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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 Nadjib, Muhammad
Jurnal Semesta Teknika Vol 15, No 1 (2012): MEI 2012
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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.
Aplikasi Jaringan Neural Untuk Pencegahan Kendali Pengukuran Keamanan Dinamis Dari Sistem Daya Terisolasi Dengan Pembaharuan Bachri, Samsul
Jurnal Semesta Teknika Vol 9, No 1 (2006): MEI 2006
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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.
Analisis Unjuk Kerja Boiler Feed Pump Turbine Untuk Kapasitas Ketel Uap 2000 Ton/Jam Di PLTU Cirebon Jawa Barat Sukamta, Sukamta; Sudarja, Sudarja; Wathon, Muhammad Mujaddid Ighna
Semesta Teknika Vol 18, No 1 (2015): MEI 2015
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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.
Kinerja dan Verifikasi Teknik Seismik Gelombang Permukaan Terintegrasi untuk Pengukuran Modulus Elastisitas Tanah Dasar Rosyidi, Sri Atmaja P
Jurnal Semesta Teknika Vol 13, No 1 (2010): MEI 2010
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An integrated-spectral analysis of surface waves (ISASW) test has been recently proposed as an alternative technique in pavement evaluation and monitoring. ISASW technique is developed from the spectral analysis of surface wave (SASW) method which has been a well known nondestructive testing (NDT) for geotechnical and pavement structures. Surface wave propagation between a set of receivers were transformed to frequency domain using fast Fourier transform (FFT). Therefore, a phase spectrum was produced for measuring the time lag between receivers. A wavelet filtering on impulse response was used for constructing an enhanced phase spectrum. Using phase different method, an experimental dispersion curve was generated. Inversion analysis based on the 3-D stiffness matrix method was then performed in order to produce the shear wave velocity profile. The elastic modulus of pavement layer was calculated based on the linear elastic theory. In this paper, the performance of ISA SW measurement for determining the elastic modulus of pavement subgrade is presented in this paper. Verification on its elastic modulus obtained from ISASW technique was also conducted by using falling weight deflectometer (FWD) test. The result shows that the dispersion curves obtained in the ISASW test are sensitive to indicate the stiffness change in each layer of a pavement structure. Stiffer layer, i.e., pavement surface layer, can be indetified by the parameter of high frequency and phase velocity range; and vice versa. ISASW technique is also able to comprehensively investigate the elastic modulus of subgrade layer in exisiting pavement without any destruction. A good agreement of elastic modulus of subgrade layer from ISASW and FWD test was also pres ented.
Studi Optimasi Peningkatan Kekuatan Bending Komposit Berpenguat Serat Nanas-Nanasan (Bromeliaceae) Kontinu Searah Rahman, Muh Budi Nur; Suwanda, Totok; Diharjo, Kuncoro
Semesta Teknika Vol 11, No 2 (2008): NOVEMBER 2008
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The objectives of this research are to observe the bending strength composite with bromeliaceae fiber with variations of alkali treatment duration, variations of fiber fraction volume and to observe the broken section characteristics. Materials used are bromilicea fiber, resin polyester, NaOH alkali and distilled water. The composite made with printing press methods. Dimensions of specimens and bending testing methods is done by to the standard ASTM D790 (bending test). Variables in this research are fiber fraction volume in the amount of 20-50% and the soaking times in alkali treatment are 0, 2, 4, 6 and 8 hours. Visualization of the broken section is shown in the macro picture. Highest bending strength and bending tensile occur in the composite with bromeliaceae fiber for 6-hour alkali treatment of 218.06 MPa and at the amount of 4.39% in fraction volume of 34.96%. Highest bending modulus occurs with 4 hours alkali treatment of 5.92% GPa. Composite with bromeliaceae fiber without alkali treatment has broken section characteristics fiber pull out, but the composite with alkali treatment has less fiber pull out characteristics.
Analisis Pelayanan Penumpang Kereta Api Prambanan Ekspres (Prameks) Trayek Yogyakarta - Solo Bambang Dwi Bowo Wisnu, Wahyu Widodo ,
Jurnal Semesta Teknika Vol 16, No 1 (2013): MEI 2013
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The aim of this study is to find out the service quality to passenger the train of Prambanan Ekspres (Prameks), passengers perception about the train, and the reason for choosing the train. Data of passenger characteristic and service quality to passengers  were collected by using questionnaire distributed to 379 passenger. To analyze the results questioner used Excel. Quality of services provided by PT . KAI  is quite satisfactory for the passengers. Prambanan Express The Train is the most desirable public transport for traveling Yogyakarta - Solo, because travel costs are cheaper , practical , safer and more comfortable than any other transport.
Durabilitas Laston Dengan Filler Abu Gambut Yuniarto, Enno; Sentosa, Leo
Jurnal Semesta Teknika Vol 9, No 2 (2006): NOVEMBER 2006
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Abstract

Campuran beraspal merupakan campuran yang digunakan untuk membentuk lapis perkerasan lentur jalan raya. Campuran beraspal umumnya terdiri dari agregat, filler dan aspal sebagai bahan pengikat.  Material yang umum digunakan sebagai filler adalah semen, pasir, kapur dan abu batu, yang persediaannya terbatas serta relatif mahal. Alternatif lain yaitu penggunaan abu gambut yang merupakan limbah industri dari bahan bakar pabrik kertas. Salah satu jenis campuran beraspal adalah Lapis Aspal Beton (Laston). Campuran Laston yang baik adalah yang memiliki stabilitas, fleksibilitas, skid resistance ,kedap air dan durabilitas yang cukup. Untuk mengetahui keandalan dari Laston dengan abu gambut dari segi durabilitasnya, maka dilakukan pengujian durabilitas dengan tes perendaman modifikasi Marshall. Indek keawetan dinyatakan dalam nilai IRS dan Indeks Keawetan Craus dkk. Dari pengujian laboratorium pada campuran Laston dengan filler abu gambut memberikan nilai IRS sebesar 88.31% pada perendaman selam 28 hari dan nilai Indeks Keawetan Pertama Craus dkk ( r) sebesar  6.44%  serta Indeks Keawetan Kedua Craus dkk (a) sebesar 20 %. Jika dibandingkan syarat nilai IRS minimal dari Bina Marga untuk Laston, yaitu 75%, nilai IRS Laston dengan filler abu gambut memenuhi syarat.
Sistem Pendeteksian Kerusakan Mesin Sepeda Motor 4-Langkah Berbasis Suara Menggunakan Support Vector Machine (SVM) et.al, Hesti Susilawati ,
Jurnal Semesta Teknika Vol 14, No 1 (2011): MEI 2011
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Detection process early towards motorcycle engine condition will be important matter especially for common user motorcycle. This detection can be used to estimate motorcycle engine condition (normal or damage), damage kind, how big damage influence towards motorcycle continuance, motorcycle duration can survive with damage and cost estimate that taked suppose will repair damage. In this research is built 4-stroke motorcycle engine damage detection system based on voice uses Support Vector Machine (SVM) multi class. In system that proposed, motorcycle engine voice is recorded and then cultivated so that produce feature shaped coefficient Linear Predictive Coding (LPC). Coefficient LPC that extracted from this motorcycle engine voice then become an input for SVM. Furthermore SVM will determine motorcycle engine condition. Engine condition detection system based on SVM this meant to detect three engine conditions that is normal condition, damage cham chain and damage ignition system. System applications that proposed show that motorcycle engine condition detection system based on voice uses SVM has good accuracy that is 100%.
Analisis Parameter Kecepatan Teoritik Dan Nilai Beda Fase Gelombang Rayleigh Lapisan Aspal Perkerasan Jalan Berdasarkan Teori Perambatan Gelombang Pada Media Yang Homogen Dan Isotropik Rosyidi, Sri Atmaja P
Semesta Teknika Vol 8, No 1 (2005): MEI 2005
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The Rayleigh wave is one of seismic waves which generated from the natural and artificial mechanical source in the earth or place on the subsurface, such as landslide, earthquake, explosion, traffic vibration, machine works, etc.  The Rayleigh wave in a possible stratified of homogeneous media is a linear combination of Primary (P) and Vertically Shear (SV) waves, which satisfied the equations of elasticity with zero body forces and zero traction on the boundary of a half-space media.  In the case of a homogeneous isotropic half-space there is a unique mode of the Rayleigh waves which propagates without being sustained by any sources or external loads.  Almost 70 % of wave energy generated from the mechanical sources is the Rayleigh wave energy.  Therefore, it is a potential characteristic of Rayleigh wave that is able to be used in engineering purposes.  One of them is a spectrum analysis that is applied in transportation engineering in order to control the quality of asphaltic material.  The aim of this paper is to predict the Rayleigh wave velocity parameters and phase different value of asphaltic layer based on a fundamental theory of Rayleigh wave propagation in a homogeneous isotopic. The results have been shown that the phase different value in homogenous isotropic media is strongly influenced by field spacing of wave measurement.  The Rayleigh wave velocity parameters were easier obtained using the simple equation considering to various Poisson value. 
Pengaruh Perlakuan Alkali terhadap Kekuatan Bending Komposit Berpenguat Serat Rami dengan Matrik Polyester Suwanda, Totok; Nur Rahman, Muhammad Budi
Jurnal Semesta Teknika Vol 13, No 2 (2010): NOVEMBER 2010
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The objective of this study was to determine the influence of alkali treatment on the flexural strength and failure mode of jute fiber waste/polyester composite materials. The materials being used in this research werewaste of jute fibers, polyester resin, where as NaOH and aquades were utilised for alcali treatment. Prior to being embedded into polyester resin to produce composite boards employing press printing techniques (press mold), the fiber was alkalitreated for 0, 2, 4 and 6 hours by soaking into a 28% volume NaOH content solution. Flexural test was carried out in accorcance with the ASTM D790 standard, and macrographs of selected fracture surfaces of the specimens were capturedfor analysis in oerder to determine the characteristics of the fracture surfaces. Test results showed that the longer the alcali treatment time in the lower the flexural stress and strain, but the the higher the flexural modulus. The composite without alkali treatment reluted in 70.39 MPa bending stress, 1.85% bending failure strain, and 3.85 GPa bending modulus, whereas the 6 hours of alkali treatment resulted in 51.70 MPa bending stress, 1.27% bending failure strain, and 4.13 GPa bending modulus. Composite with alkali-treatmed fiberdid not exhibite any fiber pull out, and also experienced debonding due to shear forces can’t afford retained by the resin.

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