Hot pressed hydroxyapatite–carbon fibre composites

Composite samples were obtained from hydroxyapatite powder and carbon fibres by hot pressing at 1100°C and 25 MPa for 15 min in argon atmosphere. Two types of cut carbon fibres produced in a carbonisation process of polyacrylonitrile (PAN) precursor were used both in non-coated or coated form. The coatings of calcium phosphate were applied by sol–gel technique. The highly sintered composite with the best strength properties was obtained from coated carbon fibres with basic character of the surface. The existence of hydroxyl groups on fibre surface makes possible formation of bonds with the calcium phosphate layer formed as a result of polycondensation following the sol–gel procedure.     

Effect of pretreatment, seeding and interlayer on nucleation and growth of HFCVD diamond films on cemented carbide tools

The direct deposition of diamond on carbide tools is difficult because formation of graphitization and thus leading to poor adhesion, due to presence of cobalt on the surface. Various methods were adopted to suppress the effect of cobalt during deposition. One of them was by putting an interlayer. In this study, carbide substrates with coatings of Ti, TiN and TiC were used. Ti coating has a strong tendency to form intermediate carbide leading to the highest nucleation density of diamond. A comparison was made on nucleation and growth of diamond crystals on various interlayers by hot filament CVD method. At the same time, the variations of diamond film growth morphology have been studied on unseeded and seeded carbide inserts. The SEM pictures revealed that among interlayer, Ti coating gave highest nucleation density compared to TiN and TiC coatings. At the same time, diamond seeded inserts, pretreated by Treat 1 [HCl + HNO₃ + H₂O (1:1:1)] for 15 min ultrasonically resulted in the highest nucleation density, compared to Treat 2 [K₃[Fe(CN)₆] + KOH + H₂O] solution in (1:1:10) for 15 min, at constant process parameters.     

Wettability and machinability study of pure aluminium towards uncoated and coated carbide cutting tool inserts

An investigation has been conducted to study wetting characteristics of aluminium towards different cutting tool materials for assessing the compatibility for dry machining of aluminum. For this purpose uncoated carbide (94%WC + 6%Co) and mono or multi-layer coated carbide tools with top coating of TiC, TiN, Al₂O₃ and diamond have been used. It was observed that aluminium had a tendency to wet uncoated carbide (94%WC + 6%Co) inserts. However, wetting was more pronounced when surface was enriched with cobalt. In contrast, wetting of aluminium was less when the WC content of the carbide tool surface increased. Coatings like TiC, TiN or Al₂O₃ could not show pure non-wetting characteristics for aluminium. The aluminium appeared to dissolve the coatings in different degrees. On the other hand, coating of diamond exhibited inertness towards aluminum leading to non-wetting behaviour. Turning test with aluminium indicated heavy material built up on uncoated (94%WC + 6%Co) tool. Built up edge formation could not be avoided when carbide inserts with a top coating of TiC, TiN, Al₂O₃ were engaged in machining of aluminium. However, the non-wetting characteristic of diamond coating was reflected during machining of aluminium. The chips slided smoothly over the rake face leaving no trace of edge built up.     

A new approach to the determination of pyrite in coals by Mössbauer spectroscopy

A new approach to the quantitative determination of pyrite in coals by Mössbauer spectroscopy is described. The method uses a duplex absorber consisting of the coal sample and an iron foil. The use of iron as an internal standard, together with a calibration graph, should allow reproducible Mössbauer spectroscopic determination of the pyrite content of coals to be made in different laboratories. Good agreement is obtained between pyrite values obtained by the Mössbauer spectroscopy and conventional methods.     

Various dimension reduction techniques for high dimensional data analysis: a review

Artificial Intelligence Review - In the era of healthcare, and its related research fields, the dimensionality problem of high dimensional data is a massive challenge as it contains a huge number...     

Influence of chemical treatment on tensile strength,water absorption,surface morphology,and thermal analysis of areca sheath fibers

Proper surface modification is highly essential to improve compatibility of natural fibers with polymer matrix to develop eco-friendly materials. In the present work, an attempt has been made to study the effect of various chemical treatments such as alkaline, acrylic acid, permanganate, sodium chlorite, and benzoylation on areca sheath fiber. After surface modifications, its density, water absorption property, mechanical property, thermal gravimetry analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and surface morphology have been thoroughly investigated. It has been observed that benzoyl chloride-treated fiber gives better performance in comparison to other treatments.     

Follower Link Prediction Using the XGBoost Classification Model with Multiple Graph Features

Wireless Personal Communications - The Follower Link Prediction is an emerging application preferred by social networking sites to increase their user network. It helps in finding potential unseen...     

Design of 2.4 GHz Improved Current Reuse Gilbert Mixer with Source Degeneration Technique

An improved Gilbert mixer with the current reuse and source degeneration techniques is investigated. This design and simulation carried out by considering UMC 180 nm CMOS process in the Cadence Tool 6.1.6 with 2.4 GHz. The investigation is presented with the current reuse topology by stacking both pMOS and nMOS transistors. The reduction of the power consumption is obtained due to the self-biasing of the shunt feedback resistor. An improvement in the conversion gain and linearity is shown through the source degeneration in this mixer design. The proposed design achieves the maximum conversion gain (CG) of 13.2 dB with the noise figure (NF) of 8.6 dB. The design circuit consumes 0.7 mW power from 1.2 V with the 1 dB compression point of ?2.63 dBm and third-order input intercept point (IIP3) of 8.2 dBm. The chip area occupied is 0.128?×?0.180 mm² shown in the layout design. This compact layout of the mixer helps to create an opportunity as a suitable building block for RF integrated circuit (RFIC) applications with moderately high performance in the receiver front end.

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Quantum-inspired binary chaotic salp swarm algorithm (QBCSSA)-based dynamic task scheduling for multiprocessor cloud computing systems

The Journal of Supercomputing - Scheduling in multiprocessor computing systems is experiencing prolific challenges in datacenters due to the alarmingly growing need for dynamic on-demand resource...