Dynamic stall of small wind systems /

"February 1983."

Modern road building; being reports of the Transactions of the first Congress of American Road Builders held at Seattle, Washington, July 4, 1909.

Session held in Washington Good Roads Building Alaska-Yukon-Pacific Exposition, Seattle.

The American journal of insanity.

From July 1844 to Apr. 1894 ed. by the medical officers of the New York State Lunatic Asylum at Utica. From July 1894 to pub. by a committee of (later "under the auspices of") the American Medico-Psychological Association.

The American Galloway herd book.

Mode of access: Internet.

The American journal of theology.

Title from caption.

Addresses and proceedings - National Education Association of the United States.

Vols. for 1866-70 include Proceedings of the American Normal School Association; 1866-69 include Proceedings of the National Association of School Superintendents; 1870 includes Addresses and journal of proceedings of the Central College Association.

American law times reports.

Vol. 1 has no general title page, being made up of vol. 1 Law times (U.S.) Court reports, vol. 1 Law times bankruptcy reports and, Vol. 1 Law times department reports.

American Wildlife

Title Varies: 1912-Mar.1913, American Game Protective and Propagation Association Bulletin. Nov.1913-Apr.1925, American Game Protective Association Bulletin. July1925-Aug.1935, American Game, Official Magazine of the American Game Association

American Shire horse stud book.

Mode of access: Internet.

Wallace's American trotting register ... /

Vols. for 1871-1891 compiled by J. H. Wallace.

Relationships of Efficiency to Reproductive Disorders in Danish Milk Production: A Stochastic Frontier Analysis

Relationships of various reproductive disorders and milk production performance of Danish dairy farms were investigated. A stochastic frontier production function was estimated using data collected in 1998 from 514 Danish dairy farms. Measures of farm-level milk production efficiency relative to this production frontier were obtained, and relationships between milk production efficiency and the incidence risk of reproductive disorders were examined. There were moderate positive relationships between milk production efficiency and retained placenta, induction of estrus, uterine infections, ovarian cysts, and induction of birth. Inclusion of reproductive management variables showed that these moderate relationships disappeared, but directions of coefficients for almost all those variables remained the same. Dystocia showed a weak negative correlation with milk production efficiency. Farms that were mainly managed by young farmers had the highest average efficiency scores. The estimated milk losses due to inefficiency averaged 1142, 488, and 256 kg of energy-corrected milk per cow, respectively, for low-, medium-, and high-efficiency herds. It is concluded that the availability of younger cows, which enabled farmers to replace cows with reproductive disorders, contributed to high cow productivity in efficient farms. Thus, a high replacement rate more than compensates for the possible negative effect of reproductive disorders. The use of frontier production and efficiency/ inefficiency functions to analyze herd data may enable dairy advisors to identify inefficient herds and to simulate the effect of alternative management procedures on the individual herd's efficiency.

Wind power forecasts using Gaussian processes and numerical weather prediction

Since wind at the earth's surface has an intrinsically complex and stochastic nature, accurate wind power forecasts are necessary for the safe and economic use of wind energy. In this paper, we investigated a combination of numeric and probabilistic models: a Gaussian process (GP) combined with a numerical weather prediction (NWP) model was applied to wind-power forecasting up to one day ahead. First, the wind-speed data from NWP was corrected by a GP, then, as there is always a defined limit on power generated in a wind turbine due to the turbine controlling strategy, wind power forecasts were realized by modeling the relationship between the corrected wind speed and power output using a censored GP. To validate the proposed approach, three real-world datasets were used for model training and testing. The empirical results were compared with several classical wind forecast models, and based on the mean absolute error (MAE), the proposed model provides around 9% to 14% improvement in forecasting accuracy compared to an artificial neural network (ANN) model, and nearly 17% improvement on a third dataset which is from a newly-built wind farm for which there is a limited amount of training data. © 2013 IEEE.

A coordinated control scheme for power demand changes in a PMSG based multi-terminal DC wind farm

Although maximum power point tracking (MPPT) is crucial in the design of a wind power generation system, the necessary control strategies should also be considered for conditions that require a power reduction, called de-loading in this paper. A coordinated control scheme for a proposed current source converter (CSC) based DC wind energy conversion system is presented in this paper. This scheme combines coordinated control of the pitch angle, a DC load dumping chopper and the DC/DC converter, to quickly achieve wind farm de-loading. MATLAB/Simulink simulations and experiments are used to validate the purpose and effectiveness of the control scheme, both at the same power level. © 2013 IEEE.

Short-term wind power forecasting using Gaussian processes

Since wind has an intrinsically complex and stochastic nature, accurate wind power forecasts are necessary for the safety and economics of wind energy utilization. In this paper, we investigate a combination of numeric and probabilistic models: one-day-ahead wind power forecasts were made with Gaussian Processes (GPs) applied to the outputs of a Numerical Weather Prediction (NWP) model. Firstly the wind speed data from NWP was corrected by a GP. Then, as there is always a defined limit on power generated in a wind turbine due the turbine controlling strategy, a Censored GP was used to model the relationship between the corrected wind speed and power output. To validate the proposed approach, two real world datasets were used for model construction and testing. The simulation results were compared with the persistence method and Artificial Neural Networks (ANNs); the proposed model achieves about 11% improvement in forecasting accuracy (Mean Absolute Error) compared to the ANN model on one dataset, and nearly 5% improvement on another.

Energy Challenges in Latin America

Co-edited by Peter Hakim, President Emeritus, Inter-American Dialogue and Genaro Arriagada, Non-Resident Senior Fellow, Inter-American Dialogue, this issue examines energy as a priority issue for nearly all Latin American and Caribbean countries and considers its impact on regional integration and both foreign and domestic policy. Articles present opportunities and challenges facing the region, as well as recommendations for addressing the energy issue in Latin America in a strategic, constructive and effective manner.