bluuebunny/crossref_metadata_2025 huggingface dataset:
Utilization of data mining for placement of books in the library using the Apriori method
Authors: Waliyansyah R R , Novita M , Saputro N D
Published: April 2021

The Apriori Algorithm is an algorithm that is well known for performing frequent itemset searches using the association rule technique. The Apriori algorithm uses knowledge about the previously known frequent itemset to process data related to borrowing books in the library to be processed into useful information. This study uses a priori algorithm method for grouping books at the PGRI University Library in Semarang based on trends that appear together in a library activity visit. By gaining knowledge from this algorithm, it can be used as a reference for the PGRI University Library in Semarang in placing book collections.
The ability of nitrogen atomic absorption in the formation of iron nitride on flake structure and nodule in cast iron
Authors: Sujana W , Widi K A , Rahardjo T , Prihatmi T N
Published: April 2021

The nitriding process can be effectively applied to steel with alloying elements. The higher the alloying element in the steel maximizes the mechanical properties, including hardness. However, the raw material can be costly, therefore using cheap materials (without alloys) is a challenge in increasing surface hardness through iron nitride formation. Furthermore Grey and nodular cast iron have different properties and characteristics in the structure. This research focuses on the ability of the cast-iron structure to affect the nitride layer formation. Gas nitriding was conducted in a fluidized bed reactor with a 550°C in 20 % N2 and 80 % NH3 atmosphere at a flow rate gasses of 0.7 m3/hr process temperature and holding for 2, 4, and 6 hours. Tests are conducted by observing the depth of hardening, SEM, and EDAX. According to the results, the nitriding process increases the surface hardness of cast iron. The highest hardness value is nodular cast iron with a holding time of 6 hours (345 HV) and a hardening depth of up to 20-micron meters. The compounds formed in the nitride layer include FeN, Fe2-3N, Fe4N, and Fe2N. The compound formed is strongly influenced by the treatment time. Furthermore, the comparison of nitriding treatment on gray and nodular cast iron was influenced by the flake and nodule structure. In general, the nodule structure is responsible for maximum hardness. The longer treatment time allows the nitrogen atoms to diffuse more to the surface, while the flake structure limits the absorption of nitrogen atoms into the surface of the cast iron. Characterization of Nodular Cast Iron shows that The hardening depth distribution trend due to the nitriding process in nodular cast iron was not much different from gray cast iron.
Concentration of sheep urine solution as watering media and organic fertilizer to production of corn fodder (Zea mays) by Hydroponic system
Authors: Kustyorini T I W , Krisnaningsih A T N , Pratama R P
Published: April 2021

The purpose of this study was to determine the concentration of urine solution as a watering medium and organic fertilizer on the productivity of hydroponic corn fodder. The research materials were corn, sheep urine, and water, while the method used was field experiments. The treatments, namely T0 (0% urine), T1 (5% urine), T2, (10% urine), T3 (15% urine), T4 (20% urine). The variables were the percentage of germination, percentage of normal sprouts, number of leaves, plant height, fresh production and dry matter production. The data obtained were analyzed using analysis of variance, if there is an effect, then continue with the LSD test. The results showed that the treatments had a very significant effect (P <0.01) on the percentage of germination, percentage of normal germination, number of leaves, plant height, fresh production, and dry matter production. The highest germination percentage was found in T1 (91.60%), normal germination percentage T1 (86.78%), number of leaves T1 (3.0), plant height T0 (31.6 cm), forage production T1 (646.6 grams), dry matter production T1 (568.41 grams). Based on the results, it was concluded that watering with 5% concentration of sheep urine solution gave the best value for the productivity of hydroponic corn fodder.
Improvement of student mathematics learning outcomes through Kahoot learning games application at elementary school
Authors: Umboh D , Tarusu D , Marini A , Sumantri M S
Published: April 2021

The purpose of this research is to improve the student mathematics learning outcomes through Kahoot learning games application at elementary school. This classroom action research adopted from Kemmis and Mc Taggart Model was conducted in three cycles for the fourth grade as many as 22 students at 02 Public Elementary school in Tomohon, North Sulawesi, in Indonesia. The result of this study shows there is an improvement of students learning outcomes from cycle one to cycle three reaching 64, 72, and 81 from the maximum score of 100. Percentage of teacher and student activities increased from cycle one to cycle three achieving 77, 80, and 86 %. It can be concluded that application of Kahoot learning games can improve the student mathematics learning outcomes at 02 Public Elementary school in Tomohon, North Sulawesi, in Indonesia.
Effect of the Missouri Mathematics Project model on mathematical creativity
Authors: Novalia R , Sobar H , Ismaya R , Marini A , Sumantri M S
Published: April 2021

The ability of creativity needs to be the focus in learning mathematics because achievements in learning mathematics develop students’ mathematical creativity abilities. The purpose of this study is to determine the effect of the Missouri Mathematics Project model on students’ mathematical creativity abilities. The research method used is an experimental method using purposive sampling techniques with instruments that use tests and questionnaires. The results of research on student responses in the Missouri Mathematics Project model obtained 87.72% who responded positively, with the value of students’ mathematical creativity ability obtained 81.30 so that it can be said to be good. The research hypothesis test results obtained tcount> ttable (7.14> 2.02) that is the results can be accepted. The conclusion is that there is a positive influence on the Missouri Mathematics Project model with students’ mathematical creativity abilities.
Household behavior towards shallow groundwater saving in Pekanbaru City
Authors: Rafi F , Karuniasa M , Asseggaf A
Published: April 2021

Growth in household activities that increase water resource needs can be incompatible and their availability can be threatened. Limited water supply makes groundwater a primary need because it is easily exploited and practical. This paper attempts to understand the behavior of shallow groundwater saving by households and to observe the influence between knowledge, attitudes, and practice with their behavior. This research was conducted in the Bukit Raya Subdistrict in Pekanbaru City with 113 respondents, analyzed using a quantitative approach (SPSS). The results showed that knowledge, attitudes, and practice had a positive influence of 32.4% on shallow groundwater saving behavior. This research concludes that knowledge is the most influencing shallow groundwater saving behavior seen from the influence of attitude and practice.
How to learn oscillation and wave in SAMR framework?
Authors: Ayu H D , Jufriadi A , Mustika S E , Kurniawati M , Pratiwi H Y , Sundaygara C , Hudha M N
Published: April 2021

This study was to see how to optimize the application and laboratory software on Oscillation and Wave material. This study was conducted using computers and android equipped with Internet access in SAMR framework. SAMR is a framework that requires the use of technology in learning The design of this research is content analysis. The results show that the Olabs application is complete and the most capable of explaining the formula if it is reviewed mathematically and physis meaning. This application is also able to explain the oscillator and wave phenomena well. Based on this research, during the Covid-19 pandemic, students can do STEM (science, technology, engineering and mathematics) from home, one of which is with the help of the Olabs and PhET application.
Distribution and abundance of macroplastic at Musi estuary, South Sumatera, Indonesia
Authors: Almiza G , Patria M P
Published: April 2021

Musi River in the upstream and estuary is used for fisheries, transportation, industry, and settlement. These activities has potential to produce plastic waste with various types and sizes, one of them is macroplastic (2.5-100 cm). This study aims to determine the distribution and abundance of macroplastic in the upstream and estuary of the Musi River. This study used a purposive sampling method with 6 stations, 2 stations in the upstream and 4 stations in the estuary. Macroplastic sampling used transect quadrants then sample is cleaned and dried, counted, identified and weighed for each type. And for macroplastic coverage by taking photos of each transect quadrant, then calculate the percent of coverage using the Point Intercept Transect (PIT) method. The results of this study indicate that the macroplastic abundance in the upstream and estuary of the Musi River ranges from 5-32 items/m2 with an average weight of 27.82 – 126.89 gr/m2. Macroplastic types are dominated by plastics fragments, food wrappers, other jugs/containers, bags/films, and cups, while macroplastic coverage is dominated by bags/films.
Assessing two-dimensional collisions second-years students using PhET simulations on momentum and impulse concept
Authors: Adimayuda R , Sari L , Ismail A , Amalia I F , Gumilar S , Samsudin A
Published: April 2021

Assessment is an important component in education that always needed. To improve the quality of education can be done by improving assessment learning quality and system. This study aims to determine the performance of students of grade X SMA N in Bandung West Java Indonesia school with 34 participants on a two-dimensional collision concept. This research is descriptive research which is conducted to examine the condition and situation that is happening, so that gives a fact-based description found in the school in other to find information factually. Problem studies that analyzed are the student’s performance after using PhET simulations on two-dimensional collision concept. The instrument utilized in this study is a written test in the form of students’ worksheets of momentum and impulse. Student worksheets test shows the average percentage on student performance in understandings concept of two-dimensional collision concept is 67.14%. These data indicated that student learning performance in good category. Learning by using virtual laboratory can provide more meaningful learning especially in physics concept that cannot be presented and observed directly in daily life.
Ab-initio calculation of cubic and tetragonal phase of CsPbI3 perovskite
Authors: Shanaz H R , Nuryadin B W , Subkhi M N , Pitriana P , Aliah H
Published: April 2021

A Study of The CsPbI3 Two-Phase Electronic Structure Has Been Made Through Calculations Using the Density Functional Theory Method. Perovskite metal halide is used as a light-absorbing material on solar cells. This material has a high level of stability and an easy fabrication process. Also, the conversion efficiency has reached 10.1%. The two crystalline phases used are the cubic phase and the tetragonal phase. The electronic structure discussed includes the ribbon electronic curve, as well as the DOS (Density of States) curve, PDOS (Projected Density of States) curve. To find out the electronic structure, and optimization calculation is performed, namely variations in lattice constants, k-points, and cut-off energy. This optimization is done to get the structure with a minimum total energy so that its stability can be achieved. It is known that the bandgap energy value of the CsPbI3 cubic is 1.44eV on the electronic and DOS curve curves. Whereas the band gap energy value of tetragonal CsPbI3 is 0.6 eV on the electronic band curve and DOS as well. This shows that CsPbI3 can be used for the perovskite semiconductor material.
Analysis of solid oxygen distribution in kakap river, kubu raya district west kalimantan
Authors: Oktaliana R , Ahmad  , Rintayati P
Published: April 2021

The people of the Kakap River area live and open businesses along the river while they directly dispose of waste into the river. The people also use the river as a source of clean water to meet their daily needs. The purpose of this study was to determine the condition of the Kakap River water quality against dissolved oxygen with BOD, COD, pH, and DO parameters. This research used purposive sampling, starting from determining the sample point to be selected. The sample points used were three locations along the Kakap River. The results of the water quality analysis of the Kakap River from the first location in the estuary: COD parameter is 5.0 mg/L, the BOD parameter is <1 mg/L, DO parameter is 5.6 mg/L and pH parameter is 6.65. The second point of Pal 9 location: COD is 41 mg/L, the BOD parameter is 13 mg/L, the DO parameter is 4.9 mg/L, and the pH parameter is 7.17. The third location at Punggur Kecil: COD parameter is 210 mg/L, the BOD parameter is 137 mg/L, the DO parameter is 3.9 mg/L, and the pH parameter is 4.86 in the low tide conditions. These results will meet the water quality standards for class IV according to PP RI No. 82 of 2001, in which it can only be utilized for irrigating crops and other uses that require the same water quality. Apart from that, the results indicate that the water quality condition of the Kakap River has been polluted so it is not appropriate for the people to use the river as a clean water source.
Establishment of student characters as citarum river pollution solution program
Authors: Supriyono  , Sartika R , Kurniawaty I
Published: April 2021

The role of universities in fostering student character can be integrated within the scope of curricular, co-curricular and extracurricular activities. Thematic Real Work Lecture activity based The Pentahelix is a curricular program in the University Pendidikan Indonesia and supposed to be a forum for student character formation. The purpose of this study is how to shape the character of students who can support the Citarum River pollution solution program. This study uses an approach that is combining the two types of methods namely qualitative and quantitative. This method is called the RnD method or research and development. The results of this study are the presence of the character of students as supporters of the Citarum River pollution prevention program.
Community perception of flood relocation efforts in pacitan subdistrict, pacitan regency
Authors: Pradikka R A , Yusup Y , Nurhadi
Published: April 2021

The flood disaster that hit Pacitan Subdistrict, Pacitan Regency has caused casualties and damage in the housing, infrastructure, and educational facilities. This disaster brought several consequences in the form of settling relocation policy. This study aims to analyze community perceptions of relocation efforts and factors that influence people’s perceptions of settlement relocation efforts. Data collection techniques through interviews, observation, and documentation of respondents in Pacitan District. Data analysis using qualitative descriptive. The results showed that some people 1) refused the existence of relocation and preferred repairs to embankments, and agreed with government efforts provided they were carefully prepared, (2) Factors influencing perceptions were physical and environmental factors in the form of embankment conditions, economic factors in the form of loss of land assets and livelihood, organizational factors in the form of delivering aspirations through various activities, and socio-cultural factors in the form of education, social relations and health.
Development of socioeconomic indicators for measuring the population wellbeing in lembah klang-langat extended metropolitan region, malaysia
Authors: Saleh Y , Mahat H , Hashim M , Nayan N , Norkhaidi S B , Mohd Zanuddin I H
Published: April 2021

This paper aims to develop a socioeconomic indicators to measure the wellbeing of the people in Lembah Klang-Langat Extended Metropolitan Region (EMR). A total of 400 respondents comprised heads of household in 15 settlement centres in Lembah Klang-Langat Extended Metropolitan Region (EMR) were selected as study sample. Quantitative approaches using SPSS and AMOS software were in this study. The data were analysed using factor analysis, namely exploratory factor analysis (EFA) and confirmatory factor analysis (CFA). The results showed that after EFA and CFA had been applied, only two sub-constructs of socioeconomic construct which were i) social, and ii) economy, and six items of B7_3, B7_4, B7_5, B7_7, B7_10 and B7_11 presented high validity values of CR exceeding 0.6. The analysis found that the measurement model met the measurement criteria for measuring suburban wellbeing. The study findings also showed that the similarity index value was equal to p=0.000, chi-square relative value of 3.553, 0.991 for GFI value, 0.983 for CFI value, 0.968 for TLI and RMSEA value of 0.051. Therefore, the findings of this study have successfully prepared a set of socioeconomic indicators that can be used by future researchers for analysing the wellbeing of socioeconomic aspect of metropolitan region’s extended area.
Geological Controls on Thermal Manifestation Occurences in Batu Gede and Batu Kapur, Subang Regency: A Preliminary Result
Authors: Sibarani Betseba br , Sianipar Juni Yesy , Daniel Danny , Apriani Lestari , Danakusumah Grandy , Suryantini
Published: April 2021

Batu Gede and Batu Kapur are administratively located in Subang Regency, West Java, precisely in the northern part of Tangkuban Perahu Geothermal Working Area. Characteristics of the manifestations in Batu Gede and Batu Kapur are generally bicarbonate neutral pH warm springs and their location exposed in the foot of Tangkuban Perahu Volcano. Despite the similar chemical characteristic of those two manifestations, there is a significant characteristic difference between them. Spring with low pH with the pungent smell emerges in the Batu Gede not far from neutral pH bicarbonate warm spring. The aim of this research is to determine control of the occurrence and relationship of manifestation in both areas by conducting geological mapping. Surface manifestations are controlled by a geological process associated with primary and secondary permeability. Both manifestations emerge dominantly in the control of fault as a secondary permeability. Primary permeability also controls the occurrence of manifestations but not significant. Batu Gede manifestations are dominantly controlled by overstepping structure, while Batu Kapur are dominantly controlled by intersections between structures. Based on high content of SO4
−2, acid pH, and the presence of sulfur, the acid manifestation might be correlated with magmatic activity beneath Batu Gede’s manifestation.
A System Design of a Solar and Geothermal Hybrid Power Plant for Flores Island
Authors: Berian Zagy Yakana , Riyanto Hendi
Published: April 2021

Solar and geothermal hybrid system will be promising in the upcoming years, Flores has both energies potential. The use of diesel electric power plant (PLTD) may harmed the environment, the hybrid system with storage energy can be an alternative solution to substitute PLTD. Hence, there is an opportunity to design and implement a hybrid geothermal and solar power plant for Flores Island. Based on existing geothermal fluid characteristics in Flores Island, a hybrid power plant is designed to comprising of a single flash geothermal power generation, a solar collector system with parabolic trough collectors (PTC) either in an East-West (E–W) or a North-South (N–S) alignment, and a thermal energy storage (TES) system with synthetic oil for heat transfer fluid (HTF) and a mixture of salts for storing thermal energy. The hybrid power plant’s operation is designed based on the result of the electricity load study for Flores Island. Solar energy potential for Flores Island is predicted by combining clear sky model empirical formulas and 2017–2019 sunshine duration data from local wheather station. Steady mass and energy balance analyses via Aspen HYSYS were performed to obtain electric power generation capacity for each standalone geothermal power plant and hybrid power plant. Besides, a comparison of carbon dioxide emission from the same capacity of a diesel-electric power plant, a standalone geothermal power plant, and a hybrid power plant is presented. The hybrid power plant is designed to have a solar collector system with a N–S alignment PTC system in which daily average solar irradiation is predicted to be 5.5 kWh/m2/day and a TES volume of 3,000 m3. The land area to be cleared for the solar collector system is estimated as 3.0 hectares (7.5 acres). For a steam turbine inlet pressure of 10 bar, a condenser pressure of 0.08 bar, and 1,215 operation hours per year, the hybrid power plant can produce 5,450 MWh/year of electric energy. The carbon dioxide emission reduction for standalone operation and a hybrid operation are 86% and 93%, respectively, compared to that of a PLTD.
Study of The Heat Loss Effect in Geothermal Steam Production Well
Authors: Wardana Andrian Putra , Saptadji Nenny Miryani , Maulana Dimas Taha
Published: April 2021

Well casing and cement temperature can change during geothermal production operation. The change of temperature occurs because of the heat transfer from the geothermal fluid to the formation. The heat transfer occurs because of the temperature difference in geothermal fluid and formation. The heat of fluid moves to the casing, cement, and formation through convection and conduction. This research aims to develop the heat transfer model in the steam production well, predict the steam heat loss and its effect on every 100 m well increment, and predict the well casing and cement temperature distribution and their effect on every well segment. The heat transfer model is an analytical calculation model developed to be the base of the calculation of heat loss and a temperature drop of well casing and cement. This model was developed for the calculation of heat loss in steam production well. The model was compared with a simulator to test the suitability. The fluid flow pressure drop and well lithology were considered in this model. The heat loss was very low during the steam production. The heat loss could be higher, along with the formation temperature drop. The material thermal conductivity and the well segment’s layer thickness could affect the steam heat transfer in the production well.
A Modified Non- Isothermal Lumped Parameter Model in Porous Media for Geothermal Reservoirs
Authors: Firanda Eric , Pasaribu Fernando , Sutopo  , Pratama Heru Berian
Published: April 2021

This paper presents a method to predict geothermal performance along production life using a lumped parameter model that has considered mass balance, heat changes, and porous media flow in geothermal reservoirs. Furthermore, the lumped model provides more information on the characteristics of geothermal reservoirs. This paper focuses on developed and combined Satman’s model on mass balance and Schilthuis’s model on material balance for oil reservoirs. This paper can calculate heat and mass balance for the non-isothermal condition with pressure and temperature changes, unlike previously published papers. Besides, this paper also includes Darcy’s equation to change the “tank” concept of lumped to be porous media as an actual reservoir condition. Thus the production mass rate can be calculated. The model developed can be used for performing history matching, “quick count’ of numerical simulation due to there is calculation well by well, if those combined, can determine an entire reservoir with a simple calculation. On the other hand, this method reduces the complexity of numerical calculation. Therefore, new lumped is expected to be an alternative for application in geothermal reservoirs.
Incremental Development Strategy of Geothermal Field Using Wellhead Unit Technology: Case Study Ulumbu Geothermal Field
Authors: Idianto Onny , Saptadji Nenny Miryani , Ashat Ali , Pratama Heru Berian , Nusiaputra Yodha Yudhistra
Published: April 2021

Geothermal development in Indonesia is still dominated by the utilization of conventional geothermal power plants with large capacities. Generally, it requires a long time development phase and often experiences delays before an operation. This study aims to provide alternative field development options with an incremental development strategy. This study was conducted to show how a wellhead unit’s effective incremental development strategy compared to conventional power plants by applying the probability approach for the Ulumbu geothermal field’s case study in East Nusa Tenggara. Besides, this study also provides a comprehensive economic condition of the obtained revenue and project investment costs. Therefore, geothermal power plant development could be more feasible and minimize the barriers in the investment. The methods used in this study is a technical and economic approach, from total project investment cost and the financial return achieved for each development strategy. The technical analysis compares the power plant’s specific steam consumption (SSC) and the generated capacity. The total investment is determined for different development strategies of 40 MW (conventional) scenario 2×20 MW, 40 MW (incremental) scenario 8×5 MW, and 40 MW (incremental) scenario 16×2.5 MW using condensing power plant. The economic analysis shows P50 for the investment cost in millions of US$/MW is 5.84, 5.58, and 5.60, respectively. Regarding the tariff-based, which is 80% under Average Cost of Electricity Generation (BPP) of the relevant local grid, P50 for the Rate of Return is 16.85%, 17.33% 17.21%, respectively. Evaluation done by comparing investment cost, economic parameters, tariff variation, and risk assessment, for incremental development scenarios of 8×5 MW and 16×25 MW is feasible as development alternative scenario of Ulumbu field.
Numerical Study of Temperature Profiles of Transient Flow in the Geothermal Oilfield
Authors: Hendrarsakti J , Rahma M
Published: April 2021

Some petroleum wells that are no longer productive still have heat in their formation rocks. Those heat can be extracted and utilized by injecting working fluid into the wellbore. The current study’s objective was to create a 2D numerical calculation program for transient flow temperatures inside the well then it was used to calculate the temperature distribution in oil and gas fields in the Arun field and BK Area. The injected fluids were modeled as a double-pipe heat exchanger. Heat transfer processes inside the wellbore were convection in the inner pipe and the annulus and conduction in the pipe walls and rock formations. The computational calculation used a finite difference method. The computation results were then compared with calculations from the literature. After being validated, the program was used to calculate the Arun field and BK Area temperature distributions. This study found that compared with the reference literature, the current results had a similar optimum temperature range of 130°C-160°C but had different profiles shape with an average deviation of 12%. In the Arun fields, simulation results indicated that the field could reach temperatures between 90°C-120°C and was classified as a medium-temperature geothermal source. BK Area could reach optimum temperatures between 50°C-80°C and be classified as the low-temperature geothermal.
An experimental evaluation on revamping the productivity of solar PV panel using wind tunnel as an optimizer
Authors: Rajasekar R , Ramkumar R , Prasannaa P
Published: April 2021

At high working temperatures, the performance of the solar photovoltaic (PV) cells will be affected. With the increase in temperature of the PV cells, the conversion of solar radiation into electrical output will be decreased. The operating temperature of the PV cells is one of the prime factors for determining its electrical conversion efficiency. In order to get the maximum electrical output from the solar PV cells, the temperature should be maintained properly. In this experimental study, the temperature of the solar PV cells was maintained by cooling both sides of the PV panel simultaneously. The front surface of the PV panel is sprayed with a thin film of pot water and the rear side is attached with a fabricated duct that was connected into a wind tunnel blower. The mass flow rate of the moist air from the wind tunnel to the rear side of the PV is ranged between 0.1m/s to 0.5m/s. The performance characteristics of both the commercially available PV panel and the experimental PV panel (PVT Clay pipe panel) were compared. The results show that the PVT clay pipe panel has an electrical efficiency of about 11.72%, whereas the commercially available PV panel has only 9.77%. Also, the overall efficiency of the experimental PVT panel is 65.55% respectively.
Modal Analysis Of Electrical Motor Casing
Authors: Srinivasan. T , Sharavanan. S , Naveen. E , Sethuvelappan  , Ramanan. P
Published: April 2021

Getting analytical and mathematical solutions for issues involving difficult geometries, loading and material properties, it is usually unacceptable. Analyticalsolutions that are given by a location in a body. This analyticalsolution usually needs standard or partial differential equations that are not obtained. Hence there is the need to rely on numerical strategies, like finite component strategies for acceptable solutions. Most sensible issues involve sophisticated domains (both material and material constitution), hundreds and non-linearities that forbid the event of analytical solutions exploitation numerical strategies. A numerical method, with the arrival of computer, is often used for the investigation and analysis of the results of varied parameters of the system on analyzed. It is price effective and saves time and material resources compared to the multitude of physical experiments required to realize a similar level of the understanding. The ability of numerical strategies and electronic computation, make incorporation of all relevant options during a mathematical model of a physical method not attainable without fear concerning its solutions by precise means. Those who are fast to use a computer program rather than think about the problem to be analyzed may find it difficult to interpret the input file to the computer program, a decent understanding of the underlyingtheoiy of the matter still as numerical methodology is needed.
Influence of Heat Treatment on Mechanical Characteristics of Al7075/Al2O3/TiC Hybrid Metal Matrix Composite
Authors: Sai Baba E , Vinitha M , Krishna Prasad Dr D V V
Published: April 2021

The present paper deals with the study and characterization of the physical and mechanical behaviors of Al-7075/Al2O3 / TiC hybrid metal matrix composite (HMMC) materials. The assimilation of dual particles like self-lubricated ceramic particles (Al2O3) along with hard particles (TiC) in the Al-7075 matrix is done using liquid stir casting method. The hybrid composite is produced with varying weight percentages of (8, 6, 4, 2, 0) Al2O3 and TiC (0, 2, 4, 6, 8) particulates. The produced Al HMMC materials are subjected to heat treatment (T6). The behavior of properties like density, hardness, impact and tensile strengths are analyzed based on experimentation. The obtained properties of cast Al-7075 HMMC materials are compared with heat treated Al-7075 composite materials. The dispersion of TiC hard particles in ductile Al-7075 matrix, predominates Al2O3 in improving mechanical properties because of its superior properties.
Optimization of EDM Process Parameters on Machining Characteristics of SiC and Graphene Reinforced Al 6061-T6nano-Composites
Authors: Ammisetty Saikiran , Ammisetti Dhanunjaykumar , Satyanarayana K. , Chitturi Suresh , Naik N.Sunil
Published: April 2021

Aluminum composites play an important role in various applications due to their low weight to strength ratio, high corrosive resistance, etc. As reinforcement materials, Graphene and SiCnano particles were used. Since, they havea high melting point, young modules, strong electrical and thermal properties etc. Electrical Discharge Machining (EDM) is one of the non-conventional machining techniques widely used for the machining of hard materials such as composites. The aim of current work is to evaluate the influence of EDM process parameters such as peak current, pulse on-time, voltage and flushing pressure on machining of Aluminium 6061 reinforced with 0.5 wt% SiC and 0.5 wt% Graphene nanoparticles. Al-based Metal Matrix Composite was casted by using liquid processing technique i.e. Stir Casting. Taguchi’s Design of Experiments was used to evaluate the effect of process parameters on machining characteristics i.e. Material Removal Rate (MRR) and Tool Wear Rate (TWR) of developed composite. From the results it was observed that peak current is the most influencing factor on MRR and TWR followed by other parameters.
Strengthening of Flexible Pavement by Adding Recron Fibre
Authors: MalathiNarra Smt , Mallikarjuna V. , Revathi Ch. , Srikanth U.
Published: April 2021

Now-a-days, there is dire necessity for roads which aremore stable and stronger. Due to weathering conditions and heavy traffic, the pavement surfaces are getting deteriorated by rutting, pot holes etc. With the addition of this Recronfiber, there is an improvement in the properties of bitumen like increase in stability value and decrease in the flow value, % of air voids etc. Recron fiber is an artificial material obtained from the polyesterand which is also used as a secondary reinforcement for attainingtensile strength. It helps to resistthe cracks obtained by the improper laying of pavement surface and heavy loaded vehicles.

In the present study, various proportions of Recron fiber such as 3%, 6%, 9% and 12%are added to Bitumen to prevent the deterioration of pavement surface andvarious tests areperformed on aggregate and bitumen. From the results, it is found that, the flow value and % of air voids decrease and stability value increases. Hence, it is proved that, it protects the pavement surface from the effect of fatigue, cracking and deformation.

The obtained results show that 9% is the optimum percentage of Recron fiber to be added to the bitumen. For nominal bitumen mix, the maximum stability value is 12.07 kN and for modified bitumen (Recron added) mix the maximum stability value is 16.79 kN.
Effect of Nano Silica & Other Industrial Wastes on Strength and Economy of Concrete
Authors: Ram D. Aditya Sai , Ramya K Sai , Kamalakar D.
Published: April 2021

The application of Nanotechnology in concrete has added a new dimension to improve its properties. Nano-materials. by virtue of their very small particle size can affect the concrete properties by altering the microstructure. In this study an attempt is made to analyze the effect of Nano-Silica on the strength of control concrete and replaced cement concrete. In replaced cement concrete. cement is partially replaced with the dolomite powder and fine aggregate with granite fine in different percentages. Workability and Strength tests were conducted on both the control concrete and concrete with Nano-Silica. dolomite and granite powder.

The replace percentage of dolomite powder 15% and 20% of granite fine gave good results. more than this percentage of mix the strength of concrete decreased. Nano-silica of different percentages 0%. 0.5%. 1%. 1.5%. 2%. 2.5% and 3% added to this selected mix (15% DP and 20% GP) and control concrete. The test results reveal that the replacement of Nano-silica from the replacement percentage of 0.5. the strength of concrete significantly increases with increasing percentage of Nano-silica upto 2.5%. The Cost of the replaced concrete increased as well as the strength also with reference to control concrete. However this is valid upto certain point. later the strength decreases with increase in cost.
The stable interfaces between various edges of hBN and step edges of Cu surface in hBN epitaxial growth: a comprehensive theoretical exploration
Authors: Zhang Leining , Ding Feng
Published: April 2021

High-index Cu surfaces were broadly shown to be substrates capable for templating the epitaxial growth of uniformly aligned hexagonal boron nitride (hBN) islands whereas the mechanism of hBN growth on high-index Cu surfaces is still missing. Since hBN nucleation prefers step edges on a high-index Cu surface, the understanding of the interfaces between the hBN edges and the step edges of Cu substrates is critical for revealing the mechanism of hBN epitaxial growth on high-index Cu surfaces. Our extensive theoretical study reveals that both types of zigzag edges and armchair edge tend to retain their pristine structures on a Cu surface due to the effective passivation of the dangling bonds of hBN edges. This study paves a way to explore the growth kinetics of hBN on high-index Cu surfaces and also sheds light on the growth mechanisms of various two-dimensional materials on active metal substrates.
Anisotropic pseudospin tunneling in two-dimensional black phosphorus junctions
Authors: Choi Young Woo , Choi Hyoung Joon
Published: April 2021

We investigate the role of pseudospin structure of few-layer black phosphorus (BP) in interband tunneling properties in lateral BP junctions. We find that interband tunneling is critically dependent on junction directions because of the anisotropic pseudospin structure of BP. When the armchair direction of BP is normal to the interface, pseudospins of incident and transmitted carriers are nearly aligned so that interband tunneling is highly effective, analogous to the Klein tunneling in graphene. However, when the zigzag direction is normal to the interface, interband tunneling is suppressed by misaligned pseudospins. We also study junctions of band-gap inverted BP where the electronic structure is characterized by two Dirac cones. In this case, intervalley tunneling is prohibited either by momentum conservation or by pseudospin mismatch while intravalley tunneling is Klein-like irrespective of the junction direction. These results provide a foundation for developing high-performance devices from BP and other pseudospin materials.
Characterizing the effects of controlled temperature and relative humidity on liquid water transport behavior of cotton/lycra elastic woven fabric
Authors: Wang Yong , Qiao Qifan , Cao Jiqiang , Zhi Chao , Li Changlong , Tao Yuan
Published: April 2021

Liquid transport (wicking) has great effect on the physiological comfort, since it directly determines the moisture management of fibrous assemblies. For elastic fabric structures, the wickability primarily depends on several factors, such as tensile strain and ambient conditions (e.g., temperature, relative humidity). The main purpose of this work was to systematically clarify the effects of water temperature and relative humidity on vertical liquid water transport of as-prepared cotton/lycra elastic woven fabric experimentally and theoretically. On the experimental side, the results indicated that our as-prepared fabric exhibited a water temperature-strengthening effect, while a humidity-weakening effect was produced simultaneously. In other words, a higher water temperature results in a higher equilibrium wicking height, whereas a higher relative humidity results in a decreased wicking height. Furthermore, the underlying wicking mechanism in each case was graphically unraveled. On the analytical side, the proposed Laughlin-Davies model turns out to be appropriate, it can replicate the wicking characteristics of fabric in both of these cases qualitatively and quantitatively. These findings are expected to provide a deep understanding of fabric wicking under a realistic regime.
Hydrogenation via a low energy mechanochemical approach: the MgB2 case
Authors: Pistidda Claudio , Santhosh Archa , Jerabek Paul , Shang Yuanyuan , Girella Alessandro , Milanese Chiara , Dore Maria , Garroni Sebastiano , Bordignon Simone , Chierotti Michele R , Klassen Thomas , Dornheim Martin
Published: April 2021

This work aims at investigating the effect that the energy transferred during particle collisions in a milling process entails on solid-gas reactions. For this purpose, the synthesis of Mg(BH4)2 from MgB2 in a pressurized hydrogen atmosphere was chosen as a model reaction. MgB2 was milled under a broad set of milling parameters (i.e. milling times and rotation regimes) and the obtained product thoroughly characterized. By proving the partial formation of Mg(BH4)2, the results of this investigation indicate that the energy transferred to the powder bed by the powder particles during milling is not negligible, in particular when the milling process is protracted for a long period.
Mechanistic insights into lepidocrocite conversion to hematite from variable temperature Raman microscopy
Authors: Liu Yutong , Zhang Jixi , Bodappa Nataraju , Smith Rodney D L
Published: April 2021

The consistent fabrication of high performance α-Fe2O3 photoanodes for the oxygen evolution reaction remains a challenge. We work towards resolving this issue by developing in situ variable temperature Raman spectroscopy as a means to better understand the formation of α-Fe2O3, using the conversion of γ-FeOOH to α-Fe2O3 under varied gaseous environments as a model case. The sensitivity of Raman spectroscopy to structural changes provides mechanistic insights that are not readily available in more conventional approaches, such as thermal gravimetric analysis and differential scanning calorimetry. The Raman spectra are combined with conventional thermal analyses to interpret the photoelectrocatalytic performance of a series of α-Fe2O3 photoanodes prepared by systematic variation of a three-stage annealing protocol. The combined results suggest that protohematite, a form of α-Fe2O3 where trapped hydroxyl ligands are balanced by Fe(III) vacancies, forms between 200 °C and 400 °C in a reaction environment-dependent fashion. This protohematite is shown to be remarkably persistent once formed, degrading photoelectrocatalytic performance. This research advances understanding of the γ-FeOOH to α-Fe2O3 structural transformation, illustrates a powerful method to study solid state phase transitions, and provides guidance for the synthesis of high quality α-Fe2O3 from a convenient precursor.
Hydrophilic treatment for strong carbon nanotube fibers
Authors: Cheon Jae Yeong , Ku Nayoung , Jung Yeonsu , Lee Kyunbae , Kim Taehoon
Published: April 2021

The hydrophobic surface characteristics of carbon nanotube fibers (CNTFs) limit their usage in aqueous systems. Herein, we report a surface treatment method for preparing hydrophilic CNTFs by attaching a sulfonic acid group onto the surface of CNTF. The introduction of a sulfonic acid group was examined by x-ray photoelectron spectroscopy. The contact angle between the CNTF and water droplets decreased after a surface treatment to 22.9°, implying enhanced hydrophilicity. The nanostructure of the CNTF is rarely changed during surface treatment, so the surface characteristics can be controlled without losing the advantages of direct-spun CNTFs. Water infiltration was examined by measuring the electric double-layer capacitance of CNTFs. The capacitance of surface-treated CNTFs (140 μF cm−1) was even higher than the as-prepared CNTFs (21 μF cm−1), meaning that the interfacial area between CNTFs and water electrolytes significantly increased, and water can infiltrate effectively into the nanopores of CNTFs as a result of the surface treatment. The sulfonic acid group is more efficient than the carboxyl group in improving hydrophilicity and water infiltration. The surface treatment also enhances the specific strength of the CNTFs by 50%, which is beneficial for preparing CNTF-based devices. The hydrophilic CNTFs prepared in this work will be useful in preparing CNTF-possessing functional nanoparticles or in use in CNTFs for electrochemical devices.
Retrieval of building heights from ICESat-2 photon data and evaluation with field measurements
Authors: Dandabathula Giribabu , Sitiraju Srinivasa Rao , Jha Chandra Shekhar
Published: April 2021

Building heights play a vital role in the field of urban morphology and allied applications. Recently there is a push to retrieve building heights from the space borne sensors. NASA’s ice, cloud, and land elevation satellite-2 (ICESat-2) carries a laser altimeter on-board that produces geolocated photon events on various types of surfaces such as glaciers, oceans, land and canopy on Earth. In this article, heights of the sampled buildings in an urban area were estimated using ICESat-2 photon data. The elevation from the geolocated photons reflected from the surface (bare Earth) of adjacent sides of a building under investigation was considered as local datum; similarly, the elevation of the building is computed from the geolocated photons reflected from the building roof. These two elevation estimates were used to compute the height of the building. These heights were evaluated using the field measurements. The estimated building heights from the profiles of ICESat-2 data agree with the field measurements with an accuracy ranging from 8 to 17 cm and suggest the utility of using ICESat-2 data for urban studies, if accuracy tolerance is in the centimeter level, is acceptable.
Captive-reared migratory monarch butterflies show natural orientation when released in the wild
Authors: Wilcox Alana A E , Newman Amy E M , Raine Nigel E , Mitchell Greg W , Norris D Ryan
Published: April 2021

Eastern North American migratory monarch butterflies (Danaus plexippus) have faced sharp declines over the past two decades. Captive rearing of monarch butterflies is a popular and widely used approach for both public education and conservation. However, recent evidence suggests that captive-reared monarchs may lose their capacity to orient southward during fall migration to their Mexican overwintering sites, raising questions about the value and ethics of this activity undertaken by tens of thousands of North American citizens, educators, volunteers and conservationists each year. We raised offspring of wild-caught monarchs on swamp milkweed (Asclepias incarnata) indoors at 29°C during the day and 23°C at night (~77% RH, 18L:6D), and after eclosion, individuals were either tested in a flight simulator or radio tracked in the wild using an array of automated telemetry towers. While 26% (10/39) of monarchs tested in the flight simulator showed a weakly concentrated southward orientation, 97% (28/29) of the radio-tracked individuals that could be reliably detected by automated towers flew in a south to southeast direction from the release site and were detected at distances of up to 200 km away. Our results suggest that, although captive rearing of monarch butterflies may cause temporary disorientation, proper orientation is likely established after exposure to natural skylight cues.