Acoustic emission technique for leak detection in an end shield of a pressurised heavy water reactor

This paper discusses the successful application of the Acoustic Emission Technique (AET) for detection and location of leak paths present on the inaccessible side of an end shield of a Pressurised Heavy Water Reactor (PHWR). The methodology was based on the fact that air and water leak AE signals have different characteristic features. Baseline data was generated from a sound end-shield of a PHWR for characterizing the background noise. A mock up end-shield system with saw cut leak paths was used to verify the validity of the methodology. It was found that air leak signals under pressurisation (as low as 3 psi) could be detected by frequency domain analysis. Signals due to air leaks from various locations of a defective end-shield were acquired and analysed. It was possible to detect and locate leak paths. Presence of detected leak paths were further confirmed by alternate test.     

Role of Silicon Coupling Grafted Natural Fillers on Visco-Elastic,Tensile-Fatigue and Water Absorption Behavior of Epoxy Resin Composite

Silicon - This work investigates the influence of silicon based coupling agents on visco-elastic properties of natural filler dispersed epoxy resin composites. Also this work attempts to explore...     

Yield optimization for complex reactor systems

For complex reactions, the choice of reactor type is important for attaining optimum product yields. Strategies for specifying reactor types have beenIn this paper, product yield in a Van de Vusse reaction scheme has been studied for a wide range of the rate constants, in a reactor system consisting     

Hydriding characteristics of palladium and platinum alloyed FeTi

Effect of alloying on the hydriding characteristics of FeTi with noble metals such as platinum and palladium (5% by weight) has been investigated. It is observed that palladium has a favourable effect with respect to easy activation, decreased hysteresis and lower plateau pressures for hydrogen absorption and desorption process. For Pd/FeTi, a saturation composition of Pd/FeTiH_1.85 having the -phase, has been obtained. Unlike this, for Pt/FeTi, the total hydrogen absorption is decreased significantly and a saturation composition of Pt/FeTiH_1.5 having only ₂ phase, is observed.     

Magnetization study of Fe-doped ZnO co-doped with Cu: Synthesized by wet chemical method

Fe- and Cu-doped ZnO of nominal compositions Zn_0.95Fe_0.05O and Zn_0.94Fe_0.05Cu_0.01O were synthesized by a wet chemical route. X-ray diffraction analysis of the samples annealed at 575 K showed that they are single phase without any secondary phases. DC magnetization measurements of Cu co-doped samples (Zn_0.94Fe_0.05Cu_0.01O) as a function of field at room temperature showed ferromagnetic signature while the samples without Cu co-doping (Zn_0.95Fe_0.05O) are paramagnetic in nature. On increasing the temperature of annealing from 575 K to 1,075 K an impurity phase emerges in both the samples, which has been identified as a variant of ZnFe₂O₄. Both the samples heated at and above 1,075 K are found to be paramagnetic at room temperature. These observations, the absence of room temperature ferromagnetism in Zn_0.95Fe_0.05O and the disappearance of ferromagnetism in Zn_0.94Fe_0.05Cu_0.01O on raising the temperature of annealing clearly rules out the likelihood of room temperature ferromagnetism arising from the impurity phases like γ-Fe₂O₃ and/or ZnFe₂O₄ that might have been formed during the synthesis. Our results strongly suggest that room temperature ferromagnetism in Zn_0.94Fe_0.05Cu_0.01O can be attributed to the formation of a secondary phase of Cu-doped ZnFe₂O₄.     

Multiobjective optimization and analysis of copper–titanium diboride electrode in EDM of monel 400™ alloy

Electrical discharge machining (EDM) is one of the most accepted machining processes in the precision manufacturing industry. In EDM process, finding an alternative tool material is the demand in modern manufacturing industry. Therefore, an attempt had been made to fabricate copper–titanium diboride powder metallurgy electrode to test in EDM on monel 400? material. The experiments are planned using center composite second-order rotatable design and the model is developed by response surface methodology. The machining characteristics have analyzed using the developed model. In this study, four input parameters such as titanium diboride percentage, pulse current, pulse on time, and flushing pressure are selected to evaluate the material removal rate (MRR) and tool wear rate (TWR). The adequacy of the developed regression model has tested through analysis of variance test. The desirability-based multiobjective optimization is used to find the optimal process parameter which has given maximum MRR and minimum TWR. The optimum process parameters obtained were titanium diboride of 16%, pulse current of 6 A, flushing pressure of 1 Mpa, and pulse on time of 35?µs. The validity of the response surface model is further verified by conducting confirmation experiments.     

Joint beam selection and user association strategy for beam space millimetre wave downlink systems

Beam space multiple‐input multiple‐output (B‐MIMO) systems operating at mmWave frequency in downlink uses different beam selection techniques for reducing the required number of radio frequency chains without apparent performance loss. In this paper, a joint beam selection and user association scheme with the objective of sum rate maximization is proposed. The proposed work on beam selection is based on a norm and uncorrrelation based approach, which considers channel correlation among the users so as to avoid inter‐user interference. Two different methods for beam user association with one modelled as a balanced assignment problem based on average sum assignment method and the other method that associates an optimal beam to every user by considering their channel gain values are also proposed along with beam selection. The proposed beam assignment methods are less complex and efficient in finding a suitable beam to every user within the cell. Simulation results show that the proposed method accomplish comparable performance in terms of sum rate and energy efficiency with appreciably low computational complexity relative to the existing methods in a correlated environment.     

Influence of Temperature on Tensile Stress–Strain and Work Hardening Behaviour of Forged Thick Section?9Cr–1Mo Ferritic Steel

True stress (??)?Ctrue plastic strain (??) behaviour examined for temperatures ranging from 300 to 873?K suggested that a combination of Ludwigson and Hollomon equations describes ??C?? behaviour most accurately in forged thick section?9Cr?C1Mo steel. Alternatively, the flow behaviour for temperature range 300?C873?K can be described adequately using single Voce equation. Good correlations have been obtained between work hardening parameters evaluated using Voce equation and the respective tensile properties. The variations of instantaneous work hardening rate (???=?d??/d??) and ??? with stress displayed two-stage behaviour characterised by a rapid decrease at low stresses (transient stage) followed by a gradual decrease at high stresses (stage-III). The variations of work hardening parameters, ?? versus ?? and ??? versus ?? with temperature exhibited three distinct temperature regimes along with signatures of dynamic strain ageing at intermediate temperatures and dominance of dynamic recovery at high temperatures. Comparison of work hardening parameters obtained using Voce equation and Kocks?CMecking approach suggested an analogy between the two for the steel.     

Optimization of inoculum to substrate ratio for bio-energy generation in co-digestion of tannery solid wastes

The inoculum to substrate (I/S) ratio is an important factor which influences the anaerobic digestion process. In this study, the effect of different I/S ratios on the performance of co-digestion of fleshings along with mixture of sludge generated during treatment of tannery wastewater was investigated. The parameters studied were biogas generation, volatile solids reduction, volatile fatty acid (VFA) production, and the stability of the digestion process based on VFA to alkalinity ratio was evaluated for various I/S ratios. Economical significance of I/S ratio as related to the volume of the anaerobic digester and the potential benefit of bio-energy generated are discussed in detail.     

Effect of ozonation and ultrasonication pretreatment processes on co-digestion of tannery solid wastes

Studies were carried out by the application of ozonation and ultrasonication as pretreatment processes on primary and secondary sludge generated during treatment of tannery wastewater to enhance the soluble chemical oxygen demand (SCOD). Further, co-digestion (simultaneous digestion of two or more substrates) studies were carried out in batch reactors using the fleshings (a solid waste generated during the processing of raw hides or skins into finished leather) along with the primary and the secondary sludge wherein biogas generation was compared with and without pre-treated sludge using ozone and ultrasonication processes, respectively. It was found that, application of pretreatment processes enhanced biogas generation by 45% in the case of ozone pre-treated sludge and 53% by ultrasonication processes, respectively, in conjunction with the fleshings. However, considering the optimum contact time required, application of ultrasonication as a pretreatment process was found to be the most appropriate and viable process to enhance the SCOD. This pretreatment process has the potential for implementation in tanneries using the shortest possible ultrasonication time to minimize energy cost when compared with ozonation time.