bluuebunny/crossref_metadata_2025 huggingface dataset:
Studying of the changes effect of the gas properties on the turbine performance using Gordon-McBride algorithm
Authors: قدّاح عاصم
Published: June 2021

The turbine performance parameters are calculated assuming that the working fluid is a calorically perfect gas with constant specific heats, whereas it is actually a perfect gas.
We will study the of the working fluid properties on the turbine performance according to Gordon-McBride algorithm which determines changes of the specific heat and the enthalpy as a function of the temperature and the fuel to air, and suggest an alternatives if the studying was carried out as calorically perfect gas.
Numerical study on a new design of solid-fuel ramjet combustor with swirl flow
Authors: Musa Omer , Xiong Chen , Huang Guoping
Published: June 2021

A new design of solid-fuel ramjet is proposed and examined numerically in this paper. Multi-physics coupling code is developed using FORTRAN and parallel computing to solve the problems of multi-physics coupling of fluid mechanics, solid pyrolysis, heat transfer, thermodynamics, and chemical kinetics. Simulations are carried out for the proposed design then the results are compared with the classic design of the solid-fuel ramjet. It is found that the proposed design has improved the regression rate significantly; besides, the amount of released solid fuel is increased for the same size. A new flame has been observed inside the combustion chamber of the proposed design then the two flamed were emerged in the afterburning chamber.
A Novel Walking Speed Control Strategy for Power Augmentation Exoskeletons based on Neural Networks
Authors: Ahmed Abusabah I.A. , H. H. Musa Mohammed
Published: June 2021

This paper addresses a novel sensing technique to minimize the interaction force of walking speed transitions during the navigation of a coupled human-exoskeleton power augmentation system. The proposed technique is able to classify the intended walking speed based on Dual Reaction Force (DRF) Sensor. The human brain as a complex information processing device is quite difficult to be simulated, especially when considering the processing speed and the speed of sensed signals through the human nervous system throughout the human body. We developed the DRF sensors for preemptive identification of pilot intentions for walking speed transitions to augment the response of the exoskeleton to shadow pilot's movements. The Dynamic Threshold Neural Networks (DTNNs) is used to classify the input signals and make a decision on the transition of system's walking speed according to the pilot's intentions and walking speed limitation. The actions for walking speed transitions are simulated in MATLAB/Simulink, and Variable Admittance Controller (VAC) and applied. To show the efficiency of the proposed walking speed control strategy, comparison is conducted with ordinary VAC algorithm technique.
تقيم الوضع الراهن لجودة مياه مدينة بورتسودان (المصدر خور أربعات)
Authors: Mustafa Mustafa SirElkhatim
Published: June 2021

Port Sudan is the main port and largest commercial centre of the Sudan located in semi-arid region. Population estimate in 2010 was about 926,000 inhabitants and the water demand estimated was about 120000-150000 m3/day. Water production from Khor Arbaat is 60,000 m3/day in good years; however, it may go down to 30,000 m3/day in bad years. In general, the overall situation of the city is characterized by regular shortages. There are three dams (U/G Dam1, SPC Dam2, FR Dam3) structured on Khor Arbaat for water harvesting (2005,2000,1992), siltation represents the greatest problem to these Dams, accordingly their capacities storage is decreases. Their storage capacities are 16*106, 5*106, and 6*106 m3 respectively, therefore the small capacities of these dams lead to inflation silt in a limited period of time. In the same way the Sea Port Corporation (Dam 2) in the year 2012 was removed by the armed forces of the corps as a result of inflation silting and thickness of silting to 6 meters. Water from Khor Arbaat gets into the transfer system without any treatment. The study is carried out to assess and evaluate the quality of surface and ground water resources in the Khor Arbaat zone. Field works included three visits to the study area, on January 2018, February 2018, and on March 2018. Sixteen typical water samples collected from different locations within Khor Arbaat and the city network were analyzed for physical and chemical water quality parameters. GIS Arc. Map and Kriging method are used to study the characteristics of water depend on coordinates and samples results.
Experimental Study on the Effect of Cross Bracing on the Behaviour of Composite Bridges
Authors: A. M Fageer Badria , Ahmed Abdalla , Daoud Osama
Published: June 2021

In this paper the results of an experimental program were presented to show the effect of cross bracing on the behavior of composite bridges. Two types of models were prepared in the laboratories of the American University in Cairo Egypt. These models were chosen to be one tenth scale of the model of the Federal Highway Administration (FHWA). Deflections and strains were measured for each model according to the set of bracing and comparisons were made to show the effect of bracing.
Review of Punching Shear Strengthening Methods [Case Study: Application of Post Installed Shear Bolt Papers]
Authors: Hussein Mohamed Ali Ali , Alamin Mohamed Aboalmaali
Published: June 2021

Flats slabs became a common solution for buildings because they are easy and fast to build. In the last few years, some building that constructed using flat slab system required strengthening for column to slab junction due to either some imperfections during design, construction or due to increase of the design load in case of change of the building function. The common strengthen methods against punching shear (column heads, drop panels) leave an obvious trace which in most cases conflicts with some extensions parts and may reduce the height of the story considered, thus it can’t be applied in such cases. A relatively new technique was studied, it consists of high tensile steel bolts installed vertically through the slabs by drilling and bonding with high-performance epoxy adhesive and mechanically anchored to the slab surface. Many studies validated the efficiency of the technique in strengthen against punching shear and also in enhancing the ductility of the slab-column connection and the results shows that the method can be applied in practice. In this paper, the post-installed bolts technique is presented and applied in a practical case study. The capacity of the slab enhanced by 53% and it was easy to design and construct. Also, it took not more than few hours for its application. In addition, the building extension utilities (Heating ventilation and air conditioning, communications...etc.) was not harmed because the slab surface remains clear. Those advantages make the technique a favorable option for owners and engineers when strengthening against punching shear.
Effects of temperature changes on voided slab integral abutment bridge
Authors: Awad Ibnouf Omer , Hassan Onsa Eltayeb
Published: June 2021

Integral Abutment Bridges (IABs) are joint-less bridges whereby the deck is monolithic with the abutment walls. IABs are outperforming their non-integral counterparts in economy and safety. Thermal effects introduce significantly complex and nonlinear soil-structure interaction into the response of abutment walls and piles of the IB. This paper carried out comprehensive study on voided slab system with five spans bridge each span is 17m long. The bridge has been modelled using SAP software. The abutments and pile foundations are modeled taking into consideration the soil-structure interaction. The study covered a design uniform temperature change of (10, 20, 30, 40 and 50) °C. To gain a better understanding of the mechanism of load transfer due to thermal actions, a 3D frame anal¬ysis is carried out on the above mentioned IABs. The results showed wide range of different linear and lightly non-linear relationships between temperature range, deformations and moments. The paper highlighted the serious effect of the deformations resulting from the repeated temperature change which causes drop in soil or bombing at the abutments ~ embankment contact zone.
Prediction of Concrete Compressive Strength & Slump using Artificial Neural Networks (ANN)
Authors: M. H. Badawi Yasir , Hummaida Ahmed Yousif
Published: June 2021

Concrete is the most used building material in the world, due to its high compressive strength and durability. Those properties are measured and assessed in fresh and hardened states of concrete, with standard methods which are time and cost consuming. In the present study, the compressive strength and slump of concrete has been predicted using Artificial Neural Network (ANN), which is constructed using different input parameters involving concrete mix design (i.e. coarse & fine aggregates properties, cement content, water/cement (W/C) ratio, admixtures type and dosage …etc.).The predicted strength was compared with the experimentally obtained actual compressive strength and slump data collected in many years for different materials and mix designs in the Sudan. An ANN model has been developed by using MATLAB neural network toolbox. A good co-relationships with regression values of 0.915 and 0.931 for strength and slump respectively have been obtained between the predicted and experimental values. It is concluded that the ANN method can gain acceptable predictions for compressive strength and slump.
إيجاد مقاومة الضغط المستقبلية الناتجة تحت تأثير محتوى الكلوريدآت والكبريتات بالخرسانة
Authors: يحي ابوصبيع ابوالقاسم , حسن اونسة الطيب
Published: June 2021

The compressive strength of concrete is the primary characteristic of concrete quality, as the high durability of concrete is one of the characteristics that gave concrete its position, and low durability is the most important problem facing concrete. This study aims to lay the foundations for forming a preliminary idea on knowing the compressive strength of future concrete other than destroying concrete and following up on it without doing destructive tests for it. In order to obtain results that simulate reality to a great degree. In this research, a laboratory study was conducted where a concrete mixture was made and after conducting experiments on the materials included in the mixture and preparing concrete cubes of ordinary Portland cement and sulfate-resistant cement and compressive strength testing on them in times of 28 days and 60 days and 90 days and 180 days and 365 days and subjected to conditions Treating (water and air) and performing chemical analyzes on it to determine the percentage of chlorides and sulfates in the concrete. From the results of the research, an engineering program was designed using Mat lab program to obtain future strength. And reached by the program to know the compressive strength of future concrete under the influence of the chlorides and sulfate content of concrete and the results were good.
Effects of Superplasticizer on the Properties of Fresh and Hardened Concrete Mixes
Authors: Muddather Randa , Hassaballa A. E.
Published: June 2021

This research aims to study the effect of superplasticizer, when mixed with local materials, on both fresh and hardened concrete properties to achieve the demands of engineers and contractors. The methodology adopted to achieve the objectives of the research focuses mainly on a collection of data from different sources, an extensive review of previous studies, designing concrete mixes and implementing a lot of laboratory experiments using different ratios of superplasticizer with low water contents. The ratios of superplasticizer added were 0.0 (as a reference mix), 0.4, 0.8, 1.2 and 1.5 Litre/ 50Kg cement for concrete ages of 3, 7 and 28 days by preparing 12 cubes for each sample. Local ordinary Portland cement (OPC) and graded natural coarse and fine aggregate were used for all concrete mixes conducted in this research. From the experimental results obtained it has been found that the ratio of (0.8 litres per 50 kg of cement) superplasticizers with a reduction of 15% (w/c) showed a clear and significant effect on improving the workability of concrete mixes. Also the ratios of 1.5L per 50 kg of cement with a 30% reduction of (w/c(and 0.4L per 50 kg of cement with a reduction of 10% )w/c) superplasticizer have resulted in high workability. Whereas, the values of absorption showed no changes with respected to the used ratios of SP or w/c contents. The results have shown substantial improvement in the properties of concrete after use of the superplasticizers for achieving the lowest possible water/cement ratio while maintaining a high workability.
Characterization of Sugar Cane Bagasse Ash: A Comparison to Densified Silica Fume and Fly Ash
Authors: A. Hussein Asma
Published: June 2021

In this study the Sugar cane bagasse ash (SCBA) was characterized for chemical composition, morphological and mineralogical properties. From XRF analysis it was found that the SCBA has SiO2, Al2O3, Fe2O3 and CaO content of 67.25%, 6.37%, 4.21% and 13% respectively and it has a very low LOI value of 0.34% and can be classified as Class F ASTM pozzolan according to ASTM C 618-2009. SCBA can be used as a pozzolanic material after grinding to less than 45 Micron. Based on the properties obtained from the characterization in this study it can be concluded that, utilization of SCBA in concrete will positively affect hardened concrete properties due to pozzolanic reaction, cementing properties and filling effect of SCBA. Moreover it will minimize the negative impacts associated with SCBA disposal.
Deep Neural Network Learning for Detection and Grading of Diabetic Retinopathy
Authors: Reddy Akshay Jakkidi , Martel James B
Published: June 2021

Purpose. To automate the retinal screening process and to improve chances of early detection/diagnosis of diabetic retinopathy which may reduce vision impairment cases due to the diseaseMethods. Experiments were conducted on EYEPACS dataset that had retinal fundus images of patients with diabetic retinopathy in all severity levels. Based on the learning done by the Inception networks during the training phase, the images were classified to 5 classes based on the severity as: Normal, Mild, Moderate, severe and proliferative diabetic retinopathy. The images were augmented to increase the number of images with the disease and were randomly chosen for the training, validation and test datasets.Results: The training was conducted using the Inception network for 100 epochs and validation accuracy was tested every 1000 iterations on a total of 109,540 images. The major misclassifications that occurred were between the adjacent classes of severity. It achieved a sensitivity of 94.6%, specificity of 81.4%, accuracy of 92% and precision of 93.2%. Conclusion: The retinal fundus images were examined and automated using Inception network by training the images from scratch. This model can be applied for detection of other retinal diseases, as the model weights are learnt to recognize subtle features present in the retinal images
Los pueblos indígenas urbanos y su derecho a una educación intercultural
Authors: Ledesma Erika
Published: June 2021

Las miradas sobre ‘pueblos indígenas’ y ‘sus necesidades educativas’ han cambiado a lo largo del tiempo y han dado lugar a diversos reconocimientos tanto en el plano del derecho internacional de los derechos humanos como en el derecho nacional, aunque muchas veces la visión de los pueblos indígenas ha sido ignorada. En esta investigación se buscó analizar las herramientas legales disponibles actualmente para una redefinición del derecho a la educación de los pueblos indígenas y su alcance y vigencia, destacando la palabra de quienes trabajan en proyectos de educación intercultural, indígenas y no indígenas, al analizar sus percepciones sobre el modelo educativo actual, la propuesta de educación intercultural estatal y las posibilidades de su implementación en las escuelas estatales secundarias de la Provincia de Buenos Aires. Para tal fin, se ha seguido el método cualitativo, con un enfoque en las experiencias y puntos de vista de estos educadores para lograr una visibilización del conocimiento local o situado, a través de entrevistas abiertas, análisis de legislación y retroalimentación de los entrevistados.
El panóptico como diseño ideal de las disciplinas y la emergencia del gobierno de la (in)seguridad
Authors: Mora Paizano Jenny
Published: June 2021

Foucault plantea que a partir del siglo XIX prevalece una sociedad disciplinaria, caracterizada por instituciones que conforman un diagrama de dominación; a simple vista puede parecer que son instituciones totalmente diferentes, pero tal como Foucault manifiesta estas son instituciones que tienen como común denominador la vigilancia sobre las/los sujetos, y destinar a producir un determinado tipo de sujeto en sociedad. En estas sociedades se establecen un ideal de modelo de prisión panóptica, la cual tiene como fin crear sujetos dóciles; este es un modelo que se extrapola a las diferentes disciplinas y saberes. En este sentido, el análisis foucaultiano ayuda a comprender a otros autores/as, a las sociedades contemporáneas como ideal de la sociedad disciplinaria en el marco de una modalidad de poder que no desaparece pero sufre mutaciones. Al interpretar a Foucault podemos ver que existe un nuevo saber o gobierno de la (in)seguridad que trae aparejado nuevas tecnologías, prácticas, técnicas, y dispositivos que se articulan en el uso del poder que es complejo y abstracto. A partir de esto, se pretende hacer un recorrido histórico sobre el modelo panóptico y su lógica de disciplinamiento y las mutaciones encontradas en las sociedades actuales.
Paradigm Shift in the Schools of European Structuralism: From Pre-Structuralism to Post-Structuralism
Authors: Abuzaifah Mohammed A.
Published: June 2021

The present article aims to review the paradigm shift, a concept proposed by Thomas Kuhn (1962), and how its manifestation in the developments of language studies contributed to the advent of different structural schools of European linguistics. To further explore the topic, this article begins by identifying the actual meaning of Kuhn’s paradigm shift and how it influenced other disciplines of science. Second, the history of structuralism is discussed and reviewed from two different perspectives, pre stage and the post stage of structuralism. The revolutions throughout the history of structuralism, primarily in the European context, led to paradigmatic shifts and the emergence of several influential and prominent structural schools, namely European structuralism, the Prague Linguistic Circle, and the London school of linguistics.
Las imágenes de digestión y excreción en los textos de Primaria
Authors: Pérez de Eulate González Lourdes , Llorente Enrique , Andrieu Amaya
Published: June 2021

In this study we compare seven textbooks of Natural Science in four levels of elementary school. We make an analysis of digestion and excretion illustrations (pictures and labels). There is evidence that pictures have problems which can bias the understanding of those topics. Some implications for using pictures in school science have also been shown.
La axiomatización en la enseñanza secundaria : una opción didáctica
Authors: Alemany Berenguer Rafael Andrés , Pérez Selles J. F.
Published: June 2021

In this article the possibility of using the logic axiomatization of a scientific theory as another tool in the process of learning as a conceptual change is discussed. This way of teaching has to show certain features and ensure that debates in the classroom are centered on the logic connections between deductions. To achieve this the didactic action must give importance to the justification of ideas, debates must be metacognitive and the role of teachers must be more active and diversified. One example of this way of teaching is also introduced herein.
La enseñanza de las ciencias y la formación de profesores de enseñanza primaria para la reforma curricular : de la teoría a la práctica
Authors: Paixao M. de Fátima , Cachapuz Antonio F.
Published: June 2021

This papers presents a qualitative study aiming to investigate how new Portuguese curriculum proposals from primary school (the intentional curriculum) are translated in the teaching of science of four prospective teachers (the operational curriculum).The research adopted a case study methodology in order to describe main features of the pedagogical profile of classroom practices of those teachers. Three different profiles were identified. Some interpretative aspects are outlined and important implications for pre-service education are put forward.
Desarrollar un currículo multirreferenciado para hacer frente a la complejidad de los aprendizajes científicos
Authors: Astolfi Jean-Pierre
Published: June 2021

Learning does not come from applying a lineal curriculum design but is the result of many interwoven factors. In this article, that summarizes the speech delivered at the 5th International Congress on Science Didactics, we review some of these factors and show how complex didactic situations can be.
Desarrollo de una unidad didáctica centrada en la alimentación humana, social y culturalmente contextualizada
Authors: Membiela Pedro , Cid María Carmen
Published: June 2021

A study of the alternative conceptions of students of several educational levels about basic feeding is carried out. These alternative conceptions show many of the characteristics which have already been mentioned and seem to evolve towards a greater degree of differentiation, although in each educational level diverse alternative conceptions coexist. The contributions of this and other research have been utilized in the design of a teaching unit about this subject, which has been implemented and evaluated for a posterior revision of changes produced in the students alternative conceptions about feeding.
El debate sobre la masa relativista: el problema definicional y otros aspectos epistemológicos
Authors: Domènech A.
Published: June 2021

Some epistemological issues concerning the controversy of relativistic mass, including the translation/incommensu- rability problem, are presented. Properties of classical and relativistic masses and alternative ontological, functional, relational, and operational definitions are compared, including, ab initio, an operational definition of relativistic mass. It is concluded that there are a number of reasons to maintain the concept of relativistic mass in science teaching.
Estudio de la progresión en la delimitación de las "ideas" del alumno sobre fuerza
Authors: Jiménez Gómez Emma , Solano Martínez Isabel , Marín Martínez Nicolás
Published: June 2021

The aim of this paper is to analyse if there has been any progress in the results that different papers about learners’ «ideas» have shown in Dynamics. To that end, a wide sample of papers about «pupils' knowledge» concerning the concept of force has been chosen and a set of categories has been establihed in order to set up the criteria that allow us to compare the information presented in those papers.
La pertinencia de la historia en la enseñanza de ciencias: argumentos y contraargumentos
Authors: Lombardi O. I.
Published: June 2021

Adding up to the debate about the possibility of a historical view in science teaching, the present article frames some responses to the criticisms that, on the basis of the need of simplification and reconstruction of history , object its intrusion in science education. In that sense, the essentially constructive character of history and, particularly, of history of science is appointed, where the epistemological position of the historian acquires special relevance. The multiplicity of historical stories is a constituent characteristic of history and, thus, it does not represent an obstacle in sciences teaching.
Conocimiento profesional y epistemología de los profesores I: Teoría, métodos e instrumentos
Authors: Porlán Ariza R. , Rivero García A. , Martín del Pozo Rosa
Published: June 2021

We present in this article the theoretic and methodological frame of the studies carried out by the authors on teacher’s professional knowledge and epistemological conceptions, taking as a reference the bases of the Model of Investigation at the School and the IRES curricular project. In a latter article we will analyse the data there obtained.
Una evaluación de las actitudes relacionadas con la ciencia
Authors: Vázquez Alonso Ángel , Manassero Mas María Antonia
Published: June 2021

A taxonomy of science related attitudes with four basic dimensions (global image, social aspects, school aspects, and science characteristics) has been assessed by means of a questionnaire, made independently of the taxonomy. The aim is to show how the use of the taxonomy allows us to overcome the méthodologie and conceptual difficulties in the measurement of attitudes. Applied to a representative sample of secondary and university students, the results show a moderately positive attitude and some significant attitudinal differences among the taxonomy’s dimensions. The image of science dimension has the best attitudinal mean score, while the social aspect dimension has the worst score. Attitudes towards school aspects of science and the characteristics of scientific knowledge elicit intermediate attitudinal scores. Science teachers can find in this paper some patterns and instruments to assess the students’ science related attitudes.
La utilización de un modelo de planificación de unidades didácticas: el estudio de las disoluciones en la educación secundaria
Authors: Sánchez Blanco Gaspar , Pro Bueno Antonio de , Valcárcel Pérez María Victoria
Published: June 2021

The planning of didactic units is an element of reflection for teachers which allows the integration of both their scientific knowledge and their experiential skills. This study focus on the implementation of a planning model based on five tasks; the analysis of scientific content and the learning content which is derived from it (conceptual, procedural and attitudinal), the analysis of the problems involved in the learning of it (previous ideas and operational skills), the setting of the learning aims, the selection of the didactic strategies and the establishment of evaluative strategies. The model is applied to the Solutions in Secondary School.
Una introducción a la literatura científica
Authors: García Molina R. , Abril I.
Published: June 2021

We discuss the convenience of an early introduction of undergraduate students to the reading of scientific papers, mostly divulgative or historical. This can encourage them to deeper readings and to search and discover in the scientific writings new sources of learning and pleasure. The aim of this activity is twofold: mainly, to approach the students to bibliographical sources different from the traditional textbooks and, collaterally, to habituate them to get acquainted with scientific information in foreign languages (mostly English). In this manner, the students can get further knowlegde and they can also learn new points of view or different topics from those commonly discussed during a typical academic course.
Modelos conceptuales sobre las relaciones entre digestión, respiración y circulación
Authors: Núñez Francisco , Banet Hernández Enrique
Published: June 2021

Conceptual patterns of the relations digestion/circulatory system and breathing/circulatory system, found in a sample of non-university students whose ages range between 11 and 17 years old are described in this work. These patterns show that students’ conceptions are relatively organized in their conceptual structure and in spite of being sometimes incomplete and wrong, they seem to be coherent for them, even making up real theories that they use to explain any problematic situation connected with these processes.
Concepciones de futuros profesores del primer ciclo de primaria sobre la naturaleza de la ciencia: contribuciones de la formación inicial
Authors: Thomaz M. F. , Cruz M. N. , Martins Isabel P. , Cachapuz Antonio F.
Published: June 2021

Research studies have showen that the image of science that students construct during their formal learning is strongly influenced by the teacher’s conceptions about the nature of scientific knowledge. It is then fundamental to investigate the impact of initial teacher’s education in the development of those conceptions in future teachers.The aim of this article is to present a study about the contribution of the three year initial teacher education, of basic education teachers (1st cycle - 6/10 years olds), in the development of their conceptions about the nature of science. The results show that the initial teacher education, as it has been developed in teacher training institutions, does not significantly influence the ideas held by future teachers about the nature of science.
Tres enfoques de la investigación sobre concepciones alternativas
Authors: Pintó Roser , Aliberas Maymí Joan , Gómez Carrillo R.
Published: June 2021

In the last years the researchers on Science Education have given preferent attention to student's conceptions. Studies have been carried out and their interest is still growing. Our purpose in this paper is to give an approach to three ways of focusing the question; the «alternative conceptions», the «ways of reasoning» and the «causal mental models» approaches. Our goal is to compare them and show, without being exhaustive, some of their findings and future spectatives.
Introducción a la genética en la enseñanza secundaria y bachillerato: I. Contenidos de enseñanza y conocimientos de los alumnos
Authors: Banet Hernández Enrique , Ayuso G. E.
Published: June 2021

In this paper an analysis is made of some of the causes which can hinder the students' learning of genetics at Secondary Level (12-17 years). This research study highlights the need of introducing changes in content at syllabus design level, and shows that students have a slight knowledge of heredity, although the basic tenets are very often wrong, even before they have their first contact with the subject as academic content at school.
Actitudes hacia la ciencia a lo largo de BUP y COU: un estudio longitudinal
Authors: Espinosa García J. , Román Galán T.
Published: June 2021

We have performed a longitudinal study among BUP and COU students, from fourteen to eighteen years old, and their attitudes to Science. This attitude becomes neither linear nor more negative through successive years. On the contrary, we have observed a «saw tooth» profile.
¿Por qué hay veranos e inviernos? Representaciones de estudiantes (12-18) y de futuros maestros sobre algunos aspectos del modelo Sol-Tierra
Authors: Manuel J. de
Published: June 2021

This paper shows the results of an investigation conducted on more than 900 students aging 12-18, and 50 teacher training students. Misconceptions related with the Sun -Earth model in relation with summers and winters were studied using a single questionnaire and an interview. Changes derived from an instruction based on a simulation activity on the model were also tested, 1, 2, and 3 years later. A comparative analysis, between instructed and uninstructed students, also carried out. These analysis and the interpretation of the probable origin of misconceptions are used for some educational suggestions.
La utilización del ordenador en la realización de experiencias de laboratorio
Authors: Herrán C. , Parrilla J.L.
Published: June 2021

In this work we expose the principles and teaching impact of the applications of the computer means to carry out the real experiments in the teaching laboratory.
Evaluación del proyecto curricular "naturaleza en la ciudad"
Authors: Membiela Pedro , Suárez M. , Nogueiras E.
Published: June 2021

The internal evaluation oía Natural History curricular project is shown, which is carried out within the framework of educational research action, through triangular prospection of opinion from students, teachers and externa] advisers.
La educación para la salud: una propuesta fundamentada desde el campo de la docencia
Authors: Gavídia Catalán V. , Rodés Sala Mª J. , Carratala Beguer A.
Published: June 2021

Is Sanitary Education the same as Health Education? Wich factors should we keep in mind when setting up a curriculum for Health Education? Is it necessary to deal with such health matters as hygiene, vacunations and so on... in order to develop this type of education for schools? These are just some of the questions that are raised in this article, and at some time we show the use of looking at sources that determine a curriculum, as in the specific case of Food -Nutrition.
Actitudes hacia la ciencia en estudiantes universitarios de ciencias
Authors: Espinosa García J. , Román Galán T.
Published: June 2021

We have performed a longitudinal study among university students, from eighteen to twenty three years old, and their attitudes toward Science. This attitude does not become neither linear nor more negative through successive years. In contrast, we have observed a «saw tooth» profile, which is clearer when the number of courses analysed increases and the sex variable is taken into account. In general, the maximums of one sex are coincidental with the minimums of the other.
Una propuesta integral de evaluación en Ciencias
Authors: Rodríguez Barreiro L. M. , Gutiérrez Múzquiz F. A. , Molledo Cea J.
Published: June 2021

In the following study, we are going to deal with evaluation problems, one of the aspects in the curriculum that has undergone less changes in the last years. In order to do so, we will analyse critically the way it is done nowadays. Next, we will enunciate a series of force -ideas to propitiate the change in this field of activity. Finally, we will show the ethnographic evaluation pattern, the one we have chosen, going deeply into the methods and techniques for data -collecting more commonly used in this kind of research. Besides, we will try to explain those patterns with examples, mostly taken from our everyday practice with BUP students.
Calificaciones, pruebas objetivas y aprendizaje significativo en Química y Física de COU
Authors: Vázquez Alonso Ángel
Published: June 2021

Herein are studied the relations between Chemistry and Physics school marks in COU and in the first university year, and the score obtained at an objective test designed on the COU curriculum. The output of correlations is low and the analysis of the regression shows that the predictive ability of the variables of the objective test with respect to the marks is smail; paradoxically, it is bigger for the marks at university than for those in COU, whose curriculum was the base for the test. Besides, predictive results are higher for Chemistry than for Physics. Non -significant learning could explain both, low results and the differences observed.
Formar a los estudiantes en el método experimental: ¿Utopía o problema superado?
Authors: Dumon A.
Published: June 2021

A laboratory work teaching sequence, based on the practical work objectives definition, on the progressive development of autonomy, and a hierarchized learning task is experimented. The evaluation of students results show that the learning strategies lead to a real mastery of experimental process.
El aprendizaje desde la instrucción: La evolución de las estrategias personales en tareas de proporcionalidad numérica
Authors: Llinares Ciscar Salvador , Sánchez García V.
Published: June 2021

This study examines the personal strategies evolution used by students in numerical proportionality task solving during instruction. The analysis of a sequence of video/audiotaped lessons allowed the observatíon of the process of cognitive construction by students in the classroom. The «local» effectiveness of intuitive strategies is considered a phase in the construction of more general strategies.
Investigación del desarrollo y aprendizaje de la noción de aceleración en adolescentes
Authors: Laburu C. E. , Carvalho Anna M. Pessoa de
Published: June 2021

The aim of this article is to present some of the conclusions reached at the clinical research of the development and learning of the notion of acceleration in teenagers between 11 and 16. From the results therein obtained we gather conclusions that concern teaching implicitly. As a criterion to accede to the understanding of acceleration we tried its comprehension from a kinetic approach (.6V/át). By means of three experiments we show the difficulties with which the students met to understand the concept of acceleration.
El ordenador y su contribución a la superación de las dificultades de aprendizaje en mecánica
Authors: Valente María Odete , Neto Antonio José
Published: June 2021

Some influential learning difficulties on introductory school mechanics are firstly identified. Then, a computer based approach attempting at overcoming some of these difficulties is described.
Creencias populares y enseñanza de la Biología
Authors: Fontes Costa M. A. , Duarte Mª C.
Published: June 2021

The existence of some popular beliefs has been referred to by several studies. A few of these popular beliefs, which seem to be also widespread in Portugal, are related to biological contents. Therefore, it can be expected that many students hold some of these beliefs when they come to the biology classes. Based on this suspicion, the authors decided to investigate:— The degree of adhesion shown by students with different biology backgrounds, to some popular beliefs.— The importance given by some biology textbooks to the popular beliefs.
Los mapas conceptuales de J.D. Novak como instrumentos para la investigación en didáctica de las ciencias experimentales
Authors: González García Fermín M.
Published: June 2021

This article is a review of Novak 's «concept mapping», used as a tool for didactical research. It emphasizes its efficiency, especially with topics related to teaching/learning processes and planning of both curriculum and instruction. A list of bibliographical references has been carefully selected.
Catastrofismo versus actualismo. Implicaciones didácticas
Authors: Pedrinaci Emilio
Published: June 2021

This paper analises the historic evolution of the «actuaIist» and «catastrophist» geologic interpretations, describes possible epistemologic obstacles and considers their treatment in the Secondary School.
¿Cúando un ser vivo puede ser considerado animal?
Authors: Velasco J. M.
Published: June 2021

The concept "animal" and students' misconceptions of this term were analysed on a population of 365 individuals composed of students of 6th EGB, 1st BUP, COU and 3rd Teacher -training School from Salamanca and Soria in order to monitor the persistence of such misconceptions throughout the learning stage. The results obtained are compared with those found in a similar study previosly conducted in New Zeland, which is critically analysed as well. Some implications of this and other similar concepts in the teaching -learning process are also discussed.
Students' learning difficulties in science. Causes and possible remedies
Authors: Kempa R. F.
Published: June 2021

In this paper, a broad analysis is presented of the main types of learning difficulties encountered by students in science education and causes underlying them.
Investigación de las ideas de los alumnos de enseñanza secundaria sobre la corriente eléctrica
Authors: Ruiz Sáenz de Miera A. , Rosado L. , Oliva Martínez José Mª
Published: June 2021

This paper deals with the ideas on electric current of secondary education (BUP and COU) students who have been given traditional tuition. The study was based on open -choice questionnaires, word -choice tests and concept trees. The results obtained show that the students' experiential and environmental models acquired from their everyday physical and social experience are preserved throughout their secondary education. However, their vocabulary gradually conforms to the «scientific model» of elect! ic current.
Origen histórico del término ion
Authors: Galache I.
Published: June 2021

This paper introduces readers to the origin of the word «ion» through the correspondence between Michael Faraday and William Whewell in the spring of 1834. Special emphasis is placed on the deep involvement of the two scientists in their discussion and their thoroughness in choosing the most appropriate term, which they knew would be of great historical and educational transcendence.
La reacción química: descripciones e interpretaciones de los alumnos de liceo
Authors: Chastrette M. , Franco M.
Published: June 2021

We have carried out a piece of research about the ass:.milation of the chemical reaction by secondary students, based on the study of their spontaneous descriptions of the process, their ability to explain it in corpuscular terms and of correctly applying the law of matter preservation The experimental sample were 19 students between 13 and 14 years of age who had been introduced to the subject the previous year. We have introduced a variant in the technique of interviews.
Esquemas conceptuales de los alumnos sobre la respiración
Authors: Banet Hernández Enrique , Núñez Francisco
Published: June 2021

In this article we report our findings about the ideas and beliefs sustained by a sample of students (from a variety of levels, i.e. EGB 6th and 8th grade levels as well as School of Education students) on the topic of human breathing. As well as specific misconceptions, alternative frameworks to scientific knowledge, which should be taken into account by the teacher when planning a lesson, are pointed out.
La enseñanza de "Fuerza y Movimiento" como cambio conceptual
Authors: Hewson P. W.
Published: June 2021

Research has shown that many students hold alternative conceptions about motion and the factors which influence it and that an important component of these conceptions are epistemological commitments, one example of which is a cause -effect relationship. The article describes a series of microcomputer programs designed to facilitate conceptual change from an ímpetus -type view to a Newtonian view. A significant feature of these programs is the explicit focus given to the nature of the relationship between cause and effect and its role in the conceptual change process.
Formación inicial del profesorado de ciencias en Francia, Inglaterra y Gales y España. Análisis de la organización de los estudios y nuevas tendencias
Authors: Dumas-Carré Andrée , Furió-Mas Carles , Garrett R. M.
Published: June 2021

This paper contains a comparative analysis of university courses on initial secondary teacher training in theses countries. The aim is to sort out the common components in these training systems. We also point out some contemporary trends in this field, trying to increase the degree of professionalisation of these courses.
La función del lenguaje en un enfoque constructivista del aprendizaje de las ciencias
Authors: Llorens Molina J. A. , Jaime M. C. de , Llopis R.
Published: June 2021

A constructivist view of science learning involves the overall knowledge of cultural factors wich can affect this process. The new trends in the theoretical aspects agree with the acceptance of the interactive nature of the language- thinking relationship. Simultaneously, some research papers show the relationship between language and cultural surroundings. In this paper we try to establish the experimental justification of the relevance of semantic analysis of the pupil's language and to test some hypotheses about the language role in concept making.
Causalidad y operaciones en la interpretación de las concepciones espontáneas
Authors: Pacca Jesuïna Lopes de Almeida , Saraiva J. A. F.
Published: June 2021

This work analyses aspects of Piagees genetic epistemology concerning the construction of the notion of causality which, although being developed in parallel with the operatory notions, cannot be identified with them. Such differentiation is important to understand the knowledge of students shown trough spontaneous conceptions. The idea of necessity, which in Piaget's theory, is essential for the construction of causal relations, is considered here as a relative necessity, making sense and having value when referred to a system of explanation. Considering alternative conceptions as models of explanation of physical phenomena, the relations in these models must be causal and necessary in respect to a physical system, incomplete and inadequate as it might be.
La didàctica de les ciències : una empresa racional
Authors: Aliberas Maymí Joan , Gutiérrez R. , Izquierdo i Aymerich Mercè
Published: June 2021

This article uses S. Toulmin 's evolutionary epistemology in order to face the present-day situation of Science Education, considered a suficiently different discipline in comparison with the other scientific disciplines, having its own professional field and research. As a result of this, the importance of timing and the pressure to find ways or collective work are emphasised. This may allow to reach theoretical agreements which have not yet been achieved in a satisfactory way. The change of teaching institutions, methods of working and training, which would allow for the innovative teaching behaviour now considered adequate by the professional staaf is also considered absolutely relevant.
Investigación en enseñanza de las ciencias en la Universidad de Cornell: esquemas teóricos, cuestiones centrales y abordes metodológicos
Authors: Moreira Marco Antonio , Novak J. D.
Published: June 2021

This paper provides a description of the kinds of telling questions, guiding theories, and research methodologies involved in the science education program at Cornell University in recent years, and that will continue to be in the research agenda in the near future. Given its research bias, it does not focus directly on matters such as curriculum development, instructional practices, and teacher preparation —which are also being carried out at Cornell —but rather on implications of research findings on these matters. By doing this, the authors attempt to be coherent with the fact that the program is theory -based and that in its development there has been a continuous effort to design both research and new instructional practices from a theoretical foundation, and in turn construct, modify, and elaborate the theoretical frameworks. An English version of this paper is available from the authors upon request.
Conocimientos profesionales de los profesores
Authors: Bromme R.
Published: June 2021

Strangely enough, professional knowledge of teachers has been rarely studied so far. This paper presents starting points for this subject and possible open lines for research are suggested.
Ideas de los alumnos sobre digestión : aspectos anatómicos
Authors: Banet Hernández Enrique , Núñez Francisco
Published: June 2021

In this article we analize the ideas that students from different levels (FOB, BUP, Teachers' Training college) as well as some teachers have in relation to some specific anatomical aspects of the digestive system. The results obtained show a very low effect of instruction on the conceptual progression of the student, and they suggest, as a working hypothesis, specific classroom tasks which could favour a more useful and lasting learning of the above mentioned concepts.
Ideas sobre los cambios de estado de agregación y las disoluciones en alumnos del 2º curso del BUP
Authors: Fernández Fernández J. M.
Published: June 2021

We have tried to learn from the pupils who start in our school the systematic study of Chemistry, which are their ideas about nature and mass preservation, in relation to changes in substance condition and solution of a solid in a liquid. We have learnt that a great majority of them have preconceptions about the above mentioned questions, however, those preconceptions do not form a solid and coherent structure, thus showing an important confusion of ideas.