Grade Material Research Articles

Analisis Kemampuan Komunikasi Matematis Setelah Penerapan PBL Materi Pola Bilangan pada Siswa Kelas VIII SMP Negeri 4 Loura

The purpose of this study is to determine students' mathematical communication skills after the application of the problem based learning model of number pattern material in grade VIII students of SMP Negeri 4 Loura. The type of research is a descriptive qualitative method. Data collection uses interviews and documentation. The data analysis process is carried out qualitatively consisting of data reduction, data presentation, and conclusion drawn. The results of the study showed that from each level of the percentage level of the student communication ability category, namely the percentage level of the high category was 20%, medium 20% and low 60%. The impact of this ability is that students do not relearn the material that has been given during learning and do not pay attention to the researcher delivering the material

Numerical Optimization of Functionally Graded Ti-HAP Material for Tibial Bone Fixation System

Functionally graded materials (FGMs) are heterogeneous composites characterized by outstanding properties. They are built from two or more components with a gradient distribution of chemical composition along a given direction. A promising graded material for biomedical engineering as an implant could be a FGM made of titanium (Ti) and hydroxyapatite (HAP). It would allow us to counteract the difference between the stiffness modulus of pure titanium and bone tissue. Moreover, it can be a good solution to the problem of stress shielding for bone fixation plates made of conventional titanium or steel. The presented paper aims to perform micromechanical modeling and optimization of a functionally Ti-HAP graded plate, followed by numerical analysis of a fractured tibia stabilization system under specific boundary conditions. Finite element analysis was performed using ANSYS Workbench 2021 software. The models of the FGM plate and tibial fixation system were made using the Space Claim tool. The ANSYS software allowed the optimization of the model considered and the selection of the appropriate structural parameters of the FGM Ti-HAP material. In general, the results proved that the osteosynthesis plate built of graded Ti-HAP material resulted in lower bone stress compared to titanium and steel plates. The results obtained confirmed the validity of the design and the possibility to use functionally graded Ti-HAP bone fixation plates.

Digital Teaching Materials for Historical Narrative Texts Oriented to Character Education for SD/MI Students

This research aims to develop digital teaching materials for historical narrative texts oriented towards character education for SD/MI students. Background to the problem of this research 1) What is the need for digital teaching materials for historical narrative texts oriented towards character education for SD/MI? 2) How are digital teaching materials for historical narrative texts oriented towards character education for SD/MI? 3) What is the feasibility of digital teaching materials for historical narrative texts oriented towards character education for SD/MI? This research uses research and development methods with the ADDIE (Analysis Design Development Implementation Evaluate) model. The steps in this research consist of needs analysis, designing digital teaching materials, developing digital teaching materials, implementing digital teaching material products, and product evaluation (digital teaching materials). Data collection in this research was by collecting data from the results of expert validation questionnaires and student assessment questionnaires. The data obtained was analyzed descriptively using a Likert scale. The results of the validation test by material experts obtained a value of 2.93, the validation test by media experts obtained a value of 3.00. The validation test by the Indonesian language teacher received a value of 3.03. The results of implementing e-module teaching materials in schools received a positive response from students with a score of 3.2. The conclusion of this research is that digital historical narrative text teaching materials oriented towards character education for SD/MI students meet the appropriate criteria for use as teaching materials by students or teachers in Indonesian language subjects. Narrative text materials for fifth grade SD/MI students.

Construction of the “Mission poCELLble” -Cellular Structure and Function: A Strategic Intervention Material (SIM) for Grade 7 Biology

This study aimed to address the persistent challenges of low student mastery in Grade 7 Biology by constructing and validating a Strategic Intervention Material (SIM) titled "Mission poCELLble" – Cellular Structure and Function. The development process was driven by the urgency to provide targeted support for students struggling with key concepts in cellular biology. A Strategic Intervention Material (SIM) for grade seven biology was the main objective of this study. The SIM was meticulously crafted based on the identified least mastered skills and the Department of Education's standard criteria for SIM construction. This research followed the input-process-output model of developing instructional material, utilizing two sets of questionnaires: one set for five identified experts and one for teacher and student users, each containing 19 statements tailored to their respective roles. Data analysis informed the construction of the SIMs, including identifying least mastered skills, assessing student-teacher agreement with the Kappa Measure, and measuring expert and readability levels with Cronbach's alpha and Flesh-Kincaid Reading Ease.The results revealed that the SIM content, pedagogical and technical aspects were “very evident” as rated by the experts. The internal consistency between responses are rated as “good”. These findings suggest the potential of the "Mission poCELLble" SIM as a valuable tool for intervention purposes in Grade 7 Biology classrooms. Further research is recommended to assess the SIM's effectiveness in improving student learning outcomes.

Non-linear AC dielectric properties of epoxy composites filled with core–shell SiC particles

Abstract Core–shell structured silicon carbide (SiC)/epoxy (EP) composites exhibit superior non–linear DC conductivity. However, the high voltage alternative current dielectric properties of the composites are rarely reported. In this paper, the time–domain measurement was employed to obtain the basic dielectric characteristics, AC conductivity, and relative permittivity of the SiC/EP and SiC@Al2O3/EP composites under less than the breakdown strength of the SiC/EP (i.e. the amplitude of 1–5 kV mm−1). In addition, in the high AC electric field (i.e. the amplitude of 6–20 kV mm−1), the non–linear AC dielectric properties of the SiC@Al2O3/EP composite are also investigated. The experimental results suggest that the SiC@Al2O3/EP composite shows more obvious non–linear AC dielectric properties than the SiC/EP composite. In the high AC electric field, the AC conductivity of the SiC@Al2O3/EP composite presents the relaxation phenomenon, which is attributed to the excitation field and its derivative. This work lays a foundation for further research on the AC steady–state and transient dielectric properties of the field grading materials, which are widely used to homogenize the nonuniform electric field distribution in many electrical and electronic equipment.

Investigation of periodic heat transfer on the transient thermal characteristics of fully wet moving semi-spherical porous fin composed of functionally graded material

This study investigates the thermal behaviour of a fully wet, moving semi-spherical porous fin made of linear Functionally Graded Material (FGM). This investigation examines the fin response to convective-radiative heat transfer under periodic variations in base temperature across three different FGM scenarios: Homogeneous material (HM), Functionally Graded Material I (FGM I) and Functionally Graded Material II (FGM II). The resultant nonlinear partial differential equation is accurately solved using the Finite Difference Method (FDM) and outcomes are benchmarked against existing literature. This research pioneers an investigation into the effects of periodic heat transfer on the detailed thermal profiles of FGM fin, an area not been explored in existing literature. It significantly enhances understanding of the influence of oscillatory base temperatures on thermal management within FGMs, uncovering pivotal insights into the interaction between material grading, amplitude of temperature oscillation and their collective effects on thermal efficiency. Additionally, this research assesses the influence of variables such as the amplitude of input temperature, frequency of oscillation, thermal conductivity grading parameter and others on temperature distribution along the fin length and over dimensionless time. Notably, periodic heat transfer induces a dynamically wavy thermal profile in the fin over time, attributable to oscillating base temperatures. Moreover, the analysis demonstrates that FGM II fin exhibit the most significant temperature distribution, followed by FGM I and HM. The fin heat transfer rate is profoundly influenced by the amplitude of input temperature and the thermal conductivity grading parameter. These insights are pivotal for optimizing fin designs in critical applications, including electronics cooling, HVAC systems, automotive engine cooling and solar energy collection, substantially improving upon traditional designs.

Impact of the Source Material Gradation on the Disaster Mechanism of Underground Debris Flows in Mines

In mines where the natural caving method is used, the frequent occurrence of underground debris flows and the complex mine environments make it difficult to prevent and control underground debris flows. The source is one of the critical conditions for the formation of debris flows, and studying the impact of source material gradation on underground debris-flow disasters can effectively help prevent and control these occurrences. This paper describes a multiscale study of underground debris flows using physical model experiments and the discrete-element method (PFC3D) to understand the impact of the source material gradation on the disaster mechanism of underground debris flows from macroscopic and microscopic perspectives. Macroscopically, an increase in content of medium and large particles in the gradation will enhance the instantaneous destructive force. Large particles can more easily cause disasters than medium and fine particles with the same content, but the disaster-causing ability is minimized when the contents of medium and large particles exceed 50% and 60%, respectively. With increasing fine particle content, the long-distance disaster-causing ability and duration is increased. On the microscopic level, the source-level pairs affect the initial flow mode, concentration area of the force chain, average velocity, average runout distance, and change in energy of the underground debris flow. Among them, the proportion of large particles in the gradation significantly affects the change in kinetic energy, change in dissipative energy, time to reach the peak kinetic energy, and time of coincidence of dissipative energy and gravitational potential energy. The process of underground debris flow can be divided into a “sudden stage”, a “continuous impact stage”, and a “convergence and accumulation stage”. This work reveals the close relationship between source material gradation and the disaster mechanism of underground debris flows and highlights the necessity of considering the source material gradation in the prevention and control of underground debris flows. It can provide an important basic theory for the study of environmental and urban sustainable development.

Experimental and simulation study on seismic performance of seawater sea-sand PVA cementitious composite columns with GFRP bars

The seismic properties of seven seawater sea-sand (SWSS) PVA cementitious composite columns with Glass Fiber Reinforced Polymer (GFRP) bars were studied. The effects of four parameters, namely polyvinyl alcohol (PVA) fiber content, axial compression ratio, cementitious composite strength and stirrup spacing, on the seismic performance of composite columns were analyzed. The failure of the specimen was observed, and the hysteresis curve, skeleton curve, stiffness degradation, energy dissipation capacity, ductility and strain of the specimen were analyzed. The test results show that the large chip-based spalling will occur when the specimen without fiber incorporation is damaged, and the incorporation of PVA fiber, the reduction of stirrup spacing and the reduction of axial compression ratio will delay the rate of crack formation and development. In addition, through cross-section analysis and considering the reinforcement effect of PVA fibers, a proposed formula for calculating the horizontal bearing capacity of composite columns is proposed. Finally, the finite element model of SWSS PVA cementitious composite columns with GFRP bars is established, and it is found that increasing the strength grade of cementitious materials can greatly improve the seismic performance of composite columns. The conclusions could be references for the engineering application. In the context of the global emphasis on green development and environmental protection, seawater and sea-sand cementitious composites and components with fiber reinforcement will have a wide range of application prospects in the construction of coastal areas.

Nonlinear elasticity tailoring and failure mode manipulation of functionally graded honeycombs under large deformation

Design of lattice metamaterials with tailored mechanical properties at a relatively higher (macro) length scale by architecting lower (micro) length scale geometric and material configurations leads to achieving unprecedented mechanical properties for fulfilling advanced multi-functional structural demands. In the design space of innovative microstructural configurations, we propose a novel class of lattice metamaterials with cell walls made of optimally designed functionally graded intrinsic materials. Under different modes of remotely applied mechanical stresses, two different intuitive architectures of functional gradations for the intrinsic cell wall materials are proposed. The large-deformation nonlinear lattices result in broadband modulation of effective stiffness, and an unprecedented manipulation capability of failure modes and corresponding strengths covering ductile and brittle types depending on architected material gradation. For estimating the nonlinear elasticity and microstructural stresses as a measure of failure mode for the proposed functionally graded lattices undergoing large deformation, a multi-scale mechanics-based semi-analytical framework is developed. Geometrically nonlinear functionally graded beams with generalized material gradation, integrated with unit cell architectures, are analyzed through iterative variational energy principle-based Ritz approach. Based on the developed physically insightful computational framework, effective nonlinear elastic properties and failure modes of the functionally graded honeycomb lattices are tailored as a function of the intrinsic material gradation at the lower length scale. The proposed novel class of lattices with optimally designed functionally graded intrinsic materials and coupled unit cell architectures would open up innovative avenues for designing advanced multi-functional engineering structures and mechanical systems.

Pengaruh Metode Quantum Teaching terhadap Pemahaman Materi Keberagaman di Kelas 4 SDN No 67/1 Sengkati Baru

This study aims to evaluate the impact of the Quantum Teaching method on the understanding of KEBERAGAMAN material in grade 4 at SDN No 67/1Sengkati Baru. Quantum Teaching is an instructional approach that focuses on actively engaging students through various learning styles, including visual, auditory, and kinesthetic. This research employs a quantitative experimental design to compare learning outcomes between students taught using the Quantum Teaching method and those taught using conventional methods. The sample consists of 25 students divided into two groups: one group using Quantum Teaching and the other using conventional methods. Data was collected through end-of-term tests to measure understanding of the material and analyzed using R Table validity test, ANOVA hypothesis testing, and frequency distribution of learning outcomes. The results indicate that all test items were valid, and there was a significant difference in learning outcomes between the two groups, with the Quantum Teaching group performing significantly better than the conventional method group. Additionally, the frequency distribution of learning outcomes shows that most students scored above average after implementing Quantum Teaching. The study also found that 80% of students preferred the Quantum Teaching method over the conventional method, indicating that this approach is more effective in enhancing student motivation and engagement in the learning process. These findings provide a strong basis for considering the implementation of Quantum Teaching as a superior alternative in primary school education.

A novel mixed mode fracture criterion for functionally graded materials considering fracture process zone

A new mixed mode I/II fracture criterion based on strain energy release rate theory is proposed for investigating fracture behavior in cracked functionally graded materials. In this study, the crack is assumed to be located along the material gradation and within the brittle side of the material. For the first time in this type of material, the fracture process zone and the energy dissipated in this region are considered to enhance the prediction accuracy of the proposed criterion. The mechanical and fracture properties of the damage zone are characterized using the microcrack density parameter. A novel method for manufacturing functionally graded materials is introduced, offering numerous advantages by controlling the gel time of the resin. The critical mixed mode and pure mode II fracture toughness of the fabricated specimens are determined through three-point and four-point bending tests. A comparison of the experimental data with the fracture limit curve demonstrates the effectiveness of the newly proposed criterion for investigating mixed mode fracture in functionally graded materials

Fatigue crack growth in functionally graded materials using an adaptive phase field method with cycle jump scheme

Functionally graded materials provide versatility in adjusting the volume fractions of constituent materials to meet specific design requirements. However, this customization often introduces mode-mixity at the crack tip, posing challenges in predicting fracture under cyclic loading with discrete approaches and computationally expensive with conventional phase-field fracture models. To address these issues, this paper introduces an adaptive phase-field fracture formulation with cycle jump scheme to elegantly predict fatigue crack nucleation and growth in functionally graded materials. Within this framework, the effective properties at a point are estimated using the Mori–Tanaka homogenization scheme, while the crack growth due to cyclic load is captured by incorporating an additional fatigue degradation parameter. Moreover, the computational efficiency of the proposed framework is improved through an adaptive mesh refinement and explicit cycle jump scheme. The adaptive refinement scheme utilizes an error indicator derived from both the displacement solution and phase-field variable. The adaptive refinement scheme is integrated with efficient quadtree decomposition, which generates a hierarchical mesh structure. Hanging nodes resulting from the quadtree decomposition are efficiently handled using a polygonal finite element method. The proposed framework is validated against experimental and numerical results reported in the literature. Furthermore, we investigate the fatigue crack growth resistance across a broad range of material gradation directions, gaining valuable insights and identifying functionally graded materials with high fatigue resistance.

Geomorphological and Sedimentological Rationale for Staged Sand Dam Construction

ABSTRACTStream sediment transport results from a convolution of climate, weather, geology, topography, biology, and human influence. In addition to providing water and food security for rural dryland communities, sand dams—small weirs designed to trap only the coarse fractions of transported sediments in seasonal and ephemeral streams—highlight many complexities of geomorphological dynamics. Sand dams store water in interstitial riverbed pores and the size of deposited sediment particles largely determines the recoverability of stored water: Fine materials limit transmission and provide lower volumetric yield. In this study, we seek to identify a practical method for evaluating the theoretical effect of staged sand dam crest construction on key sediment‐trapping processes for a proposed dam site. We argue that the Rouse number provides a useful criterion for identifying regimes where the target material grades are trapped. These ideas were tested using sediment data collected in Kenya and US Army Corps of Engineers River Analysis System numerical simulations to evaluate the sensitivity of sedimentation processes to crest height. We show that constructing sand dams in stages results in more targeted trapping of coarse material. Sedimentation is shown to be more sensitive to variation in crest height than the flood hydrograph, especially when a dam's crest height is small. By introducing a method to assess the necessity and inform design of staged crest construction based on local flow dynamics, this study offers a framework for optimising sand dam performance in data‐scarce environments. This approach provides a means to balance construction costs with expected benefits, enhancing the sustainability and functionality of sand dams in arid and semi‐arid regions.

Pengembangan Media Pembelajaran Matematika Berbasis Aplikasi Android Menggunakan Power Point dan iSpring pada Materi Himpunan untuk Siswa Kelas VII SMP Swasta Swadaya Tarus

The number of smartphone users is increasing across various demographics, including students. With the presence of smartphones among students, it should be able to assist learners in enhancing their interest and understanding of mathematics effectively, anytime and anywhere. Therefore, this research aims to develop a mathematics learning media based on an Android application using PowerPoint and iSpring for set theory material for Grade VII students at Swadaya Tarus Private Junior High School that is valid, practical, and effective. The method employed in this research is research and development using the ADDIE development model: Analysis, Design, Development, Implementation, and Evaluation. Data for this research were obtained through interviews, questionnaires, and tests. The results of this research show that the set theory class application meets the criteria for valid, practical, and effective learning media for set theory material. The average total validity score from three validators is 4.34, indicating that the Android-based mathematics learning media falls into the valid category. The average practicality score from the large class teacher is 4.38, and the responses from the small-scale trial students were 4.6, while the responses from the large-scale trial students were 4.67, placing the Android-based mathematics learning media in the practical category. Additionally, the pass rate for small-scale trial students was 80%, and the pass rate for the large-scale trial students was 70%, indicating that the developed Android-based mathematics learning media falls into the effective category.

Development of Digital Comic Learning Media Based Flipbook to Improve Understanding of the Concept of Mutual Cooperation Lifestyle Material Grade IV SDN Ngeni 05 Blitar District

Development of Digital Comic Learning Media Based Flipbook to Improve Understanding of the Concept of Mutual Cooperation Lifestyle Material Grade IV SDN Ngeni 05 Blitar District

Flotation separation of lithium–ion battery electrodes predicted by a long short-term memory network using data from physicochemical kinetic simulations and experiments

Anode and cathode active materials from spent lithium–ion batteries may be recovered and potentially used in new batteries to promote recycling and resource circulation. Froth flotation was applied to pristine active materials and the black mass obtained from pretreated spent batteries. Flotation kinetics was simulated with the use of computational fluid dynamics and surface chemistry. Bubble surface coverage and entrainment in the flotation kinetics model were selected and optimized by systematic fitting to experimental data. Entrainment influences the recovery and grade of the active materials. The optimized flotation kinetics model was used for generating additional data that, along with the fitted data, were used to train a deep learning neural network. The trained network was validated using anode–cathode and black mass flotation experiments, and its predictions showed a maximum residual error of 0.18 ± 0.11 recovery. The simulation framework was developed into a desktop application that predicts the flotation behavior of active materials. It provides information for estimating results following operational and physicochemical changes and for optimizing flotation processes. Finally, recovered anode active materials from black mass were selected for coin cell tests. The coulombic efficiency of these coin cells was initially lower (86.8 %) than that of cells made with pristine graphite particles (98.4 %).

Effect of the Material Gradation on the Fracture Trajectory in Ceramic/Metal Functionally Graded Materials

Effect of the Material Gradation on the Fracture Trajectory in Ceramic/Metal Functionally Graded Materials

A Simplified Failure Assessment to Identify Crack Growth Behavior in the Gas Pipeline by Post-Hydrostatic Pressure

Hydrostatic pressure tests on pipelines have been found to be an inadequate means of critical integrity management due to the frequency of false negatives, which result from the inability of these tests to detect crack growth. It can be argued that focusing on pipe leakage does not guarantee future operability. A study presents a failure assessment methodology based on the failure assessment diagram (FAD), which aims to predict crack growth during hydrotesting. The calibrated pipe spool is validated by the application of data from hydrostatic tests and analytical techniques to ascertain the potential growth in circumferential surface cracks. A variety of factors, including pressure, material grades, flaw dimensions, and elliptical flaw angles, were examined in an effort to assess cracks. The results demonstrate that there is no pipeline leakage and minimal trapped air. Despite its location within the plastic zone, with a normalized pressure index of ≤1, the pipeline is deemed to be within acceptable limits according to the criteria established by the FAD. The assessment point was found to be predominantly influenced by the toughness ratio of the material grade. The crack propagated in the opposite direction with a maximum length a/c= 0.125 and a crack depth a/t= 0.2, which limited the toughness ratio. The load ratio indicates uniformity in elliptical angle flaw results. In this simplified failure assessment, the parameter describing the flaw size, which exhibits a strong correlation with the toughness ratio, plays a pivotal role. Further research and recommendations are also proposed.

Upaya Meningkatkan Hasil Belajar Siswa Kelas III Pada Materi Pancaindra Melalui Model Pembalajaran PBL Berbantu Media Flashcard

By using a problem-based learning (PBL) model supported by flashcard media, classroom action research (CAR) was conducted in two cycles, with observation, reflection, implementation, and planning. The aim was to improve student learning outcomes in the five senses material in grade III. The results showed that, in the first cycle, 44% of students achieved completion, with an average score of 68%; in the second cycle, the percentage of completion increased to 86%, with an average score of 82%. These results indicate that the application of the PBL model with flashcard media can help students understand the five senses material better. As a result, this learning approach can be used as an alternative to improve the quality of learning in elementary schools.

The Effect of Educandy Game on Social Studies Learning Outcomes of Food Technology Materials in Grade 3 of SD Negeri Cibatok 1

There is minimal use of innovative learning media in schools, especially at the elementary school level, even though in elementary schools students really need help with learning media to understand the material presented by the teacher. Included in class 3 social studies subjects. The aim of this research is to find out student learning outcomes using educational games, so that we can find out students' activities in the learning process in social studies subjects using direct observation methods at school. The subjects of this research were 1 learning media expert and 1 practitioner, namely the teacher. The test subjects were 46 grade 3 students consisting of the experimental class and the control class. Data collection methods are observation, interviews, tests and questionnaires. The data analysis technique used is quantitative descriptive analysis and statistics. The results of the research, namely the results of media validity tests for the Educandy game application, based on assessments from material and media experts supported by teacher and student responses, show that the media validity value is very high and feasible with an average percentage value of 95%. The results of the T-test show that there is a significant difference in student learning outcomes before and after media use. Educandy game learning media in social studies subjects are suitable for use and are effective in improving student learning outcomes.