In this study, we focused on the large inelastic behavior of a sandwich panel made of two solid plates as a stiffener and a honeycomb core shell subjected to blast load. The loading scheme was carried out using an explosive charge bullet mounted at a standoff distance of 100 mm with three mass variations of trinitrotoluene: 1, 2, and 3 kg TNT. The numerical simulations performed using ABAQUS/CAE were validated with the experimental results of a previous study. The geometrical effects of the sandwich panel on intact and damaged models were also numerically investigated. The panel was designed using a square and hexagonal honeycomb core. The effect of honeycomb core height was also observed by modeling the core using three height variations: 31, 51, and 71 mm. The results showed that the hexagonal core was more resistant to blast loads than the square design. The core height parameter determines the energy absorption based on these results. The structural strength is also affected by the damage. The findings of this study can be used to improve structural designs that utilize sandwich panels to withstand blast loads. Doi: 10.28991/CEJ-2022-08-05-014 Full Text: PDF

This is a report of a community service program for mathematics teachers. This program was held for fostering mathematics teachers’ skills in teaching meaningful through active learning using Google Classroom flat form. The program takes place in the Karanganyar region, Surakarta, Indonesia. The participants of this program were junior high school mathematics teachers from Karanganyar district. They were 28 participants. The workshop was held for three days: two days were face-to-face workshop and one day for the online workshop. There are four main topics for the workshop: (1) active learning; (2) Mathematical Abstraction and Mathematical Skills; (3) Developing Question and Students Worksheet; and (4) Designing Active Learning on Google Classroom. The development of offline and online modules in the workshop was based on the theory of I-CARE model. I-CARE Model comprises of five components: Introduction, Connection, Application, Reflection, and Extension. The module consisted of a package for doing workshop which is: Powerpoint slides for offline and online courses; word documents for explaining the structure of the workshop and the worksheet of the participants; a Google classroom for online activity. Due to the pandemic session, the activities of discussion during the workshop were held on online flat form in Google Classroom.

Abstract. This research was conducted to: examine the problem solving ability of students in mathematics education FKIP UNS, (2) develop problem-based learning model with metacognitive strategy, (3) examine the effectiveness of problem-based learning model with metacognitive strategy. Three methods were used in this research: descriptive quantitative, research and development (RnD), and experimental method. The development method used 4-D model which consists of four phases: define, design, develop, and dessimenete. Experimental method was conducted to examine the effectiveness of learning model developed. The population in this research is all students of mathematics education FKIP UNS, while the sample used is students who took the Basics Matematics course. The data collections were used in this research: test, validation sheet, and observation sheet. Descriptive quantitative analysis technique was used to analyze the instrument development. Quantitative descriptive analysis was used to describe the validators' mark result for the learning instruments. Descriptive quantitative analysis was used to analyze the problem-solving ability test result that described by percentages. The efectiveness of model development was analyzed by T-test method. The results of this study showed that: (1) students' problem solving ability of mathematics education FKIP UNS particularly in non-algoritmic problems is still not good, but in algoritmic problems is good enough, (2) in the development of problem-based learning model with metacognitive strategy learning instruments, three instruments that qualify valid, practical, and effective there are: Learning Plan, Students' Activity Sheet, and Students' Teaching Material.

<p>A graph denoted by  is a pair of  where  is a non-empty set of vertices in G, and E is a set of edges in G. In graph theory, there are various types of graphs including star graphs, cycle graph, and wheel graph. Graph operations on two or more types of graphs can produce new graphs. Amalgamation is one of the operations on graphs. Suppose  and  are two connected graphs, amalgamating the vertices of graph 1 and graph 2 by joining vertices  and vertices   denoted by  is the graph obtained by joins vertex  of graph  and vertex  of graph  into one vertex , where  is the common vertex of the graph resulting from , while amalgamating the edges of graph  and graph  by joining edges  and edge , denoted by  are graphs obtained by combining edge of graph 1 and edge of graph 2 into one edge g, where g is common side of graph of (𝐺1,𝐺2;𝑒,𝑓). Vertex coloring is one of the fastest-growing topics in graphs. The coloring of the vertices, that is, assigning a color to each vertex of the graph so that each neighboring vertex has a different color. The minimum number of colors used to color the vertices of a graph is called the chromatic number. In this article, we discuss the chromatic number in the amalgamated graph of wheel graph and star graph and the chromatic number on the amalgamation of wheel graph and cycle graph. The results obtained are as follows: (1) the chromatic number of the amalgamated graph of the wheel graph () and the star graph () for n even is 3 and for n odd is 4, (2) the chromatic number of the graph resulting from the operation amalgamation of the wheel graph () and the cycle graph () for n even is 3 and for  odd is 4.</p>

<p class="BodyAbstract">The purpose of this study was to develop an assessment system using Moodle e-learning to improve mathematics learning outcomes in terms of knowledge, skills and attitudes of students. The development design in this study is more on how to develop learning activities with authentic assessment that must be carried out by the teacher which of course will be very difficult if everything is paper-based. The implementation of a reliable assessment with easy administration by the teacher becomes the consideration of the researcher. And with regard to the pandemic conditions that are being experienced by the Indonesian nation, online learning is an option for students and teachers. Even in the assessment that must be carried out. For this reason, the Moodle application is an alternative that allows students to access teaching materials and practice problem solving easily. This is very interesting to do a development study in SMK, why? Because vocational students usually lack positive attitudes towards mathematics. The use of the Moodle application in learning mathematics in the classroom is certainly the teacher's job to limit the time to face students, and the lack of positive attitudes of these students into "energy" to optimize student abilities. This research was conducted at SMK Warga Surakarta, in class XII Machines, using the Thiagarajan RnD 4D steps, namely Define, Design, Develop and Disseminate. From this research, an authentic assessment instrument has been developed using the Moodle application on the Limit Function material. By reviewing the basic competencies in the Function Limit material, 20 questions were developed in the C2 (8 points), C3 (6 points) and C4 (6 points) categories and validated with a professional judgment on the test instrument. In the student attendance data, it appears that the desire of students to improve their understanding of the Limit Function material is quite high, more than 70% of students want to repeat the class independently. Also, the average student attendance was 13.4 out of 10 meetings planned in the teacher's lesson plan (1 meeting for the implementation of daily tests). From the average value of assignments, there was an increase in the grades in assignment 1 and assignment 2, but in assignment 3, the average score of student achievement decreased, this was possible because the material in assignment 3 was a continuation of the material for assignments 1 and 2, but if viewed from the frequency of doing assignments in each task session, there was a decrease in the number of frequencies. This can be seen in assignment 2, where the average student did the assignment 2.87 on task 1, and in task 2 the average student did 2.43 times with the results significantly increasing. Meanwhile, the average daily test for students in class XII M1 was 78.7, which means that the class average was above the school's KKM and 73.3% of students obtained learning outcomes above the KKM on the Function Limit material. It can be said that learning can improve student learning outcomes and motivate students, because from the response questionnaire, 86.7% of students said they were motivated to try the test to get good results.</p>