Amplitude Tapers for Planar Arrays Using the McClellan Transformation: Concepts and Preliminary Design Experiments

Author(s):  
Jeffrey O. Coleman
2020 ◽  
Vol 4 (2) ◽  
pp. 100
Author(s):  
Maryati Maryati ◽  
Rully Charitas Indra Prahmana

An essential part of learning transformation geometry is rotation. Before learning more about other parts of the transformation geometry topic, such as translation, dilation, and reflection, firstly, students are required to understand well about rotation. However, several students have not been able to understand this subject properly due to the stages of learning in the rotation has not been appropriately arranged. Thus, this study aims to design a student learning trajectory in learning rotation, which develop from informal to formal level through the Indonesian Realistic Mathematics Education (IRME) approach. Furthermore, researchers used a design research method divided into three stages, namely preliminary design, design experiments, and retrospective analysis. This study describes how the bamboo woven motif contributes significantly to 31 ninth-grade students understanding the rotation concept. As a result, the woven bamboo motif's context can stimulate students' understanding of rotation. It is proven based on the strategies and models of students during their learning process which contributes to their fundamental knowledge of rotation.


Author(s):  
Christopher J. Hurt ◽  
James D. Freels ◽  
Prashant K. Jain ◽  
G. Ivan Maldonado

Safety analyses at the high flux isotope reactor (HFIR) are required to qualify experiment targets for the production of plutonium-238 (238Pu) from neptunium dioxide/aluminum cermet (NpO2/Al) pellets. High heat generation rates (HGRs) due to fissile material and low melting temperatures require a sophisticated set of steady-state thermal simulations in order to ensure sufficient safety margins. These simulations are achieved in a fully coupled thermo-mechanical analysis using comsolmultiphysics for four different preliminary target designs using an evolving set of pre- and postirradiation data inputs, and subsequently evolving solution scopes, from the unique pellet and target designs. A new comprehensive presentation of these preliminary analyses is given and revisited analyses of the first prototypical target designs are presented to reveal the effectiveness of evolving methods and input data.


2020 ◽  
Vol 3 (2) ◽  
pp. 61
Author(s):  
Maryati Maryati ◽  
Rully Charitas Indra Prahmana

Indonesia has many cultures, one of which is in the form of traditional crafts namely Anyaman Bambu. It’s a form of traditional craft in the community that uses bamboo as its basic material. However, people only see these crafts as only a form of traditional craft, even though there are many motifs in these crafts that can be used as a starting point in learning mathematics, namely geometry transformations. Therefore, this research aims also to produce the learning trajectory of students in learning one subject in geometry transformations namely translation, which develops from informal to formal level through the Indonesian Realistic Mathematics Education (IRME) approach. The research method used is design research starting from preliminary design, design experiments, and retrospective analysis. This study explores how the motifs of Anyaman Bambu make a real contribution for ninth-grade students to understand the concept of translation. The results of design experiments show that the context of the motifs of Anyaman Bambu can stimulate students to understand their knowledge of the concept of translation. All the strategies and models that students find, describe, and discuss that show how students' constructions or contributions can be used to help their initial understanding of the translation.


Author(s):  
R. Gonzalez ◽  
L. Bru

The analysis of stacking fault tetrahedra (SFT) in fatigued metals (1,2) is somewhat complicated, due partly to their relatively low density, but principally to the presence of a very high density of dislocations which hides them. In order to overcome this second difficulty, we have used in this work an austenitic stainless steel that deforms in a planar mode and, as expected, examination of the substructure revealed planar arrays of dislocation dipoles rather than the cellular structures which appear both in single and polycrystals of cyclically deformed copper and silver. This more uniform distribution of dislocations allows a better identification of the SFT.The samples were fatigue deformed at the constant total strain amplitude Δε = 0.025 for 5 cycles at three temperatures: 85, 293 and 773 K. One of the samples was tensile strained with a total deformation of 3.5%.


Author(s):  
Fitriah Khoirunnisa ◽  
Friska Septiani Silitonga ◽  
Veri Firmansyah

Penelitian ini bertujuan menganalisis kebutuhan petunjuk praktikum berbasis Keterampilan Proses Sains (KPS) untuk mencapai kemampuan merancang eksperimen pada materi kalor reaksi kalorimetri. Penelitian dilakukan terhadap peserta didik kelas XI SMA Negeri 2 Kota Tanjungpinang. Variabel penelitian mencakup analisis kebutuhan bahan ajar dan analisis kesesuaian Kompetensi Inti (KI) dan Kompetensi Dasar (KD). Jenis penelitian yang dilakukan adalah penelitian deskriptif kualitatif. Tahapan pertama dalam penelitian ini adalah menganalisis kebutuhan bahan ajar dengan cara membandingkan dua petunjuk praktikum yang selama ini telah digunakan di sekolah tersebut, ditinjau dari aspek struktur format penulisan, aspek kreativitas, dan aspek keterampilan proses sains yang terdapat dalam petunjuk praktikum. Sehingga didapatkan kesimpulan bahwa petunjuk praktikum yang selama ini digunakan tidak memberikan kesempatan kepada peserta didiknya untuk merancang eksperimen yang telah ditentukan. Tahapan kedua yaitu menganalisis kesesuaian kompetensi inti dan kompetensi dasar, yang bertujuan untuk menentukan indikator pencapaian kompetensi (IPK) yang akan menjadi acuan dalam mengembangkan petunjuk praktikum berbasis keterampilan proses sains. Dari kedua tahapan yang telah dilakukan maka dapat disimpulkan bahwa peserta didik memerlukan petunjuk praktikum yang mampu mengonstruksi pikiran dan mengaktifkan kinerja mereka, sehingga pendekatan Keterampilan Proses Sains menjadi pilihan dalam mengembangkan petunjuk praktikum yang sesuai dengan karakteristik kurikulum 2013.   This research aims to analyze the needs of Science Process Skills based Practical Instruction to achieve the ability to design experiments on the calor of reaction. This research was done to the students of class XI SMA Negeri 2 Tanjungpinang City. Research Variable includes the analysis of the needs of the learning materials and analysis of the suitability of the Core Competence (KI) and Basic Competence (KD). The type of research conducted is descriptive qualitative research. The first stages in this research is to analyze the needs of learning materials by comparing two practical instructions that had been implementing in the school, from the aspects of the structure of writing format, creativity, and science process skills embedded in practical instructions. The conclusion of this research that current practical instructions does not give an opportunity to the participants to design determined experiments. The second stage, namely analyzing the suitability of core competence and basic competence, which aims to determine the indicators of achievement of the competencies (GPA) which will be a reference in developing process skills-based teaching instructions science. Of the two stages that has been done then it can be concluded that learners need practical instructions to construct  thinking and and their performance, so the Science Process Skills approach is an option in developing practical instruction suitable for the characteristics of the curriculum of 2013.


PCI Journal ◽  
2012 ◽  
Vol 57 (2) ◽  
pp. 162-179
Author(s):  
Roberto Piccinin ◽  
Arturo E. Schultz

2013 ◽  
Vol 12 (3) ◽  
Author(s):  
Soegeng Hardjono

Parameter ratios are important information for the ship designer in the preliminary design stages. They can be used as a tool to identify the main parameter of vessel and their other technical characteristics. The information about parameter ratios of mono-hull vessel is currently available in Naval Architecture literatures, but it is not the case for the type of twin-hull vessel called catamaran. Having conducted technical analysis in this research, it has been identified that parameter ratios of passenger catamaran vessel made of FRP has values of L / B ratio from 2.52 up to 3.7, L / D ratio from 5.25 up to 11:24, slenderness ratio (Lwl/BwL) from  9 up to 12. Other values of various parameter ratios like B/T, D/T, L /√ L, and Displacement/L are also discussed.


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