Experimental study of liquid carryover in a separator drum

The phenomenon of carryover, i.e. entrainment of liquid along with separated steam is observed in all the steam separators. Due to the risks, such as turbine blade erosion and radioactivity leakage, associated with it, it is desired to have an estimate of the carryover value. This is all the more important when the separation is only under the influence of gravity as proposed in some of the new generation natural circulation reactors.Experiments were carried out in an air-water facility at atmospheric conditions to characterize the entrainment in drums with ratio of the drum diameter to riser diameter varying from 1 to 6. Various parameters influencing the liquid entrainment were identified. The vapour superficial velocity and the drum diameter to riser diameter ratio were found to be the most influencing parameters. A dimensionless prediction correlation was evolved for the liquid entrainment and it was found to agree with previous works in the literature for drum to riser diameter ratio equal to 1.     

Influence of initiators on supply chain value creation

Value creation in the supply chain has attracted considerable attention in the literature. It has typically been characterized as being the result of either external or organization spanning, or internal efforts to improve supply chain performance. Few studies have examined the simultaneous effects of internally and externally focused efforts to improve supply chain performance. Moreover, there is no discussion in the literature of the precursors or initial conditions that lead to successful supply chains. Drawing from different theoretical perspectives, two key motivators or initiators of value creation in supply chains are identified: structural mechanisms and relationship building. It is proposed that these initiators have a positive influence on value creation efforts, operationalized by the improvement of supply processes and responsiveness to customer needs (external focus), and internal production processes (internal focus). A structural equation model linking initiators and value creation mechanisms to performance is proposed and tested using data from a large sample of firms. Results suggest that firms that pay attention to initiators may derive greater benefit from their value creation efforts and thus yield improved performance.     

Evaluation and optimization of food-grade tannin acyl hydrolase production by a probiotic Lactobacillus plantarum strain in submerged and solid state fermentation

Tannin acyl hydrolase (tannase) production by Lactobacillus plantarum MTCC1407 was studied in submerged and solid-state fermentation process. Sequential optimization strategy using Plackett–Burman screening and response surface methodology was adopted to optimize the submerged fermentation process. Eight medium components were evaluated initially by Plackett–Burman two level factorial designs to identify the most significant parameters that affect the tannase production. The significant variables affecting tannase production were found to be tannic acid, glucose and MnSO₄·7H₂O. These factors were further optimized by response surface methodology. Maximum tannase activity of 9.13 U ml^?1 was observed at 30 h using the following medium composition (g l^?1): tannic acid, 13.16; glucose, 1.5; NH₄Cl, 1.0; CaCl₂·2H₂O, 1.0; K₂HPO₄, 0.5; KH₂PO₄, 0.5; MgSO4·7H₂O, 0.5 and MnSO₄·7H₂O, 0.03. Among the various carbon sources examined for tannase production by L. plantarum, glucose and tannic acid combination was found to be decisive for enhancing tannase yield. Solid state fermentation was conducted using various solid substrates and agricultural residues. Maximum tannase activity of 5.319 U gds^?1 was obtained using coffee husk as substrate.     

Calcium catalysis in air gasification of cellulosic chars

Cellulosic chars containing calcium have been prepared from carboxymethyl cellulose in the calcium form and from pure cellulose containing sorbed calcium acetate, at several heat treatment temperatures (HTTs) in the range 400–900°C. The chars have been gasified in air at 300°C. The results indicated a general decrease in reactivity with increasing HTT. However, instead of a monotonic decrease in reactivity reported previously for coal chars containing indigenous or added calcium, the reactivity versus HTT curve consisted of three distinct regions which probably reflect the transformations being undergone by the catalyst species on increasing the HTT. Crystalline CaO was detected by XRD only in chars heated to 1000°C, at which temperature the catalyst was no longer effective. The relationships between gasification rate and catalyst concentration and also mode of addition have been determined using chars of HTT 600°C. As found by earlier workers with some coal chars, the rate reached a maximum with increasing calcium content and then declined. Chars containing sorbed calcium showed a relatively early decline of rate. They also showed less reactivity than the chars containing ion-exchanged calcium at all calcium concentrations.     

Design of an “all solid-state” supercapacitor based on phosphoric acid doped polybenzimidazole (PBI) electrolyte

The effectiveness of phosphoric acid doped polybenzimidazole as a polymer electrolyte membrane to fabricate an all solid-state super capacitor has been explored using hydrous RuO₂/carbon composite electrodes (20 wt.%) of surface area 250 m² g⁻¹ with many intrinsic advantages. The electrochemical evaluation of these super capacitors through cyclic voltammetry, charge/discharge and impedance measurements demonstrate the utility of this type of thin, compact and flexible supercapacitor capable of functioning at 150 °C to yield a maximum capacitance of about 290 F g⁻¹ along with a life of more than 1,000 cycles. A power density of 300 W kg⁻¹ and energy density of 10 Wh kg⁻¹ have been accomplished although the equivalent series resistance (ESR) of about 3.7 Ω needs to be reduced further for high rated applications.     

The impact of market focus on operations practices

A key element of successful organisations is the alignment of their strategy and tactics. This study explores the relationship between a firm's competitive strategy and its operations practices in the context of a developing economy. Two competitive strategies are examined; a niche market strategy characterised by targeting specific market segments, and a broad market strategy characterised by serving a wide range of market segments. Three sets of operations practices consistent with the adoption of lean manufacturing, Total Quality Management, and relationship development in a supply chain context, are explored. Using survey data from senior managers in Thailand, results show that for firms adopting a niche market focus, competitive strategy directly influences process management and relationship development, which in turn affect workforce commitment. Only workforce commitment has a direct effect on operational performance. In contrast, for firms adopting a broad market focus, competitive strategy directly influences workforce commitment, which in turn affects process management and relationship development practices. It is the latter practices that directly influence operational performance.     

Polyoxadiazole-based coating for corrosion protection of magnesium alloy

In this study, polyoxadiazole-based coatings were molecularly designed by attaching two different functional groups, i.e., diphenyl-ether and diphenyl-hexafluoropropane, in the main polymer chain for the purpose of low water permeability and eventually for high corrosion protection of AM50 magnesium alloy. Potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS) were used to evaluate the coating performance of the two polymers. Electrochemical experiments showed that POD-6FP (poly(4,4′-diphenyl-hexafluoropropane-1,3,4-oxadiazole)) coated alloy exhibited 3-4 orders of magnitude higher corrosion resistance as compared to the POD-DPE (poly (4,4′-diphenyl-ether-1,3,4-oxadiazole)) coated alloy. The high coating performance of the POD-6FP polymer can be attributed to the hydrophobic group attached to the polyoxadiazole chain.     

Acetalation of Pentaerithritol Catalyzed by an Al-Pillared Saponite

Abstract  

Acetalation of pentaerithritol has been carried out in the presence of an Al-pillared saponite. Several carbonyl compounds were used, including aldehydes and ketones. Yields between 72 and 93% were obtained in all cases, except in the case of veratraldehyde where the carbonyl group was blocked. The high conversion could be explained by diffusion effects of intermediates and electronic effects between the reactants in the transition state. The catalyst was found to be active after three cycles.     

Non-platinum cathode catalysts for alkaline membrane fuel cells

Hydrogen–oxygen fuel cells using an alkaline anion exchange membrane were prepared and evaluated. Various non-platinum catalyst materials were investigated by fabricating membrane-electrode assemblies (MEAs) using Tokuyama membrane (# A201) and compared with commercial noble metal catalysts. Co and Fe phthalocyanine catalyst materials were synthesized using multi-walled carbon nanotubes (MWCNTs) as support materials. X-ray photoelectron spectroscopic study was conducted in order to examine the surface composition. The electroreduction of oxygen has been investigated on Fe phthalocyanine/MWCNT, Co phthalocyanine/MWCNT and commercial Pt/C catalysts. The oxygen reduction reaction kinetics on these catalyst materials were evaluated using rotating disk electrodes in 0.1 M KOH solution and the current density values were consistently higher for Co phthalocyanine based electrodes compared to Fe phthalocyanine. The fuel cell performance of the MEAs with Co and Fe phthalocyanines and Tanaka Kikinzoku Kogyo Pt/C cathode catalysts were 100, 60 and 120 mW cm⁻² using H₂ and O₂ gases.     

A feature-based generic setup planning for configuration synthesis of reconfigurable machine tools

Reconfigurable machine tool (RMT) plays a vital role in reconfigurable manufacturing systems creating modularity, convertibility, reusability, and scalability in systems. RMT also needs to be characterized for multiple spindle orientations. Different tool positioning requirements (spindle orientations) arising with a part or a part family can be associated to synthesize and customize the RMT configuration. In this paper, we have proposed a new approach of generic setup planning (GSP) for RMT configuration synthesis. From the feature-based computer-aided design data, machining features are grouped according to their tool approach direction in GSP. To support its implementation, an enriched machining feature definition is also introduced. A new algorithm is developed for automating GSP generation and verified against a standard case study.