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"The relative significance of the parallel middle body and stern form in the wake formation of single-screw large ships and their contribution to the ship’s viscous resistance are studied by using computational fluid dynamics (CFD). A 10450-DWT tanker is considered by varying the ratio of the parallel-middle-body’s length to the ship’s length (Lmb/L) and by varying the shape of the stern form from a V-like to a U-like underwater stern transom section. In all the calculations, the principal dimension and the displacement of the ships are kept constant. A larger value for the parallel-middle-body relative length (Lmb/L) of ships with the same stern form results in a larger drag coefficient but does not affect the nominal wake fraction significantly. A change in the shape of the underwater stern form, from a V-like to a U-like section, results in a much larger drag coefficient ascribed to the much larger wake fraction. The stern form dominantly affects the nominal wake fraction and the ship’s viscous resistance compared to the parallel-middle-body relative length."

"The relative significance ofthe parallel middle body and stern form in the wake formation of single-screwlarge ships and their contribution to the ship?s viscous resistance are studied by using computational fluid dynamics (CFD). A10450-DWT tanker is considered by varying the ratio of theparallel-middle-body?s length to the ship?s length (Lmb/L) and by varying the shape of the stern form from aV-like to a U-like underwater stern transom section. In all the calculations,the principal dimension and the displacement of the ships are kept constant. Alarger value for the parallel-middle-body relative length (Lmb/L) of ships with the same stern form results in alarger drag coefficient but does not affect the nominal wake fractionsignificantly. A change in the shape of the underwater stern form,from a V-like to a U-like section, results in a much larger drag coefficientascribed to the much larger wake fraction. The stern form dominantly affectsthe nominal wake fraction and the ship?s viscous resistance compared to theparallel-middle-body relative length."

"Cantik adalah lapangan yang memproduksi minyak yang berlokasi di Blok South Sumatra Extension, yang merupakan daerah operasi dari Medco E&P. Lapangan Cantik telah memproduksi minyak dari 10 sumur. Prediksi perhitungan dari volume oil in-place sekitar 4.2 MMBO, sampai saat ini cadangan yang telah dihasilkan sekitar 1.3 MMBO. Dari 2 sumur yang terakhir ditemukan bahwa reservoir tight dan sulit untuk diprosuksi. Hal tersebut membuat tantangan yang lebih besar lagi untuk mengembangkan lapangan ini. Metoda atribut dan interpretasi konvensional mempunyai keterbatasan akses untuk mendeliniasi distribusi reservoir dengan tingkat heteroginitas tinggi. Berdasarkan permasalahan heteroginitas dan interpretasi dari perangkap stratigrafi yang komplek dari batugamping, menyebabkan sulitnya untuk mengembangkan dan mengelola lapangan Cantik. Kita membutuhkan suatu pendekatan yang baru untuk memecahkan masalah tersebut, pendekatan terbaru yang memungkinkan penentuan distribusi dari reservoir adalah dengan menentukan batas dari kontak fluida. Atribut "sweetness" menunjukkan rasio dari karbonat-serpih, namun pada kasus ini ditemukan juga korelasi atribut sweetness dengan keterdapatan fluida. Dari analisa AVO diharapkan dapat mendeteksi distribusi kontak fluida berdasarkan data seismic dan sumur. Diharapkan dari hasil validasi berbagai macam atribut diharapkan dapat mendeliniasi gambaran geologi yang kompleks ini. Kombinasi dari atribut sweetness dan analisa AVO memperlihatkan distribusi dan orientasi dari target reservoir. Metoda ini membantu kita untuk menentukan tidak hanya kesuksesan sumur eksplorasi, tetapi diharapkan dapat memberikan ide untuk menambah kolam minyak yang ada. Karena dari studi inilah, resiko dari penentuan sumur development dapat secara signifikan berkurang.

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Cantik is an oil-producing field located in South Sumatra Extension Block, a Medco E&P operation area. Cantik has 10 oil producer wells. Oil in-place volumetric calculations predict approximately 4.2 MMBO, while the proven reserve is about 1.3 MMBO. From the two last drillings founded that the reservoir was tight and difficult to develop. From that point make bigger challenges to develop Cantik field. Conventional attribute and interpretation methods provide limited access for delineating a highly heterogeneous reservoir distribution. Due to the problems of heterogeneous limestone and complex stratigraphic trap interpretation, it is difficult to develop and manage Cantik field. We need new approach to solving Cantik field problem, new approach method that can help to define reservoir distribution is defining fluid contact from various attributes. Sweetness attribute was used to define carbonate-shale ratio, but in some case, we also can find the relationship between sweetness attribute and relative fluid content. And from AVO Analysis anlysis, can be detect fuid contact distribution base on well and seismic data. Hopefully with validation of various attribute can be delineated this complex geological feature. The validating of sweetnees attribute and AVO analysis reveals the distribution and orientation of the reservoir targets, which are consistent with well data. This method helped us to propose not only successful exploration wells but also gave us an idea about the extent of the pool. Because of this study, the risks of proposing development wells can significantly reduced."

"Material multiferroic merupakan material yang berkembang pesat berdasarkan peningkatan jumlah publikasi per tahun. Material multiferroic sendiri adalah material yang memiliki dua atau lebih sifat ferroic; feroelektrik, feromagnetik, dan feroelastis. Dalam penelitian ini, penulis ingin mengetahui apakah bahan magneto-listrik multiferroik atau bahan yang memiliki sifat feroelektrik dan feromagnetik dapat dipengaruhi oleh medan magnet. Dengan merancang suatu alat yang dapat mengukur perubahan nilai permitivitas relatif dengan frekuensi ketika diberikan medan magnet, penulis dapat mengetahui apakah material yang diuji merupakan material multiferroic magneto-electric. Hasil pengukuran sampel piezoelektrik diperoleh nilai permitivitas relatif dari 18047-35254 pada frekuensi 100Hz-1kHz dan 9524-18047 pada frekuensi 1kHz-10kHz. Hasil yang diperoleh tetap sama bila dipengaruhi oleh medan magnet, karena piezoelektrik merupakan bahan feroelektrik.

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Multiferroic material is a material that is growing rapidly based on the increasing number of publications per year. Multiferroic material itself is a material that has two or more ferroic properties; ferroelectric, ferromagnetic, and ferroelastic. In this research, the writer wants to know whether multiferroic magneto-electric materials or materials that have ferroelectric and ferromagnetic properties can be affected by magnetic fields. By designing a tool that can measure changes in the relative permittivity value with frequency when a magnetic field is applied, the authors can find out whether the material being tested is a magneto-electric multiferroic material. The measurement results of piezoelectric samples obtained relative permittivity values ​​from 18047-35254 at a frequency of 100Hz-1kHz and 9524-18047 at a frequency of 1kHz-10kHz. The results obtained remain the same when affected by a magnetic field, because piezoelectric is a ferroelectric material."

"ABSTRAKPenelitian ini akan membahas mengenai pengaruh variasi frekuensi danbentuk gelombang pada pembentukan cincin vorteks oleh aktuator jet sintetik.Variasi frekuensi yang digunakan dalam percobaan yaitu 80 Hz sampai dengan 200Hz, sedangkan variasi bentuk gelombangnya adalah bentuk gelombang sinusoidal,square, dan triangle. Bentuk cavity dari aktuator adalah kerucut dengan diameterorifis 3mm, 5mm, dan 8mm. Kriteria pembentukan cincin vorteks yang digunakandalam penelitian ini adalah kriteria yang dipublikasikan oleh Ryan Holman dkkuntuk jet sintetik 2 dimensi yaitu 1⁄𝑆𝑟 = 𝑅𝑒⁄𝑆2 > 1. Pengambilan dataeksperimen dilakukan pada mulut orifis (𝑥⁄𝐷 = 0 dan 𝑦⁄𝐷 ≈ 0) denganmenggunakan Constant Temperature Anemometer (CTA) dengan data rate 60,000data dalam 2 detik. Sedangkan data simulasi diperoleh dengan menggunakansoftware Fluent 6.2.36 dengan menggunakan model turbulensi Reynolds StressModel. Dari data yang diperoleh kemudian diolah untuk dimasukkan dalam kriteriapembentukan cincin vorteks. Dari hasil pengolahan data, diddaptkan rentangfrekuensi optimum serta bentuk gelombang yang paling baik untuk aktutor jetsintetik dalam pembentukan cincin vorteks.

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ABSTRACTThis study will discuss the influence of variations in frequency andwaveform on the formation of vortex rings by synthetic jet actuators. Excitationfrequency variation used in the experiment is 20 Hz to 200 Hz, with a variation ofthe waveform is sinusoidal, square, and triangle. The shape of the actuator?s cavityis conical with orifice diameter of 3mm, 5mm and 8mm. Criteria for the formationof vortex rings used in this study are the criteria published by Ryan Holman et alfor 2 dimensional synthetic jet 1/Sr = Re/S ^ 2> 1. The study was conductedpremises using experimental and computational methods. Experimental data iscapured on the mouth of the orifice (x/D = 0 and y/D≈0) using the ConstantTemperature Anemometer (CTA) with a data rate of 60,000 data in 2 seconds.While the simulation data obtained using Fluent software 2.6.36 by using ReynoldsStress Model as the turbulence model. Data which have obtained is then processedfor inclusion in the criteria for the formation of vortex rings. From the dataprocessing, obtained optimum frequency range and waveform for the synthetic jetactuator in the formation of vortex rings.;;"

"Teknologi droplet mikrofluida merupakan cabang ilmu yang penting dan telah menjadi platform penelitian ilmiah yang andal, terutama untuk analisis kimia dan biologi. Salah satu jenis droplet mikrofluida yaitu water-in-water atau droplet Aqueous Two-Phase System (ATPS). Droplet ini terdiri dari dua fluida dengan basis yang sama yaitu air, namun bertentangan karena perbedaan karakteristik yang dimiliki masing-masing fluida. Droplet jenis ini memiliki keuntungan yaitu bersifat biokompatibel sehingga memiliki peranan penting untuk aplikasi seperti ekstraksi DNA, partisi protein, dan pemisahan sel. Pembentukan droplet ATPS cukup menantang karena tegangan permukaan cenderung sangat rendah. Oleh karena itu, dalam penelitian ini akan dilakukan studi simulasi Computational Fluid Dynamics (CFD) pembentukan droplet ATPS pada saluran mikro berjenis flow focusing dengan memvariasikan laju alir fase terdispersi dan fase kontinu, sehingga variasi data berupa rasio laju alir dengan rentang 1:38 hingga 1:6. Penelitian ini bertujuan untuk mengamati bagaimana pengaruh variasi rasio laju alir terhadap ukuran dan laju pembentukan droplet serta fenomena evolusi pembentukan droplet. Hasil simulasi menunjukkan bahwa pembentukan droplet ATPS berhasil dilakukan dengan pola aliran yang terbentuk adalah dripping. Diameter droplet yang terbentuk dari hasil simulasi memiliki rentang mulai dari 57.96 μm hingga 89.94 μm, serta laju pembentukan droplet memiliki rentang 4.18 Hz hingga 35.13 Hz.

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Microfluidic droplet technology is an important field of study and has become a reliable scientific research platform, particularly for chemical and biological analysis. One type of microfluidic droplet is the water-in-water or Aqueous Two-Phase System (ATPS) droplet. This droplet consists of two fluids with the same base, which is water, but they differ in characteristics. This type of droplet has the advantage of being biocompatible, making it crucial for applications such as DNA extraction, protein partitioning, and cell separation. The formation of ATPS droplets is quite challenging due to the inherently low interfacial tension. Therefore, this research aims to conduct Computational Fluid Dynamics (CFD) simulation study on the formation of ATPS droplets in flow-focusing microchannels by varying the flow rates of the dispersed and continuous phases, resulting in flow rate ratios ranging from 1:38 to 1:6. The objective of this study is to observe the influence of flow rate ratio variations on the size and formation rate of droplets, as well as the evolution phenomena during droplet formation. The simulation results demonstrate successful formation of ATPS droplets with a dripping flow pattern. The diameter of the droplets formed in the simulation ranges from 57.96 μm to 89.94 μm, and the droplet formation rate ranges from 4.18 Hz to 35.13 Hz."

"ABSTRAKKarya tulis ini melaporkan hasil proses pembentukan nanopartikel Ba0.7Sr0.3TiO3 dan Ba0.3Sr0.7TiO3 melalui pemaduan mekanik dan destruksi ultrasonik daya tinggi. Proses destruksi ultrasonik dilaksanakan dalam 3 kondisi berbeda yaitu menggunakan variasi rasio diameter transduser dan reaktor 1:1.4, 1:1.6, dan 1:1.8 terhadap media mengandung partikel kosentrasi 3.0 gr/l selama waktu destruksi 3 jam. Secara spesifik, tujuan dari penelitian ini adalah mempelajari efek rasio diameter transduser dan diameter reaktor (dt/Dr) terhadap pembentukan nanopartikel Ba0.7Sr0.3TiO3 dan Ba0.3Sr0.7TiO3. Karakterisasi partikel yang diperoleh menggunakan XRD, PSA, dan SEM. Hasil identifikasi fasa material dari evaluasi difraksi sinar X memastikan bahwa material Ba0.7Sr0.3TiO3 dan Ba0.3Sr0.7TiO3 adalah material berfasa tunggal dan destruksi ultrasonik tidak menyebabkan perubahan fasa material. Kedua material berbeda dalam ukuran rata-rata partikel sebelum destruksi ultrasonik yaitu 538 nm untuk partikel Ba0.7Sr0.3TiO3 dan 480 nm untuk partikel Ba0.3Sr0.7TiO3. Kedua nilai ukuran rata-rata partikel ini mengalami penurunan selama proses destruksi ultrasonik. Namun, ukuran partikel terkecil masing-masing material adalah 38 nm dan 24 nm diperoleh pasca destruksi dengan (dt/Dr) adalah 1.8. Ukuran rata-rata partikel ini hampir sama dengan ukuran rata kristalitnya masing-masing 22 nm dan 14 nm. Dengan demikian hanya terdapat 1 kristalit dalam masing-masing partikel. Dapat disimpulkan bahwa nanopartikel baik material Ba0.7Sr0.3TiO3 maupun Ba0.3Sr0.7TiO3 dapat dihasilkan dari dua tahapan proses yaitu tahapan sintesis dengan pemaduan mekanik dan tahapan destruksi dengan metode destruksi ultrasonik daya tinggi. Partikel monokristalit Ba0.7Sr0.3TiO3 dengan ukuran 38 nm dan Ba0.3Sr0.7TiO3 dengan ukuran 24 nm telah dihasilkan dari destruksi ultrasonik menggunakan parameter proses (dt/Dr) 1.8 dalam durasi destruksi selama 3 jam.

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ABSTRACTWe report results of research on the formation of Ba0.7Sr0.3TiO3 and Ba0.3Sr0.7TiO3 nanoparticles through the mechanical alloying process and followed by high power ultrasonic destruction. Ultrasonic destruction process carried out in three different modes of the transducer and reactor diameter ratios respectively 1:1.4, 1:1.6, and 1:1.8 against the media containing particles of 3.0 g/l concentration during 3 hours destruction time. The specific goal of this work was to study the effect of transducer and reactor diameter ratio (dt/Dr) on the formation of Ba0.7Sr0.3TiO3 and Ba0.3Sr0.7TiO3 nanoparticles. Particle characterizations were carried out under the employment of XRD, PSA, and SEM. Results of material phase identification by XRD ensure that the synthesized Ba0.7Sr0.3TiO3 and Ba0.3Sr0.7TiO3 material are both single phase. In addition, the ultrasonic destruction to the particle materials did not cause the phase change. Prior to ultrasonic destruction, the two materials are different in their average particle size in which Ba0.7Sr0.3TiO3 and Ba0.3Sr0.7TiO3 respectively has particles with mean sizes 538 nm and 480 nm. The average value for both particles was decreased during ultrasonic destruction. However, the smallest mean particle size of each material was 38 nm and 24 nm which were obtained after the ultrasonic destruction by (dt/Dr) of 1.8. These average sizes are almost equal to the average size of their crystallites which are respectively 22 nm and 14 nm. Thus there is only one crystallite within each particle. It can be concluded that both Ba0.7Sr0.3TiO3 and Ba0.3Sr0.7TiO3 nanoparticles can be produced by a two-stage process. The first stage is a phase formation by mechanical alloying and the formation of Ba0.7Sr0.3TiO3 and Ba0.3Sr0.7TiO3 nanoparticle obtained in the second stage in which the particle sizes were further reduced by the high power ultrasonic destruction. Single crystallite particles with a mean size of 38 nm for Ba0.7Sr0.3TiO3 and that of 24 nm for Ba0.3Sr0.7TiO3 have been successively obtained by ultrasonic destruction process with a parameter (dt/Dr) of 1.8 within 3 hours destruction time."

"This book gathers the proceedings of the 11th workshop on Direct and Large Eddy Simulation (DLES), which was held in Pisa, Italy in May 2017. The event focused on modern techniques for simulating turbulent flows based on the partial or full resolution of the instantaneous turbulent flow structures, as Direct Numerical Simulation (DNS), Large-Eddy Simulation (LES) or hybrid models based on a combination of LES and RANS approaches. In light of the growing capacities of modern computers, these approaches have been gaining more and more interest over the years and will undoubtedly be developed and applied further. The workshop offered a unique opportunity to establish a state-of-the-art of DNS, LES and related techniques for the computation and modeling of turbulent and transitional flows and to discuss about recent advances and applications."

"Penelitian ini bertujuan untuk mengetahui sifat astrofisika dari bintang boson dua fluida dan perbandingannya dengan model bintang boson satu fluida pada temperatur nol dan temperatur tidak nol. Persamaan keadaan bintang boson dua fluida didapatkan pada sistem nonrelativistik dengan menggunakan representasi termodinamika serta memenuhi persamaan Gross-Pitaevskii. Penelitian ini dibatasi dengan pendekatan bahwa bintang dalam kondisi statik dan simetri bola. Persamaan keadaan bintang boson dua fluida dijadikan input Persamaan Tolman-Oppenheimer-Volkoff yang dikerjakan secara numerik dengan metode Runge-Kutta dan metode cari akar. Didapatkan relasi massa dengan jari-jari bintang boson dua fluida dengan massa maksimum pada temperatur nol dan temperatur tidak nol adalah sekitar 0.51m*. Diketahui juga bahwa pada sistem bintang boson dua fluida pada temperatur tidak nol terdapat daerah ketidakstabilan bintang pada saat tekanan dan densitas energi rendah (limit mendekati nol).

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The purpose of this study is to find out the astrophysical properties of two-fluid boson star and comparison with boson star at zero and non-zero temperature systems. The equation of state of two-fluid boson star in a non-relativistic system was found using thermodynamics representation which satisfies Gross-Pitaevskii approximation.

This study is constrained to a static and spherically symmetric approximation. The equation of state of two-fluid boson star becomes an input for The Tolman-Oppenheimer-Volkoff equation which then is solved numerically using Runge-Kutta and root-finding method.

We find the mass-radius relation of two-fluid boson star whose maximum mass at zero and non-zero temperature is about 0.51$m*$. We also find, in non-zero temperature system, that the two-fluid boson star has instability region in low pressure and low energy density (limit to zero)."