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"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."

"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."

"An efficient Region-Based Image Retrieval (RBIR) system must consider query region determination techniques and target regions in the retrieval process. A query region is a region that must contain a Region of Interest (ROI) or saliency region. A query region determination can be specified manually or automatically. However, manual determination is considered less efficient and tedious for users. The selected query region must determine specific target regions in the image collection to reduce the retrieval time. This study proposes a strategy of query region determination based on the Region Importance Index (RII) value and relative position of the Saliency Region Overlapping Block (SROB) to produce a more efficient RBIR. The entire region is formed by using the mean shift segmentation method. The RII value is calculated based on a percentage of the region area and region distance to the center of the image. Whereas the target regions are determined by considering the relative position of SROB, the performance of the proposed method is tested on a CorelDB dataset. Experimental results show that the proposed method can reduce the Average of Retrieval Time to 0.054 seconds with a 5x5 block size configuration."

"East Java Province inIndonesia is the centre of the eastern Indonesia region and it has a fairlyhigh economic significance, which has contributed 14.85% to the national GrossDomestic Product (GDP). The role of Large and Medium Scale ManufacturingIndustry (LMSMI) clusters in this province is very important and strategic asone of the main drivers for economic progress and it becomes a part of theefforts to improve the society's life. Therefore, it is necessary to evaluatethe performance of LMSMI clusters continuously. The purpose of this study is toinvestigate the productivity changes of LMSMI clusters in East Java Province,Indonesia, so that they will be able to survive, grow and compete in facingglobal competition. The method used in this study is the method of DEA-basedMalmquist Productivity Index. The result of this study indicates that 50% ofthe LMSMI clusters in East Java Province are in the category of improvedproductivity, while the remaining clusters are in the category of decliningproductivity."

"A multi modelpredictive control and proportional-integral controller switching (MMPCPIS)approach is proposed to control a nonlinear distillation column. The study wasimplemented on a multivariable nonlinear distillation column (Column A). Thesetpoint tracking and disturbance rejection performances of the proposedMMPCPIS were evaluated and compared to a proportional-integral(PI) controller and the hybrid controller (HC). MMPCPIS developed to overcome theHC?s limitation when dealing with very large disturbance changes (50%). MMPCPIS provided improvements by 27% and 31%of the ISE (integral of square error) for feed flow rate andfeed composition disturbance changes, respectively, comparedwith the PI controller, and 24% and 54% of the ISE for feed flow rate and feedcomposition disturbancechange, respectively, compared with HC."

"As a result ofwaterflooding, inorganic salt precipitation occurs in the different parts of anoil production system, thereby leading to damage of production equipment.Different parameters affect the kinetics of salt precipitation. Scaleinhibitors are widely used to prevent inorganic salt formation. In this study,the effect of reservoir pressure, temperature, and mixing ratio of injection toformation water on calcium sulfate and barium sulfate precipitation wasinvestigated. For this purpose, two different formation waters and oneinjection water were used. In addition, the effect of temperature and mixingratio on inhibition performance was studied. Four different existing industrialscale inhibitors and one new scale inhibitor were used. The performance of thescale inhibitors was determined under static and dynamic conditions. Results ofthe study showed that calcium sulfate precipitation increased with an increasein temperature and a decrease in pressure. Barium sulfate precipitation wasfound to increase with a decrease in the temperature. The effect of pressure onbarium sulfate formation was negligible. The developed scale inhibitor showedthe highest performance for the prevention of calcium sulfate and bariumsulfate formation. A change in temperature from 60°C to 120°C reduced theinhibitor performance by 3%. In the cases of calcium sulfate and bariumsulfate, the minimum performance of the scale inhibitor was observed when themixing ratios of injection to formation waters were 60:40 and 50:50,respectively."

"Santa BarbaraAmorphous-15 (SBA-15) is aninteresting mesoporous silica material with highly ordered nanopores and alarge surface area. Due to its unique properties, this material has been widelyemployed in many areas. This study aimed to predict the number of nanopores pergram of SBA-15 material based on an optimum value of surfactant addition at thedesired number of nanopores. For this purpose, SBA-15 was synthesized via asol-gel process using tetraethyl orthosilicate (TEOS, Si(OC2H5)4)as a precursor and pluronic P123 triblock copolymer surfactant (EO20PO70EO20,EO = ethylene oxide, PO = propylene oxide) as a template. There were fivedifferent surfactant concentrations, namely 0.35, 2.50, 2.70, 3.00, and 3.30millimoles, used with a fixed concentration of TEOS. The characterization wasperformed using small-angle x-ray scattering (SAXS), adsorption-desorption(BET), and transmission electron microscopy (TEM). The results showed that thesurfactant concentration did not affect the crystal structure, although anincrease in the surfactant concentration linearly correlated with an increasein the surface area. The shape and size of the pore diameter tends to beapproximately 3 nm, as characterized using BET adsorption-desorption. Theoptimum concentration of surfactant for the formation of mesoporous SBA-15material was 2.70 millimoles. The value obtained in this study was inaccordance with the calculated value, indicating that the theoreticalcalculations can be used to experimentally predict the number of pores."

"AbstrakBeton adalah hasil campuran yang diperoleh dengan cara mencampurkan semen Portland, air dan agregat (halus dan kasar) serta bahan tambah, yang sangat bervariasi mulai dari bahan kimia tambahan. Beton digunakan sebagai struktur dalam konstruksi bangunan dapat dimanfaatkan untuk banyak hal. Seperti untuk struktur beton digunakan untuk bangunan pondasi, kolom, balok, pelat atau pelat cangkang. Semen sebagai perekat banyak type/jenis semen namun yang dijual (dipasarkan) ada semen yang disebut semen OPC (ordinary Portland Cement) dalam kemasannya disebut type I dan semen PPC (Portland Puzzoland cement). Penelitian ini, adalah membandingkan dan mengetahui mutu atau kualitas beton dengan menggunakan Semen PPC sebagai penganti dari semen type I. Dari hasil pengujian dengan membuat benda uji kubus dengan ukuran 15 x 15 x 15 cm dibuat 20 buah dengan umur uji 7, 14, 21,dan 28 hari serta masing-masing umur lima buah. Perlakuan pembuatan benda uji sama antara pengunaan semen type 1 dan semen PPC. Pelaksanaan pengujian dilakukan di Laboratorium Teknik Sipil Politeknik Negeri Medan, beton dibuat dengan menggunakan berat dari masing-masing bahan sesuai rencana, selanjutnya bahan tersebut diaduk dengan molen, setelah adukan merata dituang kedalam cetakan kubus 15 x 15 x 15 cm dan dipadatkan dengan rojokan menggunakan tongkat besi sampai merata, lalu diratakan dan di catat tanggal pembuatannya, setelah benda uji dibuat berumur 24 jam cetakan dibuka dan direndam dalam bak perendaman, sehari sebelum pelaksanaan pengujian sesuai dengan umur yang diinginkan benda uji dikeluarkan dari bak perendaman selanjutnya diuji kuat tekan dengan dengan alat tes kuat tekan, selanjutnya hasilnya diolah sesuai dengan jenis semen yang direncanakan. dihitung kuat tekan beton sesuai umur dan di hitung kuat tekan rata-rata sesuai umur benda uji. Hasil pengujian untuk umur 7, 14, 21, dan 28 hari semen type I 140 kg/cm, 180 kg/cm2, 186 kg/cm2, dan 175 kg/cm2, sedang semen PPC 139 kg/cm2, 171 k/cm2, 168 kg/cm2, dan 148 kg/cm2. Dari hasil pengujian serta pengolahan data maka dapat disimpulkan semen type 1 lebih tinggi dengan umur 7, 14, 21, dan 28 hari , yaitu 0,71 % , 3,9 %, 9,8%, dan 15,43 % kualitasnya dari semen PPC."