213,687 research outputs found
COVER PIN No.16/Th.IX, April 2016
No full textFile ini berisi :1. Cover2. Susunan Redaksi3. Kata Penganta
Free-convection condensation on single horizontal pin-fin tubes
No full textPhDNew experimental data are reported for free-convection condensation of ethylene
glycol and R-113 on three-dimensional pin-fin tubes. Effects of pin geometry and tube
thermal conductivity (for copper, brass and bronze giving a mean range of 400, 120 and
80 W/m K over the range of temperature of interest) were investigated. All tests were
performed at near atmospheric pressure with downward flowing vapour at low velocity.
Heat-transfer enhancement was found to be approximately twice the corresponding
active surface area of the tubes, i.e. the surface area of the parts of the tube and pin
surface not covered by condensate retained by surface tension. For ethylene glycol, the
best performing pin-fin tube gave a heat-transfer enhancement of 5.8, about 24 %
higher than the ‘equivalent’ two-dimensional integral-fin tube (i.e. with the same finroot
diameter, longitudinal fin spacing and thickness and fin height). For R-113, the
best enhancement was 5.9, about 10 % higher than the equivalent integral-fin tube.
For both fluids tested, vapour-side, heat-transfer enhancement was found to increase
with decreasing circumferential pin spacing and increasing pin height. Circumferential
pin thickness had little effect on heat-transfer enhancement. Effects of tube thermal
conductivity were found to be more significant for ethylene glycol than R-113.
Retention angle measurements were made under static conditions (without
condensation) and were found to be larger than for equivalent integral-fin tubes. An
expression for condensate retention angle on pin-fin tubes was proposed and found to
agree with the measured retention angles to ±15%.
A semi-empirical model for condensation heat transfer on horizontal pin-fin tubes has
been developed which accounts for the combined effect of gravity and surface tension.
The model predicts the majority of available data to ±20 %
An optimization study of a multiple-row pin-vented brake disc to promote brake cooling using computational fluid dynamics
No full textBrake disc cooling is an important area of research for high-performance brake disc manufacturers, users as well as academia. In high-demand braking applications, vented discs are increasingly being used as these are considered to have high heat-dissipating characteristics. The cooling efficiency of ventilated brakes depend on three key characteristics: the mass flowrate through the disc, i.e. the pumping efficiency of the rotor, the average heat transfer coefficient on the surface of the disc, and the wetted area of the rotor. Recent research has shown that the pin-vented discs have high heat transfer rates because of an increase in turbulence which results in a higher heat transfer coefficient. The pin-vented discs also have a higher resistance to thermal deformation owing to the more even distribution of material, resulting in lower thermal stress build-up within the rotor. The pin-vented discs in general have multiple rows of pins. In this paper an optimal configuration of various rows has been found for the maximum heat transfer rate. It has also been found that the ratio of wetted area of the disc to the frontal area of pins defines the heat transfer rate from the disc uniquely and can be used as a design parameter for the optimal design of a brake dis
PIN generation using EEG : a stability study
No full textIn a previous study, it has been shown that brain activity, i.e.
electroencephalogram (EEG) signals, can be used to generate personal
identification number (PIN). The method was based on brain–computer
interface (BCI) technology using a P300-based BCI approach and showed that
a single-channel EEG was sufficient to generate PIN without any error for
three subjects. The advantage of this method is obviously its better fraud
resistance compared to conventional methods of PIN generation such as
entering the numbers using a keypad. Here, we investigate the stability of these
EEG signals when used with a neural network classifier, i.e. to investigate the
changes in the performance of the method over time. Our results, based on
recording conducted over a period of three months, indicate that a single
channel is no longer sufficient and a multiple electrode configuration is
necessary to maintain acceptable performances. Alternatively, a recording
session to retrain the neural network classifier can be conducted on shorter
intervals, though practically this might not be viable
A cohesive zone model for predicting delamination suppression in z-pin reinforced laminates
No full textThis paper presents a cohesive zone model based finite element analysis of
delamination resistance of z-pin reinforced double cantilever beam (DCB). The
main difference between this and existing cohesive zone models is that each z-
pin bridging force is governed by a traction-separation law derived from a meso-
mechanical model of the pin pullout process, which is independent of the
fracture toughness of unreinforced laminate. Therefore, two different traction-
separation laws are used: one representing the toughness of unreinforced
laminate and the other the enhanced delamination toughness owing to the pin
bridging action. This approach can account for the large scale bridging effect
and avoid using concentrated pin forces, thus removing the mesh dependency and
permitting more accurate analysis solution. Computations were performed using a
simplified unit strip model. Predicted delamination growth and load vs.
displacement relation are in excellent agreement with the prediction by a
complete model, and both models are in good agreement with test measured load
vs. displacement relation. For a pinned DCB specimen, the unit strip model can
reduce the computing time by 85%
KARAKTERISASI INGOT PADUAN U-7Mo-Zr HASIL PROSES PELEBURAN MENGGUNAKAN TUNGKU BUSUR LISTRIK
No full textKARAKTERISASI INGOT PADUAN U-7Mo-Zr HASIL PROSES PELEBURAN MENGGUNAKAN TUNGKU BUSUR LISTRIK. Telah dilakukan percobaan karakterisasi paduan U-7Mo-xZr (x = 1%, 2%, 3%) dalam rangka pengembangan bahan bakar dispersi U-7Mo-Zr/Al dengan uranium pengayaan <20% U235. Ingot paduan U-7Mo-xZr yang dikarakterisasi merupakan hasil peleburan menggunakan tungku busur listrik dalam media gas argon. Proses karakterisasi dilakukan dengan cara pengujian strukturmikro menggunakan mikroskop optik digital dan pengujian kekerasan menggunakan alat Vickers. Hasil uji metalografi menunjukkan bahwa pada bagian tepi ingot mempunyai butir berbentuk dendrit yang memanjang dan bercabang, sedangkan pada bagian tengah butiran cenderung bulat dan seragam. Hasil uji kekerasan terhadap paduan U-7Mo-xZr (x = 1%, 2%, 3%) berturut-turut adalah 294,6 VHN, 314,6 VHN dan 334,6 VHN.Kata kunci: ingot, U-7Mo-Zr/Al, tungku busur listri
2nd FUR4Sustain Happy Hour - Jean-Mathieu Pin (Polystyvert) 2022
No full text<p>Talk by Jean-Mathieu Pin (Polystyvert) in the 2nd FUR4Sustain Happy Hour on "Green Recycling of Polystyrene and Associated Copolymers"</p>
PENINGKATAN KADAR ZIRKONIUM OKSIDA DARI PASIR MINERAL ZIRKON DENGAN CARA PELINDIAN
No full textTelah dilakukan kegiatan peningkatan kadar zircon oksida dari pasir mineral zircon dengan cara pelindian. Proses Diwali dengan peleburan 300 g pasir mineral zircon dicampur dengan NaOH teknis 1:1,1. Hasil peleburan dilarutkan dalam air bebas mineral sambal diaduk dengan kecepatan 400rpm. Endapan yang dihasilkan kemudian disaring dan dicuci dengan ABM hingga air cucian mencapai pH7. Endapan yang telah disaring kemudian didiamkan selama 24 jam, kemudian200 g endapan dilarutkan dalam1000mlHCl 4 N sambal diadukkecepatan 400 rpmdan dipanaskan pada suhu 80oC hingga larut. Setelah larut dan dingin ditambahkan200 ml air bebas mineral, maka timbul endapan putih. Endapanputih disaring dan yang diambil filtrat berwarna kuning. Filtrat kemudian ditambahkan NH4OH 10N sambal diaduk hingga pH 5,5. Endapan yang terbentuk disaring dan dicuci hingga air cucian mencapai pH 7. Endapan yang telah disaring didiamkan 24 jam kemudiandikeringkandalam oven pada suhu 100oC. Setelah kering kemudian dilanjutkan kalsinasi pada suhu 700oC.Zirkon oksida hasil kalsinasi kemudian dianalisis kadarnya serta logam pengotor lainnya menggunakan XRF analyzerdan analisis struktur kristalnya dengan XRD analyzer. Dari hasil analisis XRF kadar ZrO2yang terdapat dalam pasir zirkon yang semula 69,929 % setelah dilakukan prosespelindian naik menjadi 85,022% . Sedangkan hasil analisisXRDmenunjukkan bahwa hasil kalsinasi adalah zirconium oksida dengan sitem kristal monoklinik.Kata kunci : ZrO2, peleburan pasir zirko
PENENTUAN KODUKTIVITAS PANAS KOMPOSIT MATRIKS KERAMIK SILIKON KARBIDA MENGGUNAKAN DIFFERENTIAL SCANNING CALORIMETRY
No full textABSTRAK - Penentuan konduktivitas panas menggunakan differential scanning calorimetry (DSC) untuk komposit matriks keramik (KMK) SiC yang digunakan sebagai penukar kalor telah dilakukan menggunakan Setaram DSC 92. Untuk menentukan konduktivitas panas dengan DSC menggunakan kurva entalpi bahan sensor yang digunakan adalah Indium dengan titik leleh pada 156,6 o C yang diperhitungkan dengan memperhitungkan adanya hambatan panas dari sampel KMK SiC. Pengukuran yang diperlukan adalah ketebalan KMK SiC dan luasan permukaan bahan sensor yang bersentuhan dengan sampel KMK SiC. Dari kurva entalpi diperoleh nilai hambatan panas sampel KMK SiC yang digunakan sebesar 0,897 K/mW untuk KMK-P dan 0,867 K/mW untuk KMK-PS. Perhitungan konduktivitas panas dari hambatan panas diperoleh nilai 2,919 W/m.K untuk KMK-P dan 3,065 W/m.K untuk KMK-PS. Kata Kunci : komposit matriks keramik SiC, Konduktivitas panas, bahan sensor, differensial calorimetry ABSTRACT - Thermal conductivity of silicon carbide composite matrix ceramic (CMC) was determined by differential scanning calorimetry (DSC) using Setaram DSC 92. Thermal conductivity measurement conducted by DSC was determined by enthalpi curve of sensor material was used Indium with melting point at 156,6 o C which thermal resistance of CMC SiC calculated. Thickness of CMC SiC and area of sensor material that contact to the CMC SiC sample. Thermal resistance of CMC SiC that obtained from enthalpi curve for KMK-P at 0,897 K/mW and KMK-PS at 0,867 K/mW. Thermal conductivity value that calculater from obtained thermal resistance for KMK-P at 2,919 W/m.K and KMK-PS at 3,065 W/m.K. Keywords : composite matrix ceramic SiC, heat conductivity, sensor material, differential calorimetr
EVALUASI KESIAPSIAGAAN NUKLIR DI INSTALASI RADIOMETALURGI BERDASARKAN PERKA BAPETEN NOMOR 1 TAHUN 2010
No full textEVALUASI KESIAPSIAGAN NUKLIR DI INSTALASI RADIUOMETALURGI BERDASARKAN PERKA BAPETEN NOMOR 1 TAHUN 2010. Telah dilakukan evaluasi kesiapsiagan nuklir Instalasi Radiometalurgi (IRM) berdasarkan Perka BAPETEN nomor 1 tahun 2010. Perka BAPETEN nomor 1 tahun 2010 pasal 50 menyatakan bahwa pada saat peraturan ini mulai berlaku, maka Keputusan Kepala BAPETEN No. 05-P/Ka-BAPETEN/I-03 dicabut dan dinyatakan tidak berlaku. Panduan kesiapsiagaan nuklir PTBN sat ini mengacu pada Keputusan Kepala BAPETEN No. 05-P/Ka-BAPETEN/I-03, sehingga tidak dapat diberlakukan lagi. Tujuan evaluasi kesiapsiagaan nuklir IRM adalah untuk mengetahui kesiapan seluruh unsur infrastruktur dan kemampuan fungsi penanggulangan kedaruratan nuklir. Metoda evaluasi kesiapsiagan nuklir IRM dilakukan dengan menggunakan diagram alir. Infrastruktur IRM yang terdiri dari: organisasi PKN; koordinasi penanggulangan; fasilitas dan peralatan; prosedur penanggulangan; serta pelatihan kedaruratan nuklir telah terpenuhi. Fungsi penanggulangan yang terdiri dari: identifikasi, pelaporan dan pengaktifan; tindakan mitigasi; serta tindakan perlindungan untuk petugas penanggulangan dan pekerja untuk tujuan penanggulangan mempunyai kemampuan yang memadai. Kesimpulan yang dapat diambil dari hasil evaluasi kesiapsiagaan nuklir IRM berdasarkan Perka BAPETEN nomor 1 tahun 2010, diketahui bahwa unsur infrastruktur telah terpenuhi, dan fungsi penanggulangan kedaruratan nuklir mempunyai kemampuan yang memadai. Program kesiapsiagan nuklir IRM dapat segera direvisi, sehingga memuat unsur infrastruktur dan fungsi penanggulangan serta dapat digunakan sebagai pengganti Panduan kesiapsiagaan nuklir PTBN yang lama/sebelumnya. Kata kunci: evaluasi, fungsi penanggulangan, unsur infrastruktur
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