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Pengaruh kadar tambang (Cu) terhadap sifat mekanis aluminium matrix composite berpenguat alumina dibuat secara ekstruksi
No full textThe objective of this research is to find effect of copper on the mechanical properties of aluminium matrix composite (AMC), which is reinforced by alumina and made using hot extrusion. The amount of copper of 1;3 and 5wt% and 10wt% local alumina were added to the aluminium fine powder as matrix. Each was mixed using rotary mixer for 2hr. The mixture was then uniaxially compacted with a pressure 100 MPa to produce green body. The green body was then extruded at 600°C and ratio 4/9. Each composites was tested of bending strength, porosity. hardness and wear rate. From the data testing can be found effect of copper on the mechanical properties of AMC. The results show that mechanical properties decrease with inceasine of fraction of copper. The best mechanical properties such as bending strength, porosity, hardness and wear rate is on the AMC with 1wt% copper, there are 387 MPa, 0,5%, 80 VHN and 0,013 mg/MPa.m, respectivel
Pengaruh pemanasan selama pengelasan terhadap sifat mekanik hasil pengelasan baja K100 special K
No full textKekerasan dan laju keausan komposit aluminium diperkuat dengan keramik Zirconia yang dibuat dengan metode metalurgi serbuk
No full textPenelitian ini bertujuan untuk memanfaatkan bahan Zirconia (ZrO2)sebagai penguat komposit Aluminium Matrix Composite (AMC). Serbuk ZrO2 merupakan bahan kramik yang keras dan memiliki ketahanan terhadap temperature tinggi. Serbuk ZrO2 sebanyak 0%; 2,5%; 5%; 7,5%; 10%; 12,5% dan 15% fraksi berat dicampur dengan serbuk aluminium (ukuran serbuk lebih kecil dari 40 µm). Setiap campuran diaduk menggunakan turbula mixer selama 2 jam. Campuran serbuk aluminium dan ZrO2 dikompaksi secara uniaksial dengan tekanan 300 MPa dan diikuti sintering tanpa tekanan dengan lingkungan gas argon pada temperatur 600°C . Densitas relatif, kekerasan Vikers, dan laju keausan AMC diuji. Hasil pengujian menunjukkan bahwa kekerasan meningkat seiring dengan peningkatan fraksi berat ZrO2 sampai 5% sementara laju keausan turun. Densitas relatif, kekerasan Vikers dan laju keausan berturut turut pada komposit dengan fraksi berat ZrO2 5% adalah 91%, 35 VHN dan 0,01 mg/(MPa.M
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
OPTIMASI PROSES PEMBUATAN BRIKET BIOMASSA MENGGUNAKAN METODE TAGUCHI GUNA MEMENUHI KEBUTUHAN BAHAN BAKAR ALTERNATIF YANG RAMAH LINGKUNGAN (Optimization of Biomass Briquettes Production Process Using Taguchi Method)
Get PDFABSTRAK
Permasalahan yang dihadapi pembuat dan pengguna briket adalah briket yang dihasilkan kualitasnya rendah ditinjau dari nilai kalor. Tujuan penelitian ini adalah menentukan kualitas briket terbaik dari limbah biomassa dalam memenuhi kebutuhan bahan bakar alternatif rumah tangga yang murah dan ramah lingkungan guna mewujudkan masyarakat mandiri energi. Metode yang digunakan untuk menentukan kualitas briket adalah metode Taguchi. Variabel bebas dalam penelitian ini adalah tekanan pengepressan, waktu penahanan, model cetakan, suhu pengeringan, lama pengeringan dan komposisi bahan, sedangkan variabel terikat adalah nilai kalor briket. Hasil penelitian menunjukkan bahwa kualitas briket terbaik ditinjau dari nilai kalor tertinggi yaitu pada setting parameter A2B1C2D2E2F1, artinya tekanan pengepressan 225 kg/cm2, waktu penahanan 5 menit, model cetakan sarang tawon (kotak), suhu pengeringan 60 °C, lama pengeringan 3 hari, perbandingan limbah jarak pagar : arang sekam : arang tempurung kelapa : perekat adalah 5 : 3: 2 : 1. Rata-rata nilai kalor biobriket yang dihasilkan sebesar 5.323 kal/g. Hal ini menunjukkan bahwa briket mempunyai nilai kalor yang tinggi dan memenuhi SNI, sehingga briket layak untuk memenuhi kebutuhan bahan bakar alternatif yang ramah lingkungan.
ABSTRACT
Problems that encountered on manufacturers and users of briquettes is low quality of the briquettes in terms of heat value. The aim of this research is to determine the best quality of the briquette which is made from biomass waste. The briquette is expected to be used to fulfill the need of inexpensive and environmentally friendly of alternative household fuel, by which the energy independent community could be realized.The method used to determine the quality of the briquette is Taguchi method. The independent variables involved are compressive strength, holding time, mold model, drying temperature, drying time and material composition. The dependent variable is the highest heat value of the briquette. The results show that based on the highest heat value, the best briquette quality is parameter setting of A2B1C2D2E2F1, which means that the compressive strength is 225 kg/cm2, the holding time is 5 minutes, the mold model is honeycomb of box, drying temperature is 60 °C, drying time is 3 days and the ratio of Jatropha Curcas waste : rice husk charcoal : coconut shell charcoal : adhesive is 5 : 3: 2 : 1. The average heat value of briquette is 5,323 cal/g. This matter the briquettes show that high heat value and feasible of recommendation by SNI, and so briquette decent to fulfill the need of environment friendly alternative fuel
Pemanfaatan Limbah Abu Terbang Sebagai Penguat Aluminium Matrix Composite
No full textPenelitian ini bertujuan untuk memanfaatkan abu terbang sebagai penguat komposit bermatrik aluminium (AMC). Abu terbang merupakan limbah pembakaran batu bara pada pembangkit listrik tenaga uap. Abu terbang sejumlah 2,5%; 5%; 7,5% dan 10% berat tercamput dengan serbuk aluminium (ukuran serbuk lebih kecil dari 40 µm). Setiap campuran diaduk menggunakan rotay mixer selama 3 jam. Campuran aluminium dan abu terbang dikompaksi secara uniaksial dilanjutkan kompaksi secara isostatik dengan tekanan 100 MPa dan diikuti sintering tanpa tekanan dengan lingkungan gas argon dan variasi temperatur 500°C, 525°C, 550°C, 575°C dan 600°C. Kekuatan banding, kekerasan Vickers, ketahanan aus dan densitas komposit diuji serta struktur mikro diamati menggunakan SEM. Hasil pengujian menunjukkan bahwa sifat mekanis meningkat seiring dengan peningkatan fraksi berat abu terbang sempai 5% berat, selebihnya terjadi penurunan. Kekuatan banding, kekerasan Vickers, porositas dan laju keausan berturut-turut 74 MPa, 66 VHN, 4,5% dan 0,04 mg/(MPa.m)
Utilization of fly ash waste as reinforcement of aluminium matrix composite produced using powder metallurgy (Pemanfaatan Limbah abu terbang sebagai penguat aluminium metal matrix composite dibuat dengan cara metalurgi serbuk)
No full textAluminium matrix composite (AMC) has been prepared from aluminium fine powder as a matrix and fly waste as reinforcement. In this research the amount of fly ash as much as 2,5, 5, 7,5 and 10 wt% was added to the aluminium fine powder. The mixture was compacted using uniaxial with a pressure of 100 MPa and it was pressureless sintered in argon atmosphere at various temperature of 500°, 525°, 550°, 575° and 600°C. Bending strength of AMC was determined using four point bending, hardness was tested using Vickers method, wear rate was tested using pin on disk method. Porosity was tested using Archimedes method and the micro structure was observed using SEM. The result shows that fly ash can be used as reinforcement of AMC. The bending strength and Vickers hardness of AMC increase, wear rate and porosity of AMC decrease with increasing the fly ash content up to 7.5 wt%, while fly ash higher than 7,5 wt% causes a decrease. Porosity, bending strength, wear rate and hardness of AMC are 5,4%, 68,5 MPa, 0,0571 mg/(MPa.m) and 62,6 VHB, respectively. It shows that bending strength, hardness and wear resistance of AMC are higher than pure aluminium
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