It is a well-known fact that incorporating a slip boundary into the contact surfaces improves bearing performance significantly. Regrettably, no research into the effect of slip on the behavior of ...journal bearing systems operating with non-Newtonian lubricants has been conducted thus far. The main purpose of this work is to explore the performance comparison of Newtonian and non-Newtonian fluid on a heterogeneous slip/no-slip journal bearing system. The tribological and acoustic behavior of journal bearing is investigated in this study using a rigorous program that combines CFD (computational fluid dynamics) and two-way FSI (fluid–structure interaction) procedures to simulate Newtonian vs. non-Newtonian conditions with and without slip boundary. The numerical results indicate that irrespective of the lubricant type (i.e., Newtonian or non-Newtonian), an engineered heterogeneous slip/no-slip pattern leads to the improvement of the bearing performance (i.e., increased load-carrying capacity, reduced coefficient of friction, and decreased noise) compared to conventional journal bearing. Furthermore, the influence of the eccentricity ratio is discussed, which confirms that the slip beneficial effect becomes stronger as the eccentricity ratio decreases. It has also been noticed that the Newtonian lubricant is preferable for improving tribological performance, whereas non-Newtonian fluid is recommended for lowering bearing noise.
Methane is a hydrocarbon compound that can be used for various purposes. Currently, methane is widely used as fuel, and continues to be developed as a synthetic gas material and petrochemical ...products that have added value, one of which is formaldehyde. This study aimed to study the partial catalytic oxidation reaction of methane to formaldehyde using MoO
3
/zeolite as a catalyst. Reactant gas stream consisting of pure O
2
and CH
4
were contacted with a rate ratio of 1:20, put into Fixed Bed Reactor therein contained 30 grams of catalyst MoO
3
/zeolite, and the pressure was maintained at 1 atm. The temperature and flow rate of the incoming reactant gas were used as variables. The main product produced was formaldehyde, besides that there were also CH
3
OH, CO, CO
2
, H
2
O. The results were analyzed using Gas Chromatography, so it was known that the converted methane was 5.18% and the volume fraction of formaldehyde formed was 1.46%.
Household waste becomes a problem in sub-urban area like Bekasi City. The quantity of waste to landfill increased from 2011-2015. To improve the situation the local government initiatives to reduce ...it by establishing Bank Sampah Induk Patriot (BSIP-waste bank in the city level) with the responsibilities to improve the participation of citizens on 3R (reduce, reuse, recycle) by educating and supporting them to build a waste bank in each rukun warga (RW-informal unit under village). This action is followed by issuing the new regulation concerning waste management based on community participation. This study aims to analyse the correlation between waste bank and household waste in term on reduction to landfill and financial benefit using Pearson correlation analysis. The results show issuing BSIP and new regulation impact on increasing the number of waste banks significantly. However, it is found the number of active waste bank is only 18.5%. The results show there is very strong correlation between the number of waste banks and the amount of waste reduction. It means the waste banks is effective to reduce waste to landfill. It's recommended to BSIP to encourage the inactive waste banks and coordinate with the local authorities.
The development of educational technology makes teachers have to integrate technology into the teaching and learning process. The purpose of this study was to determine the effect of Edmodo ...application of attitudes and student science achievements. The design of this study uses experimental and control class. The study sample consisted of 124 students who were divided into experimental and control class. After implementing the Edmodo application, the students were given the questionnaire to measure students' perceptions towards Edmodo application, and multiple choice questions to measure students' achievement science. Both instruments were administered to the experimental group and control group and then the results were analyzed. The data were collected using a survey and test, and then they were tabulated and analyzed using the SPSS program. The results of this study show as follows (1) The effect of Edmodo application toward students' attitude is 0.231 (2) The effect Edmodo application toward students' science achievement is 0.478. Therefore the Edmodo application usage as a learning media affects improving students' attitude and students' science achievement.
In the present study, a computational investigation into acoustic and tribological performances in journal bearings is presented. A heterogeneous pattern, in which a rough surface is engineered in ...certain regions and is absent in others, is employed to the bearing surface. The roughness is assumed to follow the sand-grain roughness model, while the bearing noise is solved based on broadband noise source theory. Three types of heterogeneous rough/smooth journal bearings exhibiting different placement and number of the rough zone are evaluated at different combinations of eccentricity ratio using the CFD method. Numerical results show that the heterogeneous rough/smooth bearings can supply lower noise and larger load-carrying capacity in comparison with conventional bearings. Moreover, the effect on the friction force is also discussed.
This study aims to test the effectiveness of JAS (Neighborhood Exploration) approach to shaping the character of conservation and metacognition ability in the students so that it can realize UNNES ...vision as a conservation university. Metacognition ability is very important because it determines the success of learning. Conservation characters include eight (8) values that are, inspiration, humanist, care, innovative, creative, sportive, honest and fair. The formation of conservation character in the students, besides done through the subject of Conservation Education, can also be implemented through the course of Plant Anatomy. This research is quantitative descriptive. The study was conducted in the even semester of 2017-2018. The population is even semester student of Biology Education program. Determination of sample taken by cluster random sampling obtained a sample of student semester four (4). The lessons were held for 4 meetings. At the end of each course, the students are asked to fill out a questionnaire about their attitude, and metacognition ability, to know the progress. Data were analysed descriptively. The results showed that of the three meetings, students' metacognitive abilities increased. Developed attitudes are religious, honest, responsible, care, innovative and sportive. Conclusion, lecture Plant Anatomy with JAS approach effective to form conservation character and developability of student metacognition.
The batch system investigation explored the effect of Sr2+ and Fe3+ cations and the stirring speed on the characteristics of precipitated barium sulfate. A series of experiments were conducted to ...evaluate the rate of barium sulfate precipitation in laboratory equipment from brines containing barium ions (3500 ppm) and varying amounts of Sr2+ and Fe3+ ions (10 and 20 ppm). Kinetic analysis was also performed to explore how stirring speeds (240 and 480 rpm) affect barium sulfate scales' crystallization by increasing the stirring speed and promoting Sr2+ and Fe3+-cation solubility while decreasing the precipitation rate. All solid crystals obtained were mostly pure barite, as the X-ray diffraction (XRD) method confirmed. The SEM micrograph of barite morphology revealed particles with tablet-shaped crystals 2 to 5 nm in size. With the presence of Sr2+ and Fe3+-cation, the shape of barium sulfate was modified into spherical tablets or flower-like clusters of tablets. Meanwhile, the morphological changes could result from increased stirring rates. Moreover, the kinetic results yielded a general reaction rate equation that might be used to estimate barium sulfate deposition in pipelines for various brine, supersaturation, and mixing time durations.
Tujuan penelitian ini adalah menganalisis pengaruh penambahan sari apel Manalagi terhadap aktivitias antioksidan, kadar protein, dan gula reduksi yoghurt susu kambing. Materi yang digunakan adalah ...susu kambing, stater komersial, sari apel Manalagi. Metode penelitian ini adalah eksperimental dengan rancangan acak lengkap 5 perlakuan dan 4 ulangan. Perlakuannya adalah penambahan sari apel 0% (P0), 4% (P1), 6% (P2), 8% (P3), dan 10% (P4). Analisis data menggunakan analisis ragam apabila ada pengaruh maka dilanjutkan dengan uji Duncan. Hasil penelitian menunjukkan bahwa penambahan sari apel Manalagi tidak berpengaruh (P<0,05) terhadap aktivitas antioksidan, kadar protein, dan gula reduksi. Penambahan 4% sari apel dalam yoghurt susu kambing menghasilkan aktivitas antioksidan sebesar 80,26%, kadar protein 4,18%, dan gula reduksi 3,44%. Simpulan penelitian ini adalah penambahan sari apel Manalagi sebanyak 4-10% tidak berpengaruh terhadap aktivitas antioksidan, kadar protein, dan gula reduksi yoghurt susu kambing. Perlu adanya penambahan konsentrasi sari apel Manalagi lebih dari 10% sehingga dapat digunakan untuk memperbaiki kualitas yoghurt susu kambing.
Pedagogical Content Knowledge (PCK) is the teacher's expertise gained since becoming a student. There are changes in PCK for prospective teacher students during lecture and changes can be seen based ...on the concept map. This study aims to analyze the changing profile of prospective PCK teachers based on concept maps. This study was conducted for biology education students at one of the private universities in West Java during the 2017/2018 school year. Participants are 6 people. Participants are asked to make a speciation concept map during evolution, micro teaching and PPL. Concept maps were analyzed using qualitative descriptive analysis. The results show changes in the concept map that includes changes in the form of concept maps from simple to complex, increasingly meaningful and easily understood as propositions, and only important concepts emerge. Based on this, PCK changes with increasing education and training experience of prospective teachers.
Abstract
Vegetable farming contributes major income to farm households in the upper Citarum watershed. The participation rate of farmers in vegetable farming reached 55%, indicating that this ...region’s farming is very intensive. However, the land holding of the vegetable farm is very diverse among farmers. The vegetable is also planted on a steep slope and is vulnerable to soil erosion. This condition implies low technological efficiency and high risk on production and profit. In addition, vegetable farming is indicated as the cause of soil erosion and sediment increase in the Citarum River. The study aims to analyze the vegetable farming pattern and profit variability in the upper Citarum watershed. The survey was conducted in the Citarum watershed Bandung and West Bandung District. The samples were farmers in the two districts who performed on-farm agriculture activities and randomly selected 499 farm households. The data were analyzed using descriptive statistics from 613 vegetable plots with 276 farm households out of 499 sample farm households. The Cumulative Distribution Function (CDF) was employed to analyze vegetable farming profit distribution. The results show that vegetable farming has a high risk. Farmers can lose significant money but also offer a high expected profit. Vegetable farming in Bandung District has a higher expected profit than in West Bandung. According to dominant commodities planted, the profit variability of tomato and chili is higher than cabbage and potato. Chili has the highest risks; over 30% of farmers had negative profits. To stabilize farmers’ incomes, improving farming technology and planting patterns suitable for vegetable farming on the upper and steep slopes and increasing access to market outlets and agricultural infrastructure in the upper Citarum watershed is necessary.
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