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111.
Mechanical and physical properties, such as tensile strength, elongation at break, modulus of elasticity, Shore D hardness,
melt flow rate (MFR), and electrical and thermal conductivities of composites with high density polyethylene matrix reinforced
with Al powders were investigated experimentally. Measurements of the mechanical and physical properties were performed up
to a reinforcing component concentration of 30% volume Al powder and compared with mathematical models from the literature.
The obtained results have shown that experimental data were in good agreement with theoretical data. The ultimate tensile
strength (UTS) and elongation at break decreased with increasing Al powder content, which was attributed to the introduction
of discontinuities in the polymer structure, and modulus of elasticity increased with increasing Al content. The composite
preparation conditions allowed the formation of a random distribution of metallic particles in the polymer matrix volume for
system high density polyethylene-Al (HDPE-Al). There was a cluster formation of Al particles at higher Al contents in the
polymer matrix. Electrical and thermal conductivity values of HDPE-Al composites were higher than pure HDPE values. 相似文献
112.
113.
The intention of the authors in this article is to contribute to the discussion concerning educational change by implementing the concept of social innovation. We argue that the application of the concept of social innovation makes it possible to better understand the process of implementation as well as sustainability and the social impact of educational changes. In the article, an integrated model of social innovation has been constructed and applied in conceptualising two consequent radical educational changes accompanying the post-communist changes in Estonia. As a result, the authors conclude that the concept of social innovation provides a promising framework, which facilitates the understanding and analysis of radical educational change. The social innovation approach is useful in identifying the different levels of change and assessing how deep the changes have been. However, in education systems in neo-liberal countries, where competition is one of the basic values, educational changes, even though becoming part of the everyday practices of actors, may redistribute power, rather than having an empowering effect for the majority of the main actors. 相似文献
114.
In this paper, cyclic codes are studied over some finite quaternion integer rings with respect to the quaternion Mannheim distance. 相似文献
115.
Mehmet Aydeniz Aybuke Pabuccu Pinar Seda Cetin Ebru Kaya 《International Journal of Science and Mathematics Education》2012,10(6):1303-1324
The purpose of this study was to explore the impact of argumentation-based pedagogy on college students?? conceptual understanding of properties and behaviors of gases. The sample consists of 108 students (52 in the control group and 56 in the intervention group) drawn from 2 general chemistry college courses taught by the same instructor. Data were collected through pre- and post-tests. The results of the study show that the intervention group students performed significantly better than the control group students on the post-test. The intervention group students also showed significant increase in their test scores between pre- and post-test. While at least 80?% of the students in the intervention group abandoned their initial ideas on all of the 17 alternative conceptions that were identified by the authors but one, the percent of student abandoning their initial ideas in the control group was less than 50. The discussion focuses on the implications of these results for addressing students?? alternative conceptions, promoting the argumentation?Cpedagogy in college science courses and the challenges associated with the use of argumentation in college science classrooms. 相似文献
116.
The communication systems and disk or tape memory can sometimes cause clusters of errors, namely burst errors. There have been many designs in order to detect and even correct such errors. Recently, a new class of codes called m-spotty byte error correcting codes has found applications in high speed memory systems that employ random access memory chips wide Input/Output data, especially at 8, 16, or 32 bits. The MacWilliams identity provides the relationship between the weight distribution of a code and that of its dual code. Also, an interesting new metric called Rosenbloom–Tsfasman metric has been studied as an alternative metric for linear codes recently. In this paper, we combine these two interesting topics and introduce the m-spotty Rosenbloom–Tsfasman weights and the m-spotty Rosenbloom–Tsfasman weight enumerator of a binary code. Moreover, we prove a MacWilliams identity for the m-spotty Rosenbloom–Tsfasman weight enumerators. 相似文献
117.
Mehmet Buldu 《Educational research; a review for teachers and all concerned with progress in education》2013,55(1):121-132
Background Since the 1950s, there has been a growing body of research dealing with perceptions children have of scientists. Typically, research studies in this area have utilized children's drawings in an effort to discern what those perceptions are. Studies assessing perceptions children have of scientists have shown that children have stereotypical images of scientists. Although there is no direct evidence to demonstrate the link between children's images of science and scientists with their career choice, several researchers (including this researcher) have assumed that children's attitudes towards science are greatly influenced by their perceptions of science and scientists. Purpose This study aimed to find out if there was a difference in the way 5- to 8-year-old children drew scientists, taking account of age, gender and socio-economic status. Sample For this study a convenience sample of 30 young children was used. Participants included young children between the ages of 5 and 8 years from a public elementary school in Ankara, the capital city of Turkey. Although the sample of the study was obtained from one school in a metropolitan area, children involved in this preliminary study were from very different socio-economic backgrounds. As the sample size is very small for making comparisons, it was intended to have a similar number of children from different age groups and socio-economic backgrounds and both genders. Design and methods The researcher worked individually with each child who participated in this study in an interview setting. Although each child was asked a set of standard questions, and given a standard set of directions, each interview session was informal enough to allow the researcher to gain additional information about children's drawings and to clarify any of their responses. During the interview sessions, children's responses were noted by the researcher. Before the children were asked to draw their picture of a scientist, they were offered a set of coloured pencils or crayons and told to feel free to colour their drawing or any parts of it they would like to accentuate. At the end of the interview and drawing sessions, the researcher went through all the drawings and notes to get a ‘feel’ for and ascertain what was being said, identifying key themes in each drawing. Results The most common scientist type drawn in this study was the stereotypical scientist type: someone who conducts research, or someone who tries to invent a new material. But unlike previous studies, around 35% of the scientist figures drawn (n = 15) were of the social scientist type. Stereotypical images drawn by the current study participants included symbols of research, such as scientific instruments and laboratory equipment of all kinds, and symbols of knowledge, principally books and cabinets, technology and the products of science. An interesting finding of this study was that perceptions of young children differed due to their age. Children at the age of 8 years drew non-stereotypical scientist images, and they drew more detail than did their younger peers. When children were compared in terms of their gender, no significant differences were observed between girls and boys. But on the other hand, none of the boys drew female scientists, and five out of 30 children who were girls drew female scientists. While children of parents with lower socio-economic status drew more stereotypical scientist images, children of parents with higher economic status drew different images of scientists, a result which showed us that the scientist perceptions of young children differ with socio-economic status. Conclusions Emergent from this research has been a non-stereotypical perception of scientists, and some evidence exists that such a non-stereotypical perception differs due to age and socio-economic status. While these images may seem amusing, they also provide a reflection of the image that children have about what a scientist looks like. These images may have a powerful impact on present functioning and future plans of young children. 相似文献
118.
This paper reports the second stage of an action research study designed to improve the effectiveness of speaking classes through negotiating the lesson contents with students. The data were collected through interviews, questionnaires and observations as a way of eliciting students’ views. The research, conducted in an English language teaching department at a university in Turkey, comprised eight weekly-based interventions that involved planning, action, observation, and reflection, in which students were given a voice and classroom activities were designed accordingly. Student negotiation allowed for the identification of both structural and affective factors influencing the quality of speaking classes. The teacher’s roles in activities, the number of students in group work activities, the level of control in speaking activities, and the role of input were found to be issues worth considering in designing speaking classes. Issues such as finding the activity ‘interesting’ and ‘useful’, ‘feeling comfortable’ and ‘being competitive’ also influenced the effectiveness of activities. Involving students in this action research study promoted positive attitudes towards classes since students reported feeling valued and important. 相似文献
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120.
Abstract： An innovative occupant friendly retrofitting technique has been developed for reinforced concrete （RC） building structures with hollow brick infill wails used as partition walls which constitute the major portion of the existing building stock in Turkey. The idea is to convert the existing hollow brick infill wall into a load carrying system acting as a cast-in-place RC wall by reinforcing it with relatively thin concrete plates bonded to the mortar coated infill wall by use of tile adhesive and fixed by qb6 （6 mm diameter） bolts. Test parameters were the shape and thickness of the plates, presence of reinforcement in plates, number and arrangement of O6 bolts. It was observed that lateral strength, stiffness, energy dissipation capacity, and ductility of the strengthened infill walls were improved and behaviour was enhanced by the proposed technique. Plates with two different basic shapes were used to strengthen the test specimens. 相似文献