Effect of deflocculants on hardness and densification of YSZ–Al2O3 (whiskers & particulates) composites

In the present study effect of deflocculants like P-Aminobenzoic Acid (PABA) and Cetyltrimethyl ammonium bromide (CTAB) on densification and hardness of 3 mol.% Yttria-stabilized ZrO₂ (abridged as YSZ) + Al₂O₃ (whiskers or particulates) composite have been studied. Maximum hardness & density were achieved at 1 wt% of CTAB or PABA, while further addition (5, 10 and 15 wt%) had no significant affect on the aforementioned properties. It was also observed that alumina addition in form of particulates only improved the density while its addition in form of whiskers significantly increased the hardness of YSZ + alumina composite. The maximum hardness achieved was more than 14 GPa in case of sample containing alumina in form of whiskers.     

Performance of a Nongasketed Flange Joint under Combined Internal Pressure and Bending Loading

Performance of a bolted flange joint is characterized mainly due to its “strength” and “sealing capability.” A number of analytical and experimental studies have been conducted to study these characteristics only under internal pressure loading. A very limited amount of work is found in the literature under combined internal pressure and bending loading. Due to the ignorance of this external loading, i.e., bending loading, the optimized performance of the bolted flange joint cannot be achieved. The present design codes do not address the effects of bending loading on the structural integrity and sealing ability. To investigate joint strength and sealing capability under combined loading, an extensive comparative experimental and numerical study of a nongasketed flange joint is carried out and overall joint performance and behavior is discussed. Actual joint load capacity is determined under both the design and proof test pressure with maximum additional external bending loading that can be applied for safe joint performance. In addition, as experimentally it is impossible to test different flange joint sizes under combined loading application, hence finite element model developed and verified with the experimental results, presented in this paper can be used as base to study the behavior for different nongasketed flange joint sizes for different classes under combined pressure and bending loading.     

Novel tunable dynamic tweezers using dark-bright soliton collision control in an optical add/drop filter

We propose a novel system of the dynamic optical tweezers generated by a dark soliton in the fiber optic loop. A dark soliton known as an optical tweezer is amplified and tuned within the microring resonator system. The required tunable tweezers with different widths and powers can be controlled. The analysis of dark-bright soliton conversion using a dark soliton pulse propagating within a microring resonator system is analyzed. The dynamic behaviors of soliton conversion in add/drop filter is also analyzed. The control dark soliton is input into the system via the add port of the add/drop filter. The dynamic behavior of the dark-bright soliton conversion is observed. The required stable signal is obtained via a drop and throughput ports of the add/drop filter with some suitable parameters. In application, the trapped light/atom and transportation can be realized by using the proposed system.     

Speckle reduction using orthogonal arrays in laser projectors

We propose using a two-level (-1 and +1 as variables) orthogonal array (OA) to generate a binary phase diffuser for speckle reduction in laser projection displays. Compared with the Hadamard matrix, the diffuser generated from OA is more flexible. The speckle contrast ratio (CR) when introducing the binary phase diffuser at an intermediate image plane within the projector is calculated, and the minimum speckle CR can be achieved by finite step change of the diffuser patterns. With Kronecker algebra, the two-dimensional diffuser can also be replaced by two one-dimensional diffusers with the same function, and it can be implemented into the laser projector electronically and easily.     

Simulation of uncontrolled loss of flow transients of a material test research reactor fuelled with low and high enriched uranium dispersion fuels

The effects of using low and high enrichment uranium fuel on the uncontrolled loss of flow transients in a material test research reactor were studied. For this purpose, simulations were carried out of an MTR fuelled separately with LEU and HEU fuel, to determine the reactor performance under loss of flow transients with totally failed external control systems. The coolant pump was assumed to loose its performance and the coolant flow rate reduced according to the relation m(t)/m₀ = exp(−t/25) to a new stable level. The new reduced flows m/m₀ = 0.2, 0.4, 0.6 and 0.8 were modeled. The nuclear reactor analysis code PARET was employed to carry out these calculations. It was observed that the reactors stabilized at new power levels which were lower than the original power level, with the power of HEU fuelled reactor slightly lesser than that of the LEU fuelled reactor. However, at the start of transient, the LEU fuelled reactor had a lower power level resulting in lower fuel, clad and coolant temperatures than the HEU fuelled reactor.     

Study of the Effect of Strontium (Sr) on the Nucleation of Eutectic Silicon (Si) in High Purity Hypoeutectic Al-5Si Alloys

High purity Al-5Si (wt. %) master alloys containing different levels of Sr additions were manufactured in an arc melter under high vacuum. The alloys were melt-spun which resulted in the production of thin ribbons. The microstructure of the ribbons consisted of Al matrix and entrained eutectic droplets. The ribbons were subsequently investigated using differential scanning calorimetry (DSC) and conventional transmission electron microscopy (CTEM) to examine the effect of Sr on the droplet undercooling and nucleation of eutectic silicon. The results indicate that the addition of Sr increases the eutectic droplet nucleation undercooling (ΔT). This may be due to Sr poisoning of the AlP phase.     

Investigation of forestry wastes: Torrefaction and their thermal properties for use in energy recovery schemes

Three biomasses like Eucalyptus, Azadirachata, and Ficus religiosa were torrefied to investigate the effect of temperature and residence time was investigated on torrefied biomasses for yield, volatile matter, fixed carbon, ash, and Gross calorific value (GCV). Thermogravimetric analysis and Hardgrove grindability index (HGI) of three torrefied samples were studied at optimum conditions of temperature and residence time. According to the results, an optimum temperature was found to be 260°C at 45 min residence time. A maximum GCV of torrefied biomasses of Eucalyptus, Azadirachata, and F. religiosa were found to be 4,301, 3,190, and 3,278 kcal/kg, respectively. According to thermogravimetric analyzer results, the Azadirachata has shown higher weight loss compared to Eucalyptus and F. religiosa during thermogravimetirc study. The weight loss rate for Azadirachata was maximum to nearly 12.8%/min compared to 6.11 and 5.12%/min for Eucalyptus and F. religiosa, respectively. The order of reactivity based on mean reactivity and combustion characterization factor was found to be Azadirachata indica > Eucalyptus > F. religiosa. According to HGI results, Eucalyptus, Azadirachata, and F. religiosa have shown HGI values of 71, 60.7, and 81.7, respectively. The results of this study could be useful for the energy recovery schemes in the country.     

Optimization of furfural production from millet husk using response surface methodology

Biomass has been recognized as a viable source for energy and bio-based chemicals. This study reported furfural production from millet husk via simultaneous hydrolysis and dehydration processes. Effect of reaction variables such as temperature (120–200°C), resident time (15–45 min), and acid concentration (5–10%) was studied using central composite design. Furfural yield (71.55%) was achieved at 184°C, 39 min, and 9% acid concentration. FT-IR spectrum of the produced furfural showed absorption at 1,697 and 2,880 cm^?1 indicating a conjugated carbonyl functional group and aldehydic hydrogen. The results revealed that millet husk could be a potential substrate for furfural production.     

Production of bioethanol from sugarcane bagasse using yeast strains: A kinetic study

In this study, sugarcane bagasse (2 mm) was pretreated with 2.5% NaOH followed by steaming at 121°C for various time periods. Maximum cellulose content of 81% and delignification of 68.5% were achieved by soaking bagasse in 2.5% NaOH with a residence time of 1 h at room temperature followed by steaming at 121°C for 30 min residence time. The pretreated substrate was analyzed by SEM and FTIR to study the structural modification and functional group of the untreated and pretreated substrates. The pretreated substrate was saccharified by commercial cellulase enzyme depicting 106 µm mesh size of substrate yields maximum saccharification rate. The saccharified material was fermented by Saccharomyces cerevisiae and Pichia stipitis in mono- and co-culture modes. Maximum product yield (Y_p/s) was observed by monoculture using Saccharomyces cerevisiae after 96 h of fermentation period.