Tinjauan Proses Pembentukan dan Penggunaan Arang Tempurung Kelapa sebagai Bahan Bakar

Serbuk arang tempurung kelapa dalam bentuk briket telah dimanfaatkan sebagai bahan bakar pengganti yang alami khususnya untuk keperluan rumah tangga dan USAha kecil. Sebagai bahan bakar, sifat termal arang termpurung kelapa adalah penting dan bergantung pada struktur dan komposisinya yang juga dipengaruhi oleh parameter proses pembentukannya yang meliputi proses pirolisis, pengilingan, pencampuran, pencetakan hingga pengeringan. Tulisan ini merupakan kajian awal mengenai proses pembentukan briket arang tempurung kelapa serta pemanfaatnya sebagai bahan bakar pengganti yang alami

Modeling Of Reactively Sputtered TiAIN Coating On Tungsten Carbide Insert Tool : Its Properties And Cutting Performance In Dry Turning Of AISI D2 Steel

An extended theoretical model of reactive sputtering of TiAlN coating has been developed to study the effect of substrate bias (Vb) and nitrogen (N2) flow rate on the coating composition and deposition rate. The model simulation results showed that the critical N2 flow rate (fn2) to achieve a stoichiometry composition of unbiased (Vb = 0 V) and biased (Vb = -80 V) substrate was 4 seem and 3 seem, respectively. At N2 flow rate lower than fN2, the coating composition increased with an increase in Vb and N2 flow rate due to the increase of ion flux to the substrate while the deposition rate decreased due to the coating densification and the decreased sputtering rate. At N2 flow rate higher than fN2, the coating composition and deposition rate did not depend on the Vb and N2 flow rate due to the domination of neutral particles deposition than ions deposition. The model verification using secondary data showed an accurately prediction on the coating composition and deposition rate at N2 flow rate higher than [N/. The calculated coating composition at N2 flow rate lower than fN2 showed a deviation due to heterogeneous reactions between the sputtered particles (Ti and AJ) and N at the substrate surface, while the deviation of calculated deposition rate was due to coating densification. The experimental investigation was designed by using Response Surface Methodology (RSM) and conducted by using magnetron sputtering in deposition of TiAIN coating on WC inserts. The coating composition and thickness were obtained by using SEM/EDX. The coating structure and morphology were obtained by using XRD and AFM, respectively. The coating hardness and adhesion were obtained by using ultra-micro hardness test and indentation test,respectively. The cutting test was carried out in CNC dry turning of AISI D2 steel. The flank wear and surface roughness were obtained by using optical microscopy and surface roughness tester, respecti,·ely. The results showed that generally the coating composition of biased substrate (- I 00, -150, -200 V) was consistently higher than that of unbiased substrate whereas the deposition rate o r biased substrate is lower than that of unbiased substrate. Analysis of the coating thickness showed that generally the coating thickness decreased with an increase , in the Vb and . N2 flow rate. At N2 flow rate lower than 50 sccm,the thinnest coating(- 1000 nm) is achieved by unbiased substrate due to low ions fluxes for reaction at the substrate surface. The coating hardness, structure and morphology were significantly influenced by the V b while' the interaction of the Vb and N2 flow rate significant ly influenced the coating adhesion. The coating hardness increased (-7 GPa)with an increase in the V b up to -200 V due to decreased coating crystal size. At N2 flow rate of 70 seem, the adhesion strength increased with an increase in the Vb up to -200 V due to decreased compressive stress.The lowest flank wear (-0.4 mm) due to high adhesion strength was achieved at -200 \' and 70 seem

X-ray Photoelectron Spectroscopy (XPS) Analysis of Undoped ZnO and ZnO:Er Thin Films

Undoped ZnO and ZnO:Er  thin films were deposited on p-type Si substrates by ultrasonic spray pyrolisis (USP). Undoped and ZnO:Er thin films have been analyzed by using X-ray Photoelectron Spectroscopy (XPS). The results show that the XPS spectrum has two Er peak at ∼157 eV and ∼168 eV. The XPS Zn 2p spectrum of undoped ZnO and ZnO:Er thin films have binding energy for Zn 2p3/2 (~ 1021 eV) and Zn 2p1/2 (~1045eV) were found no shift in binding energy after the incorporation of Er. Meanwhile, after Er incorporates into ZnO, the O 1s spectrum is composed two peak of binding energy (BE) at ~530.5eV and the shoulder about 532.5 eV.Keywords: ZnO thin films, ZnO:Er, XPS, binding energ

Pemanfaatan Briket Arang Tempurung Kelapa Sebagai Sumber Energi Alternatif

ABSTRACT: The use of charcoal briquettes contributes to the reduction of dependence on petroleum and gas fuels, especially for small urban communities while at the same time supporting the utilization of coconut shell waste as fuel. Consumption of coconut (cocos nucifera), especially as a coconut milk in Jakarta is large enough to contribute to produce coconut shell waste in the market. Generally, coconut shell waste has been used as charcoal fuel. However, the formation of coconut shell charcoal briquettes provides advantages over charcoal such as not smoky, clean and easy to pack. Furthermore, the utilization of coconut shell charcoal briquette is in line with the solution of current global problems related to pollution (pollution), alternative energy and environmentally friendly technologies. Therefore, the increased understanding and awareness through the use of briquettes, especially for the small urban community through training the formation and use of coconut shell charcoal briquettes as fuel need to be done so that the function and its objectives are achieved. The training was conducted with the number of participants of approximately 20 people also involve students as the spearhead in providing understanding and awareness using the workshop facility of coconut shell charcoal briquette's formation at FMIPA Universitas Negeri Jakarta. The training includes the formation of coconut shell charcoal briquettes from coconut shell removal, burning (pyrolysis), grinding to printing and drying (drying). Then tested the use of briquettes for cooking water.   ABSTRAK: Penggunaan briket arang tempurung memberikan kontribusi pada pengurangan ketergantungan pada bahan bakar minyak dan gas khususnya bagi masyarakat kecil di perkotaan dan pada saat yang bersamaan mendukung pemanfaatan sampah tempurung kelapa sebagai bahan bakar. Konsumsi buah kelapa (cocos nucifera) tua khususnya sebagai santan di Jakarta cukup besar sehingga turut andil dalam menghasilkan sampah tempurung kelapa di pasar. Umumnya sampah tempurung kelapa telah dimanfaatkan sebagai arang bahan bakar. Namun demikian pembentukan briket arang tempurung kelapa memberikan kelebihan dibandingkan arang seperti tidak berasap, bersih dan mudah kemas. Lebih jauh pemanfaatan briket arang tempurung kelapa sejalan dengan penyelesaian permasalahan global saat ini yang berkaitan dengan polusi (pencemaran), energi alternatif dan teknologi yang ramah lingkungan. Untuk itu peningkatan pemahaman dan kesadaran akan penggunaan briket khususnya bagi masyarakat kecil perkotaan melalui pelatihan pembentukan dan penggunaan briket arang tempurung kelapa sebagai bahan bakar perlu dilakukan agar fungsi dan tujuannya tercapai. Pelatihan yang dilaksanakan dengan jumlah peserta kurang lebih 20 orang juga melibatkan mahasiswa sebagai ujung tombak dalam memberikan pemahaman dan kesadaran tersebut dengan menggunakan fasilitas bengkel pembentukan briket arang tempurung kelapa di FMIPA Universitas Negeri Jakarta. Pelatihan meliputi proses pembentukan briket arang tempurung kelapa mulai dari pembersihan tempurung kelapa, pembakaran (pirolisis), penggilingan hingga pencetakan dan penjemuran (pengeringan). Kemudian dilakukan uji coba pemakaian briket untuk memasak air.Kata Kunci: arang tempurung kelapa, briket, pirolisis, pembakaran

Design and Contruction of Vertical Axis Wind Turbine Triple-Stage Savonius Type as the Alternative Wind Power Plant

A vertical axis wind turbine triple-stage savonius type has been created by using simple materials to generate electricity for the alternative wind power plant. The objective of this research is to design a simple wind turbine which can operate with low wind speed. The turbine was designed by making three savonius rotors and then varied the structure of angle on the three rotors, 0˚, 90˚ and 120˚. The dimension of the three rotors are created equal with each rotor diameter 35 cm and each rotor height 19 cm. The turbine was tested by using blower as the wind sources. Through the measurements obtained the comparisons of output power, rotation of turbine, and the level of efficiency generated by the three variations. The result showed that the turbine with angle of 120˚ operate most optimally because it is able to produce the highest output power and highest rotation of turbine which is 0.346 Watt and 222.7 RPM. Keywords: Output power; savonius turbine; triple-stage; the structure of angl

Coconut Shell Activated Carbon as an Alternative Renewable Energy

Research coconut shell activated carbon as an alternative renewable energy has been done. Coconut shell activated carbon is processed into fuel that can replace coal. Coconut shell densely textured, hard, and old became a mainstay to be used as activated carbon. The process of forming into a coconut shell coconut shell activated carbon made by drying, pyrolysis, and carbonization. After it was examined DSC and SEM, so the coconut shell activated carbon obtained temperature of 500 0C is activated carbon which can produce the greatest heat and durable because of the many elements contained carbon and many pores are formed. Keywords: activated carbon; alternative renewable energy; coconut shell

DEVELOPMENT OF TEACHING AID OF ELECTROMETER IN PHYSICS LEARNING

The aim of this research is to develop teaching aid of electrometer based on Coulomb’s law for twelfth grade of Senior high school and university students studying on fundamental physics. This research is done on december 2013 at laboratory of physics education, State University of Jakarta. The teaching aid of electrometer was demonstrated in physics learning to fifteen university students participating as test object. Method used in this research is research and development. Result of need analysis shows that development of teaching aid of electrometer is needed in physics learning. Teaching aid of electrometer is teaching aid used to help students understanding Coulomb’s law. Teachers doing experiment, lecturers teaching fundamental physics, and university students doing research about coulomb’s law can use the teaching aid of electrometer. The teaching aid is validated by media and concept experts in Likert scale. Result of validation given by concept and media experts and result of field test by university students assert that the teaching aid of electrometer is very good and interpretation scores are 85% from concept experts, 88% from media experts, and 84% from field test. Based on the data, it is concluded that teaching aid of electrometer can help physics learning in understanding Coulomb’s law

The Development of Web-based Instructional Media for Teaching Wave Physics on Android Mobile

This study aims to develop an Android app to support learning activities consisting of mobile applications and web server applications. Mobile applications have two applications: teacher apps and student applications, while web server applications are used by teachers and administrators. Mobile apps run on Android smartphones, while web server applications are in Chrome web browsers. In mobile applications, students can view material with pictures and videos, do online tests, perform tasks, view simulations, view announcements in the form of updates made by teachers, and see recap test scores, assignments, exams, and final score in a chapter. In a mobile application, the teacher can see how many times students access the material, view the student's time notice in performing tests and tasks, view the test scores, duties, exams and the final grade of each student who is registered on the web server. Administrator applications on the web server focus more on managing the data that will changes. This application can run on Android operating system Jelly Bean and above. The development used refers to the ADDIE model with the following stages: 1) Analysis, 2) Design (design / design), 3) Development (development), and 4) Evaluation (evaluation / feedback). The developed media has been validated by subject experts, media experts and high school physics teachers with average percentage of all aspects of subject experts is 85.50%, media experts 85.20% and physics teachers 90%, based on these results show that mobile learning android platform based on web service proper to use as a media of physics learning

The Development of Thermal Expansion Practicum Sets to Improve Science Process Skills of High-School Students

This study aims to develop thermal length expansion practicum sets that are expected to improve high-school science process skills (SPS) in expansion material on metal rods. This research was conducted at SMAN 2 Bekasi in class XI by comparing the control and the experimental class. This study uses the ADDIE approach to analyze, design, develop, implement, and evaluate the thermal expansion length practicum sets. The feasibility test of this practicum sets was carried out in two ways: conducting experiments and validating tests from experts. The experimental results for the linear expansion coefficient of an iron bar are 3.09%, the brass is 5.81%, and the aluminum is 7.39% from the reference value. All of the experimental data still below the error acceptance level which is below 10%. The validation results give 85.5% from media experts and 86.1% from material experts. The trials on users obtained 93.9% of teachers and 85.4% of students. The N-gain in control and experiment class then compared to see the increase in SPS in each category. There was an increase in the experimental class SPS value 7.3% higher than the control class, where the SPS value in the experimental class increased by 47.8%. Therefore, it can conclude that the thermal expansion practicum sets is feasible to use and can improve the science process skills of high school students