Flat Shape Research Articles

Effect of heat treatment on interface characteristics and mechanical properties of explosive welded Cu/Ti composites

Abstract Copper and titanium plates were used in the studies. Explosive welding (EW) processes were carried out using different explosive rates. The resulting composite plates were heat treated at different temperatures. Various tests were then carried out on samples with and nonheat treatment. In the SEM studies, it was observed that a flat interface shape was formed in the joints where the lowest explosive rate (R = 2.5) was used, but as the explosive rate increased, the interface shape became wavy. It was also found that a thickening diffusion layer formed as the heat treatment temperature increased. As a result of XRD and EDS analyses, it was found that Cu4Ti, CuTi2, CuTi, CuTi3, Cu3Ti2, and Cu4Ti3 intermetallic phases could be formed because of the high explosive rate and heat treatment applications. Increasing the amount of explosives increased the tensile-shear strength. However, the heat treatment applied reduced the strength values. No defects were detected in the bending tests performed on all heat-treated and nonheat-treated samples.

Audience Book Based on Pancasila Student Profiles as a Media for Introducing Quadrilaterals for Elementary School Students

Technological developments are spreading to all sectors, including education. As educators, we are required to utilize technology in learning, Many students have difficulty understanding geometric material, which is often presented in a conventional and less interesting way. On the other hand, education in Indonesia also aims to shape students' character in accordance with Pancasila values, such as mutual cooperation, integrity and independence. However, approaches that integrate character education with subject teaching are still limited. This research aims to analyze a mathematics audible book based on Pancasila student profiles that is feasible and practical as a medium for introducing rectangular flat shapes for fourth grade elementary school students by utilizing technological developments. The research uses the ADDIE model. The test subjects were fourth grade elementary school students, involving 94 students and 3 teachers. Data collection techniques through interviews and questionnaires. Data analysis uses the Aiken'v index. The results of the research show that overall the use of a mathematics audible book is feasible and practical as a medium for introducing rectangular shapes for class IV elementary school. The implications of this research are This book is designed to introduce the quadrilateral concept in an interesting way and in line with the Pancasila student profile, which emphasizes values ​​such as mutual cooperation, integrity and independence.

Digital learning using ChatGPT in elementary school mathematics learning: a systematic literature review

Digital learning with ChatGPT in elementary school mathematics learning is urgently implemented. Several studies have explored digital learning with ChatGPT in elementary school mathematics learning, but studies using SLR are minimal. This article presents the 2022-2024 SLR study on digital learning with ChatGPT in elementary school mathematics learning. This SLR and PRISMA method is supported by Publish or Perish 8, VOSviewer version 1.6.20, Mendeley version 1.19.8, and ATLAS.ti version 7.5.16. The search results obtained 1,259 Scopus articles, which were filtered to 40 and analyzed using ATLAS.ti, then the results were described according to the research question. Digital learning with ChatGPT is a learning approach using the synchronous-asynchronous mode, virtual classrooms, distance, use of interactive digital tools, digital methods and media, innovation, digital modeling, use of robotics and AI ChatGPT for children with the principle of collaboration digital, and problem-solving with the support of digital resources. ChatGPT features multilingual, natural language, advanced AI, 24/7 availability, answering math questions, recurring training, and helping students with various math tasks. Implementation of digital learning with ChatGPT in elementary school mathematics learning for problem-solving, geometry, function limits in algebra, the material on flat shapes, geometric shapes, integrated PjBL, online, mixed and flipped classes.

Manipulative interactive didactics with puzzles: An effective solution for overcoming junior high school students' learning obstacles to quadrilateral materials

The study of learning obstacles is essential to develop students' competencies and improve the quality of learning that is responsive, inclusive, and relevant in the 21st century. The purpose of this study is to identify learning obstacles related to misconceptions regarding quadrilateral material and students' mathematical creativity, and to find effective empirical didactic designs to overcome these learning obstacles. The research methodology used is didactic design research (DDR), which consists of four frameworks: Initial data collection, prospective analysis, metapedidactic analysis, and retrospective analysis. These stages are cyclical. The study involved 172 junior high school students and six model teachers. Data was collected using the quadrilateral writing creativity test, interviews, documents, and field notes. Data analysis was conducted simultaneously using quantitative and qualitative approaches. The study produced empirical didactic designs, namely manipulative interactive didactics with puzzles, which are equipped with a guide for teachers to manage learning. This empirical didactic design includes seven frameworks that have been shown to be effective in overcoming didactic and epistemological barriers—scaffolding, questioning skills, brainstorming, learning opportunities, conceptual representation of mathematical creativity, misconceptions, and concept representation. Teachers can implement or adapt this empirical instructional design for use in geometry subtopics or other mathematics materials. For instance, they can use it for subtopics such as flat shapes with the same area, spaces with the same volume, or spaces with the same surface area.

Elementary School Students' Literal Thinking Ability in Solving Flat Figure Problems Seen from the Adversity Question

This research aims to analyze students' literal thinking ability in solving plane problems in terms of the adversity quotient (AQ). This type of research is quasi-experimental and involves 55 elementary school students in Central Maluku Regency, Maluku Province, Indonesia. The data obtained was analyzed using non-parametric statistical tests with the Kruskal Wallis test type. The results of the research show that there are differences in students' literal thinking abilities in solving flat - shape problems in terms of AQ. By using the Post-Hoc test, it was found that the literal thinking ability of AQ-Cb students was significantly different from AQ-Q and AQ-Cp, while AQ-Q and AQ-Cp level students had no significant difference. This difference is because AQ-Cb level students are more thorough and work harder in solving flat shape problems compared to AQ-Q and AQ-Cp level students. Students with high AQ are generally more skilled at understanding information, interpreting problems, and being able to make solutions correctly. Keywords: lateral thinking, adversity quotient (AQ), mathematical problem solving

China's newest design of apartment buildings with modernized façade: A comparative evaluation of its energy performance in five major climate zones

Many studies have indicated that the energy efficiency of residential buildings can greatly mitigate energy shortages and environmental problems. High window-to-wall ratio, flat geometric shape, and open space layout are the key characteristics of apartment buildings with modernized façade (ABMF), and the major design trend dominating China's housing market. This study aims to understand the isolated effects of these three design factors on the energy performance of ABMF in five major climate zones using a parametric performance design method. Three important findings were concluded: 1) the energy use intensity (EUI) of ABMF showed a positive relationship to the window-to-wall ratio in five climate zones. Qingdao in Cold Region (2.12 kWh/m2) and Kunming in Temperate Region (1.04 kWh/m2) exhibited lowest average increase in EUI; 2) the reduction of EUI was twice as much in Kunming than in the other four cities, when the aspect ratio of ABMF changed from 1.75 to 0.95; 3) the ‘exterior-side hall’ was the most energy-efficient layout in the five cities. This study is the first to investigate the energy performance of the newest apartment design and hopefully can attract more studies to explore the suitability of ABMF for the sustainable development of China's housing market.

On interfacial deformation and resistance characteristics over superhydrophobic surfaces: A numerical study

The air/water interface, known as the plastron, entrapped in submerged superhydrophobic surfaces (SHSs), plays a crucial role in underwater drag reduction. However, the plastron can be easily deformed or collapsed by turbulent flow, leading to decreased drag reduction or even an increase in drag. Most previous numerical studies have simplified these interfaces as idealized flat or curved rigid boundaries. To thoroughly investigate the interfacial behavior of SHSs, this study presents a numerical comparison between ideal and dynamic interfaces. The plastron undergoes regular oscillations after a brief adaptation period, transitioning between convex, nearly flat, and concave shapes. During the oscillatory decay, the dynamic properties of the interface modify the surface drag of the SHSs by both affecting the viscous drag and introducing pressure drag. The viscous drag is affected in two main ways. First, the momentum exchange across the dynamic interface is enhanced due to the roughness-like effect, leading to an increased viscous drag in groove region. Second, the trailing interfaces induce step flows and secondary flows downstream of the grooves, creating regions of nonuniform shear stresses. Consequently, the viscous drag of the downstream walls is slightly reduced. Overall, for convex and nearly flat interfaces, the drag increase within the groove region outweighs the drag reduction at the downstream walls, resulting in a total drag increase in 47.3% and 29.8%, respectively. Conversely, for concave interfaces, the drag increase within the groove region is smaller than the drag reduction at the downstream walls, leading to a 9.8% decrease in total drag.

Effect of rolling process on deformation structure and mechanical properties of CoCrFeNiMo0.35 high entropy alloy

In this work, CoCrFeNiMo0.35 high entropy alloy was hot-rolled at 900°C by varying different reductions (10%, 20%, 30%, 40%, 50%) and the impact of hot rolling on the structure and mechanical properties of this alloy has been investigated. It is found that the phase composition of CoCrFeNiMo0.35 high entropy alloy after hot rolling has not been changed, and it still consists of FCC phase and σ phase (Cr and Mo-rich phase), which is the same as the as-cast state alloy. Besides, the grain size becomes finer after hot rolling and is stretched to a flat shape in the rolling direction, and the grain orientation gradually changes from <001> and <101> direction to <101> direction with the increase of reduction. At the same time, as the increase of rolling reduction, the volume fraction of σ phase increases, and the yield strength (∼817.8 MPa), tensile strength (∼891.7 MPa) and hardness of the alloy are improved. The comprehensive influence of fine grain strengthening, second phase strengthening and dislocation strengthening is the main reason for this result. Besides, the fracture mode of the tensile sample changes from mixed tough-brittle fracture to brittle fracture. The research results can be used as a reference for hot rolling strengthening of CoCrFeNiMo0.35 high entropy alloy.

Prediction of steel strip flatness based on the difference in drawing coefficients along its width during steel strip rolling

The paper presents a brief overview of approaches to calculating flat strip shape defects. It is shown that the most important technological factors in forming a flat sheet are the difference in draw bars across the strip width and the inter-roll gap profile, which depends mainly on elastic deformations that are uneven along the barrel length. The elastic deformations of the working roll surface were simulated, which, together with its thermal profile and wear, made it possible to estimate the transverse profile of the rolled product. The process of deformation of a set of rolls in a quarto stand was studied in the ANSYS Mechanic program using the Static Structure module. The results of calculating the elastic deformations of the roll surface in contact with the deformed strip with varying parameters over a wide range of values made it possible to obtain a statistically reliable equation for estimating the roll barrel profile in the deformation zone and the transverse profile of the rolled product. The obtained roll profile was used to study the formation of the flatness defect “waviness” using the DEFORM-3D program. It was carried out by simulating the rolling of a steel strip with a given transverse profile in profiled roll barrels. On the finished strip, the amplitude of the flat shape defect was estimated by comparing the vertical displacements of the strip section at its edge and in its middle at the exit from the rolls. Using a well-known technique, the amplitude of the “wave” and “box” was also calculated. The assessment was carried out on the basis of the difference in the elongation coefficients across the strip width. The results of the assessment and modeling of the rolling process showed very close results, which confirms the possibility of calculating the flatness parameters by the difference in the strip elongations across its width using a well-known formula.

Upaya Meningkatkan Hasil Belajar Matematika Materi Bangun Datar dengan Pendekatan Matmatika Realistik di Kelas V SDN 101766 Bandar Setia

The purpose of this research is to see the results of learning mathematics on flat shapes material after using a realistic mathematics approach in class V of SD Negeri 101766 Bandar Setia. The research method used is Classroom Action Research (CAR). The CAR model used consists of 4 stages, namely planning, action, review (observation), and reflection. The subjects in this study were 22 students of class V-B of SD Negeri 101766 Bandar Setia, consisting of 10 male students and 12 female students. The data collection technique used in this study was observation and test analysis. The results of the study from the implementation of two cycles showed that the percentage of student learning activities increased by 60% in cycle I to 88.5% in cycle II. The percentage of student learning outcomes also increased from 59% (good) in cycle I to 86% (very good) in cycle II. Based on the results of the data analysis obtained, it can be concluded that the realistic mathematics approach can improve student learning outcomes in the mathematics subject of flat shapes material in class V of SD Negeri 101766 Bandar Setia

Melting of olive oil in immiscible surroundings: experiments and theory

We report on the melting dynamics of frozen olive oil in quiescent water for Rayleigh numbers up to $10^9$ . The density difference results in an upward buoyancy-driven flow of liquid oil forming a thin film around the frozen oil. We experimentally investigate flat, cylindrical and spherical shapes and we derive theoretical expressions for the local film thickness, velocity and the local melt rate for these three canonical geometries. Our theoretical models predict the correct order of magnitude and the correct scaling as compared with our experimental findings.

Changes in mitral and tricuspid valve morphology after surgical repair of pectus excavatum

Abstract Background The effect of pectus excavatum (PE) on cardiac morphology and function has been reported previously. The right heart chamber size and cardiac output improved after the surgical correction of PE. However, the effect on the mitral and tricuspid valve has not been investigated. Purpose Our purpose was to investigate the morphological changes in the tricuspid and mitral valve after PE surgery. Methods We enrolled 25 patients who underwent Nuss surgery for PE repair. The inclusion criteria were 1) aged 15 years or older, 2) Haller Index of more than 5.0, and 3) transesophageal echocardiography (TEE) during PE surgery. We measured RV size and the sphericity index of tricuspid and mitral valve using 3D echocardiography before and after the elevation of the sternum. The sphericity index was calculated as the ratio of anterior-posterior (AP)/medial-lateral (ML) dimeter for the mitral valve (MV) and septal-lateral (SL) / AP dimeter for the tricuspid valve (TV). Results Mean age was 26±11 years, and 28% was female. The Haller index was 6.9 ± 2.8. All patients had normal left ventricular and right ventricular function evaluated with transthoracic echocardiography. The chamber diameter of the base and mid in RV increased after the elevation of the chest. The AP and SL dimeter were enlarged after the elevation of the chest in the TV, and the sphericity index of TV did not change. On the other hand, AP diameter increased but ML diameter was constant in the MV, and the sphericity index of MV increased after the elevation of the chest. Therefore, the annulus size was increased but the morphology was not changed in the TV. Unlike the TV, the morphology of MV annulus became close to circular from flat shape. In several patients, trivial mitral regurgitation was observed after elevation of chest, and possibly affected by the morphological change of the MV annulus. Conclusions The surgical repair for pectus excavatum effected not only right ventricular morphology but also on the tricuspid and mitral valve. The annulus change was different between the tricuspid and mitral valve.

Development of laser felling modes of gas-thermal coating

The use of copper and its alloys to create parts for metallurgical equipment is associated with an increase in abrasive wear and high-temperature corrosion. In this regard, there is a need to apply a protective coating. In particular, to prevent wear and premature chipping of the metal of copper tuyeres, the surface is hardened with a coating of zirconium dioxide stabilized with yttria oxide by thermal spraying in an air atmosphere. Due to the difference in the coefficient of thermal expansion of copper (at T = 300 K: 16.7 µm/m оС and at T = 750 K: 19.7 µm/m оС) and its low resistance to gas corrosion, the application of zirconium oxide (produced by a preapplied intermediate layer that plays a role in matching the coefficient of thermal expansion (CTE) between the copper base and the ceramic coating. In addition, the intermediate layer protects copper from gas corrosion. In this case, The use of copper and its alloys to create parts for metallurgical equipment is associated with an increase in abrasive wear and high-temperature corrosion. In this regard, there is a need to apply a protective coating. In particular, to prevent wear and premature chipping of the metal of copper tuyeres, the surface is hardened with a coating of zirconium dioxide stabilized with yttria oxide by thermal spraying in an air atmosphere. Due to the difference in the coefficient of thermal expansion of copper (at T = 300 K: 16.7 pm/m °G and at T = 750 K: 19.7 pm/m оG) and its low resistance to gas corrosion, the application of zirconium oxide (produced by a pre-applied intermediate layer that plays a role in matching the coefficient of thermal expansion (CTE) between the copper base and the ceramic coating. In addition, the intermediate layer protects copper from gas corrosion. In this case, nickel-based alloys were used as intermediate layers. The use of nickel as the basis of intermediate layers is due to the fact that copper and nickel form a continuous series of solid solutions, such as cupronickel or monel metal-like structures. This, in turn, assumes a smooth transition of thermophysical properties from copper to nickel alloy. To ensure increased adhesion of the transition layer to copper by increasing the area of mutual contact between copper and the sublayer (dagger penetration) and significantly increasing the homogeneity of the material of the intermediate layer made of a nickel alloy, laser melting of the intermediate sublayer (Ni–B–Si system) was used on a laser complex based on laser LS-5 with a power of 5 kW with a KUKA KR-60HA robot in an argon atmosphere. To test the modes, experiments were carried out on copper samples of a flat shape and a body of rotation. The optimal parameters for the process of melting flat samples were: processing speed 33 mm/s, power from 400 to 3900 W, focal length from 200 to 230 mm, pitch between tracks: 0.25, 0.5 and 1 mm. The optimal parameters for the process of melting rotating samples were: laser radiation power 400–450 W, processing step 0.125; 0.5, focal length from 200 to 210 mm.

Synthesis, Identification, and anti-cancer Evaluation of Some heterocyclic Chitosan-Thiosemicarbazones compounds and their nickle (II) complexes

Chitosan (CS) a chemical substance taken from the shells of sea creatures that has various uses in industry, farming, and medicine, for example in medical dressings. Its derivatives significantly inhibit two types of cancer cells: Madin Darby Canine Kidney MDCK and MCF-7. These derivatives include thiosemicarbazones, heterocyclic moieties, and their metal (II) complexes. In this study, CS from crab shells is mixed with thiosemicarbazide (TSC). Then, imidazole-2-carboxaldehyde, oxazole-2-carboxaldehyde, and thiazole-2-carboxaldehyde reacted to make three different compounds from CS-TSC: [2a], [2b], and [2c]. The chemicals were mixed with nickel chloride to create nickel (II) chitosan 2-acetyl heterocyclic-2-thiosemicarbazone complexes. SEM and X-ray tests were performed on the powder, which showed that the nickel (II) chitosan thiosemicarbazone complexes had square and flat shapes. The synthesized compounds were tested to check their effectiveness in preventing MDCK and MCF-7. The study found that chitosan derivatives significantly inhibited MDCK and MCF-7.

Three hundred sixty‐degree viewable linear grooves 3D display

AbstractWe proposed a linear grooves 3D display that can display 360° viewable 3D images by creating linear grooves that correspond to the viewpoint positions. In the conventional method, arc‐shaped grooves are drawn on a flat substrate of transparent film. However, depending on the viewing position, the image may be distorted. In addition, when a flat substrate is bent into a curved shape, the image is more affected than one observed in a flat shape. Furthermore, the conventional method of arc 3D display method cannot display a 3D image that corresponds to the viewpoint position. In this paper, we propose design and fabrication methods that reduce the image distortion for both flat and curved shapes. A 3D image displayed by the proposed method can change depending on the viewpoint position, and a natural 3D image with motion parallax can be observed. In the experiment, our proposed method fabricated a 360° 3D display by calculating the linear grooves and presented natural 3D images with smooth motion parallax.

A new method for growing epitaxial films on foreign substrates − Bent epitaxy

In recent years, to mitigate the effects of climate change, countries’ transition to the green economy has accelerated, and thereby, the demand of semiconductor industry for wide-gap semiconductors such as SiC and GaN has increased dramatically. These semiconductors are expensive. To reduce the price of the final product, industrial production of thin epitaxial films of sought-after semiconductors on accessible and cheap substrates, such as Si and sapphire, is being developed. When growing epitaxial films on foreign substrates, the resulting heterostructure bends, becomes concave or convex, due to a mismatch between the coefficients of thermal expansion (CTE) of the substrate and the epitaxial film. As a result, the quality of the epitaxial film deteriorates and further processing of the resulting heterostructures in production lines becomes difficult or even impossible. The essence of the proposed new method is that the epitaxial film is grown not on a flat, but on a pre-curved substrate with the expectation that after cooling the fabricated heterostructure to room temperature, the heterostructure will take a flat shape due to the difference in the CTE of the epitaxial film and the substrate. A round bimetallic plate, located under the substrate, bends the substrate in the required direction to the desired value at the growth temperature, and gradually reduces the bend of the fabricated heterostructure during cooling, in proportion to the thermal contraction of the epitaxial film. This allows obtaining qualitative and flat epitaxial films, regardless of the material of the substrate or epitaxial film and the diameter of the substrate or thickness of the epitaxial film, without any buffer layers or carrying out any additional operations and costs.

Regulation of Br on molecular aggregation, film morphology and electrochromic performance of polythiophene derivatives

In this work, five polythiophene derivatives were synthesized through electrochemical copolymerization of 3,3-bis(bromomethyl)-3,4-dihydro-2H-thieno[3,4-b] (Deng et al., 2023; Li et al., 2020) [1,4]dioxepine (ProDOT-Br) and 3,3-dimethyl-3,4-dihydro-2H-thieno[3,4-b] (Deng et al., 2023; Li et al., 2020) [1,4]dioxepine (ProDOT-Me) at different mass ratios. DFT results prove that the layer spacing of conjugated blocks was increased from 5.94 Å for PProDOT-Me to 8.89 Å for PProDOT-Br due to the introduction of Br atom into side chain. And, the diverse film morphologies, such as fibre shape, cellular shape, flat shape, etc, were obtained by changing Br content in polymer. Additionally, through optimizing Br content, PBM(1,2) achieved enhanced electrochromic properties relative to two reference polymers [PProDOT-Br and PProDOT-Me], such as high optical contrast (ΔT = 76 %), fast response time (0.5 s), high transparency, and good stability. Finally, the flexible electrochromic device (8 cm × 4 cm) based on PBM(1,2) was constructed, which achieves rapid color change from purple to transparent blue. The results indicate that introducing various contents of Br atom into side chain is an effective strategy for regulating molecular microstructure and optimizing electrochromic properties of conjugated polymers.

Keefektifan Model Pembelajaran Addie Berbantuan Media Miniatur Bangun Datar terhadap Prestasi Belajar Matematika Siswa Kelas II pada Mi Negeri 3 Banyumas

The development of science and technology that is not balanced with facilities, infrastructure and teacher skills in teaching in schools has caused a decline in mathematics learning achievement of grade II students from year to year. Although this problem has been improved, it has not been resolved. So another solution was made by using the ADDIE model assisted by miniature flat shape media. The problem is, is there a difference in learning achievement using the ADDIE model assisted by miniature flat shape media with learning achievement using the conventional model? The research design was a pretest-posttest control group design. The instruments used were achievement tests and student learning activity observation sheets. The data analysis technique in this study used an initial analysis using a normality test and a test of equality of two means and a final analysis using a normality test and a t-test. The result was that the initial analysis of the two samples was normal and the average was the same. While the final analysis of the two normal samples and the t-test stated that t count = 4.036&gt; t table = 2.025 so that there was a difference in the average mathematics learning achievement of those who received instruction using the ADDIE model assisted by miniature flat shape media with those who used the conventional model.

Analysis of palatal marginal alveolar exostosis and palatal torus using cone-beam computed tomography.

The aim of the present study was to analyze palatal marginal alveolar exostosis (PMAE) and palatal torus (PT). Cone-beam computed tomography (CBCT) of the maxilla in multiplanar sections and volumetric renderings were used to assess this. PT and PMAE were classified according to location and morphology. Height, width, length, and thickness of the overlying mucosa were determined. The prevalence of PT and PMAE was assessed according to sex and age group. The correlation between the occurrence of PMAE and PT was also evaluated. A total of 385 CBCT scans were examined. PT was found in 38.70% of the sample and located more frequently in the middle third of the maxilla (52.35%) with a flat shape (42.95%). PMAE was found in 54.80% of the sample, bilaterally in 56.40% of the cases, and located more frequently in the molar region (62.42%) in the form of small nodules (36.97%). The mucosa covering PMAE was generally thicker than that over PT. The use of CBCT for the identification of PT and PMAE invivo showed high frequencies of both conditions. The occurrence of PMAE was independent of the presence of PT.

Complementary correlation between surface microbubble and droplet shapes

Previous atomic force microscopy studies have suggested that surface micro- and nanobubbles exhibit a flat shape. In this study, we directly observed surface microbubbles formed in an NH3BH3 solution using an optical microscope. No flat microbubbles were observed. Instead, on an SiO2/Si substrate, we discovered a relationship where the sum of the contact angle of a microbubble and the contact angle of a droplet equaled ∼180°. This relationship allowed us to control the shape of surface microbubbles by manipulating the wettability of the surface and the surface tension of the liquid, similar to droplet control. We were able to produce almost perfectly spherical microbubbles. Conversely, on a Cu foil, this relationship did not hold, although we still observed the formation of nearly spherical microbubbles. In this scenario, the shape of microbubbles appeared to be influenced by contact line pinning.