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

Description: 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.
Date: November 24, 2003
Creator: Weber, A.H.
Partner: UNT Libraries Government Documents Department

Measurement of Turbulent Wind Velocities Using a Rotating Boom Apparatus

Description: The present report covers both the development of a rotating-boom facility and the evaluation of the spectral energy of the turbulence measured relative to the rotating boom. The rotating boom is composed of a helicopter blade driven through a pulley speed reducer by a variable speed motor. The boom is mounted on a semiportable tower that can be raised to provide various ratios of hub height to rotor diameter. The boom can be mounted to rotate in either the vertical or horizontal plane. Probes that measure the three components of turbulence can be mounted at any location along the radius of the boom. Special hot-film sensors measured two components of the turbulence at a point directly in front of the rotating blade. By using the probe rotated 90/sup 0/ about its axis, the third turbulent velocity component was measured. Evaluation of the spectral energy distributions for the three components of velocity indicates a large concentration of energy at the rotational frequency. At frequencies slightly below the rotational frequency, the spectral energy is greatly reduced over that measured for the nonrotating case measurements. Peaks in the energy at frequencies that are multiples of the rotation frequency were also observed. We conclude that the rotating boom apparatus is suitable and ready to be used in experiments for developing and testing sensors for rotational measurement of wind velocity from wind turbine rotors. It also can be used to accurately measure turbulent wind for testing theories of rotationally sampled wind velocity.
Date: April 1, 1984
Creator: Sandborn, V. A. & Connell, J. R.
Partner: UNT Libraries Government Documents Department

Measured and predicted rotor performance for the SERI advanced wind turbine blades

Description: Measured and predicted rotor performance for the SERI advanced wind turbine blades were compared to assess the accuracy of predictions and to identify the sources of error affecting both predictions and measurements. An awareness of these sources of error contributes to improved prediction and measurement methods that will ultimately benefit future rotor design efforts. Propeller/vane anemometers were found to underestimate the wind speed in turbulent environments such as the San Gorgonio Pass wind farm area. Using sonic or cup anemometers, good agreement was achieved between predicted and measured power output for wind speeds up to 8 m/sec. At higher wind speeds an optimistic predicted power output and the occurrence of peak power at wind speeds lower than measurements resulted from the omission of turbulence and yaw error. In addition, accurate two-dimensional (2-D) airfoil data prior to stall and a post stall airfoil data synthesization method that reflects three-dimensional (3-D) effects were found to be essential for accurate performance prediction. 11 refs.
Date: February 1, 1992
Creator: Tangler, J.; Smith, B.; Kelley, N. & Jager, D.
Partner: UNT Libraries Government Documents Department

NREL Large-Scale Turbine Inflow and Response Experiment--Preliminary Results: Preprint

Description: The accurate numerical dynamic simulation of new large-scale wind turbine designs operating over a wide range of inflow environments is critical because it is usually impractical to test prototypes in a variety of locations. Large turbines operate in a region of the atmospheric boundary layer that currently may not be adequately simulated by present turbulence codes. In this paper, we discuss the development and use of a 42-m (137-ft) planar array of five, high-resolution sonic anemometers upwind of a 600-kW wind turbine at the National Wind Technology Center (NWTC).
Date: January 1, 2002
Creator: Kelley, N.; Hand, M.; Larwood, S. & McKenna, E.
Partner: UNT Libraries Government Documents Department

A discussion of the results of an in-situ comparison of three full-vector anemometers

Description: Extensive field measurements and the numerical modeling of dynamic responses associated with wind turbine rotor blades have pointed to strong interactions with coherent turbulent structures in the turbine inflow. These interactions are thought to be a major source of high-cycle fatigue in the primary structural components of wind turbines. The sources of such turbulent structures are not only natural terrain features but also the wakes from upwind turbines. Many unsteady aerodynamic processes are excited by turbulent eddies ranging in size from several rotor diameters down to the dimensions of the mean blade chord. These processes are responsible for inducing large, fluctuating loads on the turbine rotor blades. For the wind turbine generators now in use, this encompasses a spatial range of about 0.1 to 300 m. To assess our ability to measure the coherent properties of inflow turbulence over such a wide range of spatial range, we performed a study to compare three full-vector anemometers. We believe that to identify the dominant fluid dynamic properties of such flows, the instrumentation used must be capable of good fidelity measurements over the desired spatial range. The sonic anemometer is a primary candidate; we also wanted to compare the results associated with a well-designed mechanical instrument which is available at considerably less cost. Two sonic designs and as propeller-bivane were exposed to turbulent flows downstream of both extremely complex and moderately rolling terrain. This paper discusses some of the results of these comparisons with an emphasis on the measurements of turbulent fluctuations.
Date: October 1, 1990
Creator: Kelley, N.D.; Scott, G.N. & Allread, J.S.
Partner: UNT Libraries Government Documents Department

Analyzing the Effects of Temporal Wind Patterns on the Value ofWind-Generated Electricity at Different Sites in California and theNorthwest

Description: Wind power production varies on a diurnal and seasonal basis. In this report, we use wind speed data modeled by TrueWind Solutions, LLC (now AWS Truewind) to assess the effects of wind timing on the value of electric power from potential wind farm locations in California and the Northwest. (Data from this dataset are referred to as ''TrueWind data'' throughout this report.) The intra-annual wind speed variations reported in the TrueWind datasets have not previously been used in published work, however, so we also compare them to a collection of anemometer wind speed measurements and to a limited set of actual wind farm production data. The research reported in this paper seeks to answer three specific questions: (1) How large of an effect can the temporal variation of wind power have on the value of wind in different wind resource areas? (2) Which locations are affected most positively or negatively by the seasonal and diurnal timing of wind speeds? (3) How compatible are wind resources in the Northwest and California with wholesale power prices and loads in either region? The latter question is motivated by the fact that wind power projects in the Northwest could sell their output into California (and vice versa), and that California has an aggressive renewable energy policy that may ultimately yield such imports. Based on our research, we reach three key conclusions. (1) Temporal patterns have a moderate impact on the wholesale market value of wind power and a larger impact on the capacity factor during peak hours. The best-timed wind power sites have a wholesale market value that is up to 4 percent higher than the average market price, while the worst-timed sites have a market value that is up to 11 percent below the average market price. The best-timed wind sites could produce ...
Date: May 31, 2006
Creator: Fripp, Matthias & Wiser, Ryan
Partner: UNT Libraries Government Documents Department

Turbine Inflow Characterization at the National Wind Technology Center: Preprint

Description: Utility-scale wind turbines operate in dynamic flows that can vary significantly over timescales from less than a second to several years. To better understand the inflow to utility-scale turbines, two inflow towers were installed and commissioned at the National Renewable Energy Laboratory's (NREL) National Wind Technology Center near Boulder, Colorado, in 2011. These towers are 135 m tall and instrumented with a combination of sonic anemometers, cup anemometers, wind vanes, and temperature measurements to characterize the inflow wind speed and direction, turbulence, stability and thermal stratification to two utility-scale turbines. Herein, we present variations in mean and turbulent wind parameters with height, atmospheric stability, and as a function of wind direction that could be important for turbine operation as well as persistence of turbine wakes. Wind speed, turbulence intensity, and dissipation are all factors that affect turbine performance. Our results shown that these all vary with height across the rotor disk, demonstrating the importance of measuring atmospheric conditions that influence wind turbine performance at multiple heights in the rotor disk, rather than relying on extrapolation from lower levels.
Date: January 1, 2012
Creator: Clifton, A.; Schreck, S.; Scott, G.; Kelley, N. & Lundquist, J.
Partner: UNT Libraries Government Documents Department

Coastal zone wind energy. Part II: Validation of the coastal zone wind power potential. A summary of the field experiment

Description: Procedures have been developed to determine the wind power potential of the coastal region from Maine to Texas. The procedures are based upon a climatological analysis and a mesoscale numerical model. The results of this procedure are encouraging but need to be tested. In January to February 1980 a field measurement program was carried out over the Delmarva Peninsula centered on Wallops Island and extending into the Atlantic Ocean and Chesapeake Bay to provide an observational basis on which to test our wind assessment methods. The field experiment is described. Listings of the measurements made by aircraft, tethered balloon, rawinsonde kites, tower mounted anemometry and surface thermometry are given together with sample results. The analysis of these data and the comparison between them and the model predicted fields are presented.
Date: June 1, 1980
Creator: Garstang, M.; Pielke, R.A. & Snow, J.W.
Partner: UNT Libraries Government Documents Department

Investigation into the feasibility of wind as an alternate energy resource at selected North Georgia sites

Description: Anemometers were placed at four selected sites in North Georgia during the period July, 1980, to June, 1982. Regular wind speed readings were taken using accumulating recorders and average daily wind speeds calculated for each location. Three wind speed categories were determined: (a) average below 7 mph; (b) average between 7 and 25 mph; (c) average above 25 mph. One site was abandoned after seven months due to lack of expected wind; another site was closed after 4.5 months due to continuing excessive and damaging winds. Two sites were determined, after 12 to 20 months of data collecting respectively, to have sufficient wind resources in a usable time pattern to merit further investigation.
Date: October 26, 1982
Creator: Brock, D.L.
Partner: UNT Libraries Government Documents Department

Analysis of the ideal phase-Doppler System: Limitations imposed by the single-particle constraint

Description: This paper explores the effects of particles statistics on the ability of a phase-Doppler system (or any single-particle diagnostic) to make accurate measurements of complex particle flows. This is accomplished by analyzing the response of an ideal phase-Doppler system to a postulated particle flux. The ideal system defined here senses particles of all sizes and velocities with perfect accuracy, but is subject to one constraint: in order for a measurement to be considered valid there must be only one particle in the probe volume at a time. A consequence of this constraint is that the measured flux of particles is similar to the true flux, but reduced by passage through two stages of filters. The first rejects particles for insufficient spacing and is controlled by a spatial Poisson process, while the second rejects particles for excessive residence time and is driven by a temporal Poisson process. The key filter parameters are the expected values of the number of particles in the probe volume and the number of particles entering the probe region during the residence time of a previous particle. Only if these values are kept below order 10{sup {minus}2} can the measured joint distribution function, flux rate, and derived quantities, be assumed to reflect the true nature of the flow. 8 refs., 30 figs., 2 tabs.
Date: June 1, 1991
Creator: Edwards, C.F. & Marx, K.D.
Partner: UNT Libraries Government Documents Department

Temperature velocity and species profile measurements for reburning in a pulverized, entrained flow. Semiannual report, April - October 1996

Description: The capability of LDA measurements for future reburning experiments has now been demonstrated. Measurements of mean and turbulent gas and particle velocity have been obtained using Laser Doppler Anemometry (LDA) in the near burner and quarl region of the pulverized coal reactor. The mean and turbulent velocity at the burner outlet, or top of the quarl were obtained under non-reacting conditions in order to obtain realistic boundary conditions for comprehensive combustion modeling. Also, under cold flow it was determined that little error occurred in measuring mean velocities with LDA using pulverized coal as the seed particle. Thus, for mean velocities, coal particle and gas velocities were similar. Coal particle velocity profiles were obtained at three swirls and three axial locations. Gas species, and temperature maps for the reactor have now also been completed at three swirl settings in addition to the LDA data. Gas species obtained include CO, CO{sub 2}, O{sub 2} and NO. Calibration of the HCN and NH{sub 3}measurement has been successfully completed but no measurements in the reactor have been obtained. The design and fabrication of fuel and air injectors to be used for reburning are complete. The injectors have not yet been tested.
Date: October 1, 1996
Partner: UNT Libraries Government Documents Department

Two powder stream diagnostics for laser deposition processes

Description: The velocity, density, and mass flow of particles suspended in a subsonic gas stream are important aspects of plasma spray and laser deposition processes. This paper will focus on two optical diagnostic techniques applied to the metal powder streams out of a powder feeder and into a new nozzle developed specifically for such applications. An important characteristic of the new powder nozzle is that it produces a very small column (approximately I mm diameter) of powder which can be used for small focus laser deposition and cladding processes. Laser Doppler Velocimetry (LDV) was applied to the nozzle`s output to better understand the kinetic parameters (velocity and spatial density) of exiting particles. Optical scattering of the powder stream was used to measure the total mass flow into the nozzle. Different light scattering detector scenarios applied to the input powder stream were used to identify signals useful for mass flow feedback control. Both of these techniques have the advantages of being fast, noninvasive diagnostics of the powder flow characteristics, and with a well established theoretical framework. Together, or individually, these diagnostics can provide real-time control or post-process analysis of the powder stream.
Date: December 31, 1995
Creator: Schanwald, L.P.
Partner: UNT Libraries Government Documents Department

Performance of a VME-based parallel processing LIDAR data acquisition system (summary)

Description: It may be possible to make accurate real time, autonomous, 2 and 3 dimensional wind measurements remotely with an elastic backscatter Light Detection and Ranging (LIDAR) system by incorporating digital parallel processing hardware into the data acquisition system. In this paper, we report the performance of a commercially available digital parallel processing system in implementing the maximum correlation technique for wind sensing using actual LIDAR data. Timing and numerical accuracy are benchmarked against a standard microprocessor impementation.
Date: May 1, 1995
Creator: Moore, K.; Buttler, B.; Caffrey, M. & Soriano, C.
Partner: UNT Libraries Government Documents Department

Physical and chemical characteristics of topographically affected airflow in an open borehole at Yucca Mountain, Nevada

Description: Borehole UZ6S, on the crest of Yucca Mountain, Nevada Test Site, has exhaled approximately 10{sup 6} m{sup 3} of gas annually during winter months for three successive years. The flow arises from thermal-topographic effects. The average composition of the exhausted gas is: N{sub 2} = 78%, O{sub 2} = 21%, Ar = 0.94%, CO{sub 2} = 0.125%, and CH{sub 4} = 0.2 ppMv. The CO{sub 2} has the following isotopic signature: {sup 14}C = 108.5 percent modern carbon (pmc), and {delta}{sup 13}C = 17.1 per mil. In the thirty-month observation period, there has been a net flux to the atmosphere of approximately 40 m{sup 3} of liquid water and 1150 kg of carbon. The gas flowing from UZ6S appears to originate in the soil and/or shallow unsaturated zone at Yucca Mountain crest. 25 refs., 6 figs., 4 tabs.
Date: December 31, 1989
Creator: Thorstenson, D.C.; Woodward, J.C.; Weeks, E.P. & Haas, H.
Partner: UNT Libraries Government Documents Department

The winds of Fermilab

Description: The drought of 1988 caused the operations group to become concerned about the rate of evaporation from the Main Ring cooling ponds. They needed a way to data-log windspeed and direction. They had an old broken Heathkit weather station. The anemometer and windvane were salvaged and repaired. An interface to two MADC channels on the PBAR CAMAC link was built on an old piece of CAMAC card with salvaged parts. The project cost nothing. It has been in service since January 1989.
Date: December 6, 1990
Creator: Tomlin, R.
Partner: UNT Libraries Government Documents Department

Wind tunnel test of Teledyne Geotech model 1564B cup anemometer

Description: The Department of Energy (DOE) Environment, Safety and Health Compliance Assessment (Tiger Team) of the Savannah River Site (SRS) questioned the method by which wind speed sensors (cup anemometers) are calibrated by the Environmental Technology Section (ETS). The Tiger Team member was concerned that calibration data was generated by running the wind tunnel to only 26 miles per hour (mph) when speeds exceeding 50 mph are readily obtainable. A wind tunnel experiment was conducted and confirmed the validity of the practice. Wind speeds common to SRS (6 mph) were predicted more accurately by 0--25 mph regression equations than 0--50 mph regression equations. Higher wind speeds were slightly overpredicted by the 0--25 mph regression equations when compared to 0--50 mph regression equations. However, the greater benefit of more accurate lower wind speed predictions accuracy outweight the benefit of slightly better high (extreme) wind speed predictions. Therefore, it is concluded that 0--25 mph regression equations should continue to be utilized by ETS at SRS. During the Department of Energy Tiger Team audit, concerns were raised about the calibration of SRS cup anemometers. Wind speed is measured by ETS with Teledyne Geotech model 1564B cup anemometers, which are calibrated in the ETS wind tunnel. Linear regression lines are fitted to data points of tunnel speed versus anemometer output voltages up to 25 mph. The regression coefficients are then implemented into the data acquisition computer software when an instrument is installed in the field. The concern raised was that since the wind tunnel at SRS is able to generate a maximum wind speed higher than 25 mph, errors may be introduced in not using the full range of the wind tunnel.
Date: April 4, 1991
Creator: Parker, M.J. & Addis, R.P.
Partner: UNT Libraries Government Documents Department

Simulation of winds as seen by a rotating vertical axis wind turbine blade

Description: The objective of this report is to provide turbulent wind analyses relevant to the design and testing of Vertical Axis Wind Turbines (VAWT). A technique was developed for utilizing high-speed turbulence wind data from a line of seven anemometers at a single level to simulate the wind seen by a rotating VAWT blade. Twelve data cases, representing a range of wind speeds and stability classes, were selected from the large volume of data available from the Clayton, New Mexico, Vertical Plane Array (VPA) project. Simulations were run of the rotationally sampled wind speed relative to the earth, as well as the tangential and radial wind speeds, which are relative to the rotating wind turbine blade. Spectral analysis is used to compare and assess wind simulations from the different wind regimes, as well as from alternate wind measurement techniques. The variance in the wind speed at frequencies at or above the blade rotation rate is computed for all cases, and is used to quantitatively compare the VAWT simulations with Horizontal Axis Wind Turbine (HAWT) simulations. Qualitative comparisons are also made with direct wind measurements from a VAWT blade.
Date: February 1, 1984
Creator: George, R.L.
Partner: UNT Libraries Government Documents Department

Rotationally sampled wind characteristics for several rotor sizes using laser anemometer measurements

Description: The concept of measuring the wind velocity rotationally around crosswind circles using a circle-scanning Doppler laser anemometer is investigated to determine the technique's suitability as an effective, simple, economical, and nonintrusive method for estimation turbulence at a wind turbine rotor. Estimates of wind features obtained using the lidar technique are compared to actual wind measurements obtained using a vertical plane array of anemometers, and to other estimates generated using a single-tower technique. Although the lack of a common data set precludes a firm conclusion regarding the lidar method's accuracy, it appears that the rotationally scanning lidar has the potential of becoming an excellent tool for measuring turbulent wind around the disk of rotation of a turbine blade. 11 refs., 21 figs., 2 tabs.
Date: February 1, 1989
Creator: Connell, J.R. & Morris, V.R.
Partner: UNT Libraries Government Documents Department

Boundary layer eddies at the Goodnoe Hills site

Description: Data from nine instrumented meteorological towers at the MOD-2 wind turbine site at Goodnoe Hills in Washington State were analyzed to evaluate high-frequency perturbations, which were observed in the lower boundary-layer flow. Horizontal winds and temperature measurements for a period of 8 min, undisturbed by turbine operation, were available for this study. The data are in 1-s values from June 27, 1985. Throughout the study, departures from the mean for the period and for each sensor were used on area maps and on line-time and tower-time cross sections. Conventional streamline and isotach analyses were employed; they show highly organized flow fields with embedded perturbations traversing the site. Most of the flow fields have a well-developed vortical structure that reaches from the surface through the top level of the highest tower. These structures consist of a system of clockwise and counter-clockwise circulations. The wave length is about 500 to 600 m. Their wave speed is slightly greater than the mean wind speed and their movement is in the general direction of the mean flow. The results of the study show two main reasons why wind conditions and turbine power output in a wind farm may vary in a remarkable and abrupt fashion in space and time under certain circumstances: (1) The boundary-layer flow contains highly organized coherent perturbations with a typical size of 300 {times} 300 M{sup 2}. (2) The transition zones between the perturbations moving through a wind farm are associated with very definitive changes in the wind field that are on the order of meters and seconds. 2 refs., 11 figs.
Date: May 1, 1991
Creator: Aspliden, C.I.; Wendell, L.L.; Clem, K.S. & Gower, G.L.
Partner: UNT Libraries Government Documents Department

Variability of wind power near Oklahoma City and implications for siting of wind turbines

Description: Data from five sites near Oklahoma City were examined to assess wind power availability. Wind turbines of identical manufacture were operated at three of the sites, one of which was also equipped with anemometers on a 100-ft tower. Comprehensive anemometric data were available from the other two sites. The study indicates that the average wind speed varies substantially over Oklahoma's rolling plains, which have often been nominally regarded as flat for purposes of wind power generation. Average wind differences may be as much as 5 mph at 20 ft above ground level, and 7 mph at 100 ft above ground level for elevation differences of about 200 ft above mean sea level, even in the absence of substantial features of local terrain. Local altitude above mean sea level seems to be as influential as the shape of local terrain in determining the average wind speed. The wind turbine used at a meteorologically instrumented site in the study produced the power expected from it for the wind regime in which it was situated. The observed variations of local wind imply variations in annual kWh of as much as a factor of four between identical turbines located at similar heights above ground level in shallow valleys and on hilltops or elevated extended flat areas. 17 refs., 39 figs., 11 tabs.
Date: September 1, 1987
Creator: Kessler, E. & Eyster, R.
Partner: UNT Libraries Government Documents Department

Evaluation and design of downhole heat exchangers for direct application

Description: Over 400 wells with downhole heat exchangers are in use in Klamath Falls, Oregon. Some have been in use for nearly 30 years. Despite the large number and the long experience, the exact nature of the mechanism of heat exchange and, therefore, the maximum output was not known, except that it had been theorized that convection cells were established in the well. Oregon Institute of Technology and Oregon State University are jointly involved in a project to study the heat exchange process and economics of the downhole heat exchanger system. The existence of significant convection cell circulation has been established and measured using a spinner, hot film anemometer, and by energy balance calculations. Based on these measurements, analytical models have been developed which predict heat extraction rates within 15% of actual measured values. The existence of significant mixing of new and circulating well fluid has been established and can be calculated, although at this time not accurately predicted before testing a well. Based on the analytical models, multi-tube heat exchangers have been designed and very recently tested with outputs within 15% of predicted values. Economic analysis shows that for small to moderate extraction rates, about 300 kW thermal, and shallow wells, DHEs may be more economical than pumped systems when surface discharge is not acceptable.
Date: January 1, 1974
Creator: Culver, G. & Reistad, G.M.
Partner: UNT Libraries Government Documents Department

LDA measurements under plasma conditions

Description: A study was made of the application of Laser Doppler Anemometry (LDA) for the measurement of the fluid and particle velocities under plasma conditions. The flow configuration, is that of a dc plasma jet called the principal jet, in which an alumina powder of a mean particle diameter of 115 ..mu..m and a standard deviation of 11.3 ..mu..m was injected using a secondary jet. The plasma jet immerged from a 7.1 mm ID nozzle while that of the secondary jet was 2 nm in diameter. The secondary jet was introduced at the nozzle level of the plasma jet directed 90/sup 0/ to its axis. Details of the nozzle and the gas flow system are shown in Figure 2.
Date: January 1, 1979
Creator: Lesinski, J.; Mizera-Lesinska, B.; Fanton, J.C. & Boulos, M.I.
Partner: UNT Libraries Government Documents Department

Particle and gas velocity measurements in a dc plasma jet

Description: Measurements were made, using Laser Doppler Anemometry (LDA), of the velocity of 53 ..mu..m alumina particles as they are injected in a dc plasma jet operated with an argon-nitrogen mixture (18.9 l/min argon and 4.7 l/min nitrogen) at a power level of 15.2 kW. Results obtained at distances between 5 and 150 mm from the nozzle showed the particles to penetrate the plasma jet and attain the gas velocity at about 50 mm from their point of injection. Plasma velocity measurements in the core region of the jet proved to be particularly difficult. Limitations of the LDA system with regard to its spatial resolution and seeding requirements are discussed.
Date: January 1, 1980
Creator: Lesinski, J.; Mizera-Lesinska, B.; Jurewicz, J. & Boulos, M.I.
Partner: UNT Libraries Government Documents Department