Flat Side Research Articles

Regulation of Wide Bandgap Perovskite by Rubidium Thiocyanate for Efficient Silicon/Perovskite Tandem Solar Cells.

Developing high-quality wide bandgap (WBG) perovskites with ≈1.7eV bandgap (Eg) is critical to couple with silicon and create efficient silicon/perovskite tandem devices. The sufferings of large open-circuit voltage (VOC) loss and unstable power output under operation continuously highlight the criticality to fully develop high-quality WBG perovskite films. In this study, rubidium and thiocyanate as additive regulators in WBG perovskites are incorporated, significantly reducing non-radiative recombination, ion-migration, and phase segregation. The optimized 1.66 eV Eg perovskite solar cells achieved state-of-art 1.3V VOC (0.36V deficit), and delivered a stabilized power conversion efficiency of 24.3%, along with good device stability (20% degradation (T80) after over 994h of operation under 1 sun at ≈65°C). When integrated with a flat front side silicon cell, silicon/perovskite two-terminal tandem device (30% efficient) is obtained with a 1.97V VOC, and T90 operational lifetime of more than 600h at room temperature.

Impact of Crop Establishment Methods on the Growth and Yield Performance of Maize Varieties in the Kharif Season

A field trial was carried out in Pantnagar, Uttarakhand, India, during the Kharif season to evaluate the performance of maize varieties using various planting methods. The study included five distinct planting techniques: Flat, Bed, Ridgetop, Ridge mid-slope and Broad Ridge mid-slope both sides. Two maize varieties were tested: the composite PSM-1 and the hybrid DKC 9144. Results showed that the Broad Ridge mid-slope on both sides method led to the highest growth parameters, including; plant height, stem girth and dry matter accumulation per plant. During both the years, the Broad Ridge mid-slope planting method led to notable increase in plant height (7% and 6.1%), stem girth (5.25 & 4.67 cm) and dry matter accumulation (13.6% & 20.7%) respectively when compared to the flat planting method. Among the varieties, the hybrid DKC 9144 exhibited greater height, stem girth, more dry matter accumulation, grain and stover yields compared to the composite PSM-1. The findings suggest that the broad ridge mid-slope planting method, and hybrid variety DKC 9144, was the most effective and viable strategy for Kharif maize production in tarai region.

PENGEMBANGAN MEDIA PEMBELAJARAN BERBASIS ISPRING SUITE PADA MATERI BANGUN RUANG SISI DATAR

This research aims to develop ispring suite-based learning media on flat side space building materials reviewed from the aspects of feasibility, practicality and effectiveness. The research uses the R&D method, namely (Research and Development), and uses the ADDIE learning design model (Analysis, Design, Development, Implementation and Evaluation). The media developed uses ispring suite software, which is software used to create interactive learning media in the form of material presentations, material videos, practice questions, and quizzes. The test subjects in this study used individual and small group trials. The individual trial was 3 students of class VIII Madrasah Tsanawiyah and for the small group trial, namely 13 students of class VIII Madrasah Tsanawiyah. The results of this study, according to the assessment of media experts and material experts, show that ispring suite-based learning media obtained criteria suitable for use with an average score of 4.1. The results of the trials conducted on individual trials and small group trials showed that the ispring suite-based learning media obtained very practical criteria with an average score of 4.3. The ispring suite-based learning media also obtained very effective criteria with an average N-gain score of 0.87 based on the results of individual trial tests and small group trial test results.

Elephant skin-inspired mycelium tiles for thermal regulation of buildings

Abstract Of all types of ecosystems, cities are the most polluting and this pollution affects more than 50% of the global population. One main cause for this pollution is related to the energy used to heat or cool down buildings. Currently, only 15% of households in Southeast Asia have an air conditioner, but this number is expected to rise, leading to an increase in demand in energy consumption, electricity and CO2 emissions which could further worsen global pollution and climate change. There is therefore an urgent need to find alternative solutions to cool buildings and regulate their temperatures. In this paper, inspiration is taken from elephants who live in very hot climates. Elephants can cool themselves thanks to the wrinkles on their skin that can limit heat gain, dissipate energy by evaporative cooling and store water. To emulate elephants’ cooling, tiles with elephant skin-inspired surface texture are designed. Computational simulations are performed to evaluate the effect of local shading due to the texture. Experimental tiles are produced using a biodegradable and natural material grown by a fungus, Pleurotus Ostreatus. These tiles are mycelium-bound composites (MBCs) where the fungus grew on bamboo microfibers, developing an interconnected web of cells called the mycelium that binds the microfibers together. The thermal properties of the tiles were measured for heating and cooling on the textured and flat side. The results show the tiles have anisotropic properties with a significant improvement by 25% in the cooling of the textured side over the flat side. In simulated rain conditions, the cooling is further improved by 42% as compared to dry conditions. The elephant-mycelium tiles are therefore promising for thermal regulation of building in Southeast Asia environments.

"Geometrical Land" Learning Media Design Material for Building Flat Side Spaces

Flat-sided space shapes are mathematical materials in the scope of geometry which discusses cubes, blocks, pyramids, and prisms. In this material, students often find it difficult to visualize objects and relate them to contextual problems. The role of teachers in overcoming these problems is certainly very necessary. One way that can be used is to utilize technology to create learning media. The application software that can be used is Articulate Storyline 3. This research aims to produce a learning media design for flat-sided building materials called "Geometrical Land". This research is part of development research which is limited to the development stage only. The stages carried out in this research include: needs analysis, media design, and media validation. The instrument used is a media expert and material expert validation sheet. There are 6 validators, consisting of 3 material expert validators and 3 media expert validators. The results of this development research are in the form of a percentage of the validation test scoring of material experts and media experts. The average percentage of validity test results for material experts was 86.18% and media experts showed 84.61%. This states that the learning media "Geometrical Land" is 'very valid' for use according to the conversion level of achievement.

Application of Problem Posing in Mathematics Learning Material for Building Flat Side Spaces

This research aims to determine the differences in the average learning outcomes of students taught using the Problem Posing learning model on flat-sided geometric material at Woloan Christian Middle School. This research used the experimental method on class VIII students at Woloan Christian Middle School. The samples in the study were class VIII-A as an experimental class with a total of 31 students and class VIII-B as a control class with a total of 31 students, a total of 62 students at Woloan Christian Middle School, even semester of the 2023/2024 academic year. The instrument used in this research consisted of a learning outcomes test in the form of a written test in the form of an essay with flat-sided geometric material. The technique for collecting observation and test data is in the form of evaluation questions. The test is carried out twice. Namely, the pretest is carried out at the beginning of the research to determine students' achievement scores before treatment, and the posttest is carried out on both control and experimental groups after treatment. Based on hypothesis testing using SPSS test statistics, where from the calculation results of the Tcount value of 1.822 with Ttable 1.671 (1.822>1.671), it can be said that there is a significant difference in the average learning outcomes of the experimental group using Problem posing and the control group using the learning model. Direct Instruction, which means that there is an influence of the application of the Problem posing learning model on the average learning outcomes of class VIII students at Woloan Christian Middle School

Development of Predict Observe Explain Based Flat Side Building Worksheets to Improve Students' Mathematical Representation Skills

Purpose of the study: This research aims to knowing student and teacher responses to Predict Observe Explain based worksheets to develop students' mathematical representation abilities. Methodology: The type of research that will be used is research and development (R&D). In this research, the 4D device development research method (Four D Model) was used as a research and development procedure. The data collection technique in research on developing student work sheets uses a questionnaire. The data collection instrument used in this research is the product trial instrument. Data obtained through trial instruments were analyzed using qualitative descriptive statistics. Main Findings: Based on the results of questionnaire data on student responses in the small-scale and large-scale field trials, the mathematical media developed in the criteria for interpreting attractiveness, it is very interesting as a source of learning material and is suitable for use. Novelty/Originality of this study: This study found that the Predict Observe Explain -based flat-sided geometric worksheet is suitable for use in improving students' mathematical representation skills and getting a positive response from students and teachers. This research contributes to the development of innovative and effective learning tools in the context of mathematics learning.

Pemahaman Konsep Matematis Peserta Didik pada Materi Bangun Ruang Sisi Datar Kubus Ditinjau Dari Gaya Belajar di Kelas VIII-8 UPT SMP Negeri 8 Medan

This research aims to analyze students' ability to understand mathematical concepts in flat-sided spatial figures in terms of learning styles in class VIII-8 UPT SMP Negeri 8 Medan. This research method uses qualitative methods. Data collection techniques from questionnaire results in the form of a Google form which contains aspects of learning styles accompanied by indicators that must be answered and observations of learning activities. The written test used in this research was in the form of description questions regarding material on the flat side of a cube. This research was conducted in class VIII-8 UPT SMP Negeri 8 Medan which also served as the research subject. Based on the research results, most students in class VIII-8 UPT SMP Negeri 8 Medan for the 2023/2024 academic year have a visual learning style with a total of 82.43%, an auditory learning style 60.9% and a kinesthetic learning style 46.5%. Students have a tendency towards one of the visual, auditory or kinesthetic learning styles. Of the 31 students, it was found that 19 students had a tendency towards a visual learning style, 10 students had a tendency towards an auditory learning style and 2 students had a tendency towards a kinesthetic learning style. So it can be concluded overall that each student with a different learning style has a different understanding of mathematical concepts.

Differences in Learning Outcomes of Class VIII Students of SMP Negeri 3 Tondano on The Material of Building Flat Side Spaces Given the Implementation of The PjBL Model

This study investigates the disparities in students' mathematical learning achievements when using the Flat-Side Building material in conjunction with the PjBL model compared to students who use the DI model. This study employs an experimental research approach utilizing a post-test-only control group design. The participants in this study consisted of two groups: an experimental group, comprising 25 students from class VIII-C, and a control group, comprising 24 students from class VIII-B at SMP Negeri 3 Tondano for the academic year 2023/2024. The selection of participants was done randomly from the two classes. The post-test research yielded an average score of 79.44 for the experimental class and 75.0208 for the control class. The hypothesis test analysis results indicate that the value of tcount is 2.302 and the value of ttable is 1.678. Since the value of tcount is greater than the value of ttable, we can infer that the null hypothesis (H0) is rejected, and the alternative hypothesis (H1) is accepted. This study determines that there is a discernible disparity in student learning outcomes when the subject of Building Flat Side Spaces is taught utilizing the Project-based Learning (PjBL) model as opposed to the Direct Instruction (DI) model in the eighth grade of SMP Negeri 3 Tondano.

Measurement of true tensile strength from Brazilian tensile strength laboratory tests

Brazilian tensile strength (BTS) testing in standard practice is a practical method to approximate tensile strength for rock core using the conversion of axial compressive vertical and diametral loading to horizontal tensile stress in the centre of the core disk. The method, however, routinely inflates tensile strength, using peak tensile stress calculated from the BTS, versus true tensile stress (TTS) from direct tensile strength (DTS) tests. This study presents a novel technique to measure TTS directly from the BTS test via the onset of nonlinearity in horizontal strain response. TTS is equivalent to the peak strength of a DTS test. While not yet standardized, the modification to achieve TTS measurements is to instrument the BTS specimen with a horizontal strain gauge on each flat side. Over 100 BTS specimens of varying lithologies were instrumented, tested, and analyzed to measure their TTS and compare to peak BTS. Results demonstrate the average measured TTS is 0.81BTS, 0.75BTS, 0.85BTS for granitoid, carbonate, and metamorphic rocks, respectively. This concurs with previous studies, validating the proposed novel TTS measurement method. We recommend measurement of TTS be adopted into standard practice for BTS laboratory testing to improve accuracy of tensile strength data in rock engineering design.

Development of electroforming technology for flexible metal substrates for high-efficiency double-sided electronic devices

In this study, we investigate a novel material that surpasses conventional concepts used for substrate materials in flexible electronic devices. Unlike traditional materials, this novel material can replace polymers with a metallic substance. This substance is capable of supporting electronic devices on both sides. Our development focuses on a metallic substrate material based on Fe-Ni. This material allows for the implementation of secondary batteries on its extremely flat opposite side through the electroforming method. The Fe (Iron)-Ni (Nickel) material produced by electroforming shows superior characteristics in terms of coefficient of thermal expansion (CTE) and mechanical properties. This superiority is due to its finer grain size, compared to Fe-Ni produced by the rolling process. Furthermore, when we use the Fe-Ni material to manufacture secondary batteries, it demonstrates equivalent or superior battery characteristics compared to the conventional aluminum (Al) collector material. During thermal shock tests, the Fe-Ni material also shows superior adhesion compared to the traditional Al collector. This advantage is attributed to Fe-Ni's low CTE. Our approach enables the implementation of secondary batteries for power generation on one side and the manufacture of electronic components for power consumption on the other. This creates a new concept for flexible substrate materials.

Studying the effect of using CFRP warping on strength of husk rice concrete columns

Abstract This research presents the effect of carbon fiber-reinforced polymer (CFRP) on a strength of concrete containing rice husk. Two shapes of columns (circular and square) were used to compare these two types in terms of resistance axial loading. Twelve concrete columns were casting; six are square and others are circular cross-section. All columns of each shape were divided into three groups, and each group consisted of two columns: the first group without CFRP, the second group covered with one layer of CFRP, and the last group covered with two layers of CFRP. The dimensions of the square columns were 300 mm × 300 mm and the height was 900 mm, with reinforced 4–6 mm steel bars. The circular columns were 300 mm in diameter with same height 900 mm and reinforced with 6–6 mm steel bars. Burnt rice husks are added at a rate of 10% of the amount of cement that should be added to the concrete mix. The test results showed the circular columns were the strongest and most resistant to axial loading than square columns. Also, the CFRP wrapping is very effective in strengthening circular concrete columns but significantly less effective in strengthening square concrete columns because the latter have sharp corners and flat sides.

Residual stresses of MAG-welded ultrahigh-strength steel rectangular hollow sections

Residual stresses are an important factor in the performance and stability of welded structures. This study investigates the characteristics and significance of residual stresses in MAG-welded ultrahigh-strength steel rectangular hollow sections. The research incorporates comprehensive X-ray diffraction residual stress measurements, electron backscatter diffraction analysis, statistical analyses, and finite element method simulations to provide valuable insights into the behaviour of welding residual stresses. The results reveal clear microstructural variations between the cold-formed corner and the flat side of the rectangular hollow section caused by welding heat input, emphasizing the need to consider these variations in residual stress assessments. Furthermore, the study examines the dependence of residual stresses on the steel grade, with higher strength steel exhibiting compressive stresses and lower strength materials experiencing tensile stresses in corner areas. Statistical analysis indicates that welding sequence and direction have negligible effects when applying the employed welding sequence. In any case, higher heat input leads to significantly larger residual stresses. Finally, the study presents a novel analytical model based on validated finite element simulations to predict the maximum variation of residual stresses depending on welding heat input. The findings provide valuable insights into the significance of welding residual stresses and their predictability. The comprehensive measurements, simulations and proposed models contributes to a better understanding of residual stress phenomena, facilitating the development of reliable design guidelines for welded structures in various engineering applications.

Pb2+ Ion Sensors Employing Gold Etching Process: Comparative Investigation on Au Nanorods and Au Nanotriangles.

The leaching phenomenon of gold (Au) nanomaterials by Pb2+ ions in the presence of 2-mercaptoethanol (2-ME) and thiosulfate (S2O32- ion) has been systematically applied to a Pb2+ ion sensor. To further investigate the role of Pb2+ ions in sensors containing Au nanomaterials, we revisited the leaching conditions for Au nanorods and compared them with the results for Au nanotriangles. By monitoring the etching rate, it was revealed that Pb2+ ions were important for the acceleration of the etching rate mainly driven by 2-ME and S2O32- pairs, and nanomolar detection of Pb2+ ions were shown to be promoted through this catalytic effect. Using the etchant, the overall size of the Au nanorods decreased but showed an unusual red-shift in UV-Vis spectrum indicating increase of aspect ratio. Indeed, the length of Au nanorods decreased by 9.4% with the width decreasing by 17.4% over a 30-min reaction time. On the other hand, the Au nanotriangles with both flat sides surrounded mostly by dense Au{111} planes showed ordinary blue-shift in UV-Vis spectrum as the length of one side was reduced by 21.3%. By observing the changes in the two types of Au nanomaterials, we inferred that there was facet-dependent alloy formation with lead, and this difference resulted in Au nanotriangles showing good sensitivity, but lower detection limits compared to the Au nanorods.

Melt flow complexity in multi-spot laser welding of asymmetric T-joints

This study investigates melt flow dynamics in asymmetric T-joint laser welding, particularly with sheets inclined up to 45°. This complex scenario requires filler wire, accessible only from the flat sheet side. High-speed imaging at the top and root captures transient phenomena leading to weld imperfections. Research on stainless-steel involved the impact of first-order welding parameters on the weld quality. This included multi-spot laser welding with two beams. The analysis focused on melt pool dynamics under these challenging conditions. The asymmetric root side’s geometry necessitates proper melt flow to form a favorable root topology, avoiding defects like wavy roots and porosity. Key observations included intermittent keyhole openings, transient melt flow effects, and potential spatter ejection at the bottom. The findings offer a comprehensive understanding of 3D asymmetric melt flow, laying the analytical groundwork for enhancing the weld quality.

PENERAPAN MODEL PROBLEM BASED LEARNING (PBL) DALAM PEMBELAJARAN MATERI BANGUN RUANG SISI DATAR DI KELAS VIII SMPN SATAP JIKO BELANGA

This research aims to compare the learning outcomes of students who are taught using the PBL model with the KBM value set by the school of 75. This type of research is experimental with a one-shot case study design, namely providing treatment to one experimental group or class. Finally, an evaluation will be given in the form of a final test. This research was conducted at SMPN Satap Jiko Belanga, Nuangan District, East Bolaang Mongondow Regency in the even semester of the 2023–2024 academic year by taking class VIII as an experimental class consisting of 20 students. The variables in this research are student learning outcomes in the material, Building Flat Side Spaces. Data was collected by giving a final test (post-test) to students after learning was carried out using the PBL model. The data analysis used to test the hypothesis is one-group t-test statistics. The results of the research show that the learning outcomes of Building Flat Side Spaces for students taught using the PBL model exceed the KBM value set by the school of 75

Behavior of large-scale FRP-confined square RC columns with UHP-ECC section curvilinearization under eccentric compression

Implementing section curvilinearization (SC) by curving flat sides into curved sides before fiber-reinforced polymer (FRP) jacketing has been proposed to enhance the FRP confinement effectiveness of FRP-confined rectangular concrete columns. In this paper, ultra-high performance engineered cementitious composite (UHP-ECC) is proposed as the added concrete for SC, with an aim to enhance both bending and axial strengths of concrete columns given that the UHP-ECC can contribute to resisting tensile stresses for columns. Thirteen large-scale FRP-confined square reinforced concrete (RC) columns with SC using UHP-ECC were tested under eccentric compression loading to explore their eccentric compressive behavior. The test parameters included the rise-to-span ratio, the FRP thickness, the eccentricity and the surface roughness of the old concrete. The test results show that FRP confinement with SC using UHP-ECC can substantially enhance the peak axial load and the bending moment than those without SC, while the ultimate lateral displacement is marginally increased. An increase in the rise-to-span ratio leads to an increase in the peak axial load.

Mathematical Framework for Accurate Prayer Times: Insights from the Bencet Tradition

Establishing a crucial connection between religious practices and mathematics is essential for comprehending the regularity and temporal discipline inherent in fulfilling religious duties, notably observed in traditional tools like bencet for determining prayer times. This qualitative ethnographic study aims to unveil the mathematical concepts involved in using and crafting bencet. This exploration of bencet represents the first-ever study in the history of ethnomathematics. Data analysis using the Miles and Huberman model reveals that the community's unconscious use of bencet tongkat demonstrates mathematical concepts, particularly in parallel lines, measurements, and the need for flat sides. Meanwhile, crafting bencet garis showcases the community's unconscious understanding of mathematical concepts related to parallel lines, perpendicular lines, the use of circles for angles, and measurements. These findings expand our understanding of cultural values and local wisdom, demonstrating their relevance to mathematical concepts. Furthermore, the study provides recommendations for future research, suggesting an exploration of ethnomathematics as an innovative alternative approach to learning.

Pengembangan Instrumen Tes Tipe Higher Order Thinking Skills (HOTS) Pokok Bahasan Bangun Ruang Sisi Datar

This study aims to determine the process and analyze the quality of the HOTS-type test instrument development on flat side space and measure students' higher-order thinking skills. This type of research is research and development with the Formative Research (Tessmeer) model. The test subjects in this study were class XI.3 students at SMP Negeri 30 Makassar, totaling 30 students. Based on the research results, it is known that 1) the development process using the Formative Research (Tessmeer) model through 4 stages, namely the preliminary stage, the self-evaluation stage, the prototyping stage, and the field test stage. 2) the quality of test development is declared valid with a CVR (Content Validity Index) value, the average total score is 1 with a very appropriate category or is in the interval 0.68-1.00, practically based on the results of the questionnaire analysis of student responses 89.07% with the response category "Very Positive”, reliable with an average of 0.752 and 0.866 in the high category (reliable), the average difficulty level of the total score is 0.69 and 0.49 in the medium category, and the different power of the average total score is 0.42 and 0.49 in the good category. 3) students' critical thinking ability averaged 67.61, which was in the good category. Thus, this HOTS-type test instrument can be used to measure students' high-order thinking skills.

The Effect of Mind Mapping Methods Types of Mind Map Syllabus on Mathematics Problem Solving Ability in Flat Side Space Construction Materials of Class VIII Students of Smp Negeri 1 Karangreja District Purbalingga

Abstract: This study aims to determine whether there is an influence of the syllabus mind mapping method on the mathematical problem solving abilities of class VIII students of SMP Negeri 1 Karangreja, Purbalingga Regency. Mathematical problem solving ability is a quality possessed by someone to solve mathematical problems so that the goals to be achieved are resolved properly. One of the factors that influence the ability to solve mathematical problems is the model or method used in learning. The researcher chose to use the mind mapping method, a type of syllabus mind map, to improve students' mathematical problem solving abilities. This study used quantitative research (experimental) with a Quasi-Experimental Design. The population of this study were all class VIII which totaled 5 classes. The samples of this study were class VIII A, which consisted of 26 students and class VIII B, which consisted of 22 students. Collecting data in this study used a test consisting of a pretest and posttest. Data analysis used the t test and the N-Gain test using the SPSS version 25 application. The results of this study indicate that there is an influence of the syllabus type mind mapping method on the math problem solving abilities of class VIII students of SMP Negeri 1 Karangreja, Purbalingga Regency. The N-Gain results show that the N-Gain of the experimental class is included in the high category with an average N-Gain of 0.70 and the control class is included in the medium category with an average N-Gain of 0.54. So that the increase in students' mathematical problem solving abilities in the experimental class is higher than the control class.
 
 Keywords: Mind Mapping , Problem Solving