bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and simulation of a rectangular patch microstrip antenna for the frequency of 28 GHz in 5G technology
Authors: Darsono M , Wijaya A R
Published: March 2020

The development and application of the fifth generation mobile communication system (5G) requires and provides high-speed and high-capacity wireless communication services. This paper describes the design of small antennas using microstrip technology as a wireless communication device operating at a frequency of 28 GHz. The technique method used for antenna design is inset feed technique with a shift to the length of the transmission line on the side of the patch gap. Antenna design is used method of moment or simulation using CST software application. To support antenna design in the simulation process using the type of material substrates used was Taconic TLY-5 type. The results of simulations the obtained, such as: bandwidth of return loss ≤ -10 dB is 454 MHz, VSWR (2:1) is 1.03, beam width is 74.4 degrees and gain is 6.72dB. An antenna design obtained through simulation shows a simple and compact antenna shape with the expected parameter value. The design is a basic element of research for antenna sub arrays for increasing radiation power.
Design an automatic fresh water distribution system with microcontroller for community sanitation needs
Authors: Setiawan A , Budiman A A , Sayuti A
Published: March 2020

Limitations and shortages of fresh water often occur problems especially for coastal communities, port areas and other areas with minimal water supply. The need and limitations of fresh water can cause distribution which is hampered due to lack of monitoring and distribution in the field, so that the distribution and distribution are evenly distributed. The purpose of this study is to overcome the problems that occur by designing and simulating tools that regulate the distribution of fresh water. The system works when the water flow sensor calculates the flow of water that passes through it and after reaching the maximum capacity previously set, the solenoid valve will automatically stop the distribution of water, so that every citizen who has the right to receive fresh water will get according to his daily allowance. In designing the simulation design there are several obstacles to the unavailability of several sensors needed, such as water flow sensors and solenoids for which we make alternative solutions by making logic C ++ algorithm in Arduino Uno R3.
Development of Knowledge Building Environment (KBE) - based colloidal system learning materials to develop student’s environmental literacy: An environmental analysis
Authors: Aisah I , Anwar S , Sumarna O
Published: March 2020

This study aims to develop a knowledge building environment (KBE)-based colloidal system learning material to develop students’ environmental literacy. To realize this, the problem questions raised in this study are: “1) What are the product characteristics of colloidal system teaching materials based on knowledge building environment to develop student environmental literacy which is developed with the 4STMD method? 2) What is the understanding aspect of colloidal system teaching materials based on knowledge building environment to develop student environmental literacy which is developed with the 4STMD method? and 3) How is the feasibility of colloidal system teaching materials based on knowledge building environment to develop student environmental literacy which is developed with the 4STMD method? The research method used is Development Research (DR) with a book development model using 4STMD. The results of the study show: 1) Characteristics of teaching materials developed are very in accordance with the following criteria: curriculum, scientific correctness, containing KBE values and environmental literacy, equipped with concept maps, structured and systematic; 2) Understanding of teaching materials by students is high (88.21%); and 3) The feasibility of teaching materials amounting to 96.81% (very feasible) fulfilling the criteria for the assessment of lesson text books based on BSNP standards means that they are worthy of use.
Analysis droughts index by Standardized Precipitation Index (SPI) and productivity of rain-fed rice fields in Indramayu West Java
Authors: Setianingsih A I , Jalaludin M , Warnadi W
Published: March 2020

This study attempts to map drought and analyze rice productivity of Rain Fed Rice Fields in Kabupaten Indramayu West Java. The methodology which used in this research is descriptive. Arc GIS 10.2 is used for mapping the SPI, and it will be used to analyze rice productivity of Rain-Fed Rice Fields in Kecamatan Indramayu West Java. The result showed that District Indramayu experienced, the drought began in May to October. The area that is prone to drought in the same period of the last ten years is Anjatan regions with 33 times scene drought. August experienced scene drought most. District of Indramayu has planting patterns in the two times rice planting season and various kind of crops. The growing season of rice starts on November-December-January and the second growing season starts on May-June-July. The Pattern of productivity from the first planting period to the second planting second on average for ten years showed a decline. The pattern is followed with dryness index. The increased productivity only happen in growing season in 2007, 2008, 2011, and 2013 in 10 years.
Influence of predominant wind angle direction to CO concentration in the surrounding area of cement industry
Authors: Bachtiar V S , Raharjo S , Regia R A , Saputra Y
Published: March 2020

This study aims to determine the effect of predominant wind angle on the concentration of CO received by receptors (receptor position) due to the cement industry. This research was conducted in the surrounding area of the cement industry in Padang City. The sampling of CO concentration was undertaken at 3 sampling points, that is Unand Blok D Residence, Padang Besi Residence, and Batu Gadang Residence, that is representing of the receptor positions (α), i.e. 0°, 45° and 90°. In addition, sampling was also conducted at background point in Bukit Sungkai, Batu Busuk, Padang City. Sampling CO concentration at 4 sampling points using an impinger. The sampling of each location was done every hour for 24 hours of measurement (24 data per sampling point), with a total of 96 data. The results showed CO concentrations range between 124,502 and 287,292 μg/Nm3. The highest concentration was found at α 0° (Unand Blok D Residence) while the lowest concentration was located at α 90° (Batu Gadang Residence). Meanwhile, CO concentrations in the background point (Bukit Sungkai, Batu Busuk) is relatively lower than the three-sampling point above, ranging from 44.22 μg/Nm3 up to 74.13 μg/Nm3. The decrease in CO concentration on wind coming angle occurred from 0° to 45° by 13.79% and α 0° to 90° by 25.38%. This decrease happened by shifting α from 0° to 90°. This indicated that there is an effect of predominant wind angle direction towards CO concentration received by the receptor.
Breeding places of mosquito larvae and pupae in Bandung City
Authors: Respati T , Feriandi Y
Published: March 2020

Mosquitoes are main vector on the transmission of a number of pathogens include arthropod-borne viruses (arboviruses), parasitic worms, and protozoa. The diseases include malaria, West Nile virus, chikungunya virus, dengue fever, yellow fever, Rift Valley fever, and many more. This study aims to analyze the breeding places that affect the presence of mosquitoes’ larvae and pupa. The survey with stratified random sampling method applied to 2035 houses and inspected 5984 containers. The survey conducted from March to July 2015. The analysis used was correlation analysis and generalized estimating equation (GEE). Volume influences the presence of larvae in containers whereas the presence of pupa as a proxy of adult mosquitoes is related to the volume of containers, plant-covered containers in total and in part, and containers that are entirely and partially closed. In conclusions, breeding places containing larvae and pupa are large volume containers that are not closed or partially closed with water sources from rainwater and well water.
Revealing the deep structure of Rotiklot Dam, Belu-Indonesia
Authors: Daud N , Indratno I , Yakin S D
Published: March 2020

The existence of infrastructure is very important to support economic development. The current infrastructure development has not considered much of the meaning of the development object. Research uses Levi Strauss structuralism approach. The revelation of meaning begins with tracing the surface structure which is composed of form and function aspects. The method of revelation of meaning begins with examining the syntagmatic relationships between dam and custom elements. The search for paradigmatic relations between the two surface structures is to be done in order to reveal the deep structure of the Rotiklot Dam. Meaning is obtained through the interpretation of deep structure. The paper concludes that the expression of the deep structure derived from the Rotiklot Dam is the balance and harmonization of the materialization of relations between the fields forming Rotiklot Dam. Finally, to reveal the deep structure of infrastructure with the case of the numinous unity in order to maintain reciprocity between humans and humans, humans and creators, and humans and nature.
Sustainable mangrove ecosystem management policy in Muaragembong coastal area, Bekasi District - Indonesia
Authors: Asyiawati Y , Hindersah H
Published: March 2020

Mangrove ecosystems in the Muaragembong Coastal Area have been used for aquaculture and ecotourism activities that provide benefits for increasing community income. In an era of technological disruption, the opportunity for ecotourism development is getting bigger. But on the other hand, there is a condition of the status of mangrove ecosystems that have been bad, which has an effect on the decline in environmental quality. This condition is because it has not been supported by management policies in Bekasi. Knowing the importance of the mangrove ecosystem, it is necessary to study of sustainable mangrove ecosystem management policy. The purpose of this study is to formulate a sustainable mangrove management policy. By using the method of descriptive analysis, super impose analysis and SWOT analysis, the results show that the management of mangrove ecosystems can be done by: (1) establishing the mangrove ecosystem area as an area designed in the spatial plan, (2) intensifying the program. mangrove ecosystem to improve the function of mangrove ecosystems; (3) increasing the role and community in managing mangrove ecosystems; (4) developing facilities and infrastructure that support the development of sustainable ecotourism activities. Through this, results can be expected for the Bekasi District Government in the context of managing the mangrove ecosystem in the Muaragembong Coastal Region successfully.
The role of knowledge-based ecological pesantren in environmental conservation
Authors: Muhardi M , Nurdin N , Irfani A
Published: March 2020

This study aims to analyze the ecological Islamic boarding school (Eco-Pesantren) and its role in environmental conservation. The study was conducted in an ecological boarding school in Garut, Indonesia. Data collection techniques are conducted through interviews, focus group discussions, and observations to obtain information on knowledge-based Eco-Pesantren and its role in efforts to preserve environmental and actualize the sustainability of organization. Research result shows that the sustainability of Eco-Pesantren is actualized by the role of pesantren leaders who put into practice the importance of caring for environmental conservation and then followed by the santri (students of pesantren) as full support to preserve the environmental. A significant contribution of Eco-Pesantren in preserving the environmental is demonstrated through the cultivation of various types of plants and the use of knowledge-based sustainable agriculture models.
The role of Indonesian education for preparing human resources in the maritime field
Authors: Danny F , Dadang S , Fridolini F , Bayu P S
Published: March 2020

The maritime sector does not only cover transportation services but also covers a variety of other fields, the manufacturing sector that supports the procurement and construction, and repair of ships and their components, the maritime defence industry, the marine management industry, and much more. There is a big problem in responding to this problem that needs to be resolved by the government in reducing the number of unemployed people in Indonesia, so that human resources can be absorbed in the industrial world, especially the maritime industry. With the literature study method and gained data from the government institution this paper wants to described the preparing human resources in maritime field. In fact, in the past four years with the sea highway program, Joko Widodo government has built approximately 100 units of ships from various types through the Ministry of Transportation, it has not had a positive impact on the absorption of competent human resources.
Municipal solid waste composition in final disposal area of Serang City Banten Province
Authors: Dwirani F , Ariesmayana A
Published: March 2020

This research aims to identify the percentage of the mass fraction of the entire waste component and composition of municipal solid waste in final disposal area which is reflects the pattern of consumption of Serang City residents in its contribution to produce waste. The study was conducted in the area of TPA Cilowong, Serang City. The research used experimental method. The techniques of data analysis are measurement of water content, observation, and deep interview. This study found that the composition of solid waste was identified according to their characteristics, which are organic waste, plastic, paper, Styrofoam, textiles, wood, glass, and pieces. The results show that the composition of urban waste is related to people’s lifestyles and economic growth of Serang City. Organic waste such as leaves, leftover vegetables, leftover fruits, and food scraps are most found in Cilowong final disposal area. While the amount of inorganic waste most collected is plastic waste. This condition illustrates that the current tendency of the people of Serang city to use various plastics such as plastic bags or plastic food packages to meet their daily needs up to 37%.
Design information system of registration and scheduling information laboratory of information systems and the decision of Bandung Islamic University
Authors: Hidayat T , Rukmana O , Nurrahman A A
Published: March 2020

The development of information technology in the field of industry is very important and it takes on the world of work. Information systems are used as a tool for taking a decision in a forefront. In this case the problems often encountered in the laboratory is still using conventional spring system by means of recording and storing the archives using the Microsoft Excel application, it takes a lot of time at the time of input and determination student teaching schedule so that the required report has delay constraint information giving rise to the proceedings and time inefficient. Approach in the development of an information system using the method Framework for the Application of Systems Thinking (FAST), Model Driven Development with strategy. The FAST method using a tool used for analyzing and designing the system. The tools which are Use Case Diagrams for communication between entities, Entity Relationship Diagram for the relationships between entities, and Data Flow diagrams for data flow between entities and processes. Stages FAST method used in the study that is up to the stage of building and testing. On the functional needs of the system that was designed as a system that can apply practical lab course schedule and choose easily and can do data reports results of students who follow the teaching. After that is done the analysis of decision is to determine and select the best candidate solutions, namely the candidates by using the MySQL database. In doing this the system design using the MySQL database with the XAMPP tool in designing a database information system registration and scheduling and Sublime Text display in designing information systems. With this system he designed, is expected to assist the laboratory in managing student data to making the student reports quickly and precisely.
Development of industrial estates in the context of supporting border economic development (Case study at Entikong National Strategic Areas)
Authors: Rahim D A , Adiatmojo G D
Published: March 2020

The Entikong National Strategic Area Center is one of the areas that is directed to be the center of strategic activities, but infrastructure and production factors have not made it possible to produce competitive and profitable products and commodities in the market. Transport costs are very expensive because distance and road conditions that limit market reach for the economy. In this situation, there is no other choice unless the community is directed and assisted to be able to produce products (semi-finished or finished) that the high value exceeds the cost of production and transportation costs. This research aimed to draw up the design of the Border Industrial Zone with two regional leading commodities, consists of pepper and rice. This area was built to accommodate industrial activities that utilize the potential of resources in the border region in an effort to increase the added value, quality and quantity of natural resources. This study used a qualitative and quantitative descriptive approach with an analytical method consisting of business feasibility analysis, supply chain analysis, and scalogram analysis. The studywas located in the Central Entikong National Strategic Area and the surrounding area, Sanggau Regency, West Kalimantan Province. The results showed that the development of the pepper and milling processing industry was feasible if the raw materials used were not only sourced from the Entikong sub-district but had to involve other sub-districts located in Sanggau District. This Special Border Industry Zone is centered on Entikong Village, Entikong Subdistrict as a location adjacent to neighboring countries and adjacent to the Entikong State Cross Border Post.In the development of industrial estates need a cooperation among sub-industries in the region to achieve economies of scale and sustainable.
The capability of selection tools to predict future academic performance of medical students
Authors: Irasanti S N , Akbar I B , Dewi M K , Susanti Y
Published: March 2020

The strong competition allows medical schools to be highly selective in their admissions, with the aim of selecting only those students who are most likely to complete their medical education and presumably become good doctors; it also minimizes the number of poor performers or ‘strugglers’, who were reported in one study to account for academic. The validity of an admission criterion is defined as the degree to which it predicts an applicant’s performance during and after his or her undergraduate medical training, and reliability is defined as the reproducibility of the results obtained when a measurement is repeated on the same study sample. Several studies also show that several non-cognitive factors have a significant influence on academic success at university, additional to the influence of prior academic attainment. The purpose of this research is to assess the correlation between the selection tools and medical student’s academic performance through their Grade Points Average (GPA) over a four-year period. Pre-admission data were matched from students who entered Bandung Islamic University, Faculty of Medicine at the year 2012 – 2016 with their GPA. A cross-sectional study was conducted in 74 selected students who had completed the specific admission test. The variables examined were high school grades, Multiple Mini Interview (MMI), Minnesota Multiphasic Personality Inventory (MMPI) test and a total of admission test score. The statistical was used SPSS and Spearman correlation test analysis. The result shows there were significant correlation and a weak relationship between MMI with 1st year GPA, 2nd year GPA, and 3rd year GPA. There was also a significant correlation and a moderate relationship between the total of admission test score with 2nd year GPA and 3rd year GPA. The conclusion is MMI was found to be steady predictor of Grade Point Average (GPA) yet the predictability of academic success is weak and increase for the early years and drops towards the end of the medical under graduated program. Total of admission test score was weak predictor for academic performance especially in the second and third year medical students.
Stress-strain behaviour of steel bars with long nut connection
Authors: Khatulistiani U , Tavio T , Raka I G P
Published: March 2020

The reinforcement of reinforced concrete always needs a connector. In order to reduce the overlapping length, the long nuts are used as steel bar connector. The tensile experimental test was obtained to find out the value of yield stress, ultimate tensile strength, elongation and ductility which can be achieved by steel bar long nut connection. The test was using UTM machine instrument which connected to the computer, thus stress-strain curve is obtained. The curve shows the values of elastic, plastic, strain hardening until ultimate tensile strength region, value of yield stress Fy, and ultimate tensile strength Fu. The result of tensile tests how’s that the yield stress value of steel bar with long nut connection has the same value with the steel bar without connection. The steel bars with long nut connection can achieve yield stress about 330 MPa, ultimate tensile strength about 340 MPa and strain value about 5%-6%, it is lower than the steel bars without connection. It indicates that long nut can be used as a connector tool in overlapping steel bar connection.
Analysis of linear regression on used car sales in Indonesia
Authors: Puteri C K , Safitri L N
Published: March 2020

There are few things that drive the business of selling used cars in Indonesia continues to increase, namely new car prices are higher. So the prospective buyers the ability to purchase power not too strong, buying a used car is one option. Linear regression is a statistical analysis of several variables relationship model according to the form of the relationship of linear equations explicitly. The purpose of this research is to apply the method of Linear Regression on selling used car Toyota Innova, and Honda CRV in Indonesia, especially in the cities of Jakarta, Bandung, Surabaya, and Semarang. Used car sales prices are influenced by the age factor car, car mileage, color car, car transmission, and car type. The results showed, an analysis of age factor car sharing and car has a mileage rating of 62.6% level of confidence. By adding some other variable that is the color of the car, the transmission and the cities of car sales has a value of more than 75% accuracy.
The need of mathematical literacy competency for informatics graduates: Preliminary study at STMIK STIKOM Indonesia
Authors: Sandika I K B , Krisna E D , Anindia I N T
Published: March 2020

This study aimed to determine the category of needs of competency of mathematical literacy for graduates of informatics bachelor’s degree and analyzing the suitability of the material taught on the group of mathematics subject at STMIK STIKOM Indonesia with the requirement of graduate mathematical literacy competence. The research design that has been used was mixed methods research with concurrent strategy (concurrent mixed methods). This method is chosen to streamline research time, as well as to produce comprehensive data (qualitative and quantitative data) at almost on the same time. The data obtained were analyzed descriptive-quantitatively. The mathematical aspects of the mathematical literacy competencies were evaluated consist of eight dimensions, namely (1) the ability to think and use logical reason in mathematics, (2) argue mathematics, (3) mathematical communication, (4) mathematical modelling, (5) propose and solve mathematical problems, (6) ) representations, (7) symbols, and (8) tools and technologies. The results shown that the competence of the taught mathematical literacy is “sufficient required” by graduates. In addition, there is an indication of the lack of conformity between the learning outcome which was formulated in the curriculum and the real competencies which were required by graduates.
The mathematical problem-solving ability of junior high school students based on their mathematical resilience
Authors: Attami D , Budiyono B , Indriati D
Published: March 2020

This research aims to describe the mathematical problem-solving ability of grade VIII students at State Junior High School in Sragen Region and found the patterns of mathematical problem-solving abilities that were analysed based on students’ mathematical resilience. The method used in this research was descriptive quantitative research with 153 students as the samples. Data were collected using a questionnaire and a written test. The results of the research give an overview that mathematical problem-solving ability of students has high resilience level of mathematics which can deal with and be able to overcome obstacles and negative situations related to the problem-solving process because they can successfully coach themselves. Students who are given non-routine mathematical problem show differences in their mathematics problem-solving based on levels of mathematical resilience.
Students’ mathematical communication ability using 7E learning cycle based on students thinking style
Authors: Rahmy S N , Usodo B , Slamet I
Published: March 2020

The aim of this research is to find out the effect of learning models, students thinking style, and interaction between the learning model and students thinking style on students’ mathematical communication ability. This research was quasi-experimental research with factorial design 2×4. The population of research was all students of the eighth-grader in the Nganjuk regency of Junior High School in academic year 2018/2019. The sample of research consists of 184 students. The data in the research were two ways of analysis of variance with unequal cells, with the 5% level of significance. The results of the research were as follow: (1) The 7E learning cycle provides better mathematical communication ability than the direct learning; (2) Students with SK and SA thinking style was better mathematical communication ability than AK and AA; (3) In each type of learning model, students with SK and SA thinking style have mathematical communication ability that was better than AK and AA; (4) In each students thinking style, students taught using the 7e learning cycle provide better mathematical communication ability than direct learning. 7E learning cycle can be used to improve the mathematical communication ability of junior high school students based on their thinking style.
Students metacognition in solving mathematical problems based on gender differences
Authors: Barokah I , Budiyono B , Saputro D R S
Published: March 2020

Metacognition has an important role in solving mathematical problems. Metacognition in this study consisted of two components, namely metacognitive knowledge (declarative knowledge, procedural knowledge, conditional knowledge) and metacognitive regulation (planning, monitoring, and evaluation). Through the use of metacognition, students can find out what strategies are used and the difficulties that occur when learning and solving mathematical problems. The purpose of this study was to understand whether or not there were differences in metacognition of male and female students in solving mathematical problems. This study was quantitative research. The study was conducted in 87 students consisting of 55 male students and 32 female students from three junior high schools in Surakarta. The instruments used in this study were questionnaires and essay test. The data analysis technique used is the multivariate F-test. The result of this study is that there are differences in metacognition of male and female students in solving mathematical problems. The difference lies in the components of the metacognitive regulation, namely planning, monitoring, and evaluation.
Critical thinking and communication skills of 10th grade students in trigonometry
Authors: Azizi H , Herman T
Published: March 2020

This study aims to determine the mathematical critical thinking and communication skills of high school students in trigonometry materials. This research uses descriptive qualitative approach. Subjects were randomly selected from 10th grade as many as five students. The instrument used was a test of critical thinking skills, communication, and non-tests in the form of an attitude scale questionnaire of 16 statements. The results showed that students had critical thinking skills and communication in the low category. Students are not able to complete trigonometry questions completely. This is because students are poorly trained in solving trigonometric problems with non-routine questions. Based on the findings, it can be concluded that: (1) mathematical critical thinking skills of five students of class X on trigonometry material are still relatively low. (2) Mathematical communication skills of five students of class X on trigonometry are still relatively low. (3) There is a relationship between critical thinking skills and mathematical communication of students. (4) And students’ attitudes toward mathematics learning, tests of mathematical critical thinking, and communication skills on trigonometric material are good. So the critical thinking skills and mathematical communication of five students in trigonometry material are still lacking because students have difficulty in modeling trigonometry problems, and stuck with modification questions because many students are not able to complete the answers to the questions given.
Analysis item test of math problem solving skills in junior high school
Authors: Muzammil A , Budiyono B , Pratiwi H
Published: March 2020

An instrument is one of tools has used to collect a data, whether or not a research instrument has needs to be seen characteristics of the instruments compiled. So this research has a purpose is to find out characteristics of instruments test for mathematical problem solving abilities have been compiled in algebraic material for class VII junior high school students. The research method used is a basic research method. Data analysis was done by qualitatively and quantitatively. Qualitative analysis is used to see characteristics of content validity, while quantitative analysis is done to see characteristics of the level of difficulty and distinguishing items, as well as the reliability coefficient of instrument test. The results has showed that all items had content validity, level of difficulty and distinguishing power were good, with high instrument reliability coefficients.
Students’ mathematics representation ability from picture form to equation
Authors: Iskak K B , Kusmayati T A , Fitriana L
Published: March 2020

Conceptual thought is the basic thought in mathematics learning. Process of learning mathematics involves a representation interpretation from a representation form to others. The aim of this research was to analysis the representation process from picture form to mathematics equation. Moreover, this research was descriptive qualitative research. The data were gotten by using test and interview towards 34 students with heterogeneous ability in Surakarta. There were 4 stages in this research, they were unpacking the source, preliminary coordination, constructing the target and determining equivalency. This process involved some other representations such as symbol, schema, verbal, and numeric. Furthermore, the research result showed that the students still had not been able to do the representation process from picture form to equation well. Interpretation process started from picture to equation through other representation mediators like symbols, words and so on. Every student had various ways to do his or her representation. The problem about students’ low mathematics representation could be finished by using a learning medium-based RME. Besides, the suggestions for further research is to do deeper research related to students’ characteristics and to do the opposite research that is an analysis of the presentation process from the equation to picture form.
Cognition processes of student with low functioning autism in solving mathematical problem
Authors: Fauziyah N , Budayasa I K , Juniati D
Published: March 2020

The purpose of this research was to describe the cognition processes of student with low functioning autism in solving mathematical problem. The subject in this research is a high school student with low functioning autism. Data was revealed through task-based interviews using instrument of mathematical problems. The cognition processes in solving mathematical problems involved understanding the problems, devising a plan, carrying out a plan, and checking to ensure the process of problem solving resulted in a correct answer. Some characteristics of autism was very perceptible during mathematical problems solving processes. The subject has difficulty in understanding the problem, even though the information in the problems is split into some simple information. The use of media provides assistance in an attempt to understand the problems even though it is not significant. The subject is unable to determine the plan of completion the problems because he has difficulty in understanding the problems. Subject provides answers that do not suitable with the question in a repetitive way. The subject speaks for itself during the process of understanding the problems.
Practical work design based on Science, Technology, Engineering, Mathematics (STEM) on manufacture of liquid sugar from cassava peel waste (Manihot esculenta) to improve student creativity
Authors: Muhardias D , Sunarya Y , Arifin M
Published: March 2020

The aim of this study is to create a practical work design based on science, technology, engineering and mathematics (STEM) on the manufacture of liquid sugar from cassava husks (Manihot esculenta) to improve the creative abilities of students. To achieve this, the question that arises in this study is “How can the characteristics of developing practical design based on science, technology, engineering and mathematics improve students’ creativity?" The researcher used Design-Based Research (DBR) method consisting of 4 phases: Problem identification and analysis, Designing a solution, Repeated cycles in testing and refining designs and Reflection to produce the principles of design and implementation. The Participants in this study were senior high school students, chemistry teacher and 3 observers who understood the STEM approach. Data was collected by interviewing, testing and observing the activities students. The results showed that student creativity increased through STEM-based practice.
How to analyze the students’ mathematization competencies in solving geometrical problems?
Authors: Suaebah E , Mardiyana M , Saputro D R S
Published: March 2020

Mathematization competency is considered in the field as the focus of the modeling process. This study aims to determine the extent to which the students mathematization competitions in solving geometrical problems. This research uses the descriptive qualitative method by using purposive sampling technique. The data in research are the result of contextual geometry problems and interview by the 8th graders of Junior High School in Surakarta. After that tested to five students can be concluded that students difficulties in horizontal and vertical mathematization. Students difficulties in horizontal mathematization refer to cannot transferring a real-world geometry problem to a mathematical model and difficulties vertical mathematization is adjusting, combining, refining and integrating models.
The effect of Double Loop Problem Solving (DLPS) on critical thinking skills and mathematical problem solving abilities
Authors: Muhammad M , Purwanto J
Published: March 2020

This research aimed to identify the effect of DLPS model on students’ critical thinking skills and mathematical problem-solving abilities. The variables involved in this research were thinking skills and mathematical problem-solving abilities as independent variables, and DLPS model as a dependent variable. One of the best learning strategies to encourage active thinking and problem-solving is the Double Loop Problem Solving (DLPS) model. DPLS model is a learning model of mathematical problem-solving approach that emphasizes students to find the main cause of the existence of a problem. This is in line with students’ mathematical problem-solving abilities that require the student to understand problems, plan or design problem-solving strategies, carry out calculations and verify the truth of the outcome or solution. The population of this study was the students at seventh grade in Junior High School State 1 Rembang, Purbalingga Regency, even semester in the school year 2017/2018. There was selected seventh grade of class B as experimental with 34 students and seventh grade of class E as control class with 34 students. The summary of the hypothesis testing, with the help of the SPSS program, is presented. Using Kolmogorov-Smirnov test for normality test and Levene’s test for equality of variances for homogeneity test, obtained significant value are 0.057; 0.145 and 0.168; 0.062 0.063; 0.681 and 0.244; 0.171 and 1.306; 2.359 more than alpha 0.05. It means that the students’ critical thinking skills and mathematical problem-solving abilities fulfilled assumption of normality test and homogeneity test. After conducting a series of normality and homogeneity tests, it was concluded that t-test for equality of means was used for hypothesis testing. The significant value is 0.019; 0.012 less than alpha 0.05. So that H0 is rejected, it means that students’ critical thinking skills and mathematical problem-solving ability taught by using DLPS model are better than students’ critical thinking skills and mathematical problem-solving ability taught by conventional learning. In other words, the DLPS model influences or effects on students’ critical thinking skills and mathematical problem-solving abilities.
Braking control strategies of modern hybrid and electric vehicles
Authors: Zaini Z
Published: March 2020

Environmental issues and oil resource depletion have urged government and car manufacturers to reduce production of combustion engine vehicle and at same time give more attention to hybrid and electric vehicle (HEV/EV). Fortunately, we have seen these future cars on the rood, for example, Nissan Leaf, Chevrolet Volt and Toyota Auris hybrid. To attract the buyers, these cars must have better efficient in term of equivalent litter per km. One way to achieve this goal, brake blending is incorporated to replace conventional brake system. This paper aims to investigate and compare the performance of such braking system using road test data. Recovered energy and driver comfort are two main aspect analyzed in aforementioned cars. Based on investigation detailed braking data on many driving conditions, it was found that different manufacturers employ different control strategies and have unique feature, respectively. Also, brake blending could cause driver confusion due to different pedal feeling experienced as in the combustion engine car.
5,10,15,20-tetraphenylporphyrin photoluminescence on nanoporous silicon substrates
Authors: Koroleva M O , Elistratova M A , Zakharova I B , Li G V , Sreseli O M
Published: March 2020

Photoluminescence of 5,10,15,20-tetraphenylporphyrin (H2TPP) on nanoporous silicon substrates has been studied. Used nanoporous silicon has a visible PL in the region of H2TPP absorption. Reradiation of porous silicon photoluminescence to the tetraphenylporphyrin long-wavelength peak of the photoluminescence spectrum is observed. The substrate microrelief plays a major role in the formation of tetraphenylporphyrin crystalline structures. The microrelief size of porous silicon was controlled by changing the technological parameters of electrochemical etching.
Photovoltage measurement by modulated photoemission on the p-GaAs surface with cesium overlayers
Authors: Khoroshilov V S , Protopopov D E , Kazantsev D M , Zhuravlev A G
Published: March 2020

A contactless two-beam modulated photoemission technique for measuring the photovoltage on the surface of highly doped semiconductors is proposed and verified for the p+-GaAs surface with adsorbed Cs. The surface photovoltage evolution under the Cs deposition on the highly doped p+-GaAs surface is compared with that observed on Cs/UP+-structures by the photoreflectance spectroscopy method. The pump intensity dependence of the photovoltage is measured. This allows us to determine the absolute photovoltage values.
Terahertz luminescence and photoconductivity associated with the impurity electron transitions in GaAs/AlGaAs quantum wells
Authors: Kurnosova A D , Makhov I S , Firsov D A
Published: March 2020

The photoconductivity and photoluminescence spectra of GaAs/AlGaAs quantum wells doped with shallow donors are studied at low lattice temperatures. The optical electron transitions between the first electron subband and donor ground states, as well as between the excited and ground donor states, are revealed in the terahertz photoluminescence and photoconductivity spectra. The temperature evolution of the impurity-related photocurrent in the terahertz spectral range is also studied.
Difference in the behavior of the photon echo of excitons in InGaAs/GaAs quantum wells from the predictions of the model of two-level system ensemble
Authors: Yanibekov I I , Solovev I A , Eliseev S A , Efimov Yu P , Lovcjus V A , Kapitonov Yu V
Published: March 2020

In this work, we studied the photon echo from heavy-hole excitons in a thin InGaAs/GaAs quantum well. To analyze the results, we used the model of an ensemble of two-level systems. The model allows us to describe the temporal profile and the moment of arrival of the echo signal, as well as the echo amplitude decay with increasing delay between pulses. In addition, excitation-induced dephasing effect was observed, that was beyond the limits of applicability of the model.
Variable-temperature luminescence studies of InAsSb-based LED heterostructures emitting beyond 5 μm
Authors: Semakova A A , Romanov V V , Moiseev K D , Bazhenov N L , Mynbaev K D
Published: March 2020

Variable-temperature (4.2 - 300 K) electroluminescence (EL) studies were performed on two asymmetrical InAs/InAsSb/InAsSbP LED heterostructures emitting at 5.02 and 5.10 μm wavelengths at 300 K (with an InSb content in the active layer of 0.15 and 0.16, respectively). For the structure with the narrowest bandgap, a weak temperature dependence of the position of the EL peak was observed. Along with strong carrier localization in the active layer, which was provided by the design of the structure, this made the studied heterostructures promising for fabrication of LEDs with working wavelengths extending beyond 5 μm at 300 K.
Acceptor-related terahertz and infrared photoconductivity in p-type GaAs/AlGaAs quantum wells
Authors: Vinnichenko M Ya , Makhov I S , Panevin V Yu , Kharin N Yu , Vorobjev L E , Sorokin S V , Sedova I V , Firsov D A
Published: March 2020

Photoconductivity in GaAs/AlGaAs quantum well nanostructures doped with acceptors was studied at low lattice temperatures in the infrared and terahertz spectral ranges. The photocurrent spectra revealed features that can be attributed to the hole transitions from the ground acceptor state to the excited acceptor states and size-quantized subbands.
Synthesis and characterization of GaPN/GaP heterostructures grown on silicon (001)
Authors: Koval O Yu , Sapunov G A , Fedorov V V
Published: March 2020

III-V compound semiconductor heterostructures grown on Si wafers are one of the promising materials in modern optoelectronics. The most promising candidate providing lattice matching with Si is III-phosphide-based alloys diluted with nitrogen. In this work, we study the effect of growth conditions on the structure and optical properties of GaP1−xNx/GaP/Si planar heterostructures synthesized by plasma assisted molecular beam epitaxy. A series of samples with a maximum impurity nitrogen content as high as 5.05% was synthesized. The morphological, structural and optical properties of heterostructures are studied with scanning electron microscopy and optical spectroscopy. All of the samples demonstrate a broad photoluminescence (PL) response in the red wavelength region at room temperature (RT). The most efficient RT PL is obtained with the samples grown under a high nitrogen gas flow through a nitrogen plasma cell.
GaAs diode structures with n+-p junction on Ge/Si templates
Authors: Rykov A V , Denisov S A , Shengurov V G , Baidus N V , Buzynin Yu N
Published: March 2020

GaAs layers were grown by metalorganic epitaxy on Ge/Si(001) substrates, which were formed by chemical vapor deposition with decomposition of GeH4 on a hot wire. High structural quality of thin Ge layers (0.2 - 0.3 μm) on a silicon substrate made it possible to grow high-quality GaAs layers. The resulting n+-GaAs/p-GaAs/p-Ge/p+-Si diode structures demonstrate low reverse currents.
Temperature activation of indirect exciton in nanostructures based on MoS2
Authors: Smirnova O O , Eliseyev I A , Rodina A V , Shubina T V
Published: March 2020

Micro-photoluminescence studies of MoS2 nanotubes have shown that both direct and indirect excitonic transitions contribute to the emission spectra despite the fact that dozens of monolayers are inside their walls and, therefore, only indirect exciton emission would be expected. In addition, the intensity of the indirect exciton band increases with temperature in contrast to the direct exciton band, the intensity of which decreases. The same effects are observed for MoS2 flakes. To describe these phenomena, we propose a theoretical model that considers the balance between exciton transitions taking into account the spin-forbidden exciton states.
Viability of encapsulated Lactobacillus casei using glucomannan iles-iles and skim milk to low pH and bile salts
Authors: Ngatirah
Published: March 2020

The aim of this study was to determine the effect of glucomannan iles-iles concentration as an encapsulating agent and skim milk concentration as the protectant agent on the viability of L. casei in the encapsulation process using spray drying, and to determine its viability in low pH and bile salts. The experiment used a randomized complete block design with two factors. The first factor was the concentration of glucomannan in three levels, A1 (5%), A2 (10%), A3 (15%). The second factor was the concentration of skim milk as a protectant agent with three levels, B1 (9%), B2 (12%) and B3 (15%). The concentration of glucomannan iles-iles and skim milk had no significant effect on the cell number of L. casei. Based on the number of L. casei after the spray drying process. Decrease in viability L. casei after spray drying and stored for 3 months, about 2 log cycles. The highest viability of encapsulated L. casei cells against low pH and bile salts was obtained at 5% glucomannan concentration and 9% skim milk.