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Semesta Teknika
Published by Universitas Muhammadiyah Yogyakarta
ISSN : 1411061X     EISSN : 25025481     DOI : https://doi.org/10.18196/st
Core Subject : Engineering,
Engineering
SEMESTA TEKNIKA is a reputable refereed journal devoted to the publication and dissemination of basic and applied research in engineering. SEMESTA TEKNIKA is a forum for publishing high quality papers and references in engineering science and technology. The Journal is published by the Faculty of Engineering, Universitas Muhammadiyah Yogyakarta, INDONESIA. Copyright is by the publisher and the authors. The Journal is issued in electronic form and also issued in printed form as annual volume for the contributors only. The journal contains original research papers, review articles, short notes and letters to the editors. The topics of interest include modeling, experimental, analytical and numerical investigations on the mechanical, physical, chemical and mineralogical properties of material, developing the prototype/instrument, technology and construction process. Topic of management in industry and civil construction is also considered. SEMESTA TEKNIKA receives manuscripts from the contributor written in the Indonesian and English. Manuscripts submitted to the journal for publication must not have been previously published or is under consideration simultaneously by any other publication. Manuscripts submitted to SEMESTA TEKNIKA will be reviewed Peer Reviewers local and foreign.
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Articles 715 Documents
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Perpindahan Kalor pada Penukar Kalor Selongsong dan Pipa Memakai Sekat Miring Tidak Sejajar Muhammad Nadjib
Semesta Teknika Vol 15, No 1 (2012): MEI 2012
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v15i1.441

Abstract

Generally speaking, baffle installation of a shell-and-tube heat exchanger is in straight-standing with respect to shell axis. A common problem of this arrangement is that there will be found a stagnant fluid condition in the death-zone. The impact is the heat transfer coefficient could not reach an optimum value. Based on baffle configuration, the death-zone effect can be minimized by installing an un-parallel tilted baffle. The purpose of this research is to investigate the effect of using non-parallel tilted baffle on heat transfer coefficient. The heat exchanger model was made with single pass fluids. Hot water is going through inside the tube bundles and cold water pass is in the shell. The baffle was installed in various angle of 0°, 15°, 30°, and 45° with respect to shell axis. The cold water flow rates were varied from 75 l/hr, 100 l/hr, 125 l/hr, 150 l/hr, 175 l/hr, to 200 l/hr. The hot water flow rate was fixed at 150 l/hr. Temperature of the hot and cold water at inlet and outlet was recorded by means of K type thermocouple and data logger. The data was then analyzed to obtain the convection heat transfer coefficient. The data were also used to determine the empirical correlation of Nusselt number and Reynolds number. The results indicate that baffle in angle 0° produce the highest convection heat transfer coefficient. Installing the baffle at tilted position is not significant in convection heat transfer coefficient. The empirical correlation of Nusselt number and Reynolds number is influenced by angle function of the baffle.
Perilaku Antarmuka Berdasarkan Data Beda Tekanan pada Peristiwa Kondensasi Aliran Uap Dengan Pendinginan dari Luar Searah pada Pipa Horisontal Berbasis Domain Waktu Sukamta Sukamta; Hasan Asy Ari Dwiearto; Sudarja Sudarja
Semesta Teknika Vol 21, No 1 (2018): MEI 2018
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.211214

Abstract

A two-phase flow pattern experiment on the condensation event of steam flow with external cooling based on the measurement of pressure difference within a horizontal pipe is carried out by varying the superficial velocity. Annulus pipes with inner pipe material made of copper and outer pipe made of galvanized iron (GIP) within an insulation of 10 mm thick were used in this experiment. The length of the pipe is 1.6 meters, outer diameter of 4 inch and inner diameter of 17 mm. The two-phase flow pattern was investigated based on differential pressure fluctuations between the inlet and outlet. To support the observation, flow pattern visualization was performed using a transparent pipe with a diameter of ¾ inch and a length of 1.3 meters connected to the test pipe section. The superficial vapor velocity was carried out from JG = 0.0689 m/s to JG = 1,9117 m/s. The results showed stratified flow patterns for the lowest superficial velocity and also obtained wavy, wavy-slug, and slug. Annular flow patterns can not be observed in this experiment. In general, increasing superficial velocity of steam will cause a significant increase in pressure fluctuations.
Aplikasi Jaringan Neural Untuk Pencegahan Kendali Pengukuran Keamanan Dinamis Dari Sistem Daya Terisolasi Dengan Pembaharuan Samsul Bachri
Semesta Teknika Vol 9, No 1 (2006): MEI 2006
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v9i1.876

Abstract

Paper ini mempresentasikan sebuah jaringan neural tiruan (ANN) pendekatan yang didasarkan untuk definisi dari strategi kendali pencegahan dari sistem kuasa otonomi dengan penetrasi kuasa dapat diperbaharui besar. Karena titik operasi ditentukan, suatu evaluasi keamanan yang dinamis cepat untuk suatu gangguan angin ditetapkan dilakukan dengan menggunakan suatu ANN. Jika ketidakkokohan dideteksi, alternatif baru titik operasi stabil diusulkan, menggunakan suatu bastar ANN-OPTIMISASI mendekati cek itu beberapa berbagai kemungkinan, sebagai hasil perubahan berkuasa yang diproduksi oleh diesel dan generator angin, dan kombinasi unit diesel yang lain sedang bekerja. Hasil memperoleh dari simulasi computer menyangkut sistem kuasa yang riil Lemnos (Yunani) mendukung kebenaran dari  pendekatan dikembangkan.
Beton Mutu Tinggi dengan Admixture Superplastisizer dan Aditif Silicafume As’at Pujianto
Semesta Teknika Vol 14, No 2 (2011): NOVEMBER 2011
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v14i2.550

Abstract

Increasing concrete strength is one of the main necessities of concrete technology. For more than the last 20 years, high strength concretes with compressive strength ranging from 50 MPa up to 140 MPa have been used worldwide in high rise buildings and bridges with long spans, or buildings in aggressive environments. But in Indonesia high strength concretes possesses maximum compressive strength of 60 MPa. The properties of concrete are affected by cementitious matrix, aggregate, and the transition zone between these two phases. Reducing the water-cement ratio and the addition of pozzolanic admixtures like fly-ash are often used to modify the microstructure of the matrix and to optimise the transition zone. The reduction of the water-cement ratio results in a decrease in porosity and refinement of capillary pores in matrix, but flowing ability of the concrete will also decrease so that it can’t be workable. Then it workablity can be improve by the use of a superplastisizer. The method used refers to the planning of normal concrete, which is contained in the SK-SNI 03-2834-1992. The results showed that superplastisizer with doses of more than 2% of the cement paste does not increase the flowing ability of the paste anymore. For all the rest of the experiments, the superplastisizer dosage was determined about 2 % of the powder mass. The first tests showed a good workability of the fresh concrete and a good self compacting ability with the silicafume dosage of 10 % of the powder mass. The interest in reducing costs for increasing the concrete strength, can be successfully achieved in this research.
Perancangan Fondasi Pada Tanah Timbunan Sampah (Studi Kasus Di Tempat Pembuangan Akhir Sampah Piyungan, Yogyakarta) Anita Widianti; Dedi Wahyudi; Willis Diana
Semesta Teknika Vol 8, No 1 (2005): MEI 2005
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v8i1.908

Abstract

Tempat Pembuangan Akhir Sampah (TPAS) merupakan kebutuhan setiap daerah guna mengatasi masalah sampah. Apakah lahan yang sangat luas tersebut  nantinya dapat dimanfaatkan kembali ? Berdasarkan pertanyaan itulah penelitian ini dilakukan. Tujuan dari penelitian ini adalah untuk merancang fondasi berdasarkan daya dukung tanah yang mampu menahan beban dan penurunan yang tidak berlebihan dari hasil uji sondir di lapangan.Penelitian dilakukan di zona pertama dari TPAS Piyungan, Yogykarta  yang merupakan zona di mana proses penimbunan dan pemadatannya telah selesai.  Hasil uji sondir pada dua titik digunakan sebagai dasar untuk merancang fondasi dari struktur bangunan dua lantai, dengan mengacu pada Standar Tata Cara Perhitungan Struktur Beton Untuk Bangunan Gedung, SK SNI-T-15-1991-03.Dari hasil analisis menunjukkan bahwa fondasi telapak dapat digunakan dengan kedalaman 1,6 m. Fondasi tersebut  dirancang berukuran 100 cm x 100 cm dengan ketebalan 25 cm, jumlah tulangan sebanyak 8 buah dengan diameter 10 mm dan spasi tulangan 12 cm. 
Analisis Unjuk Kerja Boiler Feed Pump Turbine Untuk Kapasitas Ketel Uap 2000 Ton/Jam Di PLTU Cirebon Jawa Barat Sukamta Sukamta; Sudarja Sudarja; Muhammad Mujaddid Ighna Wathon
Semesta Teknika Vol 18, No 1 (2015): MEI 2015
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v18i1.702

Abstract

Boiler feed pump turbine (BFPT) has an important role in the circulating of demin water from deaerator to the separator of  steam power plant operations (PLTU) in Cirebon. Flow rate, temperature and  pressure were important parameters in boiler feed pump process. Based on the BFPT function, it was necessary to do the analysis interpretation of the performance BFPT. Data needed for evaluation include pressure and temperature on the suction, pressure and temperature on the discharge, and flow capacity. In this study, the data were taken starting in January to December 2014. Data processing was performed using a centrifugal pump calculations, presented in tables and graphs using MS Excel. Analysis of data using qualitative interpretation of quantitative data. BFPT efficiency during operations in 2014 decreased in February - March amounted to 17.91% (BFPT A) and 18.04% (BFPT B). BFPT A highest efficiency obtained in January amounted to 73.76%, the lowest in March amounted to 55.45%. The highest efficiency BFPT B in February amounted to 72.94%, the lowest in March amounted to 54.9%. Change of Performance BFPT occur due to changes load generator power plant that led to the pressure change  and flow capacity. Other factors that degrade the performance because BFPT was operated continuously for 24 hours and the age of  BFPT sufficient old  cause decrease in pump performance.
Analisis Volume, Kecepatan, dan Kepadatan Lalu Lintas dengan Metode Greenshields dan Greenberg Wahyu Widodo; Nur Wicaksono; Harwin Harwin
Semesta Teknika Vol 15, No 2 (2012): NOVEMBER 2012
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v15i2.1361

Abstract

The creation of a transportation system that ensures the movement of people, vehicles, or goods in a smooth, safe, fast, cheap, convenient, and environmentally friendly way has been the goal of country development. An increase in traffic volume will cause a change in traffic behavior. Theoretically, there is a fundamental relationship between the flow, speed, and density of traffic. Activities and land use will affect the performance of a variety of roads. Land in Jalan Wates Km 5 is used as commercial and market area that is the center of the crowd. The purpose of this study was to determine: speed, traffic volume, density, capacity, and the relationship between speed, volume and density using Greenshields and Greenberg methods, degree of saturation, and level of service. The study was conducted in one day. The result showed that the capacity of the road is still able to accommodate the volume of existing traffic.
Implementasi Mikrokontroler Sebagai Pengendali Kapasitor Untuk Perbaikan Faktor Daya Otomatis pada Jaringan Listrik Prasetya, Dana Bagus
Semesta Teknika Vol 13, No 2 (2010): NOVEMBER 2010
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/jst.v13i2.719

Abstract

With increasing electricity rates, the demands of efficiency in electric power consumption is a major consideration. Efficient use of electric power is affected by many factors. Among them is the quality of electric power. Power quality is strongly influenced by the use of certain types of expenses that resulted in the decline of efficiency. In the distribution of electric energy there are several problem sencountered include the voltage drop, low cos Φ, and the loss of power. Load on the network load distribution can be either capacitive or inductive, but in general is an inductive load. If the inductive reactive load the higher the voltage drop will produce a zoom in, zoom power loss, cos Φ lower and lower distribution of power capacity. To reduce the inductive reactive power load required capacitive reactive power sources, one of which is to be installed in parallel capacitors. In this study will be designing and manufacturing tools for controlling capacitor banks according to cos φ m, so that power quality will be better. From the results of this research tool was able to detect the value of voltage, current,and cos φ. The resulting values of the three sensors is quite good. This tool is able tocontrol the capacitor bank in accordance with the value of cos φ meters.
Kajian Pola Operasi Jalur Ganda Kereta Api Muara Enim - Lahat Setiawan M, Dian
Semesta Teknika Vol 19, No 1 (2016): MEI 2016
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v19i1.1832

Abstract

Muara Enim – Lahat railway double track construction can optimise the passenger and freight transportation in South Sumatera. The objective of this study is to conduct railway double track operation concept analysis in order to obtain full concept of railway operation on this line. The result of this study become so important since it can be used for maintaining the optimisation steps of railway double track operation between Muara Enim – Lahat. This research was conducted by doing field survey and instantional survey to obtain primary and secondary data that is used as basic analysis of Muara Enim – Lahat railway track line operation. The key points included on this railway operation concept analysis are number of train per day, train length, maximum speed, station location, station function, station category, station type and activity, line capacity, and station layout. 
Desain Kontrol Beban Elektronik pada Pembangkit Listrik Tenaga Mikrohidro Effendy, Machmud
Semesta Teknika Vol 12, No 2 (2009): NOVEMBER 2009
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v12i2.735

Abstract

Due to its lower cost and quicker response in compassion with governor, electronic load control (ELC) has been widely used to replace governor in microhydro power plant. It has lower price and quicker response than governor. The synchronous generator used in microhydro power plant produces stable voltage, because it has been controlled by an AVR (automatic voltage regulator. If consumer loads changes, the frequency not the voltage of the electrical wave will change. Therefore, ELC is used to stabilize the electrical wave frequency and detect the change of consumer load to be transferred to ballast load. This ELC uses frequency censor to detect the change of consumer load. Frequency censor proceeses linearity level to the change of voltage which equals to R2= 0.97. The use of ELC causes the generator voltage is approximately 220,3V to 224,4V with percentage of voltage unbalance 0,56% and the geneator frequency is 49,5Hz to 50,1Hz with percentage of frequency unbalance 0,41%.

Page 45 of 72 | Total Record : 715

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