Metallurgy Commons^™

Modification Of Flow Structure Over A Van Model By Suction Flow Control To Reduce Aerodynamics Drag, Harinaldi Harinaldi, Budiarso Budiarso, Warjito Warjito, Engkos Achmad Kosasih, Rustan Tarakka, Sabar Pangihutan Simanungkalit, I Gusti Made Fredy Lay Teryanto

Makara Journal of Technology

Automobile aerodynamic studies are typically undertaken to improve safety and increase fuel efficiency as well as to find new innovation in automobile technology to deal with the problem of energy crisis and global warming. Some car companies have the objective to develop control solutions that enable to reduce the aerodynamic drag of vehicle and significant modification progress is still possible by reducing the mass, rolling friction or aerodynamic drag. Some flow control method provides the possibility to modify the flow separation to reduce the development of the swirling structures around the vehicle. In this study, a family van is modeled …

Optimizing Fermentation Medium To Produce Cyclosporin A Using Response Surface Methodology, Rofiq Sunaryanto

Makara Journal of Technology

Response surface methodology (RSM) is a three factorial model which illustrates the relationship between one or more independent variables. RSM can be used to optimize the fermentation medium for the production of Cyclosporin A from the isolate Tolypocladium inflatum. The optimal point of the response surface area is predicted by using a seconddegree polynomial model and applying the statistic model obtained from the central composite design (CCD). The results of optimizing the fermentation medium for Cyclopsorin using the three independent variables of glucose, casein, and KH2PO4 show that all three of the independent variables affect the production of Cyclosporin A. …

Age, Gender, And Muscle Strength: A Study Based On Indonesian Samples, Henny Henny, Hardianto Iridiastadi, Iftikar Zahedi Sutalaksana

Makara Journal of Technology

Age and gender have been commonly used as a main criterion in accepting a job aplicant, but it is usually not clear how these affect job performance. While a number of recent studies have been done that describe the relationships between age, gender, and participants capacity (e.g., muscle strength), the results have been inconclusive. In Indonesia, in particular, such issues have been rarely investigated, and it is still important to study the issue since the relationships between these factors are population-specific. This study aimed at describing the relationships between age and muscle strength among workers for both genders. Ninety-six male …

Circularly Polarized Microstrip Array Antenna For Ground Segment In Quasi-Zenith Satellite System, Fitri Yuli Zulkifli, Eko Tjipto Rahardjo

Makara Journal of Technology

In satellite communication system, antenna plays an important role. Therefore, the antenna must meet some requirements, such as high gain, circular polarization, and good directivity. In this paper, a four element linear array triangular patch microstrip antenna with cross slot is designed to be used for Quasi-Zenith satellite system. A simulation study as well as experimental study was carried out. The simulation showed that the 3 dB axial ratio bandwidth of 87 MHz (2.569-2.656 GHz) is achieved while the measured results showed 96 MHz (2.556-2.652 GHz). The linear array of 4 element antenna has a gain of 13.73 dB and …

Tolerance Limit For Trucks With Excess Load In Transport Regulation In Indonesia, Sigit Pranowo Hadiwardoyo, Raden Jachrizal Sumabrata, Mohammed Ali Berawi

Makara Journal of Technology

Reliability of a road is mandatory since damaged will impede the traffic. Destruction is caused by various factors; one of the most important factors is excess load. Overload may give the load of each axle of a vehicle exceeds the determined standard. This condition occurs in trucks exceeding the load limit. In designing the structure of a road based on the method of Directorate General of Highways Ministry of Public Works of the Republic of Indonesia, axle load calculated in equivalent-number, or known as equivalent axle load (EAL), of 8.16 tons of standard axle. Total equivalent-number over the service life …

Earthquake Damage Intensity Relationship For Residential Houses In West Sumatra, Febrin Anas Ismail, Abdul Hakam, Fauzan Fauzan

Makara Journal of Technology

The Sumatra 30 September 2009 earthquake has damaged hundred thousand buildings in West Sumatra Province. The earthquake is located in 100 km offshore of Padang City, the Capital City of the province. Survey has been conducted to assess the damage of the building in few days after the earthquake. In this survey, the damage of buildings are categorised into 3 level that are heavily, moderate and slightly damages. This paper explores the level damage of building and then the intensity of the shaking in the affected area. Then based on the coordinate of every building location, the buildings are scattered …

Evaluation Of Universitas Indonesia’S Recharge Pond Performance And Potential Utilization For Raw Water Source, Nyoman Suwartha, Resky Agaslian Pramadin

Makara Journal of Technology

Evaluasi Kinerja Waduk Resapan UI dan Potensi Pemanfaatannya sebagai Sumber Air Baku. Waduk resapan Universitas Indonesia (UI) telah dibangun sejak 5 tahun yang lalu. Namun kegiatan monitoring dan evaluasinya sangat minim dilakukan. Tujuan dari studi ini adalah untuk mengetahui laju resapan, dan untuk mengevaluasi kondisi kuantitas dan kualitas air waduk resapan selama musim kemarau dan penghujan. Pengukuran kedalaman muka air, intensitas curah hujan dan penguapan dilakukan untuk menentukan ketersediaan air, laju resapan, dan imbangan air waduk. Sejumlah air permukaan diambil dari waduk resapan dan sungai di tiga titik sampling untuk mengetahui kondisi kualitas air eksisting. Hasil studi menunjukkan tidak ada …

Effect Of Methanol Induction And Incubation Time On Expression Of Human Erythropoietin In Methylotropic Yeast Pichia Pastoris, Adi Santoso, Neng Herawati, Yana Rubiana

Makara Journal of Technology

Erythropoietin (EPO) is a glycoprotein hormone consists of 165 amino acids and has molecular mass of 30,400 Daltons. The large quantities of these hormone required to satisfy clinical demand are currently met by recombinant expression in mammalian cell, namely chinese hamster ovary (CHO). Pichia pastoris has become popular yeast based protein production systems to substitute mammalian expression systems. P. pastoris is capable to use methanol as sole carbon and energy source. In this study, recombinant human EPO (rhEPO) protein obtained by expressing the hEPO gene in methylotropic yeast P. pastoris, strain X33. The present work was carried out to study …

Fuel Saving Strategy In Spark Ignition Engine Using Fuzzy Logic Engine Torque Control, Aris Triwiyatno, Sumardi Sumardi

Makara Journal of Technology

In the case of injection gasoline engine, or better known as spark ignition engines, an effort to improve engine performance as well as to reduce fuel consumption is a fairly complex problem. Generally, engine performance improvement efforts will lead to increase in fuel consumption. However, this problem can be solved by implementing engine torque control based on intelligent regulation such as the fuzzy logic inference system. In this study, fuzzy logic engine torque regulation is used to control the throttle position entered by the driver to achieve optimal engine torque. An engine torque vs. throttle position and engine speed mapping …

An Agri-Food Supply Chain Model To Enhance The Business Skills Of Small-Scale Farmers Using Corporate Social Responsibility, Wahyudi Sutopo, Muh. Hisjam, Yuniaristanto Yuniaristanto

Makara Journal of Technology

In general, small-scale vegetable farmers experience problems in improving the safety and quality of vegetables for supplying high-class consumers in modern retailers. Farmer Group and/or Cooperative (FGC) should be able to assist its members to meet the relevant provisions of modern retail on product specifications, delivery terms, and internal business requirements. This study proposed an agri-food supply chain (ASC) model that involves the corporate social responsibility (CSR) activities to enhance the business skills of the FGC as supplier of modern retailer. Multi-objective optimization programming is developed to determine the amount and timing of supply, level of farmers training skills, quality …

Pineapple Liquid Waste As Nata De Pina Raw Material, Agus Sutanto

Makara Journal of Technology

This research aims to study the quantity, quality, ecological and economic feasibility of nata de pina production (NP) from pineapple liquid waste (PLW). The design of the study employs complete random design (CRD) with three treatments: PLW without nutrients addition (A), PLW nutrients addition (B), and PLW stored for six months with nutrients addition (C). The nata de pina’s production factors measured were weight, thickness, fiber content, color, brightness, and residual waste. The highest weight was reached in treatment B (899 grams), followed by treatment A (616.4 grams), and C (477.8 grams). The thickness of NP of the height and …

Modeling Of A New Structure Of Precision Air Conditioning System Using Secondary Condenser For Rh Regulation, Aries Subiantoro, Nasruddin Nasruddin, Feri Yusivar, Muhammad Idrus Al-Hamid, Bagio Budiardjo

Makara Journal of Technology

A dynamic mathematical model for a new structure of precision air conditioning (PAC) has been developed. The proposed PAC uses an additional secondary condenser for relative humidity regulation compared to a basic refrigeration system. The work mechanism for this system and a vapour-compression cycle process of the system are illustrated using psychrometric chart and pressure-enthalpy diagram. A non-linear system model is derived based on the conservation of mass and energy balance principles and then linearized at steady state operating point for developing a 8th-order state space model suited for multivariable controller design. The quality of linearized model is analyzed in …

Microstructure Selection Of Sm–Co–Al Alloys To Increase Magnetization, Brian Dick

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

An ever increasing demand for higher performing magnets drives the need for new and innovative methods to achieve this goal. Sm-Co rare earth permanent magnets have a unique eutectic microstructure that, through refinement, could become a two-phase magnet which would significantly increase their energy product. The eutectic structure of Sm₈Co₉₂ is comprised of αCo rods embedded within a Sm₂Co₁₇ matrix. If the rods are small enough to encourage exchange coupling and the matrix is smaller than the single domain limit, then an efficient two-phase magnet is created.

Refining the Co rods and matrix size …

Hot Deformation Behavior Of Friction-Stir Processed Strip-Cast 5083 Aluminum Alloys With Different Mn Contents, M. A. García-Bernal, Rajiv S. Mishra, R. Verma, D. Hernández-Silva

Materials Science and Engineering Faculty Research & Creative Works

Fine grained 5083 aluminum alloy is the most common Al-Mg alloy for superplastic forming (SPF) of lightweight sheet metal parts in the automotive and aerospace industries. the fine-grained sheet is industrially produced by massive cold rolling of conventionally rolled sheet stock at high cost. Friction stir processing (FSP) as a thermomechanical process is very effective in refining the microstructure of as-cast alloys such as that produced by continuous strip casting (CC). in this work, the effect of friction stirs processing on the superplastic properties of three CC 5083 aluminum alloys, with different Mn content, has been investigated. the three alloys …

Time-Dependent Fatigue Crack Propagation Behavior Of Two Solid-Solution-Strengthened Ni-Based Superalloys—Inconel 617 And Haynes 230, Longzhou Ma, Shawoon K. Roy, Muhammad H. Hasan, Joydeep Pal, Sudin Chatterjee

Environmental Studies Faculty Publications

The fatigue crack propagation (FCP) as well as the sustained loading crack growth (SLCG) behavior of two solid-solution-strengthened Ni-based superalloys, INCONEL 617 (Special Metals Corporation Family of Companies) and HAYNES 230 (Haynes International, Inc., Kokomo, IN), were studied at increased temperatures in laboratory air under a constant stress-intensity- factor (K) condition. The crack propagation tests were conducted using a baseline cyclic triangular waveform with a frequency of 1 3 Hz. Various hold times were imposed at the maximum load of a fatigue cycle to study the hold time effect. The results show that a linear elastic fracture mechanics (LEFM) parameter, …

A Front Tracking Model Of The Maxus-8 Microgravity Solidification Experiment On A Ti-45.5at.% Al-8at.%Nb Alloy, Robin Mooney, Shaun Mcfadden, Marek Rebow, David J. Browne

Articles

On 26th March 2010 the MAXUS-8 sounding rocket was launched from the Esrange Space Center in Sweden. As part of the Intermetallic Materials Processing in Relation to Earth and Space Solidification (IMPRESS) project, a solidification experiment was conducted on a Ti-45.5at.%Al-8at.%Nb intermetallic alloy in a module on this rocket. The experiment was designed to investigate columnar and equiaxed microstructures in the alloy. A furnace model of the MAXUS 8 experiment with a Front Tracking Model of solidification has been developed to determine the macrostructure and thermal history of the samples in the experiment. This paper gives details of results of …

Plastic Strain Accommodation And Acoustic Emission During Melting Of Embedded Indium Particles In Aluminum, Michael M. Kuba

Masters Theses

"Melting of micron-sized (0.2 to 3 µm diameter) indium particles embedded in an aluminum matrix was discovered to produce acoustic emission. Melting of embedded immiscible particles produces a pure dilation during the phase transformation and has no long-range diffusion field to control the speed of transformation. It was found that acoustic emission can no longer be considered as a criterion of displacive transformations and that melting of micron-sized embedded particles is strain energy controlled. Acoustic emission was confirmed to result from the rapid relaxation of aluminum around indium particles embedded on grain boundaries. Prismatic punching of dislocation loops is proposed …

Directional Anisotropy In The Mechanical Behavior Of Friction Stir Processed And Aged Az91 Alloy, Vipin Jain, Wei Yuan, R. S. Mishra, Gouthama, Anil K. Gupta

Materials Science and Engineering Faculty Research & Creative Works

Friction stir processing (FSP) is an emerging grain refinement technique for magnesium alloys. in this study, a cast AZ91 alloy was processed by a single-pass FSP to achieve an average grain size of ∼6 μm in the nugget zone. the FSP is found to introduce texture in the alloy due to preferred alignment of basal poles in the processing direction. the mechanical behavior is significantly influenced by texture. after FSP, the alloy was aged at different temperatures and times for continuous and discontinuous precipitation of β-Mg17Al12. a high anisotropy in yield stress is observed in the processing and transverse direction …

Development Of Third Generation Advanced High Strength Steels, Meghan C. Mcgrath

Doctoral Dissertations

"Lightweight duplex steels with combinations of either bainite, acicular ferrite, and austenite or martensite and austenite were investigated as third generation advanced high strength steels targeted for automotive applications. Large additions of manganese (>13 wt%) and carbon (

Duplex steels with different volume fractions of primary δ -ferrite were used to study the crystallography of austenite formed during the peritectic reaction. Solute profiles across the peritectic interface showed aluminum segregated near the interface which promoted bainitic ferrite formation. Thermal treatments were used to manipulate the concentration and type of oxides and the ferrite plate density was found to correlate …

Friction Stir Welding Of High Temperature Alloys, Jiye Wang

Doctoral Dissertations

"Friction stir welding (FSW) of Ti-6Al-4V alloy, nickel-based and iron-based oxide dispersion strengthened (ODS) alloys (MA754 and MA956) has been studied. The main aspects covered include tool evaluation, microstructural evolution, mechanical properties, and correlation between processing, microstructure and mechanical properties. Tool performance study was carried out for Ti-6Al-4V alloy with refractory tools made of W-1.1%La₂O₃ and two different grades of WC-Co based materials. The results showed that tool degradation can be attributed to mechanical and chemical interaction with processed material. The nature of tool-workpiece interaction was tool material dependent and influenced the resultant microstructure and weld quality in the stirred …