, air temperature, relative humidity, and precipitation), where the study also includes an estimate of the relative importance of these variables. Recorded monthly mean data are available at a gauging site in Tabriz, Azerbaijan, Iran, for the period from 2000 to 2005, gauged in the city at the outskirt of alluvial funneling mountains with an established microclimatic conditions and a diurnal wind regime. This provides a sufficiently severe test for the ANN model with a good predictive capability of 1 year of lead time but without any direct approach to refer the predicted results to local microclimatic conditions. A method is used in this paper to calculate the relative importance of each meteorological input parameters affecting wind speed, showing that air pressure and precipitation are the most and least influential parameters with approximate values of 40 and 10 %, respectively. This gained knowledge corresponds to the local knowledge of the microclimatic and geomorphologic conditions surrounding Tabriz.

Ghorbani, M. A.; Khatibi, R.; Hosseini, B.; Bilgili, M.

2013-01-01

194

Wind Generation on Winnebago Tribal Lands  

Microsoft Academic Search

The Winnebago Wind Energy Study evaluated facility-scale, community-scale and commercial-scale wind development on Winnebago Tribal lands in northeastern Nebraska. The Winnebago Tribe of Nebraska has been pursuing wind development in various forms for nearly ten years. Wind monitoring utilizing loaned met towers from NREL took place during two different periods. From April 2001 to April 2002, a 20-meter met tower

2009-01-01

195

LWST Phase I Project Conceptual Design Study: Evaluation of Design and Construction Approaches for Economical Hybird Steel/Concrete Wind Turbine Towers. (Report for June 28, 2002-July 31, 2004).  

National Technical Information Service (NTIS)

The United States Department of Energy (DOE) Wind Energy Research Program has begun a new effort to partner with U.S. industry to develop wind technology that will allow wind systems to compete in regions of low wind speed. The Class 4 and 5 sites targete...

M. W. LaNier

2005-01-01

196

Thermal Characteristics of Heating Towers  

NASA Astrophysics Data System (ADS)

Field tests and numerical calculations are described on the thermal characteristics of the cross flow heating towers using ethylene glycol solutions. continued from Part I for counterflow towers. First, a simple correlation factor method of crossflow calculation is proposed. Next, the data on the overall enthalpy-transfer coefficient. Ka. in a crossflow heating tower are presented and compared with those in a cooling tower of the same type. From the numerical calculations and discussions. diagrams and a simple relation are obtained useful for the design and performance tests of heating towers. The diagrams are expressed in terms of the number of transfer unit. flow ratio. AL. And AG as dimensionless parameters. The variation of thermal performace of heating towers may be expressed by the relation that AL= const.

Fujita, Toshihiko; Kawahara, Koshichi

197

The Physics of Shot Towers  

NASA Astrophysics Data System (ADS)

In the late 18th and throughout the 19th century, lead shot for muskets was prepared by use of a shot tower. Molten lead was poured from the top of a tower and, during its fall, the drops became spherical under the action of surface tension. In this article, we ask and answer the question: How does the size of the lead shot depend on the height of the tower? In the process, we explain the basic technology underlying an important historical invention (the shot tower) and use simple physics (Newtonian mechanics and the thermodynamic laws of cooling) to model its operation.

Lipscombe, Trevor C.; Mungan, Carl E.

2012-04-01

198

Influence of Wind Turbulence on Yaw-control Gears in Wind Turbine  

Microsoft Academic Search

This paper describes an influence of wind turbulence on yaw-control gears of nacelle in a wind power station. This site is located in Tappi cape of Aomori prefecture where is characterized by a big wind turbulence due to the western strong wind and a steep slope of the cape. In this paper two adjacent wind towers are dealt with among

Kazuo Suzuki; Naoki Hoshino; Noboru Inomata; Hiroshi Kimura; Tamiya Fujiwara

2009-01-01

199

Observational constraints on U.S. emissions of climate-active and ozone-depleting trace gases from a tall-tower and aircraft sampling network  

NASA Astrophysics Data System (ADS)

Air samples have been regularly collected at a number of tall tower sites and from aircraft profiling locations across the U.S. and Canada during the past 4 to 5 years. Measurements of approximately 50 trace gases in these samples provide a rich dataset of chemical markers related to urban, industrial, oceanic, biomass burning, fossil-fuel burning, atmospheric mixing, photosynthesis, and soil influences. Anthropogenic emission signals are readily apparent in the halocarbon and hydrocarbon data, upon which this talk will focus. Measured correlations between different halocarbons (especially hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs)) show variations as a function of season that are qualitatively consistent with the expected regional and seasonal patterns of use and emission of these industrially-produced chemicals. In some instances, annual mean correlation slopes between different trace gases are well described by the U.S. EPA Greenhouse Gas Emission Inventories, but for others, large differences are observed. Furthermore, interannual changes in correlation slopes are expected for gases that are being phased out (i.e., HCFCs) compared to those for which emissions may be increasing (i.e., HFCs) in the US. This presentation will focus on the regional, seasonal, and interannual variations in trace gas emissions implied from a straightforward analysis of this extensive measurement record.

Montzka, S. A.; Miller, B. R.; Siso, C.; Sweeney, C.; Andrews, A. E.; Karion, A.; Neff, D.; Fischer, M. L.; Higgs, J.

2010-12-01

200

Comparative analysis of neural network and regression based condition monitoring approaches for wind turbine fault detection  

NASA Astrophysics Data System (ADS)

This paper presents the research results of a comparison of three different model based approaches for wind turbine fault detection in online SCADA data, by applying developed models to five real measured faults and anomalies. The regression based model as the simplest approach to build a normal behavior model is compared to two artificial neural network based approaches, which are a full signal reconstruction and an autoregressive normal behavior model. Based on a real time series containing two generator bearing damages the capabilities of identifying the incipient fault prior to the actual failure are investigated. The period after the first bearing damage is used to develop the three normal behavior models. The developed or trained models are used to investigate how the second damage manifests in the prediction error. Furthermore the full signal reconstruction and the autoregressive approach are applied to further real time series containing gearbox bearing damages and stator temperature anomalies.The comparison revealed all three models being capable of detecting incipient faults. However, they differ in the effort required for model development and the remaining operational time after first indication of damage. The general nonlinear neural network approaches outperform the regression model. The remaining seasonality in the regression model prediction error makes it difficult to detect abnormality and leads to increased alarm levels and thus a shorter remaining operational period. For the bearing damages and the stator anomalies under investigation the full signal reconstruction neural network gave the best fault visibility and thus led to the highest confidence level.

Schlechtingen, Meik; Ferreira Santos, Ilmar

2011-07-01

201

2. Southern Light Tower and Northern Light Tower, view north, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. Southern Light Tower and Northern Light Tower, view north, south sides - Kennebec River Light Station, South side of Doubling Point Road, off State Highway 127, 1.8 miles south of U.S. Route 1, Arrowsic, Sagadahoc County, ME

202

1. Cape Elizabeth Tower with former light tower on right, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. Cape Elizabeth Tower with former light tower on right, in foreground, view northeast, northwest and southwest sides - Cape Elizabeth Light Station, Near Two Lights State Park at end of Two Lights Road, off State Highway 77, Cape Elizabeth, Cumberland County, ME

203

Numerical study of the performance of tornado-type wind energy systems  

Microsoft Academic Search

The results of an analytical investigation of the effects of changing the parameters and operating conditions of a tornado-type wind energy system are presented. The tornado tower system comprises a tower over the turbine exhaust. A vortex is formed within the tower, and contains a low pressure area at core, which enhances the wind flow velocity through the turbine. Various

S. S. Ayad

1983-01-01

204

FLORIDA TOWER FOOTPRINT EXPERIMENTS  

SciTech Connect

The Florida Footprint experiments were a series of field programs in which perfluorocarbon tracers were released in different configurations centered on a flux tower to generate a data set that can be used to test transport and dispersion models. These models are used to determine the sources of the CO{sub 2} that cause the fluxes measured at eddy covariance towers. Experiments were conducted in a managed slash pine forest, 10 km northeast of Gainesville, Florida, in 2002, 2004, and 2006 and in atmospheric conditions that ranged from well mixed, to very stable, including the transition period between convective conditions at midday to stable conditions after sun set. There were a total of 15 experiments. The characteristics of the PFTs, details of sampling and analysis methods, quality control measures, and analytical statistics including confidence limits are presented. Details of the field programs including tracer release rates, tracer source configurations, and configuration of the samplers are discussed. The result of this experiment is a high quality, well documented tracer and meteorological data set that can be used to improve and validate canopy dispersion models.

WATSON,T.B.; DIETZ, R.N.; WILKE, R.; HENDREY, G.; LEWIN, K.; NAGY, J.; LECLERC, M.

2007-01-01

205

Long-term observations of meteor winds by the SuperDARN HF radar network  

NASA Astrophysics Data System (ADS)

The HF Super Dual Auroral Radar Network (SuperDARN) radars detect a category of backscatter that is due to meteor trails in the mesosphere. The motion of the neutral atmosphere can be inferred and applied to the study of atmospheric tides and planetary waves. The current configurations of longitudinal radar chains in the northern and southern hemispheres have accumulated mesospheric wind measurements continuously since the last solar cycle maximum while the archives of some of the radars span more than a solar cycle. We have analyzed the occurrence of mesospheric tides, planetary wave, and gravity wave activity in the meteor wind data over long periods at several radar stations in both hemispheres. Understanding the behavior of planetary waves and tides is not only crucial to characterizing mesopause variability but also transport in the mesosphere and lower thermosphere. in the mesosphere and lower thermosphere. We examine the seasonal and inter-annual variations of the diurnal, semidiurnal and terdiurnal tides, and planetary waves. We find connections to the quasi-biennial oscillation and to sudden stratospheric warming (SSW) events. We present examples of intensified planetary wave activity that occurred during SSWs. Additionally, we examine the variability in tidal and planetary wave activity over the past solar cycle and correlations with lower atmospheric phenomena and other datasets.

Talaat, Elsayed; Ruohoniemi, J. Michael; McCubbin, Elizabeth; Azeem, S. M. Irfan; Greenwald, Raymond

2012-07-01

206

Failure analysis of transmission towers  

Microsoft Academic Search

This paper advocates the use of nonlinear methodology for structural failure analysis. This approach is used for structural failure prediction rather than forensic analysis. Failure prediction has been confirmed by the expensive full-scale testing of a new transmission tower design that collapsed during the test. Using this approach, tower designs can be easily modified and upgraded, which results in substantial

F. Albermani; S. Kitipornchai; R. W. K. Chan

2009-01-01

207

Advanced dry cooling tower concept  

Microsoft Academic Search

The purpose of this year's work has been to develop a new dry cooling tower surface. The new surface utilizes a modification of film type packing in wet cooling towers. It is a concept which may eliminate excessive water loss. Cost of fabrication, and effectiveness of heat transfer surface were among the major design considerations. Based on preliminary water wetting

J. Curcio; M. Giebler; L. R Glicksman; W. M. Rohsenow

1975-01-01

208

RBF neural network based PI pitch controller for a class of 5-MW wind turbines using particle swarm optimization algorithm.  

PubMed

In order to control the pitch angle of blades in wind turbines, commonly the proportional and integral (PI) controller due to its simplicity and industrial usability is employed. The neural networks and evolutionary algorithms are tools that provide a suitable ground to determine the optimal PI gains. In this paper, a radial basis function (RBF) neural network based PI controller is proposed for collective pitch control (CPC) of a 5-MW wind turbine. In order to provide an optimal dataset to train the RBF neural network, particle swarm optimization (PSO) evolutionary algorithm is used. The proposed method does not need the complexities, nonlinearities and uncertainties of the system under control. The simulation results show that the proposed controller has satisfactory performance. PMID:22738782

Poultangari, Iman; Shahnazi, Reza; Sheikhan, Mansour

2012-06-25

209

A case study on a hybrid wind speed forecasting method using BP neural network  

Microsoft Academic Search

Wind energy, which is intermittent by nature, can have a significant impact on power grid security, power system operation, and market economics, especially in areas with a high level of wind power penetration. Wind speed forecasting has been a vital part of wind farm planning and the operational planning of power grids with the aim of reducing greenhouse gas emissions.

Zhen-hai Guo; Jie Wu; Hai-yan Lu; Jian-zhou Wang

2011-01-01

210

Assessing eddy-covariance flux tower location bias across the Fluxnet-Canada Research Network based on remote sensing and footprint modelling  

Microsoft Academic Search

We describe an approach for evaluating the representativeness of eddy covariance flux measurements and assessing sensor location bias (SLB) based on footprint modelling and remote sensing. This approach was applied to the 12 main sites of the Fluxnet-Canada Research Network (FCRN)\\/Canadian Carbon Program (CCP) located along an east-west continental-scale transect, covering grassland, forest, and wetland biomes. For each site, monthly

Baozhang Chen; Nicholas C. Coops; Dongjie Fu; Hank A. Margolis; Brian D. Amiro; Alan G. Barr; T. Andrew Black; M. Altaf Arain; Charles P.-A. Bourque; Lawrence B. Flanagan; Peter M. Lafleur; J. Harry McCaughey; Steven C. Wofsy

2011-01-01

211

A New Tall-Tower Meteorological Monitoring System  

SciTech Connect

The Atmospheric Technologies Group of the Savannah River Technology Center operates an extensive meteorological monitoring network of 13 tower in and near the Savannah River Site near Aiken, South Carolina. The data from this system are available in ''real-time'' for emergency response atmospheric release modeling and operational weather forecasting.

Parker, M.J.

2003-01-14

212

A New Tall-Tower Meteorological Monitoring System  

Microsoft Academic Search

The Atmospheric Technologies Group of the Savannah River Technology Center operates an extensive meteorological monitoring network of 13 tower in and near the Savannah River Site near Aiken, South Carolina. The data from this system are available in ''real-time'' for emergency response atmospheric release modeling and operational weather forecasting.

Matthew J. Parker

2003-01-01

213

PBF Cooling Tower. Hot deck of Cooling Tower with fan ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

PBF Cooling Tower. Hot deck of Cooling Tower with fan motors in place. Fan's propeller blades (not in view) rotate within lower portion of vents. Inlet pipe is a left of view. Contractor's construction buildings in view to right. Photographer: Larry Page. Date: June 30, 1969. INEEL negative no. 69-3781 - Idaho National Engineering Laboratory, SPERT-I & Power Burst Facility Area, Scoville, Butte County, ID

214

Advanced ground surveillance for remote tower  

Microsoft Academic Search

Small and medium sized airports are normally occupied only a short time a day typically handling less than 10 flights per day. Remote tower allows to save costs by using air traffic controllers from a bigger airport tower or to have one remote tower for a couple of small and medium sized airports. Moving the tower operation of course means

Dieter Eier; Hartmut Huber

2008-01-01

215

WindFloat: A floating foundation for offshore wind turbines  

Microsoft Academic Search

This manuscript summarizes the feasibility study conducted for the WindFloat technology. The WindFloat is a three-legged floating foundation for multimegawatt offshore wind turbines. It is designed to accommodate a wind turbine, 5 MW or larger, on one of the columns of the hull with minimal modifications to the nacelle and rotor. Potential redesign of the tower and of the turbine

Dominique Roddier; Christian Cermelli; Alexia Aubault; Alla Weinstein

2010-01-01

216

World Federation of Great Towers  

NSDL National Science Digital Library

The World Federation of Great Towers (WFGT) "is an association of international monuments which join together to foster global awareness and develop international opportunities for promotion." The organization provides this eye-catching site that contains detailed information and pictures of over twenty towers from around the world. After giving a brief background summary of each tower's location and notable characteristics, specifications and technical data are provided to give an impression of the scale of the structures and the engineering skill that was needed in their construction. Although only the buildings that are members of the WFGT are featured online, the collection does a good job of capturing some of the most impressive towers in existence.

217

Tall-tower observations of pollution from near-field sources in central Texas during the Texas Air Quality Study 2006  

NASA Astrophysics Data System (ADS)

The NOAA Earth System Research Laboratory has been measuring CO2, CO and basic meteorology from a television transmitter tower outside of Waco, TX since 2001. Sample intakes are located at 30, 122 and 457 meters above ground level. From July through November 2006, O3 measurements were added at 9 and 457 magl to support the Texas Air Quality Study (TexAQS 2006). There are several large point sources and metropolitan areas in the vicinity of the tower with distinct chemical signatures. Here, we evaluate the extent to which the Stochastic Time Inverted Lagrangian Transport (STILT) model reproduces pollution events that were observed at the tower during summer and fall 2006. For this study, STILT is driven by customized output from the WRF model v2.2, which was run with a 2km nested grid surrounding the tower embedded in a 10km nest that covers most of the southern and eastern US and a 40km nest that includes all of North America. Inaccurate representation of atmospheric transport is a major source of error in inverse estimates of fluxes of CO2 and other gases, and we selected this period for in depth analysis in part because a dense network of radar profilers was deployed for TexAQS 2006. The radar profilers report wind and boundary layer height, which can be used to evaluate the fidelity of the simulated transport. STILT is a particle dispersion model that can be run either forward or backward in time, which allows us to compare the agreement between forward runs from individual pollution sources and backward runs from the tower. We will also quantitatively compare the STILT-WRF results with similar output from the FLEXPART particle dispersion model driven by high-resolution ECMWF meteorological fields. We will use several different emissions inventories to evaluate model-to-model differences and differences between modeled and observed pollution influences.

Andrews, A. E.; Kort, E.; Hirsch, A.; Eluszkiewicz, J.; Nehrkorn, T.; Michalak, A. M.; Petron, G.; Frost, G. J.; Gurney, K. R.; Stohl, A.; Wofsy, S. C.; Angevine, W. M.; White, A. B.; Oltmans, S. J.; Montzka, S. A.; Tans, P. P.

2008-12-01

218

How new technology developments will lower wind energy costs  

Microsoft Academic Search

Wind Power is a clean and renewable energy technology that is generated, most commonly through the use of a three-bladed wind turbine mounted on a tall tower (80 m - 100 m). Although wind power is most commonly generated by larger, utility scale wind turbines (1.5 MW - 3 MW in size), smaller capacity (< 500 kW) wind turbines have

D. L. Hoffman; T. S. Molinski

2009-01-01

219

Comparison of Wind Monitoring Systems. Part 2. Doppler Sodars.  

National Technical Information Service (NTIS)

Measurements of wind speed, wind direction, and the vertical component of turbulence, from four different commercially available Doppler sodars, are compared with similar measurements from in situ sensors on a 300-m instrumented tower. Results indicate th...

P. L. Finkelstein J. C. Kaimal J. E. Gaynor M. E. Graves T. J. Lockhart

1986-01-01

220

The Physics of Shot Towers  

ERIC Educational Resources Information Center

|In the late 18th and throughout the 19th century, lead shot for muskets was prepared by use of a shot tower. Molten lead was poured from the top of a tower and, during its fall, the drops became spherical under the action of surface tension. In this article, we ask and answer the question: "How does the size of the lead shot depend on the height…

Lipscombe, Trevor C.; Mungan, Carl E.

2012-01-01

221

Tower Temperature and Humidity Sensors (TWR) Handbook  

SciTech Connect

Three tall towers are installed at the Atmospheric Radiation Measurement (ARM) Climate Research Facility: a 60-meter triangular tower at the Southern Great Plains (SGP) Central Facility (CF), a 21-meter walkup scaffolding tower at the SGP Okmulgee forest site (E21), and a 40-meter triangular tower at the North Slope of Alaska (NSA) Barrow site. The towers are used for meteorological, radiological, and other measurements.

Cook, DR

2010-02-01

222

A fiber optic wind vane: A conceptual view  

SciTech Connect

The use of tall towers for the normal operation of meteorological instrumentation is ideal for ensuring that representative measurements are obtained relative to the nearby terrain. Tall towers also expose instrumentation to unwanted environmental side-effects such as lightning surges. The proximity of many industrial observation sites for meteorological towers also introduces unwanted problems including radio frequency interference (RFI) from radio, television, or microwave transmitters, explosive environments, and electrical power cabling. Typical meteorological instrumentation systems incorporate protective mechanisms such as grounding networks, surge protectors and electrical shielding to combat electrical problems. Still, even with elaborate protective systems, damages to instrumentation and a loss of valid data can occur which often results in extended outages. The use of fiber optic technology in meteorological instrumentation holds great promise to eliminate many of the problems associated with monitoring on tall towers. A fiber optic sensor would be impervious to lightning surges and all forms of RFI. The sensor would provide a high signal to noise ratio output since little or no electrical interference would be involved in data transmission. A longer field life for mechanical devices such as a wind vane would be realized since all physical contact points, such as those found in a potentiometer, would be eliminated. Therefore, the precision, resolution, linearity, starting threshold and accuracy could be dramatically improved without the hindrance of moving parts.

Parker, M.J. [Westinghouse Savannah River Co., Aiken, SC (United States); Heaverly, M. [Met One Instruments, Inc., Grants Pass, OR (United States)

1996-07-01

223

Cooling tower drift deposition measurement at the ORGDP  

SciTech Connect

In a continuing effort to investigate cooling tower drift, droplet and mineral deposition fluxes were measured near the cooling towers at the Oak Ridge Gaseous Diffusion Plant (ORGDP) from 1979 to 1982. These measurements were conducted at various times of the year to determine any seasonally induced variation in the deposition pattern. The parameters which affected the deposition flux to the greatest degree were the wind speed and the relative humidity of the ambient air. The chromium deposition flux, as measured by collection in Petrie dishes around the cooling tower, displays two distinctly different regimes for the rate of change of flux with distance. In the near field, up to 600 meters, the approximate rate of decrease of the deposition flux is an order of magnitude per 100 meters; beyond this region, the rate is drastically lower. This chromium deposition rate in the near field agrees with the values obtained by the sensitive paper method, in which the mineral flux is determined from the droplet imprints and a known mineral concentration in the drift. Hence, it is hypothesized that the chromium deposition in the near field results from drift droplets whose trajectories are influenced by the gravity force as well as wind speed; whereas, the chromium deposition pattern beyond the near field is formed from particles whose trajectories depend greatly on the wind speed.

Park, S.H.

1983-01-01

224

Voltage stability of transmission network with different penetration levels of wind generation  

Microsoft Academic Search

Voltage stability problem is an emerging phenomenon in planning and operation of modern power systems with high penetration levels of wind generation. The level of voltage stability\\/instability depends, amongst other factors, on the degree of penetration of wind generations and on their connected locations. The objective of this paper is to investigate the impact of wind generation on voltage stability

I. S. Naser; A. Garba; O. Anaya-Lara; K. L. Lo

2010-01-01

225

Long-term wind speed and power forecasting using local recurrent neural network models  

Microsoft Academic Search

This paper deals with the problem of long-term wind speed and power forecasting based on meteorological information. Hourly forecasts up to 72-h ahead are produced for a wind park on the Greek island of Crete. As inputs our models use the numerical forecasts of wind speed and direction provided by atmospheric modeling system SKIRON for four nearby positions up to

Thanasis G. Barbounis; John B. Theocharis; Minas C. Alexiadis; Petros S. Dokopoulos

2006-01-01

226

Towards a Wind Energy Climatology at Advanced Turbine Hub-Heights: Preprint  

SciTech Connect

Measurements of wind characteristics over a wide range of heights up to and above 100 m are useful to: (1) characterize the local and regional wind climate; (2) validate wind resource estimates derived from numerical models; and (3) evaluate changes in wind characteristics and wind shear over the area swept by the blades. Developing wind climatology at advanced turbine hub heights for the United States benefits wind energy development. Tall tower data from Kansas, Indiana, and Minnesota (which have the greatest number of tall towers with measurement data) will be the focus of this paper. Analyses of data from the tall towers will start the process of developing a comprehensive climatology.

Schwartz, M.; Elliott, D.

2005-05-01

227

Wind Monitoring Report for Fort Wainwright's Donnelly Training Area  

Microsoft Academic Search

Using the wind data collected at a location in Fort Wainwrights Donnelly Training Area (DTA) near the Cold Regions Test Center (CRTC) test track, Pacific Northwest National Laboratory (PNNL) estimated the gross and net energy productions that proposed turbine models would have produced exposed to the wind resource measured at the meteorological tower (met tower) location during the year of

Alice C. Orrell; Douglas R. Dixon

2011-01-01

228

Wind Variations in a 120 Meter Layer at Tarapur.  

National Technical Information Service (NTIS)

The empirical power law approach has been used in the study of wind data collected on a 120 meter high meteorological tower located near the sea coast at Tarapur. The wind instruments are installed at five different heights on this tower. Simultaneously, ...

B. B. Adiga P. R. Patel R. K. Kapoor

1980-01-01

229

Development of solar tower observatories  

NASA Astrophysics Data System (ADS)

Because the horizontal solar telescope, the Snow Telescope in Yerkes Observatory, was affected by air-currents from the warmed-up soil, George Ellery Hale had the idea of a tower telescope. In 1904, the 60-foot tower in Mt. Wilson was ready, in 1908 the 150-foot tower was built with the help of the Carnegie foundation. After World War I, Germany made heavy efforts to regain its former strong position in the field of science. Already in December 1919 - after the spectacular result of the English eclipse expedition in October 1919 - Erwin Finlay-Freundlich started a successful fund raising (“Einstein-Stiftungrdquo;) among German industrialists. The company Zeiss in Jena was responsible for the instrumentation of the 20-m solar tower, built in 1920-22. The optical design of the Einstein Tower in respect to light intensity surpassed even the Mt. Wilson solar observatory. Also abroad solar tower observatories were built in the 1920s: Utrecht,The Netherlands (1922), Canberra, Australia (1924), Arcetri, Italy (1926), Pasadena, California (1926) and Tokyo, Japan (1928). In the thirties, solar physics became important because of the solar maximum in 1938 and the new observational possibilities created by Bernard Lyot. At the end of the 1930s, Karl-Otto Kiepenheuer proposed to establish a solar tower observatory on Wendelstein in order to improve the predictions of radio interference by observing sunspots. By stressing the importance of the solar research for war efforts, Otto Heckmann of Göttingen observatory finally succeeded in winning the “Reichsluftfahrtministerium” to finance several solar observatories, like Wendelstein, Hainberg/Göttingen, Kanzelhöhe/Villach, and Schauinsland/Freiburg. Solar astronomy profited by the foundation of the new observatories - four of them existed still after the war. Abroad only the solar observatories of Oxford (1935) and the 50 foot tower of the McMath-Hulbert Observatory, University of Michigan (1936) should be mentioned. Only a short outlook will be given to the modern solar tower telescopes like the McMath-Pierce Telescope (1960) and vacuum telescope (1973) at Kitt Peak, Arizona, the Richard B. Dunn Solar Telescope (1969), Sacramento Peak, New Mexico, and the Vacuum Tower Telescope of the “Observatorio del Teide”, Izaña, Teneriffa (1987).

Wolfschmidt, Gudrun

230

The use of real-time off-site observations as a methodology for increasing forecast skill in prediction of large wind power ramps one or more hours ahead of their impact on a wind plant.  

SciTech Connect

ABSTRACT Application of Real-Time Offsite Measurements in Improved Short-Term Wind Ramp Prediction Skill Improved forecasting performance immediately preceding wind ramp events is of preeminent concern to most wind energy companies, system operators, and balancing authorities. The value of near real-time hub height-level wind data and more general meteorological measurements to short-term wind power forecasting is well understood. For some sites, access to onsite measured wind data - even historical - can reduce forecast error in the short-range to medium-range horizons by as much as 50%. Unfortunately, valuable free-stream wind measurements at tall tower are not typically available at most wind plants, thereby forcing wind forecasters to rely upon wind measurements below hub height and/or turbine nacelle anemometry. Free-stream measurements can be appropriately scaled to hub-height levels, using existing empirically-derived relationships that account for surface roughness and turbulence. But there is large uncertainty in these relationships for a given time of day and state of the boundary layer. Alternatively, forecasts can rely entirely on turbine anemometry measurements, though such measurements are themselves subject to wake effects that are not stationary. The void in free-stream hub-height level measurements of wind can be filled by remote sensing (e.g., sodar, lidar, and radar). However, the expense of such equipment may not be sustainable. There is a growing market for traditional anemometry on tall tower networks, maintained by third parties to the forecasting process (i.e., independent of forecasters and the forecast users). This study examines the value of offsite tall-tower data from the WINDataNOW Technology network for short-horizon wind power predictions at a wind farm in northern Montana. The presentation shall describe successful physical and statistical techniques for its application and the practicality of its application in an operational setting. It shall be demonstrated that when used properly, the real-time offsite measurements materially improve wind ramp capture and prediction statistics, when compared to traditional wind forecasting techniques and to a simple persistence model.

Martin Wilde, Principal Investigator

2012-12-31

231

SMUD Kokhala Power Tower Study  

SciTech Connect

Kokhala is the name of a new hybridized power tower design which integrates a nitrate-salt solar power tower with a gas turbine combined-cycle power plant. This integration achieves high value energy, low costs, and lower investor risk than a conventional solar only power tower plant. One of the primary advantages of this system is that it makes small power tower plants much more economically competitive with conventional power generation technologies. This paper is an overview of a study that performed a conceptual evaluation of a small (30 MWe) commercial plant suitable for the Sacramento Municipal Utility District`s (SMUD) Rancho Seco power plant site near Sacramento, California. This paper discusses the motivation for using a small hybrid solar plant and provides an overview of the analysis methodology used in the study. The results indicate that a power tower integrated with an advanced gas turbine, combined with Sacramento`s summer solar resource, could produce a low- risk, economically viable power generation project in the near future.

Price, Henry W. [National Renewable Energy Laboratory, Golden, CO (United States); Whitney, Daniel D.; Beebe, H.I. [Sacramento Municipal Utility District, CA (United States)

1997-06-01

232

Ride-Through Capability Predictions for Wind Power Plants in the ERCOT Network: Preprint  

SciTech Connect

Utility system operators and engineers now want a better understanding of the impacts of large wind farms on grid stability before the farms are interconnected to the grid. Utilities need wind farm electrical models and methods of analysis that will help them analyze potential problems of grid stability. Without the necessary tools and knowledge of the behavior of large wind power plants, utilities are reluctant to integrate more wind power into the grid. The dynamic models used in this paper were developed by Power Technologies Inc. (PTI), under subcontract from ERCOT. A three-phase fault on important buses will be tested, and the potential impact on wind farms will be investigated. Two methods, dynamic analysis and steady state analysis (Zbus prediction), will be used to predict the low voltage ride through capability of the wind farms. Comparison between the two methods will be presented.

Muljadi, E.; Butterfield, C. P.; Conto, J.; Donohoo, K.

2005-01-01

233

Observation and Simulation of Wind Energy Resource in Jiangsu Coastal Area  

Microsoft Academic Search

In order to assess the potential of wind energy resource in Jiangsu coastal area, observation and simulation method are used to study the evolution and distribution of wind speed and wind energy of surface layer in this region. The wind speed data in 2005 of Dongling wind tower of Rudong showed that the wind speed increased in accordance with the

Xu Xiazhen; Chen Yan; Zheng Youfei; Bai Xue; Wei Ming; Liu Yan-an

2010-01-01

234

Some observations on modelling the mechanical-draft cooling tower plume at plant Gaston  

NASA Astrophysics Data System (ADS)

Observations on the far-field time mean condensed plumes from the twin mechanical-draft cooling towers at the Gaston Steam Plant, Willsonville, Alabama taken during February 1975 and January-February 1976 are compared with a one-dimensional integral model for moist plume behaviour. Empirical modifications are required to account for the near-field effects of downwash, source geometry, wind direction relative to tower alignment and the far-field effects of vertical and wind direction shear on plume behaviour. Details on source and ambient parameters are given.

Slawson, P. R.

235

Self-assembled granular towers  

NASA Astrophysics Data System (ADS)

When some water is added to sand, cohesion among the grains is induced. In fact, only 1% of liquid volume respect to the total pore space of the sand is necessary to built impressive sandcastles. Inspired on this experience, the mechanical properties of wet piles and sand columns have been widely studied during the last years. However, most of these studies only consider wet materials with less than 35% of liquid volume. Here we report the spontaneous formation of granular towers produced when dry sand is poured on a highly wet sand bed: The impacting grains stick on the wet grains due to instantaneous liquid bridges created during the impact. The grains become wet by the capillary ascension of water and the process continues, giving rise to stable narrow sand towers. Actually, the towers can reach the maximum theoretical limit of stability predicted by previous models, only expected for low liquid volumes.

Pacheco-Vazquez, Felipe; Moreau, Florian; Vandewalle, Nicolas; Dorbolo, Stephan

2013-03-01

236

Twin tower gas fractionation apparatus  

SciTech Connect

An apparatus for adsorptive fractionation of a gaseous mixture. The apparatus is a twin tower fractionator or dryer including a pair of sorbent beds. A filter and valve assembly directs a flow of the gaseous mixture from a source thereof to one of the beds for removing a gaseous component of said mixture while simultaneously directing a flow of purge gas through the outer of said beds for stripping the adsorbed gas component therefrom and regenerating the bed. Microprocessor controlled valves control the flow of gases to and from said beds. The towers and associated manifolds are twin bore extrusion prism shaped of heat conductive material. The parallel bores extend axially longitudinally through the tower extrusion with each bore adapted to contain a sorbent bed or bed cartridge. conductivity probes are used to sense the moisture or adsorbed component front in the sorbent bed.

Null, R. A.; laughlin, L. C.; Goldberg, M. L.

1985-12-17

237

Verification of BModes: Rotary Beam and Tower Modal Analysis Code; Preprint  

SciTech Connect

This paper describes verification of BModes, a finite-element code developed to provide coupled modes for the blades and tower of a wind turbine. The blades, which may be rotating or non-rotating, and the towers, whether onshore or offshore, are modeled using specialized 15-dof beam finite elements. Both blade and tower models allow a tip attachment, which is assumed to be rigid body with six moments of inertia, and a mass centroid that may be offset from the blade or tower axis. Examples of tip attachments are aerodynamic brakes for blades and nacelle-rotor subassembly for towers. BModes modeling allows for tower supports including tension wires, floating platforms, and monopiles on elastic foundations. Coupled modes (implying coupling of flap, lag, axial, and torsional motions) are required for modeling major flexible components in a modal-based, aeroelastic code such as FAST1. These are also required for validation of turbine models using experimental data, modal-based fatigue analysis, controls design, and understanding aeroelastic-stability behavior of turbines. Verification studies began with uniform tower models, with and without tip inertia, and progressed to realistic towers. For the floating turbine, we accounted for the effects of hydrodynamic inertia, hydrostatic restoring, and mooring lines stiffness. For the monopole-supported tower, we accounted for distributed hydrodynamic mass on the submerged part of the tower and for distributed foundation stiffness. Finally, we verified a model of a blade carrying tip mass and rotating at different speeds (verifications of other blade models, rotating or non-rotating, have been reported in another paper.) Verifications were performed by comparing BModes-generated modes with analytical results, if available, or with MSC.ADAMS results. All results in general show excellent agreement.

Bir, G.

2010-04-01

238

Direct Drive Wind Turbine.  

National Technical Information Service (NTIS)

A wind turbine is provided that minimizes the size of the drive train and nacelle while maintaining the power electronics and transformer at the top of the tower. The turbine includes a direct drive generator having an integrated disk brake positioned rad...

C. Bevington D. Costin G. Bywaters J. Stowell W. Banforth

2004-01-01

239

Application of NARX neural network in storm-time SYM-H index prediction from IMF and solar wind data  

NASA Astrophysics Data System (ADS)

In this study the NARX neural network has been used for the first time to predict high-resolution magnetic storm index of SYM-H from solar wind (SW) and IMF parameters. In total 73 great storm events with IMF/SW data available from ACE satellite during 1998 to 2006 are used to establish the ANN model. Out of them, 67 are used to train the network and the other 6 samples for test. Additionally, the NARX prediction model is also validated using IMF/SW data from WIND satellite for 7 great storms during 1995-1997 and 2005, as well as for the July 2000 Bastille day storm and November 2001 superstorm using Geotail and OMNI data at 1AU. Five interplanetary parameters of IMF Bz, By and total B components along with proton density and velocity of solar wind are used as the original external inputs of the neural network to predict the SYM-H index about one hour or an even longer time ahead. For the 6 test storms registered by ACE including two super-storms with minimum SYM-H less than -200 nT, the correlation coefficient between observed and NARX network predicted SYM-H is 0.95 as a whole, even as high as 0.95 and 0.98 with average relative variance of 13.2 percent and 7.4 percent for the two super-storms, respectively. The prediction for the 7 storms with WIND data is also satisfactory, showing averaged correlation coefficient about 0.91 and RMSE of 14.2 nT. The newly developed NARX model shows much better capability than Elman network for SYM-H prediction, which can partly be attributed to a key feedback to the input layer from the output neuron with a suitable length (about 120 min). This feedback means that nearly real information of the ring current status is effectively brought to taking part in the prediction of SYM-H index by ANN. The proper history length of the output-feedback may mainly reflect on average the characteristic time of ring current decay which involves various decay mechanisms with ion lifetimes from tens of minutes to tens of hours. Besides, it is verified that this kind of model is also capable of providing satisfactory predictions of the SYM-H index 3 hours ahead from IMF/SW data with less physical parameters observed at L1 position, enhancing significantly the practicality of the model in space weather forecasting.

Cai, Lei; Ma, S. Y.; Zhou, Yunliang; Cai, Hongtao

240

Sustainable Energy Solutions Task 1.0: Networked Monitoring and Control of Small Interconnected Wind Energy Systems  

SciTech Connect

EXECUTIVE SUMARRY This report presents accomplishments, results, and future work for one task of five in the Wichita State University Sustainable Energy Solutions Project: To develop a scale model laboratory distribution system for research into questions that arise from networked control and monitoring of low-wind energy systems connected to the AC distribution system. The lab models developed under this task are located in the Electric Power Quality Lab in the Engineering Research Building on the Wichita State University campus. The lab system consists of four parts: 1. A doubly-fed induction generator 2. A wind turbine emulator 3. A solar photovoltaic emulator, with battery energy storage 4. Distribution transformers, lines, and other components, and wireless and wired communications and control These lab elements will be interconnected and will function together to form a complete testbed for distributed resource monitoring and control strategies and smart grid applications testing. Development of the lab system will continue beyond this project.

Janet.twomey@wichita.edu

2010-04-30

241

Protection from ground faults in the stator winding of generators at power plants in the Siberian networks  

SciTech Connect

The experience of many years of experience in developing and utilization of ground fault protection in the stator winding of generators in the Siberian networks is generalized. The main method of protection is to apply a direct current or an alternating current with a frequency of 25 Hz to the primary circuits of the stator. A direct current is applied to turbo generators operating in a unit with a transformer without a resistive coupling to the external grid or to other generators. Applying a 25 Hz control current is appropriate for power generation systems with compensation of a capacitive short circuit current to ground. This method forms the basis for protection of generators operating on busbars, hydroelectric generators with a neutral grounded through an arc-suppression reactor, including in consolidated units with generators operating in parallel on a single low-voltage transformer winding.

Vainshtein, R. A., E-mail: vra@tpu.ru [Tomsk Polytechnical University (Russian Federation); Lapin, V. I. [ODU Sibiri (Integrated Dispatcher Control for Siberia), branch of JSC 'SO EES' (Russian Federation); Naumov, A. M.; Doronin, A. V. [JSC NPP 'EKRA' (Russian Federation); Yudin, S. M. [Tomsk Polytechnical University (Russian Federation)

2010-05-15

242

Design and analysis of portable loadless wind power source for ubiquitous sensor network  

Microsoft Academic Search

Nowadays, green technology solution using natural power such as solar, wind, waves et al. has been interested as an alternative power source instead of battery. This paper presents a portable power source driven by natural wind power. One of very efficient energy conversion mechanisms to change mechanical energy of natural power with electrical energy is a direct piezoelectric effect. However,

Hyung-Kwan Chang; Daejoong Kim

2010-01-01

243

Control of DFIG-based wind generation for power network support  

Microsoft Academic Search

This paper addresses the design and implementation of a novel control scheme for a doubly fed induction generator (DFIG), of the type employed with wind turbines, to provide support to power system operation. It is shown that this controller provides a DFIG-based wind farm with operational and control compatibility with conventional power stations, the ability to contribute to voltage support

F. Michael Hughes; Olimpo Anaya-Lara; Nicholas Jenkins; Goran Strbac

2005-01-01

244

Knowledge base for the systematic design of wet cooling towers. Part I: Selection and tower characteristics  

Microsoft Academic Search

This paper describes part of the detailed methodology for the thermal design of wet, counterflow and crossflow types of mechanical and natural draught cooling towers. Starting with a brief introduction, an attempt is made here to present different steps of cooling tower design. The steps include: selection of a cooling tower; determination of tower characteristic ratio; computation of moist air

K Kant

1996-01-01

245

Adaptation of amoebae to cooling tower biocides  

Microsoft Academic Search

Adaptation of amoebae to four cooling tower Biocides, which included a thiocarbamate compound, tributyltin neodecanoate mixed with quaternary ammonium compounds (TBT\\/QAC), another QAC alone, and an isothiazolin derivative, was studied. Previously we found that amoebae isolated from waters of cooling towers were more resistant to cooling tower biocides than amoebae from other habitats. Acanthamoeba hatchetti and Cochliopodium bilimbosum, obtained from

S. Srikanth; S. G. Berk

1994-01-01

246

Tower reflector for solar power plant  

Microsoft Academic Search

The power tower of a solar power plant uses a large field of heliostats for collecting light and transmitting it to a central absorber on top of a tower. Since tower height is in the range 100-500 m, there are problems associated with heat transfer from the absorber at the top of the power plant to the base of the

A. Rabl

1976-01-01

247

Twin tower gas fractionation apparatus  

Microsoft Academic Search

An apparatus for adsorptive fractionation of a gaseous mixture. The apparatus is a twin tower fractionator or dryer including a pair of sorbent beds. A filter and valve assembly directs a flow of the gaseous mixture from a source thereof to one of the beds for removing a gaseous component of said mixture while simultaneously directing a flow of purge

R. A. Null; L. C. laughlin; M. L. Goldberg

1985-01-01

248

Cooling towers: Energy conservation strategy  

Microsoft Academic Search

This article proposes that practically all cooling towers can be upgraded to perform at higher levels of efficiency, providing a rapid, cost-effective payback. Topics considered include air handling, water distribution, heat transfer surfaces, and the function of lower temperatures. Case histories are presented of an anhydrous ammonia plant, a gasoline petrochemical plant, and a power generating plant. It is shown

Burger

1984-01-01

249

[Legionella outbreak in Amsterdam: a cooling tower as the source].  

PubMed

During the period 6-28 July 2006, 30 confirmed cases of Legionella infection were identified in Amsterdam, 2 of which were fatal. All had a positive urinary antigen test, by which Legionella pneumophila serogroup I could be demonstrated. Consultations between the parties involved in the control of infectious diseases started on July 7th, as soon as it became clear that there was an outbreak. On July 10th it was established that relatively many of these patients lived in the eastern part of the city centre. After a study of the prevailing winds during the past 3 weeks, the search for installations containing water was started. A cooling tower in the town centre was closed on July 11th by way of precaution. During the following week, this tower was proven to be the source of the outbreak. PMID:16967589

van den Hoek, J A R; IJzerman, E P F; Coutinho, R A

2006-08-19

250

Development Potential for California's Offshore Wind Energy Resource  

Microsoft Academic Search

An initial analysis was performed for areas suitable for offshore wind farm development near the California coast. The siting of an offshore wind farm is limited by water depth, with shallow water being the most preferable economically. Acceptable depths for offshore wind farms were broken up into three categories, based on current and future wind turbine tower support technology; <=20

M. J. Dvorak; M. Z. Jacobson; C. L. Archer

2007-01-01

251

Session: What Have Studies of Communications Towers Suggested Regarding the Impact of Guy Wires and Lights on Birds and Bats.  

National Technical Information Service (NTIS)

This session at the Wind Energy and Birds/Bats workshop consisted of one presentation followed by a discussion/question and answer period. The paper 'Wind turbines and Avian Risk: Lessons from Communications Towers' was given by Paul Kerlinger. The presen...

P. Kerlinger

2004-01-01

252

A Vortical Hot Tower Route to Tropical Cyclogenesis.  

NASA Astrophysics Data System (ADS)

A nonhydrostatic cloud model is used to examine the thermomechanics of tropical cyclogenesis under realistic meteorological conditions. Observations motivate the focus on the problem of how a midtropospheric cyclonic vortex, a frequent by-product of mesoscale convective systems during summertime conditions over tropical oceans, may be transformed into a surface-concentrated (warm core) tropical depression. As a first step, the vortex transformation is studied in the absence of vertical wind shear or zonal flow.Within the cyclonic vorticity-rich environment of the mesoscale convective vortex (MCV) embryo, the simulations demonstrate that small-scale cumulonimbus towers possessing intense cyclonic vorticity in their cores [vortical hot towers (VHTs)] emerge as the preferred coherent structures. The VHTs acquire their vertical vorticity through a combination of tilting of MCV horizontal vorticity and stretching of MCV and VHT-generated vertical vorticity. Horizontally localized and exhibiting convective lifetimes on the order of 1 h, VHTs overcome the generally adverse effects of downdrafts by consuming convective available potential energy in their local environment, humidifying the middle and upper troposphere, and undergoing diabatic vortex merger with neighboring towers.During metamorphosis, the VHTs vortically prime the mesoscale environment and collectively mimic a quasi-steady diabatic heating rate within the MCV embryo. A quasi-balanced toroidal (transverse) circulation develops on the system scale that converges cyclonic vorticity of the initial MCV and small-scale vorticity anomalies generated by subsequent tower activity. The VHTs are found to accelerate the spinup of near-surface mean tangential winds relative to an approximate axisymmetric model that excises the VHTs. This upscale growth mechanism appears capable of generating a tropical depression vortex on time scales on the order of 1 2 days, for reasonable parameter choices.Further tests of the VHT paradigm are advocated through diagnoses of operational weather prediction models, higher resolution simulations of the current configuration, examination of disruption scenarios for incipient vortices, and a meteorological field experiment.

Montgomery, M. T.; Nicholls, M. E.; Cram, T. A.; Saunders, A. B.

2006-01-01

253

Wind for Schools Project Power System Brief, Wind Powering America Fact Sheet Series  

Microsoft Academic Search

Wind Powering America's (WPA's) Wind for Schools project uses a basic system configuration for each school project. The system incorporates a single SkyStream wind turbine, a 70-ft guyed tower, disconnect boxes at the base of the turbine and at the school, and an interconnection to the school's electrical system. This document provides a detailed description of each system component.

Baring-Gould

2009-01-01

254

Optimal control of a regional power microgrid network driven by wind and solar energy  

Microsoft Academic Search

Abst ract - In this paper, a model to support optimal decisions in a network of microgrids is formalized as an original discrete and centralized problem defined here as cooperative network of smart power grids problem. The control variables are the instantaneous flows of power in the network of microgrids, which can be obtained from the solution of a linear

Hanane Dagdougui; Riccardo Minciardi; Ahmed Ouammi; Roberto Sacile

2011-01-01

255

Coupling a Neural Network-Based forward Model and a Bayesian Inversion Approach to Retrieve Wind Field from Spaceborne Polarimetric Radiometers  

PubMed Central

A simulation study to assess the potentiality of sea surface wind vector estimation based on the approximation of the forward model through Neural Networks and on the Bayesian theory of parameter estimation is presented. A polarimetric microwave radiometer has been considered and its observations have been simulated by means of the two scale model. To perform the simulations, the atmospheric and surface parameters have been derived from ECMWF analysis fields. To retrieve wind speed, Minimum Variance (MV) and Maximum Posterior Probability (MAP) criteria have been used while, for wind direction, a Maximum Likelihood (ML) criterion has been exploited. To minimize the cost function of MAP and ML, conventional Gradient Descent method, as well as Simulated Annealing optimization technique, have been employed. Results have shown that the standard deviation of the wind speed retrieval error is approximately 1.1 m/s for the best estimator. As for the wind direction, the standard deviation of the estimation error is less than 13° for wind speeds larger than 6 m/s. For lower wind velocities, the wind direction signal is too weak to ensure reliable retrievals. A method to deal with the non-uniqueness of the wind direction solution has been also developed. A test on a case study has yielded encouraging results.

Pulvirenti, Luca; Pierdicca, Nazzareno; Marzano, Frank S.

2008-01-01

256

Development and whirl tower test of the SMART active flap rotor  

Microsoft Academic Search

A full scale Smart Material Actuated Rotor Technology (SMART) system with piezoelectric actuated blade flaps was developed and whirl tower tested. The development effort included design, fabrication, and component testing of rotor blades, trailing edge flaps, piezoelectric actuators, switching power amplifiers, and the data\\/power system. Simulations and model scale wind tunnel tests have shown that this system can provide 80%

Friedrich K. Straub; Dennis K. Kennedy; Alan D. Stemple; V. R. Anand; Terry S. Birchette

2004-01-01

257

40M Open Air Foucault Pendulum of Eurajoki Water Tower, Finland.  

National Technical Information Service (NTIS)

A method of exploiting tall buildings like water towers for school pendulum experiments is described. A 40m long Foucault pendulum with a heavy bob is relatively insensitive even to moderate winds if used outdoors. This is especially so at high latitudes ...

J. O. Mattila

1986-01-01

258

Tower Hamlets History On Line  

NSDL National Science Digital Library

The London Borough of Tower Hamlets is considered by some to be the heart of the East End, the sometimes infamous section of London that fascinated journalists, novelists, and social scientists through the nineteenth century and well into the twentieth. This site offers an excellent collection of both contemporary writings and historical essays, all taken from the Tower Hamlets' Local History Library and Archives, that provide a fascinating look at life in the East End in the nineteenth and early twentieth centuries. Especially useful to scholars and students in British or urban history or literature, the texts can be browsed by title, author, or subject. Separate listings of eyewitness accounts and images are also available, as is a keyword search engine.

259

Stability and turbulence in the atmospheric boundary layer: A comparison of remote sensing and tower observations  

NASA Astrophysics Data System (ADS)

When monitoring winds and atmospheric stability for wind energy applications, remote sensing instruments present some advantages to in-situ instrumentation such as larger vertical extent, in some cases easy installation and maintenance, measurements of vertical humidity profiles throughout the boundary layer, and no restrictions on prevailing wind directions. In this study, we compare remote sensing devices, Windcube lidar and microwave radiometer, to meteorological in-situ tower measurements to demonstrate the accuracy of these measurements and to assess the utility of the remote sensing instruments in overcoming tower limitations. We compare temperature and wind observations, as well as calculations of Brunt-Väisälä frequency and Richardson numbers for the instrument deployment period in May-June 2011 at the U.S. Department of Energy National Renewable Energy Laboratory's National Wind Technology Center near Boulder, Colorado. The study reveals that a lidar and radiometer measure wind and temperature with the same accuracy as tower instruments, while also providing advantages for monitoring stability and turbulence. We demonstrate that the atmospheric stability is determined more accurately when the liquid-water mixing ratio derived from the vertical humidity profile is considered under moist-adiabatic conditions.

Friedrich, Katja; Lundquist, Julie K.; Aitken, Matthew; Kalina, Evan A.; Marshall, Robert F.

2012-02-01

260

Wind Measurements and Energy Potential for a Remote Village in Saudi Arabia  

Microsoft Academic Search

Site specific wind speed measurements are critical for techno-economical development of wind energy applications. This paper presents the wind power potential at Rawdat Ben Habbas village where meteorological measurements were made using a 40 meter tall wind tower for a period of one year. The wind speeds were recorded at 20, 30 and 40 meters above ground level (AGL) and

S. Rehman; I. M. El-Amin; S. Shaahid; A. Ahmad; F. Ahmad; T. Thabit

2007-01-01

261

Measuring thermospheric winds and temperatures with a tri-static Fabry-Perot interferometer network in Alaska  

NASA Astrophysics Data System (ADS)

For some 35 years Fabry-Perot interferometer (FPI) measurements in the auroral region have been carried out with a single ground-based observatory. The problem with this approach is that the three components of the neutral wind vector within the region observed along the line-of-sight cannot be determined. Only the radial motion of the emitting species of atomic oxygen atoms, O1D, can be determined for any single direction toward the auroral or airglow source region. This poses a problem in studying the polar ion-neutral coupling that takes place in the course of geostrophic adjustment at high latitudes. This process describes the thermospheric response to the changing forcing functions represented by the day-to-night pressure gradient, the Pedersen ion drag imposed upon the neutral atmosphere by the polar ionospheric plasma convection, and the thermospheric Joule and soft-particle heating sources. The balancing of these forcing functions is also influenced by the action of the Coriolis force modifying the flow field at high latitudes. To study these changes during the course of auroral sub-storm activity that enters into the ion-neutral coupling interaction of the thermosphere-ionosphere system, it is of great importance to measure the three components of the neutral wind vector within a common volume. This is especially true for the auroral region where the vertical wind cannot be assumed to be zero during auroral substorm events. Accordingly, a tri-static FPI network will be installed in central Alaska to support the AMISR radar facility, which would measure the thermospheric electric fields in the region of overlap with the common volume observed by the AkFPI network of three FPI observatories. The three FPI instruments will be installed in the three Alaskan locations of Eagle, Ft. Yukon, and Poker Flat, and first results are expected as of October, 2006. The FPI instruments are classified as imaging FPIs, and the sensitivities are expected to be 3-5 ms-1 and 15-20 K for the horizontal thermospheric wind speed and temperature for an integration period of 60 s and an auroral signal of 250 R.

Meriwether, J. W.; Larsen, M. F.; Hedden, R.; Faivre, M.

2006-12-01

262

Wind pattern recognition in neural fuzzy wind turbine control system  

Microsoft Academic Search

This paper introduces a new approach utilizing a fuzzy classifier and a modular temporal neural network to predict wind speed and direction for advanced wind turbine control systems. The fuzzy classifier estimates wind patterns and then assigns weights accordingly to each module of the temporal neural network. The finite-duration impulse response multiple-layer structure of the temporal network makes it possible

Guangdian G. Wu; Zhijie Dou

1994-01-01

263

Toward model free atmospheric sensing by aerial robot networks in strong wind fields  

Microsoft Academic Search

This paper presents a system for in situ atmospheric sensing using an aerial robot system in the presence of a strong wind field. The geostatistical concept of the variogram is used to characterize regions of the environment with high variability, which is assumed to correlate with scientific interest. After regions of interest are identified, ordered upwind methods are used to

Jack Elston; Maciej Stachura; Eric W. Frew; Ute C. Herzfeld

2009-01-01

264

Impacts of grid integration of wind energy in the Namibian power network  

Microsoft Academic Search

This paper discusses the general impact of grid integration of wind energy in the Namibian context. The paper focuses on the current electricity situation in Namibia, which presents a demanding task to energy and power engineers in the country to develop ways of rescuing the dire electricity need for Namibia's nation. The efforts made by the country's power utility, NamPower

A. I. Elombo; S. P. Chowdhury; H. J. Vermeulen

2010-01-01

265

A Study of the Solar Wind-Magnetosphere Coupling Using Neural Networks  

Microsoft Academic Search

The interaction between solar wind plasma and interplanetary magnetic field (IMF) and Earth's magnetosphere induces geomagnetic activity. Geomagnetic storms can cause many adverse effects on technical systems in space and on the Earth. It is therefore of great significance to accurately predict geomagnetic activity so as to minimize the amount of disruption to these operational systems and to allow them

Jian-Guo Wu; Henrik Lundstedt

1996-01-01

266

Optimal wind clustering methodology for electrical network adequacy studies using non sequential Monte Carlo simulation  

Microsoft Academic Search

In this paper, several clustering methodologies are investigated in order to group together wind parks with close statistical behaviour. The proposed approach is practically founded on a fast incremental algorithm. The latter requires the definition of an objective function which is based in the present case on the definition of a Pearson correlation coefficient level. The advantage of such a

Francois Vallee; Guillaume Brunieau; Marc Pirlot; Olivier Deblecker; Jacques Lobry

2011-01-01

267

Sumberged buoyant offshore drilling and production tower  

SciTech Connect

A submerged tubular tower is connected at its lower end to an ocean floor at a site where at least one subsea hydrocarbon well is to be drilled. A riser duct for each well to be drilled extends from an upwardly accessible connection point at the upper end of the tower to the lower end of the tower. The tower is positively buoyant to stand erect in an unguyed manner. The upper end of the tower is located a substantial distance above the ocean floor at a depth sufficiently small to enable wells to be drilled through the riser ducts, through equipment landed on the top of the tower, using floating drilling equipment designed for use in substantially shallower water depths.

Horton, E. E.

1985-04-16

268

2. Abandoned light tower and keeper's house/light tower, view southeast, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. Abandoned light tower and keeper's house/light tower, view southeast, north northwest and west southwest sides - Matinicus Rock Light Station, Matinicus Island, on Matinicus Rock, Matinicus, Knox County, ME

269

1. Light tower/keeper's house and abandoned light tower, view northwest, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. Light tower/keeper's house and abandoned light tower, view northwest, south southeast and east northeast sides - Matinicus Rock Light Station, Matinicus Island, on Matinicus Rock, Matinicus, Knox County, ME

270

Coupling a Neural Network-Based forward Model and a Bayesian Inversion Approach to Retrieve Wind Field from Spaceborne Polarimetric Radiometers  

Microsoft Academic Search

A simulation study to assess the potentiality of sea surface wind vector estimation based on the approximation of the forward model through Neural Networks and on the Bayesian theory of parameter estimation is presented. A polarimetric microwave radiometer has been considered and its observations have been simulated by means of the two scale model. To perform the simulations, the atmospheric

Luca Pulvirenti; Nazzareno Pierdicca; Frank S. Marzano

2008-01-01

271

Emergency-shutdown cooling towers: considerations in the evolution of optimum tower design  

Microsoft Academic Search

The article discusses the various regulatory requirements and criteria governing the design of emergency-shutdown cooling towers for nuclear power plants. The effects of key tower parameters (e.g., wet-bulb temperature, flow rates, and heat load) on tower size and their interactions with system and safety requirements are explored. The evolution of the Seabrook station tower and its relationship to a companion

1976-01-01

272

COOLING TOWER PUMP HOUSE, TRA606. CONNECTION TO COOLING TOWER. PUMPHOUSE ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

COOLING TOWER PUMP HOUSE, TRA-606. CONNECTION TO COOLING TOWER. PUMP-HOUSE FLOOR PLAN AND FOUNDATION PLANS. LAYOUT OF SIX COOLING TOWER UNITS. BLAW-KNOX 3150-807-2, 12/1950. INL INDEX NO. 53-0607-62-098-100671, REV. 1. - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

273

Magnetic towers and binary-formed disks: New results for planetary nebula evolution  

NASA Astrophysics Data System (ADS)

We present new results of 3-D AMR MHD simulations focusing on two distinct aspects of PPN evolution. We first report new simulations of collimated outflows driven entirely by magnetic fields. These Poynting flux dominated ``magnetic towers'' hold promise for explaining key properties of PPN flows. Our simulations address magnetic tower evolution and stability. We also present results of a campaign of simulations to explore the development of accretion disks formed via wind capture. Our result focus on the limits of disk formation and the range of disk properties.

Huarte-Espinosa, Martín; Frank, Adam

2012-08-01

274

A recurrent neural network approach to quantitatively studying solar wind effects on TEC derived from GPS; preliminary results  

NASA Astrophysics Data System (ADS)

This paper attempts to describe the search for the parameter(s) to represent solar wind effects in Global Positioning System total electron content (GPS TEC) modelling using the technique of neural networks (NNs). A study is carried out by including solar wind velocity (Vsw), proton number density (Np) and the Bz component of the interplanetary magnetic field (IMF Bz) obtained from the Advanced Composition Explorer (ACE) satellite as separate inputs to the NN each along with day number of the year (DN), hour (HR), a 4-month running mean of the daily sunspot number (R4) and the running mean of the previous eight 3-hourly magnetic A index values (A8). Hourly GPS TEC values derived from a dual frequency receiver located at Sutherland (32.38° S, 20.81° E), South Africa for 8 years (2000-2007) have been used to train the Elman neural network (ENN) and the result has been used to predict TEC variations for a GPS station located at Cape Town (33.95° S, 18.47° E). Quantitative results indicate that each of the parameters considered may have some degree of influence on GPS TEC at certain periods although a decrease in prediction accuracy is also observed for some parameters for different days and seasons. It is also evident that there is still a difficulty in predicting TEC values during disturbed conditions. The improvements and degradation in prediction accuracies are both close to the benchmark values which lends weight to the belief that diurnal, seasonal, solar and magnetic variabilities may be the major determinants of TEC variability.

Habarulema, J. B.; McKinnell, L.-A.; Opperman, B. D. L.

2009-05-01

275

Short-Term Wind Power Forecast Based on Cluster Analysis and Artificial Neural Networks  

Microsoft Academic Search

\\u000a In this paper an architecture for an estimator of short-term wind farm power is proposed. The estimator is made up of a Linear\\u000a Machine classifier and a set of k Multilayer Perceptrons, training each one for a specific subspace of the input space. The splitting of the input dataset\\u000a into the k clusters is done using a k-means technique, obtaining

Javier Lorenzo; Juan Méndez; Modesto Castrillón; Daniel Hernández

276

Tidal winds from the MLT global radar network during the first LTCS Campaign - September 1987  

NASA Astrophysics Data System (ADS)

Results are presented from the first Lower Thermosphere Coupling Study Campaign in September 1987, in which winds and tides were measured by mesosphere/lower thermosphere radars at locations between 43-70 deg N and 35-68 deg S. The semidiurnal and diurnal tidal profiles in the Northern and Southern Hemispheres are described in detail. The observational results are compared with the model of Forbes and Hagan (1988).

Manson, A. H.; Meek, C. E.; Schminder, R.; Kuerschner, D.; Clark, R. R.

1990-03-01

277

The Argonne Boundary Layer Experiments Facility: Using Minisodars to Complement a Wind Profiler Network  

Microsoft Academic Search

Summary   A description of the Argonne Boundary Layer Experiments (ABLE) facility, located in southern Kansas, USA, to study the planetary\\u000a boundary layer on a continuous basis is given. The use and role of the minisodars in these studies is shown to be important\\u000a and necessary in the study of surface boundary layers, extension of wind profiles to the surface, and

R. L. Coulter; G. Klazura; B. M. Lesht; T. J. Martin; J. D. Shannon; D. L. Sisterson; M. L. Wesely

1999-01-01

278

INL Wind Farm Project Description Document.  

National Technical Information Service (NTIS)

The INL Wind Farm project proposes to install a 20 MW to 40 MW wind farm on government property, consisting of approximately ten to twenty full-sized (80-meter hub height) towers with 2 MW turbines, and access roads. This includes identifying the optimal ...

G. Siefert

2009-01-01

279

Session: What have studies of communications towers suggested regarding the impact of guy wires and lights on birds and bats  

SciTech Connect

This session at the Wind Energy and Birds/Bats workshop consisted of one presentation followed by a discussion/question and answer period. The paper ''Wind turbines and Avian Risk: Lessons from Communications Towers'' was given by Paul Kerlinger. The presenter outlined lessons that have been learned from research on communications (not cell) towers and about the impacts of guy wires and lights on birds and bats and how they could be useful to wind energy developers. The paper also provided specific information about a large 'fatality' event that occurred at the Mountaineer, WC wind energy site in May 2003, and a table of Night Migrant Carcass search findings for various wind sites in the US.

Kerlinger, Paul

2004-09-01

280

40 CFR 63.1329 - Process contact cooling towers provisions.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 false Process contact cooling towers provisions. 63.1329 Section... § 63.1329 Process contact cooling towers provisions. (a) The...that utilizes a process contact cooling tower shall comply with...

2009-07-01

281

40 CFR 63.1329 - Process contact cooling towers provisions.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 true Process contact cooling towers provisions. 63.1329 Section... § 63.1329 Process contact cooling towers provisions. (a) The...that utilizes a process contact cooling tower shall comply with...

2010-07-01

282

158. Copy of Louis Rosenberg Etching (original in the Tower ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

158. Copy of Louis Rosenberg Etching (original in the Tower City Development Office) TERMINAL TOWER UNDER CONSTRUCTION, PUBLIC SQUARE FACADE, VIEW WEST TO EAST - Terminal Tower Building, Cleveland Union Terminal, 50 Public Square, Cleveland, Cuyahoga County, OH

283

153. Copy of Louis Rosenberg Etching (original in the Tower ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

153. Copy of Louis Rosenberg Etching (original in the Tower City Development Office, Cleveland, Ohio) TERMINAL TOWER UNDER CONSTRUCTION, PUBLIC SQUARE ELEVATION, VIEW NORTHWEST TO SOUTHEAST - Terminal Tower Building, Cleveland Union Terminal, 50 Public Square, Cleveland, Cuyahoga County, OH

284

157. Copy of Louis Rosenberg Etching (original in the Tower ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

157. Copy of Louis Rosenberg Etching (original in the Tower City Development Office) TERMINAL TOWER UNDER CONSTRUCTION, STEEL FRAMEWORK OF THE SOUTHWEST WING, VIEW WEST TO EAST - Terminal Tower Building, Cleveland Union Terminal, 50 Public Square, Cleveland, Cuyahoga County, OH

285

DETAIL OF VALVE TOWER SHOWING SLUICE GATE ON EAST SIDE ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

DETAIL OF VALVE TOWER SHOWING SLUICE GATE ON EAST SIDE OF TOWER. VIEW FACING WEST - Schofield Barracks Military Reservation, Ku Tree Reservoir, Valve Tower, Kalakoa Stream East Range, Wahiawa, Honolulu County, HI

286

APPROACH BRIDGE PORTION OF VALVE TOWER FOOT BRIDGE, AS SEEN ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

APPROACH BRIDGE PORTION OF VALVE TOWER FOOT BRIDGE, AS SEEN FROM BELOW, SHOWING VALVE TOWER TO RIGHT. VIEW FACING NORTH - Schofield Barracks Military Reservation, Ku Tree Reservoir, Valve Tower Foot Bridge, Kalakoa Stream East Range, Wahiawa, Honolulu County, HI

287

Combined-cycle power tower  

SciTech Connect

This paper evaluates a new power tower concept that offers significant benefits for commercialization of power tower technology. The concept uses a molten nitrate salt centralreceiver plant to supply heat, in the form of combustion air preheat, to a conventional combined-cycle power plant. The evaluation focused on first commercial plants, examined three plant capacities (31, 100, and 300 MWe), and compared these plants with a solar-only 100-MWe plant and with gas-only combined-cycle plants in the same three capacities. Results of the analysis point to several benefits relative to the solar-only plant including low energy cost for first plants, low capital cost for first plants, reduced risk with respect to business uncertainties, and the potential for new markets. In addition, the concept appears to have minimal technology development requirements. Significantly, the results show that it is possible to build a first plant with this concept that can compete with existing gas-only combined-cycle plants.

Bohn, M.S.; Williams, T.A.; Price, H.W.

1994-10-01

288

CUORE: The Three Towers Test  

NASA Astrophysics Data System (ADS)

CUORE (Cryogenic Underground Observatory for Rare Events) will be part of the next generation of detectors used to search for neutrinoless double beta decay (0???). Located in Assergi, Italy at the Gran Sasso National Laboratory (LNGS), CUORE will be a large cryogenic bolometer composed of 988 tellurium dioxide (TeO2) detectors with a total mass of 750 kg, and will search for 0??? in ^130Te. The intermediate upgrade, CUORE-0, first involves the disassembly of Cuoricino, CUORE's smaller counterpart in operation since 2003, and the readying of the Three Towers test, a diagnostic detector configuration. As the experiment will monitor the extremely rare event of 0???, all factors contributing to background need to be minimized to effectively increase the sensitivity. We assisted the LNGS researchers over the summer of 2008 by supporting R&D work with the Three Towers test to reduce the radioactive background of the experiment. Activities involved decontaminating the copper frame of radon daughters, and chemically etching and lapping the TeO2 crystals with nitric acid and silicon dioxide, respectively, to remove surface contaminants which contribute to background counts. This work was supported in part by NSF grant PHY- 0653284 and the California State Faculty Support Grant.

Goodsell, Alison; Sparks, Laura

2008-10-01

289

Wind turbine generators using superconducting coils and bulks  

Microsoft Academic Search

Wind power generation has been expected as a promising clean energy source in the world. Recently, generation capacity produced by wind power generators has been growing with increasing size of windmills. However, huge nacelles result in extreme load for towers supporting them. We have focused on a wind power generator using superconducting wires and superconducting bulks to solve the problem.

H. Ohsaki; Y. Terao; M. Sekino

2010-01-01

290

On Pitch Control of Horizontal-Axis Large Wind Turbines  

Microsoft Academic Search

ó Most commercial large wind turbines use blade pitch action to mitigate structural loads in high wind velocity conditions. In this paper, we study the linearized dynamics of the map from blade pitch to tower top fore-aft deection in horizontal-axis wind turbines. We show that the mass and stiffness distribution of the blades at certain operating conditions determine the presence

Shashikanth Suryanarayanan; Amit Dixit

291

Behaviour of guyed transmission line structures under tornado wind loading  

Microsoft Academic Search

Localized severe wind events, in the form of downbursts and tornadoes, are responsible of the majority of transmission line structures failures in many regions around the globe. The wind profiles associated with these events are different than the conventional boundary layer wind profile that is typically used to design the supporting towers. A comprehensive study is presented in this paper

A. Hamada; A. A. El Damatty

2011-01-01

292

Wind turbine spoiler  

DOEpatents

An aerodynamic spoiler system for a vertical axis wind turbine includes spoilers on the blades initially stored near the rotor axis to minimize drag. A solenoid latch adjacent the central support tower releases the spoilers and centrifugal force causes the spoilers to move up the turbine blades away from the rotor axis, thereby producing a braking effect and actual slowing of the associated wind turbine, if desired. The spoiler system can also be used as an infinitely variable power control by regulated movement of the spoilers on the blades over the range between the undeployed and fully deployed positions. This is done by the use of a suitable powered reel and cable located at the rotor tower to move the spoilers.

Sullivan, William N. (Albuquerque, NM)

1985-01-01

293

A comprehensive approach to cooling tower design  

Microsoft Academic Search

In this paper, a mathematical model for a counterflow wet cooling tower is derived, which is based on one-dimensional heat and mass balance equations using the measured heat transfer coefficient. The balance equations are solved numerically to predict the temperature change of air and water, as well as the humidity as a function of the cooling tower high. Experimental measurements

Nenad Milosavljevic; Pertti Heikkilä

2001-01-01

294

Modelling of cooling tower splash pack  

Microsoft Academic Search

A mathematical model and a computer simulation program have been developed for the modelling of counterflow cooling tower splash pack thermal performance. The one-dimensional model uses basic aerodynamic, hydrodynamic and heat\\/mass transfer information to predict the performance of the packing material without depending on cooling tower test data. The predicted transfer characteristics and pressure drop data obtained with the simulation

A. A. Dreyer; P. J. Erens

1996-01-01

295

Evaluation of central solar tower power plant  

Microsoft Academic Search

A baseline design for heliostat, receiver, tower, and energy transport subsystems for a solar tower power plant has been defined down to the major component level. Preliminary manufacturing plans have been prepared for component fabrication, assembly, and installation. Capital costs have been estimated for the baseline design. The major cost element, other than the power plant, is the heliostat and

C. R. Easton; R. W. Hallet Jr.; S. Gronich; R. L. Gervais

1974-01-01

296

Characterization of Current Tower Cab Environments.  

National Technical Information Service (NTIS)

This report describes the general tower cab environment in terms of: (a) the evolution of the tower cab, current cab classification and staffing levels, and the basic flow of ATC data relevant to cab operations, (b) a breakdown of functions performed by t...

V. J. Hobbs D. F. Clapp P. Rempfer D. Devoe J. Bellantoni

1977-01-01

297

Shower Tower, Miele Showroom, Johannesburg South Africa  

Microsoft Academic Search

This paper presents the design and testing results of a prototype passive downdraft evaporative cooling tower PDEC installed and tested to guide the design of a permanent tower intended as a cost effective retrofit to the Miele Showroom at the South African head offices in Johannesburg. The showroom forms a large part of the building which was completed 2 years

Paul Carew; Gerry Joubert

298

Environmental impact assessment of cooling towers  

Microsoft Academic Search

The increasing numbers of large cooling towers make it essential to consider the environmental effects. The following methods of quantitatively assessing their impact are reviewed: drift loss deposition; determination of chromium and zinc concentrations in vegetation; droplet size distribution; and emission from stacks of airborne particulates. Mechanisms by which salt concentrations increase in the watershed of cooling towers are discussed.

J. R. Bartlit; M. D. Williams

1975-01-01

299

The new Drop Tower catapult system  

Microsoft Academic Search

The Center of Applied Space Technology and Microgravity (ZARM) was founded in 1985 as an institute of the University Bremen, which focuses on research on gravitational and space-related phenomena. In 1988, the construction of the ``Drop Tower'' began. Since then, the eye-catching tower with a height of 146 m and its characteristic glass roof has become the emblem of the

Peter von Kampen; Ulrich Kaczmarczik; Hans J. Rath

2006-01-01

300

Wind energy integration into 110 kV system - impact on power quality of MV and LV networks  

Microsoft Academic Search

The amount of electrical energy produced by wind farms is constantly increasing. Nowadays detailed analyses considering the impact of wind energy integration on the transmission system are required. Therefore several wind impact studies have been carried out lately in different countries. The conclusions of these studies are related to different aspects of wind power, such as its fluctuating nature, distributed

E. Vilchez; J. Stenzel

2008-01-01

301

VALVE TOWER FROM HIGH GROUND NEAR APPROACH BRIDGE. VIEW FACING ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

VALVE TOWER FROM HIGH GROUND NEAR APPROACH BRIDGE. VIEW FACING NORTHEAST - Schofield Barracks Military Reservation, Ku Tree Reservoir, Valve Tower, Kalakoa Stream East Range, Wahiawa, Honolulu County, HI

302

Local vibration of transmission line towers due to flood flow. Technical report  

SciTech Connect

Local vibration of transmission line tower due to flood affects the lattices close to ground level, the lattices being slender. This is specially the case with broad based tangent towers for single conductor lines, since the stresses in the lattices are nominal and these have to be designed on the consideration of upper limit of slenderness ratio. Sustained flood flow can cause dynamic stresses resulting in yielding of the lattices ultimately leading to failure of the tower itself. Provision of intermediate supports for the lattices at suitable locations can bring down the amplitude of vibration and hence dynamic stresses. Interference with the vortex shedding by provision of wire winding or strakes, are also suitable steps to keep down the high dynamic stress due to flood flow.

Not Available

1982-05-01

303

Network investment planning for high penetration of wind energy under demand response program  

Microsoft Academic Search

The role of demand response becomes more crucial when there is a large penetration of intermittent renewable energy sources into the electrical grid. Flexible demand can be arranged to follow intermittent generation balancing demand and supply. Moreover, the transmission network where renewable energy resources are accommodated can constrain the capacity of green energy sources due to congestion or other operational

A. K. Kazerooni; J. Mutale

2010-01-01

304

Which Way Will The Wind Blow? Networked Computer Tools For Studying The Weather  

Microsoft Academic Search

A suite of networked computer tools within a pedagogical framework was designed to enhance earth science education at the high school level. These tools give students access to live satellite images, weather maps, and other scientific data dealing with the weather, and make it easy for students to make their own weather forecasts by creating high-quality weather maps. These tools

Barry J. Fishman; Laura M. D'Amico

305

Measured and calculated characteristics of wind turbine noise  

NASA Astrophysics Data System (ADS)

The results of an analytical and experimental investigation of wind turbine noise are presented. Noise calculations indicate that for configurations with the rotor downwind of the support tower, the primary source of noise is the rapid change in rotor loadings which occurs as the rotor passes through the tower wake. Noise measurements are presented for solid and truss type tower models with both upwind and downwind rotors. Upwind rotor configurations are shown to be significantly quieter than downwind configurations. The model data suggest that averaged noise measurements and noise calculations based on averaged tower wake characteristics may not accurately represent the impulsive noise characteristics of downwind rotor configurations.

Greene, G. C.

1981-05-01

306

A comparison of CO2 and sensible heat flux measurements from aircraft and tower-based platforms  

NASA Astrophysics Data System (ADS)

Eddy covariance fluxes of CO2 from a twin-engine Beechcraft Duchess were compared to the Ameriflux tower- based platform over a northern hardwood, deciduous forest between June 21 and July 24, 2006. Vertical wind was measured using a combination of a hemispherical pressure sensor probe and GPS/INS system on the aircraft and a sonic anemometer on the tower. The platforms employed NDIR analyzers to measure CO2 concentrations. Six flight legs, 5km in length, were averaged at heights of 150, 210, and 275m and compared with 30min averaged CO2 and sensible heat fluxes at the top of the 46m flux tower. Aircraft-based flux measurements as a function of altitude allow for assessment of flux divergence. In this paper, we compare the aircraft and tower data sets, and assess the differences in averaged fluxes, based in part on the footprint of the two platforms and flux divergence.

Martins, D. K.; Shepson, P. B.; Jacox, M.; Smith, J.; Hahn, M.; Garrity, S.; Vierling, L.; Schmid, H. P.; Vogel, C.; Zimmerman, J. R.; Wyss, P.; Santini, R.; Stirm, B.

2006-12-01

307

Wind shear climatology for large wind turbine generators  

SciTech Connect

Climatological wind shear analyses relevant to the design and operation of multimegawatt wind turbines are provided. Insight is provided for relating the wind experienced by a rotating blade in a shear flow to the analysis results. A simple analysis of the wind experienced by a rotating blade for three types of wind shear profiles under steady-state conditions is presented in graphical form. Comparisons of the magnitude and frequency of the variations in 1) the wind sensed by a single blade element, 2) the sum, and 3) the difference of the winds sensed by opposite blade elements show strong sensitivity to profile shape. These three items represent forcing functions that can be related to 1) flatwise bending moment, 2) torque on the shaft, and 3) teeter angle. A computer model was constructed to simulate rotational sampling of 10-s sampled winds from a tall tower for three different types of large wind turbines. Time series produced by the model indicated that the forcing functions on a rotating blade vary according to the shear profile encountered during each revolution as opposed to a profile derived from average wind conditions, e.g., hourly average winds. An analysis scheme was developed to establish a climatology of wind shear profiles derived from 10-s sampled winds and hourly average winds measured over a one-year period at several levels on a tall tower. Because of the sensitivity of the forcing function variability to profile shape, the analyses performed and presented are in the form of joint frequency distributions of velocity differences of the the top-to-hub versus the hub-to-bottom portion of disks of rotation for the three turbine configurations.

Elliott, D.L.; Wendell, L.L.; Heflick, S.K.

1982-10-01

308

Addressing the unique safety and design concerns for operating tower-based scientific field campaigns  

Microsoft Academic Search

Scientific field campaigns often require specialized technical infrastructure for data collection. NASA's LBA- ECO Science Team needed a network of towers, up to 65 meters in height, to be constructed in the Amazon forest to serve as platforms for instrumentation used to estimate carbon dioxide and trace gas fluxes between the forest and the atmosphere. The design, construction, and operation

A. C. Steele

2006-01-01

309

Evaluation of RF EMF exposure pattern on selected communication towers in Malaysia  

Microsoft Academic Search

Wireless communication technologies and devices based on radio frequency (RF) field propagation are fast expanding in this information era. In this industry, radio propagation models are useful in the designing phase of radio systems and network. The rapid development in the telecommunication industry also means an increase in communication towers in the surrounding environment. This has also created awareness among

W. N. L. Mahadi; N. M. Ali; Quek Pei Wen

2010-01-01

310

Wind Monitoring Report for Fort Wainwright's Donnelly Training Area  

SciTech Connect

Using the wind data collected at a location in Fort Wainwright’s Donnelly Training Area (DTA) near the Cold Regions Test Center (CRTC) test track, Pacific Northwest National Laboratory (PNNL) estimated the gross and net energy productions that proposed turbine models would have produced exposed to the wind resource measured at the meteorological tower (met tower) location during the year of measurement. Calculations are based on the proposed turbine models’ standard atmospheric conditions power curves, the annual average wind speeds, wind shear estimates, and standard industry assumptions.

Orrell, Alice C.; Dixon, Douglas R.

2011-01-18

311

Wind Climate Analyses for SRTC's Central Climatology Site  

SciTech Connect

This report was written to present climatological summaries of the wind data at the Central Climatology (CC) tower in a convenient format and to point out some features of the wind speed and direction that have not been widely appreciated in the past. Short-term (two-week) wind roses provide a means to demonstrate the temporal and spatial relationships that wind speed and direction undergo using a ten-year database from the CC tower. These relationships are best demonstrated by examining the figures provided in this report or looking at loops of computer-generated images provided by the authors.

Weber, A.H.

2003-06-23

312

Multistory transmission tower model for lightning surge analysis  

Microsoft Academic Search

Transmission towers have been modeled for lightning surge analysis based on the measurements on the towers alone. For an actual high voltage transmission tower, however, ground wires are equipped in many cases. This paper proposes a multistory transmission tower model to be used in the multi-conductor analysis by EMTP. The circuit parameters of the model are determined based on the

M. Ishii; T. Kawamura; T. Kouno; E. Ohsaki; K. Shiokawa; K. Murotani; T. Higuchi

1991-01-01

313

5. View of south tower, facing northnortheast from south bank ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. View of south tower, facing north-northeast from south bank of the Columbia River. Center tower and north tower in background, lower right. - Pasco-Kennewick Transmission Line, Columbia River Crossing Towers, Columbia Drive & Gum Street, Kennewick, Benton County, WA

314

Operation and control of a grid-connected DFIG-based wind turbine with series grid-side converter during network unbalance  

Microsoft Academic Search

This paper proposes a control scheme of a grid-connected doubly-fed induction generator (DFIG) wind turbine with series grid-side converter (SGSC) to improve the control and operation performance of DFIG system during network unbalance. The behaviors of DFIG system with SGSC under unbalanced grid voltage conditions are described. The SGSC is controlled to inject voltage in series to balance the stator

Yong Liao; Hui Li; Jun Yao; Kai Zhuang

2011-01-01

315

Wind Power Prediction by a New Forecast Engine Composed of Modified Hybrid Neural Network and Enhanced Particle Swarm Optimization  

Microsoft Academic Search

Following the growing share of wind energy in elec- tric power systems, several wind power forecasting techniques have been reported in the literature in recent years. In this paper, a wind power forecasting strategy composed of a feature selection component and a forecasting engine is proposed. The feature se- lection component applies an irrelevancy filter and a redundancy filter to

Nima Amjady; Farshid Keynia; Hamidreza Zareipour

2011-01-01

316

Multistory transmission tower model for lightning surge analysis  

SciTech Connect

Transmission towers have been modeled for lightning surge analysis based on the measurements on the towers alone. For an actual high voltage transmission tower, however, ground wires are equipped in many cases. This paper proposes a multistory transmission tower model to be used in the multi-conductor analysis by EMTP. The circuit parameters of the model are determined based on the measurement of voltages across the insulator strings on an actual 500 kV transmission tower. The flashover phase and current in response to a lightning stroke to a UHV transmission tower are also analyzed by using both conventional and new tower models for comparison.

Ishii, M.; Kawamura, T.; Kouno, T. (Tokyo Univ. (Japan)); Ohsaki, E.; Shiokawa, K. (Tokyo Electric Power Co., Inc. (Japan)); Murotani, K. (Nissin Electric Co., Ltd., Kyoto (JP)); Higuchi, T. (Kansai Electric Power Co., Inc., Osaka (Japan))

1991-07-01

317

Twin tower distillation of crude oil  

Microsoft Academic Search

A sequential twin tower fractionation arrangement for separating crude oil is described which is particularly concerned with lowering fractionation heat requirements in conjunction with reducing steam utilization in the combination operation.

R. I. Graham; J. R. Mcclernon; A. M. Peiser

1980-01-01

318

Nonlinear Seismic Response of Articulated Offshore Tower.  

National Technical Information Service (NTIS)

The seismic response of articulated offshore tower has been investigated by the spectral analysis method which is based on the principle of random vibration, where seismic excitation is assumed to be a broadband stationary process. The nonlinear dynamic e...

N. Islam S. Ahmad

2002-01-01

319

76 FR 490 - Marking Meteorological Evaluation Towers  

Federal Register 2010, 2011, 2012, 2013

...conducting operations in these areas. The FAA has received complaints...from agricultural operations in remote or rural areas regarding the safety impacts of these towers on low-level agricultural operations. In addition, representatives...

2011-01-05

320

Soaring Towers: Building with Recycled Materials  

NSDL National Science Digital Library

In this activity, learners will build the highest tower they can out of recycled materials. As they work on this activity, they explore which shapes and sizes make good tower bases, which work well in the middle, and how to make sure the configuration is stable, even when some of the shapes are quite irregular. Available as a web page, downloadable pdf, and in Spanish.

Terc

2010-01-01

321

The new Drop Tower catapult system  

Microsoft Academic Search

The Center of Applied Space Technology and Microgravity (ZARM) was founded in 1985 as an institute of the University Bremen, which focuses on research on gravitational and space-related phenomena. In 1988, the construction of the “Drop Tower” began. Since then, the eye-catching tower with a height of 146m and its characteristic glass roof has become the emblem of the technology

Peter von Kampen; Ulrich Kaczmarczik; Hans J. Rath

2006-01-01

322

Wind Spires as an Alternative Energy Source  

SciTech Connect

This report discloses the design and development of an innovative wind tower system having an axisymmetric wind deflecting structure with a plurality of symmetrically mounted rooftop size wind turbines near the axisymmetric structure. The purpose of the wind deflecting structure is to increase the ambient wind speed that in turn results in an overall increase in the power capacity of the wind turbines. Two working prototypes were constructed and installed in the summer of 2009 and 2012 respectively. The system installed in the Summer of 2009 has a cylindrical wind deflecting structure, while the tower installed in 2012 has a spiral-shape wind deflecting structure. Each tower has 4 turbines, each rated at 1.65 KW Name-Plate-Rating. Before fabricating the full-size prototypes, computational fluid dynamic (CFD) analyses and scaled-down table-top models were used to predict the performance of the full-scale models. The performance results obtained from the full-size prototypes validated the results obtained from the computational models and those of the scaled-down models. The second prototype (spiral configuration) showed at a wind speed of 11 miles per hour (4.9 m/s) the power output of the system could reach 1,288 watt, when a typical turbine installation, with no wind deflecting structure, could produce only 200 watt by the same turbines at the same wind speed. At a wind speed of 18 miles per hour (8 m/sec), the spiral prototype produces 6,143 watt, while the power generated by the same turbines would be 1,412 watt in the absence of a wind deflecting structure under the same wind speed. Four US patents were allowed, and are in print, as the results of this project (US 7,540,706, US 7,679,209, US 7,845,904, and US 8,002,516).

Majid Rashidi, Ph.D., P.E.

2012-10-30

323

CFD MODELING AND ANALYSIS FOR A-AREA AND H-AREA COOLING TOWERS  

SciTech Connect

Mechanical draft cooling towers are designed to cool process water via sensible and latent heat transfer to air. Heat and mass transfer take place simultaneously. Heat is transferred as sensible heat due to the temperature difference between liquid and gas phases, and as the latent heat of the water as it evaporates. Mass of water vapor is transferred due to the difference between the vapor pressure at the air-liquid interface and the partial pressure of water vapor in the bulk of the air. Equations to govern these phenomena are discussed here. The governing equations are solved by taking a computational fluid dynamics (CFD) approach. The purpose of the work is to develop a three-dimensional CFD model to evaluate the flow patterns inside the cooling tower cell driven by cooling fan and wind, considering the cooling fans to be on or off. Two types of the cooling towers are considered here. One is cross-flow type cooling tower located in A-Area, and the other is counterflow type cooling tower located in H-Area. The cooling tower located in A-Area is mechanical draft cooling tower (MDCT) consisting of four compartment cells as shown in Fig. 1. It is 13.7m wide, 36.8m long, and 9.4m high. Each cell has its own cooling fan and shroud without any flow communications between two adjacent cells. There are water distribution decks on both sides of the fan shroud. The deck floor has an array of about 25mm size holes through which water droplet falls into the cell region cooled by the ambient air driven by fan and wind, and it is eventually collected in basin area. As shown in Fig. 1, about 0.15-m thick drift eliminator allows ambient air to be humidified through the evaporative cooling process without entrainment of water droplets into the shroud exit. The H-Area cooling tower is about 7.3 m wide, 29.3 m long, and 9.0 m high. Each cell has its own cooling fan and shroud, but each of two corner cells has two panels to shield wind at the bottom of the cells. There is some degree of flow communications between adjacent cells through the 9-in gap at the bottom of the tower cells as shown in Fig. 2. Detailed geometrical dimensions for the H-Area tower configurations are presented in the figure. The model was benchmarked and verified against off-site and on-site test results. The verified model was applied to the investigation of cooling fan and wind effects on water cooling in cells when fans are off and on. This report will discuss the modeling and test results.

Lee, S.; Garrett, A.; Bollinger, J.

2009-09-02

324

Science and Technical Considerations for Wind Farm Siting  

NSDL National Science Digital Library

This instructional module was created at the 2009 ATEEC Fellows Institute on Wind Power. The following sections are provided: An introduction to wind power classes, Offshore turbine tower foundations, Wind speed lab, Wind shear project, Turbulence and links to supporting resources. The classroom lessons include student worksheets. The entire guide may be downloaded in PDF file format. This resource is free to download. Users must first create a login with ATEEC's website to access the file.

2013-06-21

325

On the design and feasibility of a pneumatically supported actively guided space tower  

NASA Astrophysics Data System (ADS)

Space tethers have been investigated widely as a means to provide easy access to space. However, the design and construction of such a device presents significant unsolved technological challenges. An alternative approach is proposed to the construction of a space elevator that utilises a free-standing core structure to provide access to near space regions and to reduce the cost of space launch. The theoretical and experimental investigation of the bending of inflatable cylindrical cantilevered beams made of modem fabric materials provides the basis for the design of an inflatable space tower. Experimental model structures were deployed and tested in order to determine design guidelines for the core structure. The feasibility of the construction of a thin walled inflatable space tower of 20 km vertical extent comprised of pneumatically inflated sections that are actively controlled and stabilised to balance external disturbances and support the structure is discussed. The response of the structure under wind loads is analyzed and taken into account for determining design guidelines. Such an approach avoids problems associated with a space tether including material strength constraints, the need for in-space construction, the fabrication of a cable at least 50,000 km in length, and the ageing and meteorite damage effects associated with a thin tether or cable in Low Earth Orbit. A suborbital tower of 20 km height would provide an ideal mounting point where a geostationary orbital space tether could be attached without experiencing atmospheric turbulence and weathering in the lower atmosphere. The tower can be utilized as a platform for various scientific and space missions or as an elevator to carry payloads and tourists. In addition, space towers can significantly be utilized to generate electrical power by harvesting high altitude renewable energy sources. Keywords: Space Elevator, Inflatable Space Tower, Inflatable Structure, Inflatable Beam, Inflatable Multiple-beam Structure, Cantilevered Beam, Pneumatic Structures.

Seth, Raj Kumar

2010-07-01

326

COOLING TOWER PUMP HOUSE, TRA606. SECTION, LAYOUT OF TOWERS. BLAWKNOX ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

COOLING TOWER PUMP HOUSE, TRA-606. SECTION, LAYOUT OF TOWERS. BLAW-KNOX 3150-7-2, 9/1950. INL INDEX NO. 531-0607-00-098-100014, REV. 2. - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

327

Wet cooling towers: rule-of-thumb design and simulation  

SciTech Connect

A survey of wet cooling tower literature was performed to develop a simplified method of cooling tower design and simulation for use in power plant cycle optimization. The theory of heat exchange in wet cooling towers is briefly summarized. The Merkel equation (the fundamental equation of heat transfer in wet cooling towers) is presented and discussed. The cooling tower fill constant (Ka) is defined and values derived. A rule-of-thumb method for the optimized design of cooling towers is presented. The rule-of-thumb design method provides information useful in power plant cycle optimization, including tower dimensions, water consumption rate, exit air temperature, power requirements and construction cost. In addition, a method for simulation of cooling tower performance at various operating conditions is presented. This information is also useful in power plant cycle evaluation. Using the information presented, it will be possible to incorporate wet cooling tower design and simulation into a procedure to evaluate and optimize power plant cycles.

Leeper, S.A.

1981-07-01

328

Characterising the effect of a variety of surface roughness on boundary layer wind and dynamics within the scanning Doppler lidar network in Finland  

NASA Astrophysics Data System (ADS)

Aerosol particle and trace gas atmospheric content is controlled by natural and anthropological emissions. However, further dispersion in the atmosphere is driven by wind and dynamic mixing. Atmospheric surface and boundary layer dynamics have direct and indirect effects on weather, air quality and processes affecting climate (e.g. gas exchange between ecosystem and atmosphere). In addition to the amount of solar energy and prevailing meteorological condition, the surface topography has a strong influence on the close to surface wind field and turbulence, particularly in urban areas (e.g. Barlow and Coceal, 2009). In order to characterise the effect of forest, urban and coastal surfaces on boundary layer wind and mixing, we have utilised the Finnish Doppler lidar network (Hirsikko et al., 2013). The network consists of five 1.5 ?m Doppler lidars (HALO Photonics, Pearson et al., 2009), of which four are capable of full hemispheric scanning and are located at Helsinki (60.12°N, 25.58°E, 45 m asl.), Utö island (59.47°N, 21.23°E, 8 m asl.), SMEAR II at Hyytiälä (61.50°N, 24.17°E, 181 m asl.) and Kuopio (62.44°N, 27.32°E, 190 m asl.). The fifth lidar at Sodankylä (67.37°N, 26.63°E, 171 m asl.) is a new model designed for the Arctic environment with no external moving parts, but still retains limited scan capability. Investigation of boundary layer wind and mixing condition can now be extended beyond vertical profiles of horizontal wind, and dissipation rate of turbulent kinetic energy (O'Connor et al., 2010) throughout the boundary layer. We have applied custom designed scanning routines for 3D-observation of the wind fields and simultaneous aerosol particle distribution continuously for over one year at Helsinki and Utö, and began similar scanning routines at Kuopio and Hyytiälä in spring 2013. In this long term project, our aims are to 1) characterise the effect of the land-sea interface and the urban environment on the wind and its turbulent nature near the surface (< 200 m above the ground) observed at our four measurement sites, 2) characterise aerosol particle spatial and temporal distribution, and 3) deploy obtained results in air quality monitoring purpose and weather models. Here, we focus on wind field characterisation. The effect of sea, land and certain buildings were clear and evident in our wind data. The results compare favourably with in-situ point observations available indicating the applicability of the 3D-measurement routines and subsequent data analysis. Acknowledgements This research was supported by funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant 262254, and by the Maj and Tor Nessling foundation (Dispersion of air pollution in the boundary layer - new approach with scanning Doppler lidars). References Barlow J. and Coceal, O.: A review of urban roughness sublayer turbulence, Met Office Tech. Rep., Exeter, p. 68, 2009. Hirsikko, A., et al.: Observing aerosol particles, clouds and boundary layer wind: a new remote sensing network in Finland, in preparation for Atmos. Meas. Tech., 2013. O'Connor, E.J., Illingworth, A.J., Brooks, I.M., Westbrook, C.D., Hogan, R.J., Davies, F. and Brooks, B.J.: A Method for Estimating the Turbulent Kinetic Energy Dissipation Rate from a Vertically Pointing Doppler Lidar, and Independent Evaluation from Balloon-Borne In Situ Measurements, J. Atmos. Ocean. Technol., 27, 1652-1664, 2010. Pearson, G., Davies, F., and Collier, C.: An Analysis of the Performance of the UFAM Pulsed Doppler Lidar for Observing the Boundary Layer, J. Atmos. Ocean. Tech., 26, 240-250, 2009.

Hirsikko, Anne; O'Connor, Ewan J.; Wood, Curtis R.; Vakkari, Ville

2013-04-01

329

The Drop Tower Bremen -An Overview  

NASA Astrophysics Data System (ADS)

The Center of Applied Space Technology and Microgravity (ZARM) was founded in 1985 as an institute of the University of Bremen, which focuses on research on gravitational and space-related phenomena. In 1988, the construction of ZARM`s drop tower began. Since its inau-guration in September 1990, the eye-catching Drop Tower Bremen with a height of 146m and its characteristic glass roof has become twice a landmark on the campus of the University of Bremen and the emblem of the technology park Bremen. As such an outstanding symbol of space science in Bremen the drop tower provides an european unique facility for experiments under conditions of high-quality weightlessness with residual gravitational accelerations in the microgravity regime. The period of maximum 4.74s of each freely falling experiment at the Drop Tower Bremen is only limited by the height of the drop tower vacuum tube, which was fully manufactured of steal and enclosed by an outer concrete shell. Thus, the pure free fall height of each microgravity drop experiment is approximately 110m. By using the later in-stalled catapult system established in 2004 ZARM`s short-term microgravity laboratory is able to nearly double the time of free fall. This world-wide inimitable capsule catapult system meets scientists` demand of extending the period of weightlessness. During the catapult operation the experiment capsule performs a vertical parabolic flight within the drop tower vacuum tube. In this way the time of microgravity can be extended to slightly over 9s. Either in the drop or in the catapult operation routine the repetition rates of microgravity experiments at ZARM`s drop tower facility are the same, generally up to 3 times per day. In comparison to orbital platforms the ground-based laboratory Drop Tower Bremen represents an economic alternative with a permanent access to weightlessness on earth. Moreover, the exceptional high quality of weightlessness in order of 1e-6 g (in the frequency range below 100Hz) demonstrates a perfect experimental environment for unperturbed investigations of scientific phenomena. Motivated by these prospects many national and international groups have initialized research programs taking advantage of this drop tower facility. In respect thereof the spectrum of research fields and technologies in space-related conditions can be continuously enhanced at ZARM. In the first of our two talks we will give you an overview about the inner structure of ZARM, as well as the service and the operation offered by the ZARM Drop Tower Operation and Service Company (ZARM FAB mbH). The ZARM FAB mbH owned by the State Government of Bremen is a public company maintaining the drop tower facility and supporting experimentalists in scientific and technical questions before, during and after their drop or catapult campaigns. In detail, we will present you important technical drop tower informations, our support and the idea, how you can proceed with your microgravity-related experiment including all your requirements to successfully accomplish an entire drop or catapult campaign. In summary, we will illustrate the complete procedure, how to drop or to catapult an experiment capsule at the Drop Tower Bremen.

von Kampen, Peter; Könemann, Thorben; Rath, Hans J.

330

Harnessing wind power  

NASA Astrophysics Data System (ADS)

The design goals, test results, operating mechanisms, and ultimate limits of large wind energy conversion systems (WECS) are explored. NASA is currently managing and monitoring the performance of the Mod O, Mod OA, Mod 1, and Mod 2 wind turbines, which produce from 100 kW-2.5 MWe for grid interconnection. The Mod 2 machines have a 300 ft diam rotor, begin producing at 14 mph and achieve the rated output at 20 mph. Testing has shown the necessity of incorporating partial span pitch control, a flexible shaft, yaw control, microprocessor monitored wind condition sensors, and a soft-shell tower to lower vibration hazards with WECS. Large WECS have proved to be relatively nonpolluting, although some television and radio interference is present. Institutional issues for the protection of land, of aircraft flight paths, and for utility interconnect are outlined, and large WECS development programs in Denmark, Sweden, Spain, and Germany are described.

Fagenbaum, J.

1982-04-01

331

Wind Turbine Safety and Function Test Report for the Gaia-Wind 11-kW Wind Turbine  

SciTech Connect

This test was conducted as part of the U.S. Department of Energy's (DOE) Independent Testing project. This project was established to help reduce the barriers to wind energy expansion by providing independent testing results for small wind turbines (SWT). In total, four turbines were tested at the National Wind Technology Center (NWTC) as a part of this project. Safety and function testing is one of up to five tests performed on the turbines, including power performance, duration, noise, and power-quality tests. The results of the testing provide the manufacturers with reports that can be used for small wind turbine certification. The test equipment includes a Gaia-Wind 11-kW wind turbine mounted on an 18-m monopole tower. Gaia-Wind Ltd. manufactured the turbine in Denmark. The system was installed by the NWTC site operations group with guidance and assistance from Gaia-Wind.

Huskey, A.; Bowen, A.; Jager, D.

2010-01-01

332

Wind vanes in the antiquity  

NASA Astrophysics Data System (ADS)

Mesopotamia: An Akkadian tablet, the original of which was incised between about 1800 and 1600 B.C., makes explicit mention of a wind vane. Further three Sumero-Akkadian “dictionaries” have three different names for the single Akkadian name for wind vane. Since the latest period of flourishing of the Sumerian civilization took place between about 2 100 and 2000 B.C., wind vanes must have been in use in ancient Mesopotamia already about 4000 years ago, i.e. about 2000 years before the Chinese and Greeks had wind vanes. The Mesopotamian wind vanes were made of wood. China: It appears from the old Chinese literature that streamers were in use about the 2nd century B.C. in China for wind vanes. Shortly thereafter, a wind vane in the shape of a bird made of bronze is mentioned in the literature. Greece: The wind vane in the shape of a triton that was fixed, according to Vitruvius, to the top of the Tower of Winds at Athens, must have disappeared before A.D. 1436. Roman Empire: According to a passage in Dio Chrysostom's writtings, streamers appear to have been used for wind vanes. What seems to be the first wind vane in the shape of a cock, was erected in the 2nd century A.D. on the top of the mausoleum of the Flavians, in a North African province of the Roman Empire.

Lindgrén, S.; Neumann, J.

1983-06-01

333

Scaling wind characteristics for designing small and large wind turbines  

SciTech Connect

Since rotationally sampled wind speed spectra are required to explain the turbulence experienced by rotating wind-turbine blades, methods of estimating the shape and magnitude of the rotationally sampled wind-speed spectra for different sizes of turbines have been developed. The primary model used in this paper, called STRS-2, is an empirical one that processes turbulence measurements from a single meteorologial tower at any chosen site. The secondary model used is based upon homogeneous, isotropic turbulence theory. Several examples of direct measurement of rotationally sampled wind velocity for small turbines are used to complement the two models. Several comparisons of the estimates of turbulence experienced by different sizes of turbines indicate that all turbines will experience previously unanticipated turublence in the higher-frequency region. Further, the character and intensity of rotational sampled wind are shown to vary with the variation of turbine diameter, hub height, and rotation rate in a predictable manner.

Connell, J.R.; George, R.L.

1983-05-01

334

Establishing a Comprehensive Wind Energy Program  

SciTech Connect

This project was directed at establishing a comprehensive wind energy program in Indiana, including both educational and research components. A graduate/undergraduate course ME-514 - Fundamentals of Wind Energy has been established and offered and an interactive prediction of VAWT performance developed. Vertical axis wind turbines for education and research have been acquired, instrumented and installed on the roof top of a building on the Calumet campus and at West Lafayette (Kepner Lab). Computational Fluid Dynamics (CFD) calculations have been performed to simulate these urban wind environments. Also, modal dynamic testing of the West Lafayette VAWT has been performed and a novel horizontal axis design initiated. The 50-meter meteorological tower data obtained at the Purdue Beck Agricultural Research Center have been analyzed and the Purdue Reconfigurable Micro Wind Farm established and simulations directed at the investigation of wind farm configurations initiated. The virtual wind turbine and wind turbine farm simulation in the Visualization Lab has been initiated.

Fleeter, Sanford [Purdue University

2012-09-30

335

Pilot projects of network wind power plants in the eisk region of Krasnodar krai: the state and prospects  

NASA Astrophysics Data System (ADS)

The market of electric energy in the Krasnodar krai and the specific features of electric power supply in the Eisk region are analyzed. The basic aspects of designing wind power plants are considered. The main technical, economic, and environmental indicators of the wind power plants being designed are presented.

Gordeev, I. G.; Ermolenko, G. V.; Nikomarova, A. V.; Ryzhenkov, M. A.; Tskhomariya, V. N.

2012-11-01

336

WIND TUNNEL INVESTIGATION OF THE RESPONSE OF A SONIC ANEMOMETER  

EPA Science Inventory

An Applied Technology Inc. (ATI) sonic of the type used by J. C. Kaimal at the Boulder Tower was tested in the large wind tunnel at the U.S. EPA Fluid Modeling Facility. The wind tunnel is approximately 6 ft high, 10 ft wide with a test section bed 60 ft long. The air speed in th...

337

Wind, terrain and structural damping characteristics under tropical cyclone conditions  

Microsoft Academic Search

A large number of buildings and structures, including some well-engineered structures, have been reported to be damaged during tropical cyclones. This stresses the need to study the various characteristics of tropical cyclone winds. A full-scale field experiment on a 52 m tall steel lattice tower has been undertaken to study the wind, terrain and structural characteristics under normal and tropical

J. Shanmugasundaram; P. Harikrishna; S. Gomathinayagam; N. Lakshmanan

1999-01-01

338

RCS and radar propagation near offshore wind farms  

Microsoft Academic Search

The wind farm impact on marine radars has not been widely reported. Some past publications have touched on the subject but there has been no accurate model in place to readily examine the effects of different farm geometries, tower shapes and turbine sizes. This paper discusses the radar propagation modeling near offshore wind farms including the methods used to model

Laith S Rashid; Anthony K Brown

2007-01-01

339

Socioeconomic Impacts of the Langdon Wind Energy Center  

Microsoft Academic Search

The Langdon Wind Energy Center is the largest wind energy facility to be developed in North Dakota to date and consists of 106 turbines with a generating capacity of 1.5 MW each, mounted on towers 262 feet tall. The project is owned by FPL Energy and Ottertail Power Company; FPL Energy was the project developer. Construction of the facility began

F. Larry Leistritz; Randal C. Coon

2008-01-01

340

Wind energy systems  

NASA Astrophysics Data System (ADS)

Wind energy has matured to a level of development where it is ready to become a generally accepted utility generation technology. A brief discussion of this development is presented, and the operating and design principles are discussed. Alternative designs for wind turbines and the tradeoffs that must be considered are briefly compared. Development of a wind energy system and the impacts on the utility network including frequency stability, voltage stability, and power quality are discussed. The assessment of wind power station economics and the key economic factors that determine the economic viability of a wind power plant are presented.

Richardson, R. D.; McNerney, Gerald M.

1993-03-01

341

Influence of Wind Turbulence on Yaw-control Gears in Wind Turbine  

NASA Astrophysics Data System (ADS)

This paper describes an influence of wind turbulence on yaw-control gears of nacelle in a wind power station. This site is located in Tappi cape of Aomori prefecture where is characterized by a big wind turbulence due to the western strong wind and a steep slope of the cape. In this paper two adjacent wind towers are dealt with among eleven ones. To clarify an influence of the wind turbulence on the leeward wind power generator. The measurement results showed that the turbulence and the standard deviation exceeded IEC Wind Turbine Standards frequently. Accordingly the torque applied to the yaw control gears vibrated with short time period and its magnitude was frequently larger than 4.8 ton-m (47kN-m) regarded as the metal fatigue limit. By the method where the output of the wind turbine generator is controlled, the magnitude of the vibrating torque can be reduced under the limit of the material fatigue.

Suzuki, Kazuo; Hoshino, Naoki; Inomata, Noboru; Kimura, Hiroshi; Fujiwara, Tamiya

342

Radar Measurement of Cooling Tower Drift.  

NASA Astrophysics Data System (ADS)

A method of radar measurement of drift, generated by the wet cooling towers of power plants, is proposed. The water given off by the evaporative towers consists of two kinds of droplets: the recondensation droplets-generally less than 20 m in diameter and with a negligible rate of fall-and the drift droplets, arising from spraying of cooling water, entrained out of the tower in the exhaust air flow. Both components partake in the radar reflectivity of the plumes. A very close relation is found between the water content and the reflectivity factor of the recondensation cloud. For a same liquid water content, the reflectivity of the recondensation cloud is 20 dB lower than that of warm cumulus clouds. The knowledge of the cooling tower working point and of the surrounding air conditions enables the evaluation of the recondensation cloud contribution to the reflectivity. In the next step, assuming that the drift droplet population is represented by a gamma distribution, functional relations are developed enabling the computation of the number density, the water content and the precipitation rate of cooling tower drift from the radar reflectivity factor of the drift component. Some observations are presented to illustrate the proposed method and to show that, owing to the presence of the cooling droplets, the radar outlines of the plume noticeably differ from its visual outlines. The radar thus enables a quantitative monitoring of the microstructure of the plumes emitted by the atmospheric cooling tower parks, i.e., a measurement of the efficiency of the drift droplet eliminators.

Sauvageot, Henri

1989-09-01

343

Wind resource characterization results to support the Sandia Wind Farm Feasibility Study : August 2008 through March 2009.  

SciTech Connect

Sandia National Laboratories Wind Technology Department is investigating the feasibility of using local wind resources to meet the requirements of Executive Order 13423 and DOE Order 430.2B. These Orders, along with the DOE TEAM initiative, identify the use of on-site renewable energy projects to meet specified renewable energy goals over the next 3 to 5 years. A temporary 30-meter meteorological tower was used to perform interim monitoring while the National Environmental Policy Act (NEPA) process for the larger Wind Feasibility Project ensued. This report presents the analysis of the data collected from the 30-meter meteorological tower.

Deola, Regina Anne

2010-01-01

344

Keystone station cooling tower fill fouling  

SciTech Connect

This paper reports on Keystone Station which is a coal-fired nine-mouth electric generating station located 50 miles northeast of Pittsburgh in western Pennsylvania, with two 850 MW supercritical pressure generating units. Main condenser and service water cooling is provided by two natural draft hyperbolic cooling towers per unit. Each of the four cooling towers is 325 feet tall and 247 feet across at the basin. Operation of the station began in 1967. A consortium of mid-Atlantic utilities owns Keystone Station, and it is operated by the Pennsylvania Electric Company.

Gall, G.P. (Pennsylvania Electric Co., Keystone Generating Station, Shelocta, PA (US))

1992-01-01

345

The new Drop Tower catapult system  

NASA Astrophysics Data System (ADS)

The Center of Applied Space Technology and Microgravity (ZARM) was founded in 1985 as an institute of the University Bremen, which focuses on research on gravitational and space-related phenomena. In 1988, the construction of the "Drop Tower" began. Since then, the eye-catching tower with a height of 146 m and its characteristic glass roof has become the emblem of the technology centre in Bremen. The Drop Tower Bremen provides a facility for experiments under conditions of weightlessness. Items are considered weightless, when they are in "free fall", i.e. moving without propulsion within the gravity field of the earth. The height of the tower limits the simple "free fall" experiment period to max. 4.74 s. With the inauguration of the catapult system in December 2004, the ZARM is entering a new dimension. This world novelty will meet scientists' demands of extending the experiment period up to 9.5 s. Since turning the first sod on May 3rd, 1988, the later installation of the catapult system has been taken into account by building the necessary chamber under the tower. The catapult system is located in a chamber 10 m below the base of the tower. This chamber is almost completely occupied by 12 huge pressure tanks. These tanks are placed around the elongation of the vacuum chamber of the drop tube. In its centre there is the pneumatic piston that accelerates the drop capsule by the pressure difference between the vacuum inside the drop tube and the pressure inside the tanks. The acceleration level is adjusted by means of a servo hydraulic breaking system controlling the piston velocity. After only a quarter of a second the drop capsule achieves its lift-off speed of 175 km/h. With this exact speed, the capsule will rise up to the top of the tower and afterwards fall down again into the deceleration unit which has been moved under the drop tube in the meantime. The scientific advantages of the doubled experiment time are obvious: during almost 10 s of high-quality weightlessness the range of compatible experiments amplifies even more and researchers can observe processes for a longer period of time. Thus, the new earth-bound laboratory of the ZARM offers unique conditions for scientific research. Moreover, it increases the attractiveness of the Drop Tower and contributes an important part to the establishment of the Bremen as an international centre for space technology.

von Kampen, Peter; Kaczmarczik, Ulrich; Rath, Hans J.

2006-07-01

346

Wind Energy Opportunities, Challenges, and Progress Within the Federal Government (Poster)  

SciTech Connect

Wind Powering America (WPA) works with Federal agencies to increase their understanding of wind resources and assessment; facilitate project development activities through Met tower loans, wind data analysis, and technical assistance; and provide advice on RFP development and financing options. This poster provides an overview of WPA's activities with the federal sector.

Robichaud, R.

2009-05-01

347

Research results for the Tornado wind energy system: analysis and conclusions  

Microsoft Academic Search

The Tornado Wind Energy System (TWES) concept utilizes a wind-driven vortex confined by a hollow tower to create a low-pressure core intended to serve as a turbine exhaust reservoir. The turbine inlet flow is provided by a separate ram air supply. Numerous experimental and analytical research efforts have investigated the potential of the TWES as a wind energy conversion system

E. W. Jacobs

1985-01-01

348

Wind Turbulence Characteristics Analysis of Near Sea Area, Rudong, Jiangsu Province, China  

Microsoft Academic Search

The wind characteristics of coastal area are analyzed with the whole year observations of 2005 at a wind observation tower locating at Rudong County, Jiangsu Province, China. In this area both turbulence intensity and gust factor vary with time, height and wind speed. Gust factor and turbulence intensity share a strong linear relationship. Turbulence intensity is of medium-level at low

Yan Chen; Xiazhen Xu

2009-01-01

349

LARGE SCALE DEPLOYMENT OF RENEWABLE ENERGY BY COMBINING WIND FARMS WITH SOLAR THERMAL POWER PLANTS  

Technology Transfer Automated Retrieval System (TEKTRAN)

The installation of megawatt-size wind turbines on 65 to 80 meter towers at Class 4 wind sites in Texas has resulted in the cheapest form of renewable energy ($0.04/kWh). However, wind farm output has a diurnal mismatch to the utility electrical loading. Combining solar thermal power plants with w...

350

On the dynamics of the pitch control loop in horizontal-axis large wind turbines  

Microsoft Academic Search

Most commercial large wind turbines use blade pitch action to mitigate structural loads in high wind velocity conditions. In this paper, we study the linearized dynamics of the map from blade pitch to tower top fore-aft deflection in horizontal-axis wind turbines. We show that the mass and stiffness distribution of the blades at certain operating conditions determine the presence (or

Shashikanth Suryanarayanan; Amit Dixit

2005-01-01

351

2. Slacking Tower south side, view to the northnortheast. ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. Slacking Tower south side, view to the north-northeast. - Washington Water Power Clark Fork River Noxon Rapids Hydroelectric Development, Slacking Tower, South bank of Clark Fork River at Noxon Rapids, Noxon, Sanders County, MT

352

North and west sides of the cooling tower, utility building ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

North and west sides of the cooling tower, utility building (building 2606) is in the background at right - March Air Force Base, Strategic Air Command, Cooling Tower, 5220 Riverside Drive, Moreno Valley, Riverside County, CA

353

1. Keeper's house and light tower, view northwest, south and ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. Keeper's house and light tower, view northwest, south and east sides of keeper's house, southwest and southeast sides of light tower - Curtis Island Light Station, Curtis Island, at entrance to Camden Harbor, Camden, Knox County, ME

354

View of EPA Farm metal weather tower, facing east, showing ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

View of EPA Farm metal weather tower, facing east, showing thirty-acre irrigated field - Nevada Test Site, Environmental Protection Agency Farm, Weather Tower, Area 15, Yucca Flat, 10-2 Road near Circle Road, Mercury, Nye County, NV

355

50. NORTHERN VIEW OF NONEVAPORATIVE WASTE WATER TREATMENT COOLING TOWERS ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

50. NORTHERN VIEW OF NON-EVAPORATIVE WASTE WATER TREATMENT COOLING TOWERS IN CENTER, AND EVAPORATIVE WASTE WATER COOLING TOWERS ON RIGHT. (Jet Lowe) - U.S. Steel Duquesne Works, Blast Furnace Plant, Along Monongahela River, Duquesne, Allegheny County, PA

356

26. Evening view of concrete mixing plant, concrete placement tower, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

26. Evening view of concrete mixing plant, concrete placement tower, cableway tower, power line and derrick. Photographer unknown, 1927. Source: MWD. - Waddell Dam, On Agua Fria River, 35 miles northwest of Phoenix, Phoenix, Maricopa County, AZ

357

FIELD INVESTIGATIONS OF MECHANICAL DRAFT COOLING TOWER PLUMES  

EPA Science Inventory

Tethered Kitoon (small blimp) sampling techniques were devised to measure the distribution of temperature and humidity in the invisible portion of power plant cooling tower plumes from both single cell and multiple cell cooling towers under several conditions. These measurements,...

358

1. VIEW NORTHWEST, operations building, height finder radar tower, and ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. VIEW NORTHWEST, operations building, height finder radar tower, and radar tower (unknown function) - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

359

9. VIEW OF THE EAST BASE CONNECTION OF ANTENNA TOWER ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

9. VIEW OF THE EAST BASE CONNECTION OF ANTENNA TOWER S-111 FACING SOUTHWEST. BUILDING 205 IN THE BACKGROUND. - U.S. Naval Base, Pearl Harbor, Lualualei Radio Transmitter, Edison & Tower Drives, Pearl City, Honolulu County, HI

360

Cooling Tower Drift Deposition Measurement at the ORGDP.  

National Technical Information Service (NTIS)

In a continuing effort to investigate cooling tower drift, droplet and mineral deposition fluxes were measured near the cooling towers at the Oak Ridge Gaseous Diffusion Plant (ORGDP) from 1979 to 1982. These measurements were conducted at various times o...

S. H. Park

1983-01-01

361

Interception and Retention of Simulated Cooling Tower Drift by Vegetation.  

National Technical Information Service (NTIS)

A key issue concerning environmental impacts from cooling tower operation is the interception of drift by vegetation and the efficiency of plants in retaining the residue scavenged from the atmosphere. Chromated drift water, typical of the cooling towers ...

F. G. Taylor P. D. Parr

1978-01-01

362

28. WEST CONFEDERATE AVENUE, OBSERVATION TOWER, VIEW FROM THE TOP ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

28. WEST CONFEDERATE AVENUE, OBSERVATION TOWER, VIEW FROM THE TOP OF TOWER TO SOUTH. NOTE FOREST AND AGRICULTURAL LANDSCAPES. VIEW S. - Gettysburg National Military Park Tour Roads, Gettysburg, Adams County, PA

363

29. Photocopy of 1921 photograph. Glass Negative Box IX, Tower ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

29. Photocopy of 1921 photograph. Glass Negative Box IX, Tower Grove, Missouri Botanical Garden. ITALIAN GARDEN AND NEW PALM HOUSE (DEMOLISHED), LOOKING NORTHEAST - Missouri Botanical Garden, 2345 Tower Grove Avenue, Saint Louis, Independent City, MO

364

10. View west along carillon tower axis from base of ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

10. View west along carillon tower axis from base of tower to gates in western estate wall at SR 141 - A. I. Du Pont Estate, Junction of State Route 141 & Rockland Road, Wilmington, New Castle County, DE

365

4. View of center tower at Clover Island, facing northeast. ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

4. View of center tower at Clover Island, facing northeast. Pasco-Kennewick automobile bridge in background, lower right. - Pasco-Kennewick Transmission Line, Columbia River Crossing Towers, Columbia Drive & Gum Street, Kennewick, Benton County, WA

366

3. View of north tower, facing north across the main ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. View of north tower, facing north across the main channel of the Columbus River from Clover Island. - Pasco-Kennewick Transmission Line, Columbia River Crossing Towers, Columbia Drive & Gum Street, Kennewick, Benton County, WA

367

6. View of south tower, facing south from Clover Island, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. View of south tower, facing south from Clover Island, across boat moorage channel. - Pasco-Kennewick Transmission Line, Columbia River Crossing Towers, Columbia Drive & Gum Street, Kennewick, Benton County, WA

368

1. View of north tower, facing northwest from dike on ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. View of north tower, facing northwest from dike on north bank of the Columbia River. - Pasco-Kennewick Transmission Line, Columbia River Crossing Towers, Columbia Drive & Gum Street, Kennewick, Benton County, WA

369

15. VIEW OF COAL TOWER No. 2, LOOKING WEST TO ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

15. VIEW OF COAL TOWER No. 2, LOOKING WEST TO EAST FROM COAL TOWER No. 1 (FLOOR BELOW CRANE CONTROL) - Delaware County Electric Company, Chester Station, Delaware River at South end of Ward Street, Chester, Delaware County, PA

370

14. WEST ELEVATION OF COAL TOWER No. 2, LOOKING WEST ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

14. WEST ELEVATION OF COAL TOWER No. 2, LOOKING WEST TO EAST FROM COAL TOWER No. 1 (FLOOR BELOW THE CRANE CONTROL) - Delaware County Electric Company, Chester Station, Delaware River at South end of Ward Street, Chester, Delaware County, PA

371

156. Copy of Louis Rosenberg Etching (original in the Tower ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

156. Copy of Louis Rosenberg Etching (original in the Tower City Development Office) THE STEAM CONCOURSE UNDER CONSTRUCTION, PROSPECT AVENUE, VIEW EAST TO WEST - Terminal Tower Building, Cleveland Union Terminal, 50 Public Square, Cleveland, Cuyahoga County, OH

372

154. Copy of Louis Rosenberg Etching (original in the Tower ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

154. Copy of Louis Rosenberg Etching (original in the Tower City Development Office) THE STATION AREA UNDER CONSTRUCTION, TEMPORARY BRIDGES, VIEW WEST TO EAST - Terminal Tower Building, Cleveland Union Terminal, 50 Public Square, Cleveland, Cuyahoga County, OH

373

155. Copy of Louis Rosenberg Etching (original in the Tower ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

155. Copy of Louis Rosenberg Etching (original in the Tower City Development Office) EXCAVATION OF TRACK AREA TO THE SOUTH OF HURON ROAD, VIEW WEST TO EAST - Terminal Tower Building, Cleveland Union Terminal, 50 Public Square, Cleveland, Cuyahoga County, OH

374

152. Copy of Louis Rosenberg Etching (original in the Tower ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

152. Copy of Louis Rosenberg Etching (original in the Tower City Development Office, Cleveland, Ohio) SOUTH ELEVATION FROM ACROSS THE CUYAHOGA RIVER, VIEW TO NORTH - Terminal Tower Building, Cleveland Union Terminal, 50 Public Square, Cleveland, Cuyahoga County, OH

375

OVERVIEW OF VALVE TOWER FROM EASTERN SIDE OF BASIN SHOWING ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

OVERVIEW OF VALVE TOWER FROM EASTERN SIDE OF BASIN SHOWING BRIDGE SUPPORTS ON HILLTOP. VIEW FACING WEST - Schofield Barracks Military Reservation, Ku Tree Reservoir, Valve Tower, Kalakoa Stream East Range, Wahiawa, Honolulu County, HI

376

OVERVIEW OF VALVE TOWER FROM NORTHERN SIDE OF BASIN. VIEW ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

OVERVIEW OF VALVE TOWER FROM NORTHERN SIDE OF BASIN. VIEW FACING SOUTHWEST - Schofield Barracks Military Reservation, Ku Tree Reservoir, Valve Tower, Kalakoa Stream East Range, Wahiawa, Honolulu County, HI

377

APPROACH BRIDGE PORTION OF VALVE TOWER FOOT BRIDGE, AS SEEN ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

APPROACH BRIDGE PORTION OF VALVE TOWER FOOT BRIDGE, AS SEEN FROM ENTRY. VIEW FACING NORTHWEST - Schofield Barracks Military Reservation, Ku Tree Reservoir, Valve Tower Foot Bridge, Kalakoa Stream East Range, Wahiawa, Honolulu County, HI

378

Input turbulence features at a megawatt-size wind turbine, Medicine Bow, Wyoming  

SciTech Connect

In response to recent observations that wind turbulence has a strong effect on wind turbine fatigue life, measurements of turbulent wind velocity profiles have been made at the Medicine Bow, Wyoming, WTS-4 wind turbine site. These measurements were taken at seven levels spanning the WTS-4 rotor height on a single meteorological tower 1.75 rotor diameters upstream of the turbine. Concurrent measurements of rotor response were also made. Analysis of the winds at the Medicine Bow site reveals the influence of atmospheric and geographic conditions on what may at first glance appear to be a 'classic, simple, flat terrain' case. The turbulence data are then analyzed to (1) characterize the wind in terms of fixed-point, single-tower properties and (2) model the wind properties as they would be experienced by points on rotating turbine blades. The STRS-2 model, developed by the Pacific Northwest Laboratory, is used to convert single-tower wind characteristics into those that would be measured from an array of towers arranged in a crosswind line covering the rotor disk. A response function for the flatwise root bending moment of one of the WTS-4 turbine blades is computed using the turbine data and the STRS-2 data. The STRS-2 model provides a substantially improved correlation with wind turbine blade bending moment over other single-tower estimation methods. 14 refs., 10 figs., 1 tab.

Connell, J.R.; Morris, V.R.; Hinchee, M.E.

1986-12-01

379

Input turbulence features at a megawatt-size wind turbine, Medicine Bow, Wyoming  

NASA Astrophysics Data System (ADS)

In response to recent observations that wind turbulence has a strong effect on wind turbine fatigue life, measurements of turbulent wind velocity profiles have been made at the Medicine Bow, Wyoming, WTS-4 wind turbine site. These measurements were taken at seven levels spanning the WTS-4 rotor height on a single meteorological tower 1.75 rotor diameters upstream of the turbine. Concurrent measurements of rotor response were also made. Analysis of the winds at the Medicine Bow site reveals the influence of atmospheric and geographic conditions on what may at first glance appear to be a classic, simple, flat terrain case. The turbulence data are then analyzed to: (1) characterize the wind in terms of fixed-point, single-tower properties, and (2) model the wind properties as they would be experienced by points on rotating turbine blades. The STRS-2 model, developed by the Pacific Northwest Laboratory, is used to convert single-tower wind characteristics into those that would be measured from an array of towers arranged in a crosswind line covering the rotor disk. A response function for the flatwise root bending moment of one of the WTS-4 turbine blades is computed using the turbine data and the STRS-2 data. The STRS-2 model provides a substantially improved correlation with wind turbine blade bending moment over other single-tower estimation methods.

Connell, J. R.; Morris, V. R.; Hinchee, M. E.

1986-12-01

380

Input turbulence features at a megawatt-size wind turbine at Medicine Bow, Wyoming  

SciTech Connect

In response to recent observations that wind turbulence has a strong effect on wind turbine fatigue life, measurements of turbulent wind velocity profiles have been made at the Medicine Bow, Wyo., WTS-4 wind turbine site. These measurements were taken at seven levels spanning the WTS-4 rotor height on a single meteorological tower 1.75 rotor diameters upstream of the turbine. Concurrent measurements of rotor response were also made. Analysis of the winds at the Medicine Bow site reveals the influence of atmospheric and geographic conditions on what may, at first glance, appear to be a classic, simple, flat terrain case. The turbulence data are analyzed to (1) characterize the wind in terms of fixed-point, single-tower properties and (2) model the wind properties as they would be experienced by points on rotating turbine blades. The STRS-2 model, developed by the Pacific Northwest Laboratory, is used to convert single-tower wind characteristics into an estimate of those that would be measured from an array of towers arranged in a crosswind line covering the rotor disk. A response function for the flatwise root bending moment of one of the WTS-4 turbine blades is computed using the turbine data and the STRS-2 data. The STRS-2 model provides a substantially improved correlation with wind turbine blade bending moment over other single-tower estimation methods.

Connell, J.R.; Morris, V.R.; Hinchee, M.E.

1989-02-01

381

Addressing the unique safety and design concerns for operating tower-based scientific field campaigns.  

NASA Astrophysics Data System (ADS)

Scientific field campaigns often require specialized technical infrastructure for data collection. NASA's LBA- ECO Science Team needed a network of towers, up to 65 meters in height, to be constructed in the Amazon forest to serve as platforms for instrumentation used to estimate carbon dioxide and trace gas fluxes between the forest and the atmosphere. The design, construction, and operation of these scientific towers represented unique challenges to the construction crews, the logistics support staff, and the scientists due to operational requirements beyond tower site norms. These included selection of safe sites at remote locations within a dense forest; building towers without damaging the natural environment; locating diesel generators so that exhaust would not contaminate the measurement area; performing maintenance on continuously energized towers so as not to interrupt data collection; training inexperienced climbers needing safe access to towers; and addressing unique safety concerns (e.g. venomous animal response, chainsaw safety, off road driving). To meet the challenges of the complex field site, a comprehensive safety and site operation model was designed to ensure that NASA field safety standards were met, even under extreme conditions in the remote forests of the Amazon. The model includes all phases of field site safety and operation, including site design, construction, operational practices and policies, and personnel safety training. This operational model was employed over eight years, supporting a team of nearly 400 scientists, making several thousand site visits, without loss of life or major injury. The presentation will explore these concerns and present a model for comprehensive safety plans for NASA field missions.

Steele, A. C.

2006-12-01

382

Tower packings cut olefin-plant energy needs  

Microsoft Academic Search

Replacing trays with metal tower packings in ethylene plant hot-section towers results in significant pressure drop reductions. Major ethylene producers are applying this technology to achieve various process improvements. At E.I. du Pont de Nemours and Co.'s Sabine River works (Texas) ethylene plant, tower packing was installed in the top section of the water quench tower to reduce energy requirements

J. R. Sauter; W. E. Younts

1986-01-01

383

1. Slacking Tower north side, view to the southsouthwest. The ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. Slacking Tower north side, view to the south-southwest. The tower was used for dredging the river downstream of the powerhouse. - Washington Water Power Clark Fork River Noxon Rapids Hydroelectric Development, Slacking Tower, South bank of Clark Fork River at Noxon Rapids, Noxon, Sanders County, MT

384

Energy and Mass Transfer Phenomena in Natural Draft Cooling Towers  

Microsoft Academic Search

In this paper, the development of natural draft cooling towers diagnostics is presented. Diagnostic method is based on measurements of velocity and temperature fields of the airflow in the entire surface area of cooling tower and the raised phenomenological model of heat and mass transfer in a selected reference vertical segment of cooling tower. Velocity and temperature fields of the

B. Sirok; B. Blagojevic; M. Novak; M. Hocevar; F. Jere

2003-01-01

385

Investigations on Operational Behaviour of Hybrid Cooling Towers.  

National Technical Information Service (NTIS)

The operating characteristics of various types of hybrid cooling towers have been compared. For this purpose, a given wet cooling tower has been combined with a given dry cooling tower by varying the air and water circuit without changing the operating co...

U. Haeuser

1981-01-01

386

Improving the efficiency of natural draft cooling towers  

Microsoft Academic Search

This study shows how the efficiency of a natural draft cooling tower can be improved by optimising the heat transfer along the cooling tower (CT) packing using a suitable water distribution across the plane area of the cooling tower. On the basis of cooling air measurements, it is possible to distribute the water in such a way that it approaches

J. Smrekar; J. Oman; B. Širok

2006-01-01

387

Legionnaires' disease outbreaks and cooling towers with amplified Legionella concentrations  

Microsoft Academic Search

This study was designed to investigate the possible association of high colony counts of legionellae from cooling towers and evaporative condensers with Legionnaires' disease outbreaks. We obtained legionellae counts from samples of cooling towers and evaporative condensers that were the likely sources of two different Legionnaires' disease outbreaks and compared these counts with those from cooling towers that were not

Brian G. Shelton; W. Dana Flanders; George K. Morris

1994-01-01

388

Performance characteristics of counter flow wet cooling towers  

Microsoft Academic Search

Cooling towers are one of the biggest heat and mass transfer devices that are in widespread use. In this paper, we use a detailed model of counter flow wet cooling towers in investigating the performance characteristics. The validity of the model is checked by experimental data reported in the literature. The thermal performance of the cooling towers is clearly explained

Jameel-Ur-Rehman Khan; M. Yaqub; Syed M. Zubair

2003-01-01

389

An investigation into a falling film type cooling tower  

Microsoft Academic Search

A model for a falling film type cooling tower has been developed to investigate the effect of tower parameters as well as the effect of liquid-side thermal resistance on the tower performance. The energy equation is used to determine the temperature distribution across the liquid film. The heat and mass transfer processes between the liquid film and air bulk are

M. Z Anabtawi

1995-01-01

390

Solar Power Tower Design Basis Document, Revision 0  

Microsoft Academic Search

This report contains the design basis for a generic molten-salt solar power tower. A solar power tower uses a field of tracking mirrors (heliostats) that redirect sunlight on to a centrally located receiver mounted on top a tower, which absorbs the concentrated sunlight. Molten nitrate salt, pumped from a tank at ground level, absorbs the sunlight, heating it up to

ALEXIS B

2001-01-01

391

Solar Power Tower Design Basis Document, Revision 0.  

National Technical Information Service (NTIS)

This report contains the design basis for a generic molten-salt solar power tower. A solar power tower uses a field of tracking mirrors (heliostats) that redirect sunlight on to a centrally located receiver mounted on top a tower, which absorbs the concen...

Zavoico

2001-01-01

392

Tower Investigation and the Egg. Grades 6-8.  

ERIC Educational Resources Information Center

|Towers have been a part of developing society for centuries. In this activity, students investigate towers that serve a variety of purposes. Student groups build three types of towers, engineering them to hold an egg one foot high for 15 seconds. This activity requires a 60-minute time period for completion. (Author/SOE)|

Rushton, Erik; Ryan, Emily; Swift, Charles

393

3. View from former light tower to Cape Elizabeth Light ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. View from former light tower to Cape Elizabeth Light Tower, view northeast, southwest side of Cape Elizabeth Tower - Cape Elizabeth Light Station, Near Two Lights State Park at end of Two Lights Road, off State Highway 77, Cape Elizabeth, Cumberland County, ME

394

6. Detail of northeast corner of Shell Interlocking Tower, showing ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. Detail of northeast corner of Shell Interlocking Tower, showing ornamental east concrete beltcourse and tower shield with bronze numerals. - New York, New Haven, & Hartford Railroad, Shell Interlocking Tower, New Haven Milepost 16, approximately 100 feel east of New Rochelle Junction, New Rochelle, Westchester County, NY

395

Initial Model For Fires In The World Trade Center Towers  

Microsoft Academic Search

Based on preliminary assumptions and analysis, mathematical models have been used to estimate the behavior of the fires in the twin towers of the World Trade Center (WTC) on September 11, 2001. The hijacked-plane collision with each tower produced significant structural damage, generated a spectacular external fireball, and started burning within the tower. The fuel consumed by the fireball was

Ronald G. Rehm; William M. Pitts; Howard R. Baum; David D. Evans; Kuldeep Prasad; Kevin B. McGrattan; Glenn P. Forney

2003-01-01

396

Assessment of damages and repair of antenna tower concrete foundations  

Microsoft Academic Search

Deterioration of antenna tower foundations is fast becoming an issue of critical importance. A great effort has been carried out to develop the international standards for design and construction of antenna towers and antenna-supporting structures. Comparatively little attention has been directed toward the design against failure of buried tower components. In this paper a case study is introduced for the

H. A. Abdalla

2002-01-01

397

38. View from top of Brooklyn Tower showing man walking ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

38. View from top of Brooklyn Tower showing man walking up main cable, stay cables radiating from top of tower and tower cornice. Jet Lowe, photographer, 1982. - Brooklyn Bridge, Spanning East River between Park Row, Manhattan and Sands Street, Brooklyn, New York, New York County, NY

398

2. VIEW SOUTHWEST, prime search radar tower, height finder radar ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. VIEW SOUTHWEST, prime search radar tower, height finder radar towards, height finder radar towers, and radar tower (unknown function) - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

399

4. VIEW NORTHEAST, radar tower (unknown function), prime search radar ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

4. VIEW NORTHEAST, radar tower (unknown function), prime search radar tower, emergency power building, and height finder radar tower - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

400

CONCRETE PAD AND SUSPENSION BRIDGE TOWERS FOR CABLES FORMERLY SUPPORTING ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

CONCRETE PAD AND SUSPENSION BRIDGE TOWERS FOR CABLES FORMERLY SUPPORTING THE SUSPENSION BRIDGE PORTION OF VALVE TOWER FOOT BRIDGE. VIEW FACING NORTHEAST - Schofield Barracks Military Reservation, Ku Tree Reservoir, Valve Tower Foot Bridge, Kalakoa Stream East Range, Wahiawa, Honolulu County, HI

401

Evaluation of cooling tower environmental effects  

Microsoft Academic Search

Cooling towers interact with the environment through the discharge of blowdown to a lake or stream and through the emission of moisture and warmed air to the atmosphere. The environmental effects of these interactions can be evaluated by measuring various physical and chemical properties of the cooling system and of the ambient meteorology and hydrology. Blowdown parameters used in this

G. W. Nicholas; D. M. Sopocy

1974-01-01

402

CFD simulation of wet cooling towers  

Microsoft Academic Search

Heat and mass transfer inside a natural draft wet cooling tower (NDWCT) have been investigated numerically under different operating and crosswind conditions. The three-dimensional CFD model has utilized the standard k–? turbulence model as the turbulence closure. The current simulation has adopted both the Eulerian approach for the air phase and the Lagrangian approach for the water phase. The film

Rafat Al-Waked; Masud Behnia

2006-01-01

403

On the optimum sizing of cooling towers  

Microsoft Academic Search

The optimum heat and mass transfer area at which minimum cost exists throughout the technical life of forced draft counter-current cooling towers is studied in the present work. Original formulae are developed and presented for the best thermoeconomical performance as a design point.

M. S Söylemez

2001-01-01

404

Tower Power: Producing Fuels from Solar Energy  

ERIC Educational Resources Information Center

This article examines the use of power tower technologies for the production of synthetic fuels. This process overcomes the limitations of other processes by using a solar furnace to drive endothermic fuel producing reactions and the resulting fuels serve as a medium for storing solar energy. (BT)

Antal, M. J., Jr.

1976-01-01

405

Solar thermal electricity - Power tower dominates research  

Microsoft Academic Search

The Energy Research and Development Administration (ERDA) has tended to favor development of centralized solar thermal generating plants at the expense of smaller scale intermediate-temperature systems, though, according to a report from the Office of Technology Assessment (OTA), the large solar electric plant, such as the 'power tower' presently being promoted by ERDA and the Electric Power Research Institute (EPRI),

W. D. Metz

1977-01-01

406

Cooling Towers. Bibliography, January--December 1978.  

National Technical Information Service (NTIS)

Included are 382 citations to references on cooling towers for fossil-fuel or nuclear power plants. A few citations are included on other types of condenser cooling systems, e.g., cooling ponds and canals. The citations were taken from the DOE Energy Info...

D. O. Galde

1979-01-01

407

WET/DRY COOLING TOWER TEST MODULE  

EPA Science Inventory

The report gives results of an evaluation of the engineering performance of a single-cell wet/dry cooling tower (about 25 MW) in an 18-month field test at San Bernardino, CA. Test objectives included determination of the water conservation and operating characteristics, and verif...

408

Critical point wetting drop tower experiment  

Microsoft Academic Search

Experiments with the wetting behavior of immiscible fluids against the container below the critical temperature are being performed in the MSFC Drop Tower Facility. Microgravity conditions extending up to three seconds (of the 4.5 second drop) are generated for the experiment. Specimens consist of glass cylindrical ampoules partially filled with fluid phases. How the fluids develop the meniscus geometry as

William F. Kaulker

1988-01-01

409

Computational intelligence and tower defence games  

Microsoft Academic Search

The aim of this paper is to introduce the use of Tower Defence (TD) games in Computational Intelligence (CI) research. We show how TD games can provide an important test-bed for the often under-represented casual games research area. Additionally, the use of CI in the TD games has the potential to create a more interesting, interactive and ongoing game experience

Phillipa Avery; Julian Togelius; Elvis Alistar; Robert Pieter van Leeuwen

2011-01-01

410

The Tower and Glass Marbles Problem  

ERIC Educational Resources Information Center

|The Catseye Marble company tests the strength of its marbles by dropping them from various levels of their office tower, to find the highest floor from which a marble will not break. We find the smallest number of drops required and from which floor each drop should be made. We also find out how these answers change if a restriction is placed on…

Denman, Richard T.; Hailey, David; Rothenberg, Michael

2010-01-01

411

The linear twin Towers of Hanoi problem  

Microsoft Academic Search

We propose a simple new variation of the Towers of Hanoi problem, in which there are three pegs arranged in a row and there are two stacks (black, white) of n rings each, initially located on the end pegs. The object is to exchange the stacks in accordance with the usual Hanoi rules, and with the additional restriction that rings

Steven Minsker

2007-01-01

412

Update: Cooling tower and spray pond technology  

Microsoft Academic Search

The 9th Cooling Tower and Spray Pond Symposium, under the auspices of the International Association for Hydraulic Research, took place at the von Karman Institute for Fluid Dynamics, Belgium, in September 1994. Technical topics discussed included cooling system design, performance, operation, environmental effects, modeling and components. Symposium proceedings will not be published. However, information of primary interest to staffs of

Bartz

1995-01-01

413

Optimized Pointing Strategies for Solar Tower ACTs  

NASA Astrophysics Data System (ADS)

We discuss simulations of novel heliostat pointing configurations designed to improve the angular and energy resolution of a solar tower wavefront-sampling atmospheric Cherenkov telescope. One such configuration will be tested via observations of the Crab Nebula with the STACEE detector in the fall of 2003.

Scalzo, R. A.; Boone, L.M.; Bramel, D.; Carson, J.; Covault, C.E.; Fortin, P.; Gaunthier, G.; Gingrich, D.; Hanna, D.; Jarvis, A.; Kildea, J.; Mueller, C.; Mukherjee, R.; Ong, R.A.; Ragan, K.; Williams, D.A.; Zweerink, J.

2003-07-01

414

The tower experiment and the Copernican revolution  

Microsoft Academic Search

During the Copernican revolution the supporters of the Ptolemaic theory argued that the tower experiment refuted the Copernican hypothesis of the (diurnal) motion of the earth, but was in agreement with the Ptolemaic theory. In his defence of the Copernican theory Galileo argued that the experiment was in agreement both with Copernican and Ptolemaic theory. The reason for these different

Gunnar Andersson

1991-01-01

415

Joint slip in steel electric transmission towers  

Microsoft Academic Search

Joint slip is the relative displacement of a bolted joint under shear. It is greater in transmission towers as bolt diameters are small, members joined are thin, bearing type joints with a lower clamping force are used, and coefficient of friction of galvanized faying surfaces is low. This study on behaviour of such joints, incorporated 36 joint tests, generated joint

N Ungkurapinan; S. R. De S Chandrakeerthy; R. K. N. D Rajapakse; S. B Yue

2003-01-01

416

Troubleshooting crude vacuum tower overhead ejector systems  

SciTech Connect

Routinely surveying tower overhead vacuum systems can improve performance and product quality. These vacuum systems normally provide reliable and consistent operation. However, process conditions, supplied utilities, corrosion, erosion and fouling all have an impact on ejector system performance. Refinery vacuum distillation towers use ejector systems to maintain tower top pressure and remove overhead gases. However, as with virtually all refinery equipment, performance may be affected by a number of variables. These variables may act independently or concurrently. It is important to understand basic operating principles of vacuum systems and how performance is affected by: utilities, corrosion and erosion, fouling, and process conditions. Reputable vacuum-system suppliers have service engineers that will come to a refinery to survey the system and troubleshoot performance or offer suggestions for improvement. A skilled vacuum-system engineer may be needed to diagnose and remedy system problems. The affect of these variables on performance is discussed. A case history is described of a vacuum system on a crude tower in a South American refinery.

Lines, J.R.; Frens, L.L. (Graham Manufacturing Co., Inc., Batavia, NY (United States))

1995-03-01

417

Ozone Production Efficiency at the Williams Tower  

Microsoft Academic Search

We present an analysis of the ozone production efficiency (OPE) in two air masses that had passed over the greater Houston metropolitan area during the Texas 2000 Air Quality Study. These results, using preliminary observations from the Williams Tower, suggest OPE values much higher than those found at many other sites. The days selected for analysis had relatively smooth increase

Carl M. Berkowitz; Rahul A. Zaveri; C W. Spicer; Paul Doskey; Judy Weinstein-Lloyd

2002-01-01

418

ETR COOLING TOWER. PUMP HOUSE (TRA645) IN SHADOW OF TOWER ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

ETR COOLING TOWER. PUMP HOUSE (TRA-645) IN SHADOW OF TOWER ON LEFT. AT LEFT OF VIEW, HIGH-BAY BUILDING IS ETR. ONE STORY ATTACHMENT IS ETR ELECTRICAL BUILDING. STACK AT RIGHT IS ETR STACK; MTR STACK IS TOWARD LEFT. CAMERA FACING NORTHEAST. INL NEGATIVE NO. 56-3799. Jack L. Anderson, 11/26/1956 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

419

Wind Speed Estimation Based Sensorless Output Maximization Control for a Wind Turbine Driving a DFIG  

Microsoft Academic Search

This paper proposes a wind speed estimation based sensorless maximum wind power tracking control for variable-speed wind turbine generators (WTGs). A specific design of the proposed control algorithm for a wind turbine equipped with a doubly fed induction generator (DFIG) is presented. The aerodynamic characteristics of the wind turbine are approximated by a Gaussian radial basis function network based nonlinear

Wei Qiao; Wei Zhou; JosÉ M. Aller; Ronald G. Harley

2008-01-01

420

GA-ANN model for optimizing the locations of tower crane and supply points for high-rise public housing construction  

Microsoft Academic Search

Site layout planning is a complicated issue due to the existence of a vast number of trades and inter-related planning constraints. In this paper, artificial neural networks are used to model the non-linear operations of a key site facility: a tower crane — for high-rise public housing construction. Then genetic algorithms are used to determine the locations of the tower

C. M. Tam; Thomas K. L. Tong

2003-01-01

421

Observations of wind turbine wakes and surface roughness effects on wind flow variability  

SciTech Connect

Wind data collected at nine meteorological towers at the Goodnoe Hills MOD-2 wind turbine site were analyzed to characterize the wind flow over the site both in the absence and presence of wind turbine wakes. Free-flow characteristics examined were the variability of wind speed and turbulence intensity across the site as a function of wind direction and surface roughness. The nine towers' data revealed that scattered areas of trees upwind of the site caused pronounced variations in the wind flow over the site. Wind turbine wake characteristics analyzed included the average velocity deficits, wake turbulence, wake width, wake trajectory, vertical profile of the wake, and the stratification of wake properties as a function of the ambient wind speed and turbulence intensity. The wind turbine rotor disk spanned a height of 15 m to 107 m. The nine towers' data permitted a detailed analysis of the wake behavior at a height of 32 m at various downwind distances from 2 to 10 rotor diameters (D). The relationship between velocity deficit and downwind distance was surprisingly linear, with average maximum deficits ranging from 34% at 2 D to 7% at 10 D. Largest deficits were at low wind speeds and low turbulence intensities. Average wake widths were 2.8 D at a downwind distance of 10 D. Implications for turbine spacing are that, for a wind farm with a 10-D row separation, array losses would be significantly greater for a 2-D than a 3-D spacing because of incremental effects caused by overlapping wakes. Other interesting wake properties observed were the wake turbulence, the vertical variation of deficits, and the trajectory of the wake.

Elliott, D.L.; Barnard, J.C. (Pacific Northwest Lab., Richland, WA (USA))

1990-01-01

422

Earthquake response spectrum analysis of intake-outlet towers  

SciTech Connect

A simplified analysis procedure is developed to determine the maximum earthquake forces in intake-outlet towers directly from the design earthquake spectrum without the need for a response history analysis. All the significant effects of tower-water interaction and tower-foundation-soil interaction are included in the analysis. It is demonstrated that the hydrodynamic effects can be approximated by added mass functions for outside and inside water. An equivalent SDF system is developed to consider approximately the effects of tower-foundation-soil interaction in the fundamental mode response of towers.

Goyal, A. (California Univ., Berkeley, CA (USA). Dept. of Civil Engineering); Chopra, A.K. (California Univ., Berkeley, CA (USA). Dept. of Civil Engineering)

1989-07-01

423

Sharing from Scratch: How To Network CD-ROM.  

ERIC Educational Resources Information Center

|Examines common CD-ROM networking architectures: via existing operating systems (OS), thin server towers, and dedicated servers. Discusses digital video disc (DVD) and non-CD/DVD optical storage solutions and presents case studies of networks that work. (PEN)|

Doering, David

1998-01-01

424

Accuracy of Wind Prediction Methods in the California Sea Breeze  

Microsoft Academic Search

In this study, we investigate the accuracy of measure-correlate-predict (MCP) algorithms and log law\\/power law scaling using data from two tall towers in coastal environments. We find that MCP algorithms accurately predict sea breeze winds and that log law\\/power law scaling methods struggle to predict 50-meter wind speeds. MCP methods have received significant attention as the wind industry has grown

B. D. Sumers; M. J. Dvorak; J. E. Ten Hoeve; M. Z. Jacobson

2010-01-01

425

Hurricane Bonnie wind flow characteristics as determined from WEMITE  

Microsoft Academic Search

The Wind Engineering Mobile Instrumented Tower Experiment (WEMITE) successfully gathered high-resolution wind speed data from within Hurricane Bonnie as it made landfall near Wilmington, North Carolina, on 27 August 1998, at 04:00UTC. This data is used to inspect the variations in turbulent characteristics of the wind during the passage of the storm. Specifically, turbulence intensities, integral scales, gust factors and

John L. Schroeder; Douglas A. Smith

2003-01-01

426

Wind Generation on Winnebago Tribal Lands  

SciTech Connect

The Winnebago Wind Energy Study evaluated facility-scale, community-scale and commercial-scale wind development on Winnebago Tribal lands in northeastern Nebraska. The Winnebago Tribe of Nebraska has been pursuing wind development in various forms for nearly ten years. Wind monitoring utilizing loaned met towers from NREL took place during two different periods. From April 2001 to April 2002, a 20-meter met tower monitored wind data at the WinnaVegas Casino on the far eastern edge of the Winnebago reservation in Iowa. In late 2006, a 50-meter tower was installed, and subsequently monitored wind data at the WinnaVegas site from late 2006 through late 2008. Significant challenges with the NREL wind monitoring equipment limited the availability of valid data, but based on the available data, average wind speeds between 13.6 – 14.3 miles were indicated, reflecting a 2+/3- wind class. Based on the anticipated cost of energy produced by a WinnaVegas wind turbine, and the utility policies and rates in place at this time, a WinnaVegas wind project did not appear to make economic sense. However, if substantial grant funding were available for energy equipment at the casino site, and if either Woodbury REC backup rates were lower, or NIPCO was willing to pay more for wind power, a WinnaVegas wind project could be feasible. With funding remaining in the DOE-funded project budget,a number of other possible wind project locations on the Winnebago reservation were considered. in early 2009, a NPPD-owned met tower was installed at a site identified in the study pursuant to a verbal agreement with NPPD which provided for power from any ultimately developed project on the Western Winnebago site to be sold to NPPD. Results from the first seven months of wind monitoring at the Western Winnebago site were as expected at just over 7 meters per second at 50-meter tower height, reflecting Class 4 wind speeds, adequate for commercial development. If wind data collected in the remaining months of the twelve-month collection period is consistent with that collected in the first seven months, the Western Winnebago site may present an interesting opportunity for Winnebago. Given the distance to nearby substations, and high cost of interconnection at higher voltage transmission lines, Winnebago would likely need to be part of a larger project in order to reduce power costs to more attractive levels. Another alternative would be to pursue grant funding for a portion of development or equipment costs, which would also help reduce the cost of power produced. The NREL tower from the WinnaVegas site was taken down in late 2008, re-instrumented and installation attempted on the Thunderway site south of the Winnebago community. Based on projected wind speeds, current equipment costs, and the project’s proximity to substations for possible interconnection, a Thunderway community-scale wind project could also be feasible.

Multiple

2009-09-30

427

Low Frequency Loss in Regional Scale Flux Observations from a Tall Tower  

NASA Astrophysics Data System (ADS)

Direct measurements of surface fluxes are nowadays often performed with the eddy-correlation technique. The method is well established for observations in the lowest few meters of the atmosphere which gives flux estimates with a footprint of typically 100 m. Models and satellite products often give results on the kilometer scale or larger and benefit for their evaluation from flux estimates with larger horizontal scales. Until now only a limited number of techniques are available for direct flux observation at larger scale, e.g. airborne eddy correlation, tall tower based observations and scintillometers. Elevated observations "see" a larger footprint. We focus on tall tower flux observations. Specific problems arise when estimating surface fluxes from these elevated observations related to storage below the observation level and advection. A third concern and the focus of this presentation is the increase of length scale of the transporting turbulent eddies when going to higher levels in the atmospheric boundary layer and the related issue of low frequency loss. With the Cabauw 200 m meteorological tower in the Netherlands a unique platform is available to perform tall tower flux observations. The tower has been equipped with eddy correlation systems at 5, 60, 100 and 180 m height which measures fluxes of momentum, temperature, humidity and CO2. In addition wind speed, temperature, humidity and CO2 concentration are measured at a number of intermediate levels. This set of instruments has been augmented with an extra large aperture scintillometer which operates at the 60 m level over the 10 km path between a TV-tower and the Cabauw meteorological tower. Typically turbulence flux data is calculated on a 10 to 30 minute time basis. For atmospheric surface layer observation well established similarity relations exist to estimate low-frequency flux contributions. Low frequency contributions above the surface layer are less well established. We have analysed a large number of days and determined the flux contribution at timescales beyond the averaging time. On the basis of this analysis the surface layer relations for low frequency flux contributions are then generalized to higher levels in the atmospheric boundary layer.

Bosveld, F. C.; Schalkwijk, J.; Siebesma, A. P.

2010-09-01

428

Characterizing Inflow Conditions Across the Rotor Disk of a Utility-Scale Wind Turbine (Poster)  

SciTech Connect

Multi-megawatt utility-scale wind turbines operate in a turbulent, thermally-driven atmosphere where wind speed and air temperature vary with height. Turbines convert the wind's momentum into electrical power, and so changes in the atmosphere across the rotor disk influence the power produced by the turbine. To characterize the inflow into utility scale turbines at the National Wind Technology Center (NWTC) near Boulder, Colorado, NREL recently built two 135-meter inflow monitoring towers. This poster introduces the towers and the measurements that are made, showing some of the data obtained in the first few months of operation in 2011.

Clifton, A.; Lundquist, J. K.; Kelley, N.; Scott, G.; Jager, D.; Schreck, S.

2012-01-01

429

Wind turbine acoustic standards  

NASA Astrophysics Data System (ADS)

A program is being conducted to develop noise standards for wind turbines which minimize annoyance and which can be used to design specifications. The approach consists of presenting wind turbine noise stimuli to test subjects in a laboratory listening chamber. The responses of the subjects are recorded for a range of stimuli which encompass the designs, operating conditions, and ambient noise levels of current and future installations. Results to date have established the threshold of detectability for a range of impulsive stimuli of the type associated with blade/tower wake interactions. The status of the ongoing psychoacoustic tests, the subjective data, and the approach to the development of acoustic criteria/standards are described.

Stephens, D. G.; Shepherd, K. P.; Grosveld, F.

1981-05-01

430

Wind Flow Characteristics over Rough Surfaces  

NASA Astrophysics Data System (ADS)

The presence of roughness elements such as isolated boulders or sparse vegetation, common to many arid and semi-arid environments, protect the underlying finer-grained sediments from wind erosion, principally by absorbing momentum from the wind. As a result, wind shear stress is partitioned between the isolated roughness elements and the intervening surface. As part of a larger wind erosion study, a series of wind profile measurement experiments were conducted over a relatively flat un-vegetated, crusted field with an area of approximately 10,000 meters square, located at the Jornada Experimental Range, USDA ARS, Las Cruces, NM. Near the upwind margin of the field a triangular shaped area 2000 meters square (with the triangle base located downwind and perpendicular to the dominant wind direction) was covered with up to 1,9250, commercially available, 5-gallon buckets in regularly spaced staggered arrays. The buckets were used to produce four different roughness densities to investigate changes in wind flow patterns and momentum over the roughness configurations. Wind profiles were measured on two 9 m towers located at the upwind and downwind margins of the triangular arrays along the central axis. Wind speed was measured with 8 anemometers spaced logarithmically from 0.5 to 9 m. Wind direction was measured at the top of each tower with a wind vane. Wind speed and direction data were recorded with a data logger at 1s intervals with an averaging time of 10 minutes. Wind profiles at the leading edge of the arrays approaching at angles less than or equal to 10 degrees from normal to the front of the roughness array are associated with the wind flow over the flat, crusted surfaces and are well described by the Prandtl-von Karman log-linear relationship. For the same free stream wind speeds, the profiles at the downwind edge of the arrays are also characteristically log-linear when a displacement height (d) is included in the Prandtl-von Karman equation. A strong linear relationship (R2= 0.97) was found between the ratio of d to inter-element spacing (l) and the roughness density. As well, for similar free stream wind speeds, shear velocity increased markedly between the upwind and down wind towers, the difference of which was dependent on roughness density. Average momentum losses across the arrays (determined from the momentum deficit law) increased linearly with roughness density, indicating the increasing absorption of momentum by the roughness elements as the number of elements per unit area increased.

Bryant, J. M.; Nickling, W. G.; Gillies, J. A.

2004-12-01

431

A neural network approach for modeling nonlinear transfer functions: Application for wind retrieval from spaceborne scatterometer data  

NASA Astrophysics Data System (ADS)

The present paper shows that a wide class of complex transfer functions encountered in geophysics can be efficiently modeled using neural networks. Neural networks can approximate numerical and nonnumerical transfer functions. They provide an optimum basis of nonlinear functions allowing a uniform approximation of any continuous function. Neural networks can also realize classification tasks. It is shown that the classifier mode is related to Bayes discriminant functions, which give the minimum error risk classification. This mode is useful for extracting information from an unknown process. These properties are applied to the ERS1 simulated scatterometer data. Compared to other methods, neural network solutions are the most skillful.

Thiria, S.; Mejia, C.; Badran, F.; Crepon, M.

1993-12-01

432

A Study of Lightning Current Distribution at a Wind Turbine Foot  

NASA Astrophysics Data System (ADS)

A Rogowski coil, used for measuring lightning current through a wind turbine generator system, is generally set up at the foot of a tower. In most wind turbines, there is an entrance at the foot of the tower, which leads to a flight of stairs or a ladder. When lightning strikes the wind turbine, the lightning current flows to the ground through the blades, nacelle, and tower. The current is shunted to the tower and the stairs/ladder at the foot of the tower, from where it may flow into the foundation and the earth. A Rogowski coil is usually set up at only the foot of a tower. The lightning current shunted to the stairs/ladder cannot be measured using the Rogowski. The installation position of the Rogowski coil depends on the construction of the stairs/ladder. In this study, the lightning current distribution at the foot of a tower is calculated using the FDTD (Finite Difference Time Domain) method, which is one of methods used for numerical analyses of electromagnetic fields. We also studied the effect that the setup of the stairs/ladder and the resistivity of the ground have on the lightning current distribution. The results of the current distribution are very important for predicting the total current that flows through an existing wind turbine generator system.

Yamamoto, Kazuo; Ueda, Naoya; Ametani, Akihiro; Natsuno, Daisuke

433

Effects of structure flexibility on horizontal axis wind turbine performances  

NASA Astrophysics Data System (ADS)

This work illustrates the effects of flexibility of rotor blades and turbine tower on the performances of an horizontal axis wind turbine (HAWT) designed by our ADAG research group, by means of several example applied on a recent project for a active pitch controlled upwind 60 kW HAWT. The influence of structural flexibility for blade only, tower only and blade coupled with tower configuration is investigated using an aero-elastic computer-aided engineering (CAE) tool for horizontal axis wind turbines named FAST developed at National Renewable Energy Laboratory (NREL) of USA. For unsteady inflow conditions in front of the isolated HAWT the performances in rigid and flexible operation mode are computed and compared in order to illustrate the limitation included within a classical rigid body approach to wind turbine simulation.

Coiro, D. P.; Daniele, E.; Scherillo, F.

2013-10-01

434

A Neural Networks Based Method to Estimate Higher Resolution Aerosol Optical Thickness Using Historical Data Sets of SEVIRI Dust Indices, Soil Moisture and Wind Speed  

NASA Astrophysics Data System (ADS)

Dust emission has a large temporal and spatial variation making it extremely challenging to model. This challenge is mainly due to the number of uncertainties in estimating the amount of dust emission and deposition. Dust emission and deposition are associated with several factors such as surface roughness, soil particle properties, wind speed and direction, precipitation, humidity, and threshold wind friction velocity. Aerosol optical thickness (AOT) is a widely used quantitative indicator of dust in the atmosphere but its use is limited either because the availability of AOT data measured at ground is very limited or satellite-derived AOT suffers from the coarser temporal and spatial resolution. SEVIRI data have been widely used for qualitative detection of dust because of the availability of thermal channels and their high temporal resolution. However, no SEVIRI-derived AOT products are available yet. Freely available AOT product over land as well as ocean derived using MODIS data has a limited temporal (daily) and spatial resolution (1°×1°). The combination of satellite and land surface data will be useful in forecasting dust storms. This is mainly because some input parameters like AOT, soil moisture and land cover properties can be more effectively obtained using satellite data. However, other parameters like soil type, wind speed and soil particle size distribution requires more accurate ground measurement. Neural networks can be effectively used to study the non-linear relationship between complex input parameters and specified output(s). In this work higher resolution SEVIRI dust indices have been used as input parameters to derive higher resolution AOT data as output with MODIS AOT as target. Apart from SEVIRI dust indices, satellite derived soil moisture data from AMSR-E and wind speed data measured at ground station have also been used as additional inputs. The selection of these additional inputs was mainly motivated by their direct and indirect relationship with dust emission. In fact, AOT is inversely proportional to the soil moisture and directly proportional to the wind speed in general when the major fraction of the aerosols consists of wind eroded dust. MODIS AOT data used in this study include all the available cloud free days of the year 2009 and the input parameters were retrieved at a closest time (13:45) of MODIS/Aqua overpass over a small area (25×25 km) centered at (23.38° N, 53.88° E) in the UAE. A total of 191 points were available for analysis of which two-thirds were used to train the neural network and the rest one-thirds were used for validation. A strong correlation was observed both in training and validation phase which was used to simulate higher resolution AOT with the available SEVIRI dust indices, soil moisture and wind speed data as inputs.

Parajuli, S. P.; Ghedira, H.; Gherboudj, I.

2011-12-01

435

Overview of SAR Chesapeake tower experiment  

NASA Astrophysics Data System (ADS)

Synthetic aperture radar (SAR) imaging of the ocean surface promises to be an important tool in ocean remote sensing. The long-range goal of the work reported here is to understand SAR imaging in sufficient detail that airborne and/or spaceborne SARs become reliable tools for oceanic research and operational use.TOWARD (Tower Ocean Wave and Radar Dependence Experiment) [see Shemdin, 1988, 1990], a predecessor experiment to the SAR and X-Band Ocean Nonlinearities Experiment at Chesapeake Light Tower (SAXON:CLT), provided a comprehensive data set to test the theoretical concepts advanced on SAR imaging of the ocean surface. A significant achievement of TOWARD is determining that none of the then available theories on SAR imaging of long surface waves could explain all the SAR observations satisfactorily. Improved models immediately followed as a consequence of the TOWARD finding. In spite of the significant insights gained in TOWARD, gaps remain in understanding radar backscatter from the sea surface.

Shemdin, O. H.

436

Heat storage to cut towers' demand costs  

SciTech Connect

A thermal-storage system that will permit a Dallas office building (twin towers) to run its chiller at night during off-peak hours will lower electricity-demand charges $495,000 per year. A $411,000 utility credit will cut equipment costs to $340,000, an incentive the utility feels will help to reduce peak-demand load and delay the need for new generating capacity. Three storage tanks holding up to a total of 1.5 million gallons of water will be retrofitted into the office towers. One tank will hold hot water in the winter for morning space heating, but chilling is required on a year-round basis. (DCK)

Raymond, M.

1983-01-24

437

NOVA Online: Why the Towers Fell  

NSDL National Science Digital Library

Why the Towers Fell is a special episode of NOVA scheduled for broadcast on PBS on April 30, 2002. This online material complements the television program by assessing the exact cause of the disaster from an engineer's standpoint. One section of the Web site is an interview with a materials engineering professor from the Massachusetts Institute of Technology. In the dialog, he describes the most probable reasons for the towers' collapse and some building safety improvements that can be made in the future. There are two multimedia features on the site: one explores the structure of metal while the other looks at firefighter equipment. A particularly moving account of the Trade Center collapse comprises another section, from one of only four people who escaped from above the floors where either plane hit.

2002-01-01

438

Wind Turbines Adaptation to the Variability of the Wind Field  

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

439

Factors Influencing Wind Energy Curtailment  

Microsoft Academic Search

Nonphysically firm wind generation connections (i.e., those to which curtailment can apply) may be necessary for signifi- cant wind integration to congested transmission networks. A study of factors influencing this associated wind energy curtailment is, therefore,oftimelyimportance.Inthispaper,thewindcurtailment estimation effects of natural inter-yearly wind profile variability, systemdemand-profile\\/fuel-priceparameteruncertainty,andmin- imum system inertial constraints are studied in detail. Results in- dicate that curtailment estimation error

Daniel J. Burke; Mark J. O'Malley

2011-01-01

440

Aerodynamic interference between two Darrieus wind turbines  

SciTech Connect

The effect of aerodynamic interference on the performance of two curved bladed Darrieus-type vertical axis wind turbines has been calculated using a vortex/lifting line aerodynamic model. The turbines have a tower-to-tower separation distance of 1.5 turbine diameters, with the line of turbine centers varying with respect to the ambient wind direction. The effects of freestream turbulence were neglected. For the cases examined, the calculations showed that the downwind turbine power decrement (1) was significant only when the line of turbine centers was coincident with the ambient wind direction, (2) increased with increasing tipspeed ratio, and (3) is due more to induced flow angularities downstream than to speed deficits near the downstream turbine.

Schatzle, P.R.; Klimas, P.C.; Spahr, H.R.

1981-04-01

441

Progressive Collapse of Towers: The Resistance Effect  

Microsoft Academic Search

In the recent paper (Cherepanov, 2006), objections were raised against the widely accepted version of the WTC collapse and\\u000a an alternative calculation was presented. The present work uses the model advanced in the mentioned paper and incorporates\\u000a the effect of non-zero resistance that slows down the progressive collapse. The analysis shows that the collapses of twin\\u000a towers started from a

Genady P. Cherepanov; Ivan E. Esparragoza

2007-01-01

442

Heat storage to cut towers' demand costs  

Microsoft Academic Search

A thermal-storage system that will permit a Dallas office building (twin towers) to run its chiller at night during off-peak hours will lower electricity-demand charges $495,000 per year. A $411,000 utility credit will cut equipment costs to $340,000, an incentive the utility feels will help to reduce peak-demand load and delay the need for new generating capacity. Three storage tanks

1983-01-01

443

Wet/dry cooling tower and method  

DOEpatents

A wet/dry cooling tower wherein a liquid to-be-cooled is flowed along channels of a corrugated open surface or the like, which surface is swept by cooling air. The amount of the surface covered by the liquid is kept small compared to the dry part thereof so that said dry part acts as a fin for the wet part for heat dissipation.

Glicksman, Leon R. (Lynnfield, MA); Rohsenow, Warren R. (Waban, MA)

1981-01-01

444

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

Microsoft Academic Search

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

J. Ekanayake; N. Jenkins

2004-01-01

445

Legionella in Puerto Rico cooling towers  

SciTech Connect

Water samples from air conditioning cooling towers receiving different treatment protocols on five large municipal buildings in San Juan, Puerto Rico were assayed for various species and serogroups of Legionella spp. using direct immunofluorescence. Several water quality parameters were also measured with each sample. Guinea pigs were inoculated with water samples to confirm pathogenicity and recover viable organisms. Legionella pneumophila (1-6), L. bozemanii, L. micdadei, L. dumoffii, and L. gormanii were observed in at least one of the cooling towers. L. pneumophila was the most abundant species, reaching 10{sup 5} cells/ml, within the range that is considered potentially pathogenic to humans. A significantly higher density of L. pneumophila was observed in the cooling tower water that was not being treated with biocides. Percent respiration (INT) and total cell activity (AODC), were inversely correlated with bacterial density. This study demonstrates that Legionella spp. are present in tropical air-conditioning cooling systems, and without continuous biocide treatment may reach densities that present a health risk.

Negron-Alviro, A.; Perez-Suarez, I.; Hazen, T.C. [Univ. of Puerto Rico, Rio Piedras (Puerto Rico)

1988-12-31

446

Legionella spp. in Puerto Rico cooling towers  

SciTech Connect

Water samples from air conditioning cooling towers receiving different treatment protocols on five large municipal buildings in San Juan, P.R., were assayed for various Legionella spp. and serogroups by using direct immunofluorescence. Several water quality parameters were also measured for each sample. Guinea pigs were inoculated with water samples to confirm pathogenicity and recover viable organisms. Legionella pneumophila serogroups 1 to 6, L. bozemanii, L. micdadei, L. dumoffii, and L. gormanii were observed in at least one of the cooling towers. L. pneumophila was the most abundant species; its density reached 10{sup 5} cells per ml, which is within the range that is considered potentially pathogenic to humans. A significantly higher density of L. pneumophila was observed in the cooling tower water that was not being treated with biocides. Percent respiration (INT) and total cell activity (acridine orange direct count) were inversely correlated with bacterial density. This study demonstrates that Legionella spp. are present in tropical air-conditioning cooling systems and that, without continuous biocide treatment, they may reach densities that present a health risk.

Negron-Alvira, A.; Perez-Suarez, I.; Hazen, T.C. (Univ. of Puerto Rico, Rio Piedras (Puerto Rico))

1988-10-01

447

Comparison of alternative methods for measuring cooling-tower drift. Final report  

SciTech Connect

An international comparison of methods for measurement of cooling tower draft has been performed at the Massachusetts Institute of Technology, sponsored by the Electric Power Research Institute. Participants from Belgium, the United States and the Federal Republic of Germany participated in mesurements of a spectrum of test environments, which span the range of cases which would typically be encountered in operating cooling towers. The environments differed according to droplet mass flux, droplet size distribution and air speed. A wind tunnel was built to provide the various test environments, and a special optical drift measurement system was built to permit simultaneous monitoring of the environment sampled in the tests. Cases tested included both mechanical and natural draft cooling tower environments. Among the types of instruments tested are the PILLS light scattering system, sensitive paper and other sensitive surface droplet impaction systems, isokinetic drift mass flux measurement systems and photographic systems. The results indicate that the instruments tested vary widely in their capabilities, with droplet sizing instruments being more effective in low load, small droplet size spectrum situations, and isokinetic mass and chemical assay techniques being most accurate in high load, large droplet distribution cases. Instruments relying upon thermodynamic state measurements experienced significant difficulties when the gas flow relative humidity was less than 98 percent.

Golay, M.W.; Glantschnig, W.J.; Best, F.R.

1984-02-01

448

Offshore Wind Resource Assessment Based on Mesoscale Modeling  

NASA Astrophysics Data System (ADS)

A methodology for assessing regional offshore wind energy development potential using mesoscale modeling for wind fields has been developed. Recommendations are made on selecting the best mesoscale modeling domain resolution, as well as choosing the best data for model initial and boundary conditions, based on a sensitivity study using the Penn State/NCAR MM5 mesoscale model near California coast validated with offshore buoy wind data and coastal meteorological stations. Annual wind speed averages are developed by modeling four seasonal months to reduce total computational time, as well as to allow study of the innterannual variability. Four seasonal months of 2005, 2006, and 2007 were compared to using a complete modeled year for 2007 to calculate how the overall energy answer changed. Results from summer 2006 MM5 simulations show the average 10 m wind speed to be calculated within one percent when using three months of data (Jun, Jul, Aug) versus using July alone. Siting restrictions were developed based on bathymetry depth limits for offshore turbine tower support structures with economic and structural limitations for monopiles, multi-leg, and future floating tower support types corresponding to 30, 70, and 200 m depth respectively. Other exclusionary entities such as shipping lanes and avarian flyways were also considered as exclusion zones inside of areas amenable for offshore wind energy farms. A method to validate the modeled wind fields though error calculations against offshore buoy wind data, as well as onshore coastal meteorological towers is presented.

Dvorak, M. J.; Jacobson, M. Z.

2008-12-01

449

Gust Buffeting and Aeroelastic Behaviour of Poles and Monotubular Towers  

NASA Astrophysics Data System (ADS)

The evolution in the constructional field and the realization of ever more slender and light structures have emphasized the increasing difficulty of properly evaluating the actions and effects of wind on poles and monotubular towers. Faced with this situation the Italian constructors, united in a consortium coordinated by ACS ACAI Servizi, entrusted the Department of Structural and Geotechnical Engineering of Genova University with the task of formulating an ad hoc calculation procedure for this type of structure. This gave rise to a wide-ranging research project in which theoretical models, experimental evaluations and engineering methods were developed in parallel through an effective and quite a unique co-operation between researchers, designers and builders. This paper illustrates the physical aspects, the general principles and the basic formulation of the method proposed, with special emphasis on gust buffeting and aeroelastic phenomena. Preliminary results of full-scale measurements of the structural damping are also presented. The conclusions highlight the scientific and technical perspectives of this research.

Solari, G.; Pagnini, L. C.

1999-10-01

450

Tidal winds from the mesosphere, lower thermosphere global radar network during the second LTCS campaign - December 1988  

NASA Astrophysics Data System (ADS)

Winds and tides were measured by nine MLT (mesosphere, lower thermosphere) radars with locations between 70 deg N and 78 deg S, including an equatorial station at Christmas Island, 2 deg N (Avery et al., 1990). The mean winds were eastward (westward) in the Northern (Southern) Hemisphere mesosphere, consistent with midwinter circulations. For the 12-hour tide, observations and the model of Forbes and Vial (1989) were in generally good agreement: in both cases northward components were closer to being in phase in the two hemispheres, and winter wavelengths were shorter than those of the midlatitude summer. Major differences were large (small) amplitudes at 70 deg N for model (observations); and poor agreement of equatorial tidal profiles. For the 24-hour, the radar observations and model of Forbes and Hagan (1988) were in useful agreement in the summer hemisphere.

Manson, A. H.; Meek, C. E.; Avery, S. K.; Fraser, G. J.; Vincent, R. A.

1991-02-01

451

Radiation scanning aids tower diagnosis at Arun LNG plant  

SciTech Connect

Radiation scanning has been used effectively to troubleshoot the treating towers of the Arun LNG plant in Sumatra, Indonesia. The plant is one of the world's largest such facilities. The analysis was part of an investigation aimed at increasing the capacity of the treater section of the plant. Radiation scanning is a tool which, in addition to tower differential pressure and product purity, can aid in diagnosing tower performance.

Naklie, M.M. (Mobil Exploration and Producing Services Inc., Dallas, TX (US)); Pless, L. (Tru-Tec Inc., Houston, TX (US)); Gurning, T.P.; Hyasak, M. (P.T. Arun Natural Gas Liquefaction Co., Sumatera (USA))

1990-03-26

452

37. VIEW LOOKING SOUTH AT THE STATIC TEST TOWER. THIS ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

37. VIEW LOOKING SOUTH AT THE STATIC TEST TOWER. THIS VIEW SHOWS TWO MAJOR CHANGES TO THE STATIC TEST TOWER: THE ADDITION OF THE NASA LOGO TO THE FACADE AND THE ADDITION OF THE UPPER STAGES TO THE JUPITER MISSILE IN THE WEST POSITION ON THE TOWER TO REPRESENT THE JUNO II CONFIGURATION. 1961, PHOTOGRAPHER UNKNOWN, FRED ORDWAY COLLECTION, U. S. SPACE AND ROCKET CENTER, HUNTSVILLE, AL. - Marshall Space Flight Center, Saturn Propulsion & Structural Test Facility, East Test Area, Huntsville, Madison County, AL

453

10. Photocopy of photograph of tower as constructed at Cape ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

10. Photocopy of photograph of tower as constructed at Cape Henlopen, Delaware, September 1926 (original photograph in National Archives and Records Service, Still Pictures Branch, RG 26, 26-LG-22-A), photographer G.W. Hitchens, September 10, 1926. "New Tower. Camera Station West 100 ft." - Mispillion Lighthouse, Beacon Tower, South bank of Mispillion River at it confluence with Delaware River at northeast end of County Road 203, 7 miles east of Milford, Milford, Sussex County, DE

454

60Hertz Electric-Field Exposures in Transmission Line Towers  

Microsoft Academic Search

This article reports on an investigation of 60-Hz electric-field exposures of line workers in 230- to 765-kV transmission line towers. The exposures were based on computations of the unperturbed electric field along climbing routes and at work positions on the towers and on insulated ladders suspended in towers. Computed exposures were expressed in terms of the unperturbed electric field averaged

T. Bracken; Russell Senior; Joseph Dudman

2005-01-01

455

Subhourly wind forecasting techniques for wind turbine operations  

SciTech Connect

Three models for making automated forecasts of subhourly wind and wind power fluctuations were examined to determine the models' appropriateness, accuracy, and reliability in wind forecasting for wind turbine operation. Such automated forecasts appear to have value not only in wind turbine control and operating strategies, but also in improving individual wind turbine control and operating strategies, but also in improving individual wind turbine operating strategies (such as determining when to attempt startup). A simple persistence model, an autoregressive model, and a generalized equivalent Markhov (GEM) model were developed and tested using spring season data from the WKY television tower located near Oklahoma City, Oklahoma. The three models represent a pure measurement approach, a pure statistical method and a statistical-dynamical model, respectively. Forecasting models of wind speed means and measures of deviations about the mean were developed and tested for all three forecasting techniques for the 45-meter level and for the 10-, 30- and 60-minute time intervals. The results of this exploratory study indicate that a persistence-based approach, using onsite measurements, will probably be superior in the 10-minute time frame. The GEM model appears to have the most potential in 30-minute and longer time frames, particularly when forecasting wind speed fluctuations. However, several improvements to the GEM model are suggested. In comparison to the other models, the autoregressive model performed poorly at all time frames; but, it is recommended that this model be upgraded to an autoregressive moving average (ARMA or ARIMA) model. The primary constraint in adapting the forecasting models to the production of wind turbine cluster power output forecasts is the lack of either actual data, or suitable models, for simulating wind turbine cluster performance.

Wegley, H.L.; Kosorok, M.R.; Formica, W.J.

1984-08-01

456

Networking.  

ERIC Educational Resources Information Center

|This theme issue on the role of networking in improving services for gifted individuals presents two feature articles and several regular columns. "A Network of Scholars" by Jerry Flack describes efforts of a group of professional educators and researchers of gifted persons in Colorado who worked cooperatively to create the Colorado Academy of…

Silverman, Linda Kreger, Ed.

1994-01-01

457

93. TOWER STAIRHALL, SOUTH WALL, WEST TABERNACLE FRAME. DETAIL OF ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

93. TOWER STAIRHALL, SOUTH WALL, WEST TABERNACLE FRAME. DETAIL OF DOG EAR AND TRUSS (BRACKET) - Independence Hall Complex, Independence Hall, 500 Chestnut Street, Philadelphia, Philadelphia County, PA

458

Convective Cloud Towers and Precipitation Initiation, Frequency and Intensity  

NASA Astrophysics Data System (ADS)

Geosynchronous satellite retrieval of precipitation is desirable because it would provide continuous observation throughout most of the globe in regions where radar data is not available. Most current IR retrievals are pixel based rather than based on the overall geometry of a cloud. In the current work the distribution of precipitation rates is examined as a function of convective cloud tower area and average cloud top temperature in the tower. A thunderstorm tracking algorithm developed at Meteo-France is used to track cumulus towers that are matched up with radar data at 5 minute 1 km resolution. It is found that most (80%) of the precipitation occurs in the cloud mass that surrounds the towers, and when a tower is first detected the precipitation is already in progress 50% of the time. The average density of precipitation per area is greater as the towers become smaller and colder, yet the averaged shape of the precipitation intensity distribution is remarkably constant in all convective situations. This suggests that on average all convective precipitation events look the same, unaffected by the higher frequency of occurrence per area inside the convective towers. The smaller total area of the convective towers compared to the overall cloud mass means that the accumulated precipitation from the relatively more active cloud towers is overshadowed by precipitation from the rest of the cloud.

Mahani, S. E.; Vant-Hull, B. L.; Rabin, R.; Khanbilvardi, R.

2011-12-01

459

Effect of foundation nonlinearity on modal properties of offshore towers  

SciTech Connect

An analysis of pile axial and lateral response to transient dynamic loading is presented allowing for nonlinear soil behavior, the discontinuity conditions at the pile-soil interface, and energy dissipation through radiation damping and soil hysteresis. In addition, the effect of neighboring piles is taken into account for piles in a group. This analysis is used to derive the stiffness of foundation piles of fixed offshore towers. The effect of foundation nonlinearity and pile-soil-pile interaction on the dynamic characteristics of the tower is investigated. It was found that the tower`s dynamic characteristics are greatly influenced by the foundation nonlinearity and the pile-soil-pile interaction.

El Naggar, M.H.; Novak, M. [Univ. of Western Ontario, London, Ontario (Canada)

1995-09-01

460

2. HI PAR (ACQUISITION RADAR) TOWER AND ENLISTED MEN (EM) ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. HI PAR (ACQUISITION RADAR) TOWER AND ENLISTED MEN (EM) BARRACKS WITH RADAR ATTACHED. - Nike Hercules Missile Battery Summit Site, Battery Control Administration & Barracks Building, Anchorage, Anchorage, AK

461

COMPARATIVE PERFORMANCES OF `TOWER-TOP' AND `TOWER-REFLECTOR' CENTRAL SOLAR RECEIVERS  

Microsoft Academic Search

The optics of various types of solar tower configurations and receivers are analyzed. The power values that are finally available for the process, for a given field and different optical arrangements at specified operating temperatures (above 1100 K), are compared. At these temperatures the use of secondary concentrators placed in front of the receivers is peremptorily justified from optical and

A. Segal; M. Epstein

1999-01-01

462

There's Money in Those Towers! Communication Towers Can Be Money Makers.  

ERIC Educational Resources Information Center

To interlink major systems, some communication companies are proposing construction of communication towers on school grounds. Schools and municipal governments possess strategically located, unzoned properties. Districts planning to tap this financial oil well should draw up a lease agreement specifying property use, term, rent, access rights,…

Perry, Richard E.

1995-01-01

463

Solar power tower development: Recent experiences  

SciTech Connect

Recent experiences with the 10 MW{sub e} Solar Two and the 2.5 MW{sub t} TSA (Technology Program Solar Air Receiver) demonstration plants are reported. The heat transfer fluids used in these solar power towers are molten-nitrate salt and atmospheric air, respectively. Lessons learned and suggested technology improvements for next-generation plants are categorized according to subsystem. The next steps to be taken in the commercialization process for each these new power plant technologies is also presented.

Tyner, C.; Kolb, G.; Prairie, M. [and others

1996-12-01

464

Dynamic modeling of doubly fed induction generator wind turbines  

Microsoft Academic Search

It is now recognized that many large wind farms will employ doubly fed induction generator (DFIG) variable speed wind turbines. A number of such wind farms are already in operation and more are planned or under construction. With the rising penetration of wind power into electricity networks, increasingly comprehensive studies are required to identify the interaction between the wind farm(s)

Janaka B. Ekanayake; Lee Holdsworth; XueGuang Wu; Nicholas Jenkins

2003-01-01

465

6. VIEW OF ANTENNA TOWER S111 FACING NORTHWEST. COMMUNICATIONS CONTROL ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. VIEW OF ANTENNA TOWER S-111 FACING NORTHWEST. COMMUNICATIONS CONTROL LINK BUILDING (BLDG NO. 205) LOCATED JUST INFONT OF THE TOWER. - U.S. Naval Base, Pearl Harbor, Lualualei Radio Transmitter, Edison & Tower Drives, Pearl City, Honolulu County, HI

466

Tidal winds from the mesosphere, lower thermosphere global radar network during the second LTCS campaign: December 1988  

SciTech Connect

Winds and tides were measured by nine MLT (mesophere, lower thermosphere) radars with locations between 70{degree}N and 78{degree}S, including an equatorial station at Christmas Island, 2{degree}N (Avery et al., 1990). The mean winds were eastward (westward) in the northern (southern) hemisphere mesophere, consistent with midwinter circulations. For the 12-hour (semidiurnal) tide, observations and the model of Forbes and Vial (1989) were in generally good agreement: in both cases northward components were closer to being in phase in the two hemispheres, and winter wavelengths were shorter than those of the midlatitude summer. Major differences were large (small) amplitudes at 70{degree}N for model(observations); and poor agreement of equatorial tidal profiles. For the 24-hour (diurnal tide), the radar observations and model of Forbes and Hagan (1988) were in useful agreement in the summer hemisphere. However, the short (long) wavelengths at mid (high) latitudes of the model's winter hemisphere were not observed during LTCS (lower Thermosphere Coupling Study) 2, nor in climatologies for December. Suggestions as to the reason for this disparity are presented.

Manson, A.H.; Meek, C.E. (Univ. of Saskatchewan, Saskatoon (Canada)); Avery, S.K. (Univ. of Colorado, Boulder (USA)); Fraser, G.J. (Univ. of Canterbury, Christchurch (New Zealand)); Vincent, R.A.; Phillips, A. (Univ. of Adelaide (Australia)); Clark, R.R. (Univ. of New Hampshire, Durham (USA)); Schminder, R.; Kurschner, D. (Karl Marx Univ., Collm (West Germany)); Kazimirovsky, E.S. (Siberian Inst. of Terrestrial Magnetism, Ionosphere and Radio Propagation, Irkutsk (USSR))

1991-02-01

467

Fatigue loading parameter identification of a wind turbine operating in complex terrain  

Microsoft Academic Search

An analytic tool is introduced for the evaluation of the fatigue loading of a wind turbine operating in complex terrain, from large scale experimental data. The fatigue loading magnitudes quantified by the equivalent load ranges of the different wind turbine components, namely blade, main shaft and tower, are modelled using multiple regression analysis in order to identify the fatigue inducing

F Mouzakis; E Morfiadakis; P Dellaportas

1999-01-01

468

Estimates of diabatic wind speed profiles from near-surface weather observations  

Microsoft Academic Search

In this paper we analyse diabatic wind profiles observed at the 213 m meteorological tower at Cabauw, the Netherlands. It is shown that the wind speed profiles agree with the well-known similarity functions of the atmospheric surface layer, when we substitute an effective roughness length. For very unstable conditions, the agreement is good up to at least 200 m or

A. A. M. Holtslag

1984-01-01

469

A Multilevel Modular Converter for a Large, Light Weight Wind Turbine Generator  

Microsoft Academic Search

In an onshore horizontal axis wind turbine, generator and converter are usually in the nacelle on the top of the tower, while the grid step-up transformer is placed at the bottom. Electric power is transmitted down through flexible cables of high current rating which are expensive and can suffer from large I2 R loss. An offshore wind turbine usually has

Chong H. Ng; Max A. Parker; Li Ran; Peter J. Tavner; Jim R. Bumby; Ed Spooner

2008-01-01

470

Development of Fully Coupled Aeroelastic and Hydrodynamic Models for Offshore Wind Turbines: Preprint  

Microsoft Academic Search

Aeroelastic simulation tools are routinely used to design and analyze onshore wind turbines, in order to obtain cost effective machines that achieve favorable performance while maintaining structural integrity. These tools employ sophisticated models of wind-inflow; aerodynamic, gravitational, and inertial loading of the rotor, nacelle, and tower; elastic effects within and between components; and mechanical actuation and electrical responses of the

J. M. Jonkman; P. D. Sclavounos

2006-01-01

471

Meteorological Measurements in the Northern German Coastal Area for Wind Energy Prospection.  

National Technical Information Service (NTIS)

Wind speed and direction were measured for the period from April 1979 to February 1982. The wind sensors were mounted at the towers up to a maximum height of 46 m at six different sites in the northern German coastal area. The raw data were checked, conve...

A. Hoff G. Tetzlaff H. Laude H. J. Belitz S. Theunert

1984-01-01

472

Fully Simulated Nonlinear Analysis of Large Structures Subjected to Turbulent Artificial Wind  

Microsoft Academic Search

A fully numerical model is presented for simulating the response of slender structures to artificial wind loading. The deterministic method in the time domain is adopted to evaluate the response of very large systems during turbulent gusts lasting 1 to 10?min. Particular attention is devoted to very high-wind-sensitive systems such as guyed masts, as well as television reticulated towers. For

Claudio Borri; Wolfhard Zahlten

1991-01-01

473

Spatially averaging cross-wind sensors and numerical-model results for nocturnal drainage winds in complex terrain  

SciTech Connect

Recent studies in The Geysers region of Northern California have concentrated on drainage wind effects on tracer transport and diffusion in complex terrain, as part of the Atmospheric Studies in Complex Terrain (ASCOT) project. These studies combined tracer measurements, conventional tower and remote sensing meteorological measurements, and numerical wind field transport and diffusion models. One part of the meteorological measurement support used eight optical cross-path wind sensors across the principle air drainage valleys. These sensors had varying optical path lengths within the drainage layer of approx. 300 m to 3 km. Results of this study indicate that the combination of spatially averaged cross-path optical wind sensor and conventional tower mounted cup-vane anemometer data into a numerical plume transport and diffusion model for complex terrain has provided useful results. The most important of these results is an independent measure of wind data on a spatial scale compatible with necessarily large grid scales in numerical wind field models with topography. This allows assessment of terrain associated exposure problems for tower anemometers in complex terrain. The optical cross wind data can be used to compare necessary averaging times, and spatial distribution of point sensors and provide verification data to improve the logistics of instrument placement in combination with numerical models.

Porch, W.M.; Lange, R.

1982-11-01

474

16. TYPICAL VIEW OF PEARL HARBOR FROM SIGNAL TOWER OFFICE, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

16. TYPICAL VIEW OF PEARL HARBOR FROM SIGNAL TOWER OFFICE, LOOKING OUT AT MAIN CHANNEL ENTRANCE, WITH FORD ISLAND ON THE RIGHT. - U.S. Naval Base, Pearl Harbor, Signal Tower, Corner of Seventh Street & Avenue D east of Drydock No. 1, Pearl City, Honolulu County, HI

475

Application of CFD to closed-wet cooling towers  

Microsoft Academic Search

Computational fluid dynamics (CFD) is applied to predicting the performance of closed-wet cooling towers (CWCTs) for chilled ceilings according to the cooling capacity and pressure loss. The prediction involves the two-phase flow of gas and water droplets. The predicted thermal performance is compared with experimental measurement for a large industrial CWCT and a small prototype cooling tower. CFD is then

G Gan; S. B Riffat; L Shao; P Doherty

2001-01-01

476

Design of cooling towers by the effectiveness-NTU method  

Microsoft Academic Search

This paper develops the effectiveness-NTU, number of transfer units, design method for cooling towers. The definitions for effectiveness and NTU are totally consistent with the fundamental definitions used in heat exchanger design. Sample calculations are presented for counter and crossflow cooling towers. Using the proper definitions, a person competent in heat transfer design can easily use the same basic method

H. Jaber; R. L. Webb

1989-01-01

477

Performance of cooling tower in south of Tunisia  

Microsoft Academic Search

This paper presents a mathematical model for the numerical prediction of the performance of crossflow cooling towers. The mathematical model is based on the heat and mass transfer equations. The leading parameters are the Lewis number Le, the number of transfer units U, the percentage of water evaporation, the water losses and the tower efficiency. This model is used to

Lakdar Kairouani; Mohamed Hassairi; Zermani Tarek

2004-01-01

478

PBF Cooling Tower. Camera facing southwest. Round piers will support ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

PBF Cooling Tower. Camera facing southwest. Round piers will support Tower's wood "fill" or "packing." Black-topped stack in far distance is at Idaho Chemical Processing Plant. Photographer: John Capek. Date: October 16, 1968. INEEL negative no. 68-4097 - Idaho National Engineering Laboratory, SPERT-I & Power Burst Facility Area, Scoville, Butte County, ID

479

Testing for commercialization of the central power tower  

Microsoft Academic Search

The construction of a central power tower system for a 10 megawatt electrical power plant is examined. Attention is given to the concept development which employs a central receiver system using a large field of heliostats that reflect sunlight to a receiver installed at the top of a steel tower. The design of the receiver utilizes a water\\/steam single pass

F. Duquette

1979-01-01

480

32. VIEW LOOKING EAST AT THE STATIC TEST TOWER WHILE ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

32. VIEW LOOKING EAST AT THE STATIC TEST TOWER WHILE A JUPITER MISSILE IS BEING POSITIONED ONTO THE TEST TOWER. DATE AND PHOTOGRAPHER UNKNOWN, MSFC PHOTO LAB. - Marshall Space Flight Center, Saturn Propulsion & Structural Test Facility, East Test Area, Huntsville, Madison County, AL

481

Optimal Electrostatic Space Tower (Mast, New Space Elevator)  

Microsoft Academic Search

Author offers and researched the new and revolutionary inflatable electrostatic AB space towers (mast, new space elevator) up to one hundred twenty thousands kilometers (or more) in height. The main innovation is filling the tower by electron gas, which can create pressure up one atmosphere, has negligible small weight and surprising properties. The suggested mast has following advantages in comparison

Alexander A. Bolonkin

2007-01-01

482

1. Oil house, keeper's house, Southern Light Tower and Northern ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. Oil house, keeper's house, Southern Light Tower and Northern Light Tower, view northwest, south and east sides - Kennebec River Light Station, South side of Doubling Point Road, off State Highway 127, 1.8 miles south of U.S. Route 1, Arrowsic, Sagadahoc County, ME

483

2. Barn, light tower and keeper's house, view southeast, west ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. Barn, light tower and keeper's house, view southeast, west and north sides of barn, northwest side of light tower, and west northwest and north northeast sides of keeper's house - Curtis Island Light Station, Curtis Island, at entrance to Camden Harbor, Camden, Knox County, ME

484

Automation of existing tower cranes: economic and technological feasibility  

Microsoft Academic Search

Tower cranes enjoy a long useful working life. Therefore, a vast population of cranes are still in use today that do not feature the advanced automation and sensor technologies such as those with which some of the new models are equipped. This paper examines the technological and economic feasibility of retrofitting existing tower cranes with semi-automatic devices for motion control.

Yehiel Rosenfeld; Aviad Shapira

1998-01-01

485

Experience with Scour at the Christchurch Bay Tower.  

National Technical Information Service (NTIS)

The purpose of this work was to study wave forces and the behavior of the gravity foundations on Christchurch Bay Tower, a small offshore structure sited in 9m of water near the UK coast. Foundation failures had occurred with the first tower and it had be...

J. R. Bishop

1981-01-01

486

1. VIEW NORTHWEST, NORTHEAST SIDE AND SOUTHEAST FRONT OF TOWER ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. VIEW NORTHWEST, NORTHEAST SIDE AND SOUTHEAST FRONT OF TOWER AND ORIGINAL LIGHTHOUSE - Mispillion Lighthouse, Beacon Tower, South bank of Mispillion River at it confluence with Delaware River at northeast end of County Road 203, 7 miles east of Milford, Milford, Sussex County, DE

487

1. Keeper's house, small boathouse, and light tower, view east, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. Keeper's house, small boathouse, and light tower, view east, west and south sides of keeper's house, west side of boathouse and tower - Great Duck Island Light Station, At southern tip of Great Duck Island southeast of Bass Harbor & northeast of Frenchboro, Frenchboro, Hancock County, ME

488

18. Upstream face of arches, concrete placing tower is at ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

18. Upstream face of arches, concrete placing tower is at far right. Tower at center was used to convey material. Photographer unknown, January 29, 1927. Source: MWD. - Waddell Dam, On Agua Fria River, 35 miles northwest of Phoenix, Phoenix, Maricopa County, AZ

489

Within compound, from Guard Tower (Building 5762), looking southwest, Technical ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Within compound, from Guard Tower (Building 5762), looking southwest, Technical Equipment Building (Building 5760) to left, Microwave Tower (associated with Building 5769) and Civil Engineering Storage Building (Building 5766) to left - Beale Air Force Base, Perimeter Acquisition Vehicle Entry Phased-Array Warning System, End of Spencer Paul Road, north of Warren Shingle Road (14th Street), Marysville, Yuba County, CA

490

Initial Model for Fires in the World Trade Center Towers.  

National Technical Information Service (NTIS)

Based on preliminary assumptions and analysis, mathematical models have been used to estimate the behavior of the fires in the twin towers of the World Trade Center (WTC) on September 11, 2001. The hijacked-plane collision with each tower produced signifi...

R. G. Rehm W. M. Pitts H. R. Baum D. D. Evans K. Prasad

2002-01-01

491

PBF Cooling Tower. View of stairway to fan deck. Vents ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

PBF Cooling Tower. View of stairway to fan deck. Vents are made of redwood. Camera facing southwest toward north side of Cooling Tower. Siding is corrugated asbestos concrete. Photographer: