bluuebunny/crossref_metadata_2025 huggingface dataset:
Valorización de residuos de sílice para la obtención de vidrio soluble mediante análisis térmico diferencial
Authors: Agudo L. , Cornejo N. , Ayala N. , García-Carcedo F.
Published: December 2010

En la industria del silicio metálico se genera como residuo microsílice, de granulometría muy fina, con alto contenido en sílice (>92 %). En el presente trabajo se estudia la posibilidad de sustituir, completa o parcialmente, las arenas comerciales por microsílice para la fabricación de vidrio soluble por fusión. Este estudio se lleva a cabo mediante el análisis termogravimétrico y térmico diferencial de las materias primas y mezclas de estas. El balance energético del sistema indica que al utilizar la microsílice requiere el aporte de menor energía externa. La presencia de impurezas en la microsílice puede dar lugar a la formación de compuestos insolubles en el vidrio de silicato. Se concluye que la microsílice puede ser utilizada parcialmente en la elaboración de silicato sódico.
Influencia del tamaño de los carburos del acero para cojinetes de bolas relacionada con estabilización de diámetros y las propiedades mecánicas después del tratamiento térmico final
Authors: Filipek J. W. , Rincón E.
Published: December 2010

El presente trabajo está dando un enfoque específico de lo que es la influencia de la estructura de la materia prima (dispersión y forma de los carburos) en estado recocido para la cantidad de austenita retenida, la dureza y otras propiedades después del tratamiento térmico final (temple y revenido). Se observó, con base en los resultados, que existe una estrecha relación entre las estructuras (tamaño y forma de carburos) y las propiedades mecánicas.
Estudio del comportamiento térmico del polvo de aluminio estabilizado con el yeso
Authors: López-Delgado A. , Medina J. A. , Alonso P. , Tayibi H. , Pérez C. , López F. A.
Published: December 2010

El polvo de aluminio (pAl) es un residuo peligroso procedente de la metalurgia secundaría del aluminio. Con objeto de reducir la reactividad del mismo, en el CENIM se ha desarrollado un proceso de estabilización/solidificación mediante su fraguado con yeso. En este trabajo se presenta el estudio del comportamiento térmico del pAl estabilizado con el yeso, con el fin de establecer la influencia del residuo en las reacciones de hidratación/deshidratación del yeso durante el proceso del fraguado, a saber: deshidratación parcial del sulfato cálcico dihidrato, deshidratación del hemihidrato, deshidratación del hidróxido de aluminio y transformación de anhidrita soluble en anhidrita insoluble. Asimismo se ha estudiado la cinética asociada a cada una de las reacciones anteriormente mencionadas mediante Calorimetría Diferencial de Barrido.
La recuperación de los envases de hojalata de los RSU en España: calidad de la chatarra
Authors: López-Delgado A. , Peña C. , López V. , Lobo-Recio M. A. , López F. A.
Published: December 2010

Los envases de hojalata procedentes de RSU se recuperan y reciclan con mayor facilidad que otros materiales gracias a sus propiedades magnéticas. El acero empleado para la fabricación de este tipo de envases es de alta calidad, por lo tanto, tras su utilización se recupera una chatarra de calidad, cuyo reciclado supone una oportunidad importante para reducir el consumo de materias primas. En este trabajo, se analizan los escenarios de la recuperación de envases de hojalata de los RSU en España, se caracteriza la chatarra férrica procedente de plantas de incineración y de compostaje estableciéndose la relación calidad/tecnología de recuperación y se ensayan técnicas de fragmentación/separación magnética/fundido y de desestañado térmico para conseguir la mejora de la calidad de las chatarras previa a su reutilización.
Influencia de la relación velocidad de corte-avance en la calidad superficial de muestras taladradas de fibra de carbono
Authors: Álvarez M. , Carrillero M. S. , Ares J. E. , González J. M. , Marcos M.
Published: December 2010

En los últimos años, la fibra de carbono (FC) encuentra, cada vez, más aplicaciones en los distintos sectores industriales. En el caso particular de la industria aeronáutica, este tipo de materiales se somete frecuentemente a operaciones de taladrado formando parte de estructuras híbridas PC/substrato metálico, debido a las necesidades de montaje en los elementos estructurales de una aeronave. Sin embargo, en el taladrado de FC se puede presentar una serie de problemas como las delaminaciones, la pérdida de calidad en el acabado superficial o el desgaste rápido y excesivo de la herramienta de corte. En este trabajo se lleva a cabo un primer estudio de la calidad de acabado superficial obtenida en muestras de FC taladradas en función de las condiciones de corte impuestas.
Estudio mediante EIS de capas lantánidas de conversión desarrolladas mediante activación térmica sobre aleaciones de Al-Mg
Authors: Bethencourt M. , Botana F. J. , Cano M. J. , Montero M. , Marcos M.
Published: December 2010

En la actualidad, se encuentran en desarrollo una gran variedad de tratamientos anticorrosivos que pueden emplearse como alternativas a los basados en Cr(VI). Algunos conllevan el empleo de lantánidos. En este trabajo, se lleva a cabo un estudio de las características morfológicas y anticorrosivas de capas desarrolladas sobre la aleación AA5083 a partir de disoluciones de Ce(III), mediante tratamientos de inmersión a 323K en baños de sal de cerio. Estudios SEM/EDS sobre la muestras tratadas han puesto de manifiesto la existencia de una capa heterogénea formada por una película de óxido/hidróxido de aluminio sobre la matriz y una serie de islas dispersas de cerio, sobre los intermetálicos catódicos. Para evaluar el grado de protección de las capas de conversión desarrolladas, así como para caracterizar la contribución individual de la respuesta electroquímica del sistema en NaCl, se han llevado a cabo ensayos de EIS.
Empleo del método electroquímico acelerado AC-DC-AC para la predicción del tiempo de vida útil de pinturas base agua
Authors: Bethencourt M. , Botana F. J. , González-Rovira L. , Marcos M. , Osuna R. M.
Published: December 2010

En este trabajo se propone un método acelerado de evaluación de metales pintados. Concretamente, el método se ha aplicado al estudio del proceso de degradación de dos pinturas de base agua aplicadas sobre un acero al carbono. El método está basado en la aplicación de ciclos en los que se combinan la medida de espectros de impedancia electroquímica, etapas de polarización catódica y el registro de la evolución del potencial de corrosión del sistema en función del tiempo. Los resultados obtenidos mediante este método se comparan con los obtenidos al estudiar la evolución de los espectros de impedancia de ambos sistemas en función del tiempo de inmersión, para periodos de inmersión del orden de 200 d.
Influencia mutua de la deformación y composición química sobre la precipitación inducida en aceros microaleados
Authors: Quispe A. , Medina S. F. , Gómez M.
Published: December 2010

Mediante ensayos de torsión y usando el método back extrapolation se ha determinado la cinética de recristalización estática de aceros microaleados con vanadio (V), niobio (Nb) y titanio (Ti) y, a partir de las mismas, ha sido posible dibujar los diagramas recristalizaciónprecipitación- tiempo-temperatura (RPTT), que muestran gráficamente la interacción recristalización-precipitación. Estos diagramas muestran que el efecto de la deformación en la cinética de precipitación depende del contenido de microaleante. En este sentido, se propone una nueva expresión para relacionar la influencia de la deformación y del contenido de microaleante sobre el periodo mínimo de incubación de la precipitación inducida.
Aplicación de la nanoindentación para la determinación de las propiedades mecánicas interfaciales en materiales compuestos de matriz de aluminio
Authors: Ureña A. , Rams J. , Campo M. , Sánchez M.
Published: December 2010

El presente trabajo contempla la aplicación de la técnica de nanoindentación, para determinar el comportamiento mecánico de las intercaras matriz-refuerzo, presentes en materiales compuestos de matriz de aluminio. Los materiales ensayados han sido aleaciones de aluminio 6061 reforzadas tanto con partículas de SiC como con fibras cortas de grafito. Ambos tipos de materiales se fabricaron mediante técnicas de fusión que implican condiciones de alta reactividad entre la matriz de aluminio fundido con el refuerzo correspondiente. Para controlarla, se aplicaron diferentes recubrimientos sobre ambos tipos de refuerzo (SiO2 mediante sol-gel sobre el SiC y cobre por electroless sobre el grafito). La caracterización se realizó empleando un Nanoindenter XP, aplicando fuerzas comprendidas entre 0,5 y 150 mN con una pirámide de diamante tipo Berkovich, procediendo, posteriormente al estudio por SEM de las huellas de nanoindentación resultantes. Las curvas fuerza-desplazamiento obtenidas permitieron evaluar la variación de rigidez y dureza a través de las intercaras y los mecanismos de fallo que tienen lugar.
Anisotropía en el comportamiento a tracción de la aleación Ti-6Al-2Sn-4Zr-6Mo
Authors: Corzo M. , Mañero J. M. , Anglada M. , Mateo A.
Published: December 2010

Se ha realizado un estudio del comportamiento mecánico a tracción de la aleación Ti-6Al-2Sn-4Zr-6Mo, forjada en la región β con un tratamiento posterior de doble envejecimiento. Puesto que esta aleación suele presentar una fuerte anisotropía, se consideraron las direcciones radial y tangencial con respecto al eje de forja. Se ha observado una fuerte disminución en el límite de elástico para la dirección radial junto con un notable aumento de la ductilidad. Análisis mediante microscopía electrónica de transmisión y difracción de rayos X, permiten concluir que este comportamiento está asociado con la transformación martensítica inducida por deformación, la existencia de maclado, y en menor grado con la presencia de fase α, a lo largo de los límites de grano.
Influencia del Cu sobre la ductilidad en caliente de aceros C-Mn-Al y microaleados Ti-Nb
Authors: Comineli O. , Lou H. , Liimatainen H. M. , Karjalainen L. P.
Published: December 2010

Se ha observado un efecto beneficioso del cobre sobre la ductilidad en caliente del acero microaleado al Ti-Nb, en el rango de temperaturas 800-1.000 °C. La influencia fue observada a velocidades de enfriamiento bajas, 0,4 °C/s, mientras que a 4 °C/s no se aprecia. En el acero C-Mn-Al, la influencia de cobre no fue detectada. En el acero microaleado se detectó la presencia de precipidados que contienen niobio y titanio, la dimensión de los cuales es mayor cuando se enfría a 0,4 °C/s. En este acero no se detectó la presencia de precipitados con contenidos de cobre, en contraste con el acero C-Mn-Al, donde sí se observaron partículas de CuS. Se proponen dos mecanismos para explicar la influencia positiva del cobre en aceros microaleados. El primero es el aumento de la actividad de carbono y nitrógeno en austenita debido a presencia de átomos de cobre en solución sólida, con el mismo efecto que el silicio, el cual aumenta la precipitación a altas temperaturas. El otro mecanismo sugiere que los átomos de cobre pueden prolongar la permanencia de vacantes generadas por deformación, facilitando la formación de complejos de vacantes con átomos de Ti-Nb, y como consecuencia agrandando las partículas precipitadas.
Decapado del acero inoxidable AISI 316L utilizando una mezcla ecológica de H2O2-H2SO4-HF
Authors: Narváez L. , Cano E. , Bastidas D. M. , Gómez P. P.
Published: December 2010

En la presente investigación se estudia el decapado del acero inoxidable AISI 316L utilizando una mezcla de agua oxigenada (H2O2) y los ácidos sulfúrico (H2SO4) y fluorhídrico (HF) a pH 2,0. La estabilidad de la mezcla H2O2-H2SO4-HF se ha ensayado variando el contenido de iones férrico de O a 40 g/l y la temperatura de 25 a 60 °C. La velocidad de decapado a 50 °C ha sido de 2,6 y 0,2 mg/dm2 día (mdd), en ausencia y presencia de 40 g/l de iones férrico, respectivamente. Se ha utilizado el ácido p-toluen sulfónico como estabilizante del H2O2.
Caracterización superficial de nuevos pre-tratamientos a base de silanos aplicados sobre aluminio
Authors: Gener M. , Chico B. , Simancas J. , De la Fuente D. , Morcillo M.
Published: December 2010

Un proceso alternativo a los pre-tratamientos comerciales anticorrosivos a base de cromo, sin problemas de salubridad y que en estudios exploratorios iniciales ha dado resultados prometedores en cuanto a la protección frente a la corrosión y la mejora de la adherencia, son los pre-tratamientos a base de silanos. En el marco de la investigación sobre la capacidad anticorrosiva de estos compuestos que se está realizando para diferentes silanos y substratos, se presentan en este artículo algunos de los resultados preliminares. En concreto, se discuten los resultados de la caracterización superficial mediante técnicas de SEM-EDS (Scanning Electron Microscopy) y XPS (X-Ray Photoelectron Spectroscopy) para dos silanos con distintos grupos funcionales (3-aminopropiltrietoxisilano o γ-APS y 3-glicidiloxipropiltrimetoxisilano o γ-GPS), preparados a distintos pH y aplicados como imprimación sobre un substrato de aluminio.
Transformaciones α↔β en la aleación Ti-6Al-6V-2Sn: caracterización y características mecánicas y microestructurales
Authors: Tarín P. , García-Simón A. , Piris N. M. , Badía J. M. , Antoranz J. M.
Published: December 2010

Para estudiar la cinética de la transformación α↔β en la aleación Ti-6Al-6V-2Sn, del tipo α+β, y valorar el porcentaje de fase a no trasformada (α primaria) y la influencia en transformaciones posteriores en enfriamiento, se realizaron ensayos de análisis térmico (diferencial y dilatométrico), estudios metalográficos y medidas de dureza, tras tratamientos térmicos controlados. Partiendo del estado de entrega (mill annealed), se realizaron tratamientos de solución, mediante calentamiento de 1 h entre 650 °C y 1.050 °C, con enfriamiento en agua con agitación. Posteriormente, se han sometido las muestras a un calentamiento a 570 °C durante 4 h y enfriamiento final al aire. Finalmente, se determinaron las características en tracción.
Recubrimientos de hidroxiapatita preparados mediante un proceso sol-gel
Authors: Peón E. , Jiménez Morales A. , Fernández-Escalante E. , García-Alonso M. C. , Escudero M. L. , Galván J. C.
Published: December 2010

Se han preparado nuevos recubrimientos de hidroxiapatita (HAp) obtenidos a partir de precursores de tipo sol-gel, depositados sobre sustratos metálicos de una aleación de base hierro denominada MA956, previamente oxidados a elevadas temperaturas, para mejorar la adherencia con los recubrimientos de hidroxiapatita. El recubrimiento sol-gel se obtuvo aplicando una ruta acuosa, utilizando como precursores del fósforo y del calcio trietilfosfito y nitrato cálcico tetrahidratado, respectivamente. Sobre los geles resultantes se aplicaron distintos tratamientos térmicos de sinterización, hasta la obtención de recubrimientos de hidroxiapatita homogéneos, adherentes y cristalinos. Las técnicas de caracterización utilizadas para realizar este estudio han sido microscopía óptica, MBE/EDX, DRX y FTIR. Así mismo, se ha determinado la adherencia entre el substrato y el recubrimiento de hidroxiapatita según la norma ASTM D 3359-02. Los resultados obtenidos han mostrado que el tratamiento térmico óptimo se consigue cuando se aplica una temperatura de sinterización de 550 °C durante un tiempo igual a 72 h.
Influencia del acabado superficial sobre el comportamiento tribológico de capas nitrocarburadas en acero X40CrMoV5 1
Authors: Miguel V. , Calatayud A. , Coello J. , Martínez A. , Caminero A.
Published: December 2010

En este trabajo se estudia la influencia que el acabado superficial del acero X40CrMoV5 1 tiene sobre la capa blanca o de combinación formada en el proceso de la nitrocarburación gaseosa. Se consideran acabados superficiales en el rango de 0,02 a 1,50 μm para Ra. Los resultados obtenidos indican que la rugosidad aumenta en todos los casos, aunque tiene poca influencia sobre el espesor de capa formada. También se ha investigado el comportamiento frente al desgaste abrasivo de las capas obtenidas que están constituidas en su totalidad por nitrocarburo ε y son de un espesor aproximado de 6 μm. Se ha encontrado un comportamiento diferenciado frente al desgaste de la zona externa de la capa frente a la zona subsuperficial. Los resultados revelan que la capa externa de la capa de combinación es poco efectiva frente al desgaste en relación con la capa subsuperficial. La zona de peor comportamiento es mayor para las probetas con acabados superficiales más finos.
La tecnología de producción de coque de horno alto ante el nuevo milenio
Authors: Álvarez R. , Díez M. A. , Barriocanal C. , G. Cimadevilla J. L.
Published: December 2010

Para el funcionamiento del Horno Alto el coque es imprescindible. Sin embargo, la ausencia de construcción de nuevas plantas de coquización a lo largo de los últimos años ha producido un envejecimiento de las infraestructuras existentes para la producción de coque siderúrgico. De esta forma, el desafío al que se enfrenta la industria de coquización ante el nuevo milenio es la modernización de las viejas estructuras de producción de coque. En cuanto a los sistemas de coquización alternativos, en la Unión Europea se ha desarrollado el reactor Jumbo o Single Chamber System (SCS); en EE.UU. se tiende a emplear hornos no recuperadores basados en los primitivos hornos de colmena; y en Japón se está desarrollando el proyecto SCOPE 21.
Comparación de la calidad del coque siderúrgico obtenido a diferentes escalas
Authors: G. Cimadevilla J. L. , Díaz-Faes M. E. , Casal M. D. , Suárez C. , Barriocanal C. , Díez M. A. , Álvarez R.
Published: December 2010

La resistencia mecánica en frío del coque siderúrgico -evaluada mediante el ensayo IRSID-, la reactividad frente al CO2 (CRI) y la resistencia mecánica post-reacción (CSR) son los parámetros más importantes empleados para controlar la calidad del coque en España. En el INCAR, antes del cierre de la Coquería Experimental en Julio de 1999, se ha realizado un estudio para determinar la correlación existente entre la calidad del coque obtenido a escala semi-industrial -homo de 6 t - y a escala piloto -horno de pared móvil (HPM) de 250 kg-. En este trabajo se describen los estudios realizados y los resultados obtenidos, los cuales permiten predecir la calidad del coque que se vaya a obtener a escala industrial a partir de los datos obtenidos en el HPM.
Variación del módulo de Young con el tratamiento térmico en aceros al carbono hipoeutectoides
Authors: Villuendas A. , Jorba J. , Roca A.
Published: December 2010

En trabajos anteriores se ha constatado que varios aceros al carbono hipoeutectoides, en estado de temple, presentan valores del módulo de Young inferiores a los correspondientes en estado de revenido. En todos los casos la determinación se ha realizado mediante ultrasonidos. En concreto, para el acero C22E (EN 10083), el módulo se incrementa ligeramente desde 209 GPa (material templado) hasta 211 GPa (revenido a 650 °C), para el acero C45E el módulo aumenta desde 199 GPa hasta 211 GPa (revenido a 500 °C) y para el acero C55E el módulo varía desde 202 GPa hasta 209 GPa para el acero revenido a 650 °C. El presente trabajo se centra en la caracterización estructural de los tres aceros mencionados a los distintos estados de tratamiento térmico, utilizando las técnicas de microscopía óptica de reflexión y microscopía electrónica de barrido, y se propone una explicación de la variación del módulo a partir del comportamiento de las dislocaciones y su interacción con átomos de soluto y con otras dislocaciones.
Desarrollo de aceros reforzados con carburos primarios vía metalurgia líquida
Authors: Agote I. , Gutiérrez M. , Orbegozo M. , Asensio M. , Erauskin J. I. , Erausquin L. Á. , Echeverría J. I. , Roncal J.
Published: December 2010

Para que el reforzamiento de los aceros con carburos primarios vía metalurgia líquida sea técnicamente viable se requiere del desarrollo de un tipo de producto reforzante sólido, adecuado para su incorporación al acero, así como de la optimización de dicha vía metalúrgica de adición del producto reforzante al material base en estado líquido. Además, la mejora de características de la aleación reforzada es función directa de la naturaleza de las partículas, de su homogénea y uniforme distribución en la matriz y del tamaño y morfología regular de las mismas. Estas condiciones se consiguen cuando las partículas de carburo se elaboran previamente mediante la técnica SHS (selfpropagating high temperature synthesis) y se añaden al baño de acero líquido previo a su colada en moldes o lingoteras.
Los códices de la Historia Roderici y sus relaciones
Authors: RUIZ ALBI Irene
Published: December 2010

La Historia Roderici o Gesta Roderici Campidocti es una de las fuentes principales para conocer la vida de Rodrigo Díaz de Vivar. Su uso frecuente en la cronística medieval nos hace suponer que debieron existir muchos ejemplares de la Historia Roderici, pero tan solo se nos han conservado tres manuscritos, custodiados todos en la Biblioteca de la Real Academia de la Historia. En el presente trabajo pretendemos analizar las relaciones que existen entre los códices, en especial las existentes entre el manuscrito I, datable a comienzos del siglo XIII y procedente del monasterio de San Isidoro de León, y el manuscrito S, de fines del XV o comienzos del XVI. La filiación del códice M, del siglo XVIII, no presenta ningún problema, ya que como se manifiesta al comienzo del propio manuscrito, es copia de I.
A Study in Developing a Mobile Learning System based on Human-Computer Interaction Design Principles
Authors: Su Kuo-Wei , Liu Cheng-Li , Kuo Meng-Fang
Published: December 2010

Today, the learning model of a single instructor interacting with many students that is applied in conventional classrooms forms a passive bottleneck. Moreover, the instructor cannot effectively record students’ individual learning histories for instantaneous and suitable feedback. To address these issues using a mobile learning system (MLS) the authors have applied the principles of human-computer interaction (HCI) to construct a usable MLS on a personal digital assistant (PDA) The research focuses on adaptive content delivery within the context of small-screen design. The authors utilized task analysis, a literature review, experimental design and approaches to small-screen design, and addressed potential issues with presentation in order to design a friendly PDA interface whose performance was analyzed with a postexperiment user satisfaction questionnaire. The results of this experiment show that the mobile-based classroom learning experience provides appropriate mobile tools to help students to become capable, self-reliant, self-motivated, and independent. The findings also demonstrate that variations among students’ preference for content are associated with differences in the display presentation mode, and that thelandscape interface is recommended for use in some contexts.
E-Professional Development and Rural Teachers
Authors: Kitchenham Andrew
Published: December 2010

This paper describes the outcomes of a study on teacher supply and demand issues in Northern Canada. Using questionnaires and interviews, participants were asked to comment on professional development models currently used and models to be considered. In particular, comments on the use of blended learning as a viable method of e-professional development model were favorable. In subsequent research to follow up those comments, the researcher provided professional development model exemplars and asked the participants to discuss the advantages and disadvantages for rural teaching professionals. The researcher argues that the chosen blended learning model is superior to others as it is based on adult-learning principles. The results of this study are promising as the majority of participants chose blended learning as their primary choice for professional development.
IMPLICATIONS OF PERFORMANCE MEASURES AND STANDARDS FOR EVALUATION AND ASSESSMENT IN AGRICULTURAL EDUCATION
Authors: Belcher Greg , McCaslin N. L. , Headley W. Scot
Published: December 2010

The Carl D. Perkins Vocational and Applied Technology Education Act Amendments of 1990 mandated that states develop a system of performance measures and standards to be used for program evaluation and improvement. The purpose of this study was to examine the systems of performance measures and standards that each state had approved in response to the Perkins Act of 1990 for secondary vocational programs and identify implications for agricultural educators. Ninety-six percent of the states reported academic measures and standards for secondary programs. Academic areas of mathematics, reading, and language were ranked high by states as an approved measures for academic skill in both basic and advanced skill area. For other performance, one hundred percent of the states had approved at least one measure for secondary programs. The most common types of measures for other performance were work skill attainment and any placement. Agricultural educators need to be aware of these measures and standards as they plan and modify programs. Agricultural educators should place more emphasis on mathematics, reading, and language. In addition, agricultural educators need to increase their knowledge and skills related to assessment since states indicated a heavy reliance on locally developed assessment techniques.
Opinions Of Instructors, Practitioners, & Alumni Concerning Curricular Requirements Of Agricultural Communication Students At The Univeristy Of Florida
Authors: Sprecker Kimberly J. , Rudd Rick D.
Published: December 2010

Since the debut of the University of Florida's agricultural communication program in 1990, no study had been conducted to determine whether the curriculum adequately prepared graduates for the agricultural industry. The purpose of this study was to determine skills and knowledge needed by graduates of the University of Florida 's agricultural communication program for successful professional service in fields related to agricultural communication. Personal interviews were conducted with six instructors of the program's required journalism and communication courses, four instructors of the required agricultural communication courses, I4 agricultural communication practitioners in Florida, and six alumni of the agricultural communication program. All groups said instruction about Florida agriculture on a broad level (including commodities, trade/economics and policy/law) was important. However, all said that communication skills were more important than agricultural knowledge. All groups said students must have versatile communication skills and learn to network with others. Instructors and alumni emphasized in-depth communication courses. Practitioners and alumni stressed desktop publishing. Instructors and practitioners underscored internships and training in issues management. Only instructors emphasized electronic media/inter-net. Incorporation of these findings into the curriculum will help ensure that students graduate equipped to excel in their careers.
Using The Delphi Technique To Assess Educational Needs Related To Extension's 4-H Beef Program
Authors: Shih Ching-Chun , Gamon Julia A.
Published: December 2010

This Delphi study identified what should be included in 4-H beef instructional materials from the viewpoint of knowledgeable adults. A series of three questionnaires was mailed to four groups: parents of outstanding livestock participants, 4-H specialists, Extension beef specialists, and beef industry representatives. The respondents identified 31 subject-matter and 30 life-skill topics that were important to include in 4-H beef manuals. Emerging topics to consider were concerns of consumers and the environment. Results of the study would be useful to those who are developing materials and activities for youth with livestock projects.
Studying Agriculture Through Videotape: Learner Strategies And Cognitive Styles
Authors: Miller Greg
Published: December 2010

The purpose of this study was to describe learning strategies used by students enrolled in videotaped courses and to explore associations between selected learning strategies and cognitive style. Results suggest that students took advantage of the convenience that videotaped instruction affords by controlling when, where and for how long instruction tookplace. Furthermore, the distant learners tended to study independently and learned by viewing the videotape, completing reading assignments, and reading class notes. They rarely studied with others and rarely called the instructor. Since learners relied heavily on the videotapes, recommendations were made about how the quality of communication in videotaped courses could be enhanced. Students adopted a relatively consistent approach to learning from videotape. Instructors should be made aware of the learning strategies employed by their distant students and in some cases may wish to recommend alternative approaches. Field-dependent and field-independent students employed very similar learning strategies. Differences were noted that were consistent with the learning style literature. Further research was recommended to determine if practical associations exist between learning strategies and cognitive style in the context of other distance learning delivery media.
Agriculture Teachers And Students: In Concert Or Conflict?
Authors: Garton Bryan L. , Thompson Gregory W. , Cano Jamie
Published: December 2010

The purpose of the study was to describe the learning preferences of secondary teachers and students of agricultural education. The Individual Learning Preference Checklist (ILP) was administered to first and second year secondary agriculture teachers (N= 37) and their students (n = 1507). A majority of the teachers leaned toward the Extraversion, Intuition, Thinking, and Judgement learning preferences, indicating a preference for active learning and exercises that stimulated thought. A majority of the students preferred the Introversion, Sensation, Feeling, and Judgement learning preferences, indicating a need for a quiet learning environment, structured learning activities, and "real-life" illustrations to better learn the concepts being taught. The learning preferences of the teachers and students differed, indicating a need for teachers to be cognizant of the learning differences between them and their students.
Assessment Of Junior High/Middle School Agricultural Education Programs In Nebraska
Authors: Fritz Susan , Moody Linda
Published: December 2010

The purpose of the study was to identify, describe and assess the junior high/middle school agricultural education programs in Nebraska. Seventy-three programs reported having a junior high/middle school agricultural education program. Most of the programs had been in existence 10 years or less. A clear majroity of respondents had nine-week programs. Over half of the respondents that did not have junior high/middle school programs wanted to add the program, but the "school class schedule" was the most frequently identified deterrent. Those instructors not interested in adding a program cited a "full instructor schedule" as their major deterrent. For those who offered junior high/middle school programs, the most frequently cited opportunities for offering the program were to "promote agriculture awareness," "recruitment for agriculture classes," and "exposure to career opportunities in agriculture."
Perceptions Of Iowa Secondary School Agricultural Education Teachers And Students Regarding Sustainable Agriculture
Authors: Williams David L. , Wise Kenneth L.
Published: December 2010

The purpose of this study was to determine the perceptions of Iowa agricultural education teachers and students about sustainable agriculture. The teacher population for the study included all secondary school agricultural education teachers in Iowa (N=248). A stratified random sample of 60 teachers (schools) was selected, 10 from each of the six FFA districts. Teachers in the sample were asked to administer instruments to all eleventh and twelfth grade students in their agricultural education classes, yielding 464 student participants. Likert-type scales were used to measure perceptions related to knowledge and impact of sustainable agriculture. Teachers perceived themselves as having additional things to learn about sustainable agriculture practices and students measured themselves as only "knowing a little" about them. Teachers and students alike perceived sustainable agriculture impacting agriculture and the environment in several ways. Relatively high perceptions of sustainable agriculture were observed for both groups. The findings of this study support the need to integrate sustainable agriculture into the secondary school agricultural education curriculum.
Attitude Formulation Of Ethnic Minority Students Toward The Food And Agricultural Sciences
Authors: Wiley Zelia Z. , Bowen Blannie E. , Bowen Cathy F. , Heinsohn Anne L.
Published: December 2010

Most solutions that have been implemented to eliminate the persistent under-representation of ethnic minority students in colleges of agricultural sciences have produced limited success. Many of these solutions ignore theories which suggest that education and substantive experiences must precede positive attitudes and resultant behaviors toward the food and agricultural sciences (FAS). Also, during high school, many minorities do not enroll in upper level science courses that FAS majors require. Given these scenarios, this research investigated the influence of an FAS pre-college workshop on the attitudes of participants. Forty-four academically talented high school minority students were selected for the one-week workshop taught by college faculty and 28 students participated Objective #1 focused on the stability of the 28 participants' FAS attitudes. When the workshop began, the participants agreed that they (1) knew little about food and agricultural science careers and (2) associated the FAS with farms. However, they left the workshop with more positive attitudes that were maintained a year later. Objective #2 compared the attitudes of the 28 workshop participants and 16 comparable students who did not participate in the workshop. On six of 10 indicators, the participants had significantly more positive attitudes than nonparticipants.Recommendations for future pre-college programming are offered based on the findings.
How Ohio Teachers Use AgVenture Magazine To Increase Agricultural Literacy Among Their Students
Authors: Swortzel Kirk A.
Published: December 2010

This study was conducted to evaluate how elementary teachers in Ohio use AgVenture Magazine to increase their student's awareness about Ohio agriculture. A randomly selected sample of 750 fourth-grade teachers was mailed a questionnaire to collect data on how they used AgVenture Magazine with their students and assess their perceptions on the value of AgVenture Magazine as an instructional aid. Teachers used AgVenture Magazine approximately nine hours per year, primarily in social studies classes. Teachers used very few outside resources to help them teach their students about the importance of Ohio agriculture. Overall, teachers had positive perceptions about AgVenture Magazine as an instructional aid to help teach students about agriculture. Members of the Editorial Review Board and the writers of AgVenture Magazine should continue to use fourth-grade teachers to help review the content and terminology of each issue before being published. Additional research needs to be conducted to determine if AgVenture Magazine makes a difference in helping students become more aware about the importance of Ohio agriculture.
A Pre-Posttest Evaluation Of Livestock Management Instructional Materials
Authors: Gamon Julia A. , Shih Ching-Chun , Wu Chia-Hsing
Published: December 2010

A set of instructional materials on Total Quality Management livestock practices was evaluated by preposttest measures of attitudes. The posttest was administered one year after the pretest, and students were paired on three measures, gender, grade in school, and whether or not they raised livestock. Contrary to researchers' expectations, attitudes after use of the materials tended to be lower than attitudes before use of the materials. But when ratings on the posttest were compared with a control group of students, there were significant differences favoring those taught with the new materials. Females rated their use of TQM livestock practices higher than males as did those with livestock compared with those without. Also, the 10th and 11th graders had higher ratings than 12th graders. This study illustrated some of the difficulites in evaluating instructional materials without disrupting the flow of classes. Historical factors and differential selection are two of the extraneous variables cited as affecting this pre-post study. Recommendations for future evaluations of instructional materials are to use a variety of methods to assess their value.
Self-Perceived Youth Leadership And Life Skills Of Iowa FFA Members
Authors: Wingenbach Gary J. , Kahler Alan A.
Published: December 2010

Iowa FFA members were surveyed to determine if a significant relationship existed between their self-perceived youth leadership and life skills development scores and their participation in youth leadership activities. This study was patterned after research done by Dormody and Seevers (1994) of New Mexico State University. Responses were received from 316 Iowa FFA members. Iowa FFA members' Youth Leadership And Life Skill Development Scale (YLLSDS) scores ranged from 0 to 90 with a composite mean of 62.6. The three highest shill means were observed for the YLLSDS items "getting along with others, " "respect others, " and "show a responsible attitude. " FFA members participated most actively in chapter meetings, fundraising and chapter banquets. Respondents indicated the highest leadership opportunities for non FFA activities occurred through participation in sports, church groups, and after school jobs. The strongest relationship existed between YLLSDS scores and FFA leadership activities followed by years of membership in FFA, age, jobs, achievement expectancy, club officer, church groups, and class officer. A total of 22.26% of the variance in YLLSDS scores was explained by a combination of participation in FFA leadership activities, after school jobs, years in the FFA, self-reported cumulative grades, and gender.
Focusing Agricultural Education Research: An Agenda For The Graduate Student
Authors: Williams David L.
Published: December 2010

The agricultural education profession has been challenged to focus its research as a means to further develop the discipline. Recognizing that much of the research in agricultural education is conducted by graduate students under the supervision of mentors, the purpose of this article is to present an agenda for focusing research by graduate students in agricultural education. The thouhts presented are inteded to provoke a discussion among agricultural education graduate students and their mentors and to guide individualized action by graduate students. The plan includes eight action points for graduate students: (1) assess professional experiences, (2) understand the discipline, (3) review trends and priorities, (4) study requirements ofpositions, (5) identify mentors, (6) build on a theoretical base, (7) practice good science, and (8) become a scholar. Action on these points can help develop a new generation of scholars in agricultural education and strengthen the contribution of graduate student research to the discipline.
Assessing Reliability Of Measurements With Generalizability Theory: An Application To Inter-Rater Reliability
Authors: VanLeeuwen Dawn M.
Published: December 2010

This article introduces the application of Generalizability Theory to assessing the reliability of measurements. Generalizability Theory can be used to assess reliability in the presence of multiple sources of error and also can be applied to assess reliability in the presence of different types of sources of error. In particular, the application of Generalizability Theory to measurements involving multiple raters is considered. An example illustrates its application to assessing reliability in the presence of inter-rater variability.
A Review Of Subject Matter Topics Researched In Agricultural And Extension Education
Authors: Radhakrishna Rama B. , Xu Wenwei
Published: December 2010

Two premier publications of the agricultural and extension education profession were examined toidentify subject matter topics researched in agricultural and extension education. A total of 853 articles (402 in Journal of Agricultural Education and 451 in National Agricultural Education Research Meetings) published during 1986-1996 were reviewed. A total of 30 subject matter topics were identified using an expert panel. The 853 articles were categorized into the relevant subject matter topics. The top five subject matter topics researched during this 11 years were: secondary ag programs, learning styles/theory, extension education, professionalism, and ag mechanics/engineering. Emerging topics included distance education, international, undergraduate/graduate education, agricultural literacy, diverse audiences and environment/sustainability. Agricultural and extension educators research a variety of subject matter topics which address diverse issues related to the profession. It is recommended that the profession develop a systematic research agenda focusing on: 1) critical issues of the profession; 2) collaborative approach to research; and 3) periodic reviews of premier publications of the profession.
FFA Advisors' Educational Exposure To, Use Of, And Attitude Toward The Program Of Activities
Authors: Torres Robert M. , Dormody Thomas J.
Published: December 2010

A basic responsibility of the agricultural education teacher is to integrate the FFA organization into their education program. Serving as a FFA advisor, the teacher's role is to facilitate the activities and events of the FFA organization. One educational tool available for the advisor and students is the program of activities (POA). Thus, the study sought to determine the use of the program or activities by FFA chapter advisors. Descriptive survey research used to gather data found that fifty percent of the advisors were exposed to a POA as a former FFA member. The greatest influence on advisors for using a POA was state mandate. Advisors use other teachers as a source of knowledge in developing a POA with most adopting the National FFA Organization committee structure. Additionally, POA committee meetings tend to be convened during class, and advisors report to involve their students in planning, implementing and evaluating POA activities. Furthermore, advisors tend to have a moderately positive attitude toward the POA. Reccomendations are offered based on these findings.
Recruitment, Retention, And Participation Of Underrepresented Groups On Pennsylvania Cooperative Extension Advisory Boards And Committees
Authors: Ingram Patreese D. , Nyangara Florence M.
Published: December 2010

With the changing demographics of American society, the Cooperative Extension System must reexamine its educational responsibility to local communities. In order for extension programming to truly reflect the needs of increasingly diverse communities, extension boards and program committees must include and involve people from diverse audiences. Between 1993 and 1996, Pennsylvania State University conducted an extensive civil rights assessment of Cooperative Extension programs in its 67 counties. Utilizing the data collected during the civil rights assessment, this study examined the responses of extension professionals relative to recruitment, retention, and participation of underrepresented groups on extension advisory boards and committees. A number of problems, as well as strategies for successful recruitment and involvement of underrepresented groups, were revealed. Several recommendations based on study results were oflered.
FACULTY NEEDS ASSOCIATED WITH AGRICULTURAL DISTANCE EDUCATION
Authors: Murphy Tim H. , Terry H. Robert
Published: December 2010

A census survey of the teaching faculty in a land grant university’s College of Agriculture was conducted The survey instrument was a three-part questionnaire designed by the researchers. The purpose of this study was to provide baseline data and focus for the improvement of instruction in a College of Agriculture through the utilization of electronic teaching technologies. The objectives, stated as questions, were: I) What are selected personal and professional characteristics of the teaching faculty?; 2) What is the perceived level of competence that members of the teaching faculty have in using electronic technologies associated with distance education ?; 3) How important do teaching faculty members perceive that these technologies are or will be in teaching and learning?; and 4) What is the perceived availability of equipment, facilities, and training for faculty to use these technologies? Findings indicated that teaching faculty lack both competence in using these electronic technologies, and confidence in their ability to use appropriate distance teaching methodologies to deliver courses. However, they believe that using electronic technologies would enhance their teaching, and that the development and use of electronic teaching technologies will change how, but not change what, they teach over the next five years.
WOMEN’S SELF-PERCEIVED LEADERSHIP SKILLS IN A COLLEGIATE AGRICULTURAL EDUCATION COURSE
Authors: Thorp Laurie , Cummins Richard , Townsend Christine
Published: December 2010

Leadership is evolving from its patriarchal roots to the emerging paradigm of a network of shared leadership. This new model which values the traits and abilities of communication, inclusion and nurturance has paved the way for greater participation of women in the leadership equation. However, preparation of young women leaders in agriculture may require changes in our educational methodologies. The purpose of this study was to evaluate the effectiveness of leadership education methodologies for female students. Students enrolled in a collegiate agricultural leadership development course constituted the sample of the study. No relationship was discovered between women 's previous leadership experiences and their perceived ability to work with groups, make decisions, communicate or understand self. However, women in an all-female section had a stronger perception of their ability to lead, work with groups, make decisions, communicate and understand themselves than women in a coeducational section. Based on these findings it was recommended that an all-female class be made available for women in collegiate agricultural leadership development courses.
INFLUENCE OF STUDENT AND SCHOOL FACTORS ON AFRICAN AMERICAN ENROLLMENT IN AGRICULTURAL SCIENCE COURSES
Authors: Jones Kenneth R. , Bowen Blannie E.
Published: December 2010

The purpose of this study was to identify factors related to African American enrollment in secondary agricultural science courses. Questionnaires were completed by 380 students from Mississippi, North Carolina, and Virginia high schools. Attitudes of students enrolled in agricultural science courses and those not enrolled (biology students) were analyzed by race. Agricultural science students were more positive than biology students on three attitudinal constructs (image of the agricultural sciences, future value of the agricultural sciences, and the role of significant others on student enrollment). Also, African Americans were more negative toward the agricultural sciences than students of other races on all three constructs. Three variables (gender, future value, and teacher attitude) explained 24% of the variance in students’ enrollment decisions. Students who were males, positive about the future value of the agricultural sciences, and who were enrolled in schools that had a agricultural science teacher with positive attitudes toward teaching tended to enroll in agricultural science courses.