345,979 research outputs found
The Influence of Specimen Misalignment on Wear in Conforming Pin on Disk Tests
No full textA pin-on-disk test apparatus was modified to decrease the degree of misalignment
between the pin end and the disk counterface. This was achieved by separate
alignment of both pin and disk. Disk alignment was allowed by incorporating a
kinematic three-ball arrangement into the disk under-face. A self-aligning pin
alignment system was introduced which did not require the perpendicularity of
the pin to be measured. The unmodified system had an alignment within that
permitted by the ASTM G99-95a standard. However, the modified, and improved,
alignment system produced significant changes in recorded wear behaviour in
comparison with the unmodified system. The standard deviation of the wear data
was considerably reduced and the correlation of the wear data with applied load
significantly improved. The modified alignment also reduced the absolute value
of wear recorded. This effect was observed for both wear volume assessed from
mass change and wear volume assessed from pin height change. The reduced
constraint of a misaligned pin in comparison with that of a well-aligned pin may
account for the difference in these results
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 %
A model of friction for a pin-on-disc configuration with imposed pin rotation
No full textA friction model is developed by considering the Coulomb friction model, a probabilistic
approach of wear prediction, the kinematics of the pin-on-disc configuration and the elastic
theory of bending. The model estimates the magnitude and direction of the frictional force, the
pin torque, the probability of asperity contact and the real area of contact distinguishing
between the part due to elastic and plastic asperity contacts respectively. Therefore, the
proposed model is suitable for the prediction of adhesive wear. It can be applied to metal
contacts for conductance characterisation through the plastically deformed asperities which is
of great interest for electrical contact resistance studies
Pin & Mix: When Pins Become Interaction Components...
No full textThis paper introduces a study into the realization of physical interaction components, based on a technology for providing network connectivity and power to small objects via a layered surface. Small pin-like components can be activated and networked by attaching them to the same, augmented surface, and can be used to dynamically create an interlinked set of atomic interaction components. The physical connection becomes thus also a digital link between components. To demonstrate our proposed platform, we have built atomic interface components in the form of dials and multicolour lights that are activated and integrated in a network by simply pushing their pin connectors in an augmented surface. They allow to pick and mix colours using the red, green, and blue primaries, as a physical alternative for the traditional WIMP colour mixer tools
STUDI PENAMBAHAN PERISAI RADIASI DI KANAL HUBUNG S-5 UNTUK MENGURANGI PAPARAN LINGKUNGAN
No full textABSTRAK ─ Telah dilakukan studi rencana penambahan perisai radiasi di atap kanal hubung S-5 dengan menggunakan bahan utama air. Tujuan penambahan perisai radiasi untuk mengurangi paparan pada atap kanal hubung S-5 agar pekerja radiasi tidak berpotensi menerima dosis radiasi melebihi Nilai Batas Dosis (NBD) yang diijinkan oleh BAPETEN, yaitu 20 mSv/tahun. Studi penambahan perisai radiasi dilakukan dengan membuat sebuah kolam pengukuran yang berukuran 8000(p)X2400(l)X300(t) mm3. Di dalam kolam ditentukan 9 titik pengukuran yang berjarak 1 meter. Pengukuran paparan radiasi, baik neutron maupun sinar-g, pada titik pengukuran dilakukan pada saat reactor beroperasi normal (15 MW), main shutter dan lithium shutter terbuka, dalam kondisi kolam belum diisi air, diisi air sedalam 15 cm dan 30 cm. Hasil pengukuran menunjukkan bahwa pada kedalaman air 30 cm paparan radiasi pada titik terdekat dengan sumber menurun dari 101,57 ɥSv/jam menjadi 1,09 ɥSv/jam untuk neutron dan 13.7 ɥSv/jam menjadi 3,95 ɥSv/jam untuk sinar γ. Paparan rad ini sudah tidak berpotensi menyebabkan pekerja radiasi mempunyai dosis melebihi NBD yang diijinkan oleh BAPETEN. Dari data pengukuran juga diperoleh data bahwa air sangat efektif untuk meredam radiasi neutron, tetapi kurang efektif untuk meredam radiasi sinar-g. Dari hasil studi rencana ini, akan dibuat perencanaan pembuatan perisai radiasi di atap kanal hubung S-5. Kata kunci: perisai radiasi kanal hubung S-5, laju dosis S-5, paparan radiasi atap kanal hubung S-5 ABSTRACT ─ A study has been conducted for the addition of radiation shield on the roof of the S-5 canal using the main water material. The purpose of the adding a radiation shield is to reduce exposure to the S-5 canal roof so that radiation workers do not potentially receive radiation doses exceeding the Dose Limit (NBD) permitted by BAPETEN, ie 20 mSv/year. The study of the radiation shields additions was made by making a measuring pool with dimension 8000 X 2400 X 300 mm. Inside the pool is determined nine measurement point within 1 meter. Measurements of radiation exposure, both neutrons and g-rays, at the point of measurement are performed when the reactor operates normally (15 MW), the main shutter and open lithium shutter, in the condition the pool is not filled with water, filled with water as deep as 15 cm and 30 cm. The measurements showed that at a water depth of 30 cm the radiation exposure at the nearest point with the source decreased from 101.57 ɥSv/h to 1.09 ɥSv / h for neutrons and 13.7 ɥSv / hr to 3.95 ɥSv / h for γ rays. This radiation exposure has no potential to cause radiation workers to have a dose exceeding the NBD permitted by BAPETEN. From the measurement data also obtained data that water is very effective to reduce the radiation of neutrons, but less effective to reduce g-ray radiation. From the results of this study, will be made planning of radiation shielding on the roof of the S-5 canal. Keywords: radiation shield S-5 canal, S-5 dose rate, radiation exposure of S-5 canal roo
Introduction
No full textIntroduction to the topics of Law, Religion and Tradition. The Chapter focuses on the intellectual mainframe according to which the contributions in the book tackle the issu
STUDI PEMBUATAN SPESIMEN MINI UJI TARIK DENGAN TEKNIK BLANKING/PUNCHING
No full textABSTRAK STUDI PEMBUATAN SPESIMEN MINI UJI TARIK DENGAN TEKNIK BLANKING/PUNCHING. Telah dilakukan studi pembuatan spesimen mini uji tarik dengan teknik blanking/punching. Tujuan dari studi ini adalah untuk memperoleh informasi-informasi teknis yang akan digunakan untuk merancang rangkaian dies spesimen mini uji tarik. Uji tarik dengan spesimen mini merupakan bagian dari program investigasi efek radiasi terhadap material komponen reaktor, di Instalasi Radiometalurgi. Metoda yang dilakukan dalam pengkajian ini berupa kombinasi studi literatur dan peninjauan di lapangan. Informasi-informasi teknis tersebut mencakup proses blanking, bentuk dan dimensi dari spesimen mini uji tarik, daya blanking (kapasitas mesin preSS), material, serta suaian (clearance) antara punch dan dies. Spesimen mini uji tarik jenis sheet type spesimen dengan pin loaded dapat dijadikan kandidat (Gambar-1, [c]). Daya blanking merupakan perkalian shear strength material yang dipotong (0,7 x UTS, Ultimate Tensile Strength) dengan luasan permukaan potong (tebal x keliling dari bagian yang dipotong). Material dapat berupa logam keras seperti baja A533 B (UTS 656 MPa), baja nirkarat 316 sebesar (UTS 593 MPa) dan Zircaloy-4 (UTS 473 MPa) dan paduan Aluminium seperti Al-6061 (T6, UTS 311 MPa) dan Al-5052 (H38, UTS 335 MPa). Suaian antara punch dan dies berpengaruh terhadap kepresisian hasil blanking. Besar suaian bervariasi dari 1% s/d 10% dari tebal lembaran benda kerja. Suaian dari material yang lunak lebih kecil dari material yang keras. Pemolesan terhadap permukaan spesimen mini uji tarik dapat dilakukan untuk menghilangkan burrs setelah proses blanking. Disarankan untuk penggunaan satu rangkaian dies dengan beberapa material uji (baja A533 B, baja nirkarat 316, Zircaloy-4, Al-5052 dan Al-6061), dapat menggunakan SS-316 sebagai asumsi material dan tebal 1 mm, serta suaian punch dan dies sebesar 7%. Kata kunci: blanking, spesimen mini, uji tari
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
An experimental investigation into pin loading effects on fatigue crack growth in Fibre Metal Laminates
No full textAbstractThis paper provides an experimental investigation into the pin loading effects on the crack growth behaviour in Fibre Metal Laminates. The pin loading effects and bypass loading effects are incorporated in two different tested joints. The analysis of the test results shows that pin loading dominates the crack growth only in the vicinity of the pin hole and the superposition method for analysing stress intensity factor in FMLs with pin loading effects can be applied
Risks of Offline Verify PIN on Contactless Cards
No full textContactless card payments are being introduced around the world al- lowing customers to use a card to pay for small purchases by simply placing the card onto the Point of Sale terminal. Contactless transactions do not require veri- fication of the cardholder’s PIN. However our research has found the redundant verify PIN functionality is present on the most commonly issued contactless credit and debit cards currently in circulation in the UK. This paper presents a plausible attack scenario which exploits contactless verify PIN to give unlimited attempts to guess the cardholder’s PIN without their knowledge. It also gives experimental data to demonstrate the practical viability of the attack as well as references to support our argument that contactless verify PIN is redundant functionality which compromises the security of payment cards and the cardholder
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