16,775 research outputs found

    Low velocity impact response of rc beam with artificial polyethylene aggregate as concrete block infill

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    In structural design, an ideal situation for saving materials would be to reduce the weight of the structure without having to compromise on its strength and serviceability. A new lightweight composite reinforced concrete section was developed with a novel use of a lightweight concrete block as infill utilizing Artificial Polyethylene Aggregate (APEA and MAPEA). The concrete near the neutral axis acts as a stress transfer medium between the compression and tension zones. Partial replacement of the concrete near the neutral axis could create a reduction in weight and savings in the use of materials. In this experimental work, APEA and MAPEA were utilized as replacement for normal aggregates (NA) at percentages of 0%, 3%, 6%, and 9%, 12%, and 100% in the concrete mix. In this study, the concrete block infill uses the 100% MAPEA as a replacement for coarse aggregate. A total of sixteen beams were prepared measuring 170 mm × 250 mm × 1000 mm, in which four specimens were used as control samples (NRC) and twelve specimens were the reinforced concrete beam incorporated with different size of concrete block infill (RCAI) consisting of 100% MAPEA. All beams were tested with 100 kg steel weight dropped vertically from a height of 0.6 m and 1.54 m, which was equivalent to 3.5 m/s and 5.5 m/s respectively. Based on the experimental results, the impact force, displacement and crack patterns were affected by the impact load. For RCAI specimens, the impact force was larger but smaller displacement value was observed, compared to the NRC specimens. Furthermore, the width of the cracks generated in the RCAI specimens near the mid-span was less than that on the NRC specimen. All experiment results were validated against FEM. The transient impact force histories, displacement and crack patterns obtained from FEM matched reasonably well with the experiment results. The error reported a range of 1% to 15%. The results showed that the proposed use of concrete block infill produced desirable results under the impact loads. The main advantages of the concrete block infill that utilized MAPEA from waste plastic bags due to the weight reduction about 6% in the concrete beams

    Functional-semantic Characteristics of Conjugated Syntagmas

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    There is the close correlation between conjugation and syntagmatic segmentation of speech expressed in cer-tain syntagma typicality. The conjugated syntagma in live Russian speech and language of piece of art are identical on its structural-grammatical models. In the article is carried out an analysis of syntagmatic peculiarities of few Tur-kic languages, syntagma structures, its spontaneity, its additional functions, universal peculiarities of speech, possi-bility of syntagmatic segmentations; there was defined that all these peculiarities are more typical for informal lan-guage. At the same time there are specified the lexical and grammatical means at determination of the role of syn-tagma in speech sections conjunction. Among these means it is very important to consider the role of intonation and conjunctive means (prepositions, addresses and so on). The character of intonation-semantic unity in Turkic lan-guages somewhat differs from the other language groups including Slavic or Romanic-Germanic ones. This is ex-pressed in fact that syntagmas conjugated to the main structural-grammatical part of sentence are typified. The modern language processes that are represented first of all in formation of bilingualism have an influence on substantial syntagmas characteristics including Turkic languages

    Charakterizace tenkovrstvých elektroluminiscenčních součástek

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    Jádrem této disertační práce bylo studovat optické a elektrické charakteristiky tenkovrstvých elektroluminiscenčních součástek řízených střídavým proudem (ACTFEL) a zejména vliv procesu stárnutí luminiforů na jejich optické a elektrické vlastnosti. Cílem této studie měl být příspěvek ke zvýšení celkové účinnosti luminoforů, vyjádřené pomocí jasu, účinnosti a stability. Vzhledem k tomu, že současnou dominantní technologií plochých obrazovek je LCD, musí se další alternativní technologie plošných displejů porovnávat s LCD. Výhodou ACTFEL displejů proti LCD je lepší rozlišení, větší teplotní rozsah činnosti, větší čtecí úhel, či možnost čtení při mnohem vyšší intenzitě pozadí. Na druhou stranu je jejich nevýhodou vyšší energetická náročnost, problém s odpovídající barevností tří základních barev a podstatně vyšší napětí nutné pro činnost displeje. K dosažení tohoto cíle jsme provedli optická, elektrická a optoelektrická měření ACTFEL struktur a ZnS:Mn luminoforů. Navíc jsme studovali vliv dotování vrstvy pomocí KCl na chování mikrostruktury a na elektroluminiscenční vlastnosti (zejména na jas a světelnou účinnost) ZnS:Mn luminoforů. Provedli jsme i některá, ne zcela obvyklá, měření ACTFEL součástek. Vypočítali jsme i rozptylový poměr nabitých barevných center a simulovali transportní charakteristiky v ACTFEL součástkách. Studovali jsme vliv stárnutí dvou typů ZnS:Mn luminoforů (s vrstvou napařenou či získanou pomocí epitaxe atomových vrstev) monitorováním závislostí svítivost-napětí (L-V), velikost vnitřního náboje - elektrické pole luminoforu (Q-Fp) a kapacitance-napětí (C-V) ve zvolených časových intervalech v průběhu stárnutí. Provedli jsme krátkodobá i dlouhodobá měření a pokusili jsme se i o vizualizaci struktury luminoforu se subvlnovým rozlišením pomocí optického rastrovacího mikroskopu pracujícího v blízkém poli (SNOM). Na praktickém případu zeleného Zn2GeO4:Mn (2% Mn) ACTFEL displeje, pracujícího při 50 Hz, jsme také studovali stabilitu svítivosti pomocí měření závislosti svítivosti na napětí (L-V) a světelné účinnosti na napětí (eta-V). Přitom byl zhodnocen význam těchto charakteristik. Nezanedbatelnou a neoddělitelnou součástí této práce je i její pedagogický aspekt. Předložený text by mohl být využit i jako učebnice pro studenty na mé univerzitě v Lybii.The objective of this thesis is to study the optical and electrical characterization of Alternating-Current Thin-Film ElectroLuminescent (ACTFEL) devices, and specifically the aging process of phosphor materials that comprise the ACTFEL display in an effort to improve the overall performance of the primary phosphor colors in terms of brightness, efficiency and stability. Since the dominant flat-panel display technology is the LCD, an alternative flat-panel display technology must gauge itself in terms of the LCD. The advantages of ACTFEL displays in comparison with LCDs are the ability to pattern much smaller pixel, performance over a wider temperature range, full-viewing angle, and readability with much greater intensity background light. The disadvantages of ACTFEL displays against LCD ones are larger power consumption, lack of adequate chromaticity of the three primary colors, and much larger driving voltages. To achieve these objectives, the optical, electrical, and opto-electric measurements of the ACTFEL structures and ZnS:Mn phosphor hosts were carried out. Moreover, the effect of KCl co-doping on the microstructure and the electroluminescent properties (mainly brightness and luminous efficiency) of ZnS:Mn phosphors has been investigated, too. A non-common electrical characterization of ACTFEL devices has also been provided. We also calculated charged center scattering rates, and simulated the electron transport process in an ACTFEL device The study of the aging characteristics of evaporated and atomic layer epitaxy ZnS:Mn phosphors has been undertaken by monitoring the luminance-voltage (L-V) internal charge-phosphor field (Q-Fp) and capacitance-voltage (C-V) electrical characteristics at in selected time intervals during aging. Short-term and long-term ACTFEL aging studies has been provided and an attempt to visualize locally the structure of phosphor with a subwavelenght resolution using Scanning near-field optical microscope (SNOM) has also been presented. The practical case of a green Zn2GeO4:Mn (2% Mn) ACTFEL device operated at 50 Hz was studied and a luminance stability by a measurement of luminance-voltage (L-V) and luminous efficiency-voltage (eta-V) characteristics has been evaluated. A non-negligible and indiscreptible task of this thesis was also its pedagogical aspect. Therefore, the presented text can be considered as a textbook suitable for our students in Libya.

    Reflecting Theories in Three Themes of Professional Development

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    There are three themes of professional development will be discussed in this paper; a commitment to professional development, a commitment to collaborative reflection on practice, recognizing context and culture in professional development. All Themes are elaborated respectively and relate the professional development theories to the Indonesian education system, and as a result, develop any potential understanding. All themes seem to support each other. the succeed effort of a teacher will contribute positively to their profession, in collaborative work or in the context and culture. The progress of the teacher professional development should come from the all parties' effort. As we all know that education does not only stand alone but it is strongly influenced by the present context of politics, social, culture, or religious. In, Indonesia the advancement of this sector would strongly rely on government action rather than grassroots or professional organization initiatives. Based on the reflection, the paper proposes narrowing gaps between the universities and the schools. Implementing this direction is believed to some extent would reach certain advancement in teacher professional development in Indonesia

    Student Assessment And Misconceptions Of Photosynthesis: A Notion Of Shifting Perspective

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    Photosynthesis topic is as a compulsory topic ineducation typically in the second year of secondary high school. There is perception of some students that the photosynthesis topic is difficult to learn by student. This paper will clarify questions such as what assessment does mean, what student misconceptions in photosynthesis are, how teachers deal with student misconceptions, and last, why do teachers, school and curriculum need to change perspective in assessment. Based on the discussion, there are some parts that need to be reaffirmed. The teachers should not just recognize assessment as a formal paper, but in term of perspective and classroom instruction. It should be actualized in teaching-learning that there is no judgement of right and wrong for students in leaning.  Thus, dealing with student conception could be difficult for the teacher. The principal way is the teacher needs to be clear on the topic's planning and negotiate the meaning of all representations used in the classroom. Changing the type of assessments does not just simply mean changing teaching strategies or having appropriate types of assessment tool, but it could be a powerful source when it is integrated in the curriculum
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