High-temperature deformation processing of Ti-24Al-20Nb

Power dissipation maps have been generated in the temperature range of 900 ‡C to 1150 ‡C and strain rate range of 10^-3 to 10 s^-1 for a cast aluminide alloy Ti-24Al-20Nb using dynamic material model. The results define two distinct regimes of temperature and strain rate in which efficiency of power dissipation is maximum. The first region, centered around 975 ‡C/0.1 s^-1, is shown to correspond to dynamic recrystallization of the α₂ phase and the second, centered around 1150 ‡C/0.001 s^-1, corresponds to dynamic recovery and superplastic deformation of the β phase. Thermal activation analysis using the power law creep equation yielded apparent activation energies of 854 and 627 kJ/mol for the first and second regimes, respectively. Reanalyzing the data by alternate methods yielded activation energies in the range of 170 to 220 kJ/mol and 220 to 270 kJ/mol for the first and second regimes, respectively. Cross slip was shown to constitute the activation barrier in both cases. Two distinct regimes of processing instability—one at high strain rates and the other at the low strain rates in the lower temperature regions—have been identified, within which shear bands are formed. Formerly with the Defence Metallurgical Research Laboratory     

Induction of γ irradiation for decontamination and to increase the storage stability of black teas

The handling and storage of black tea at high humidity increases its moisture content, which encourages microbial growth. γ irradiation is one of the most efficient techniques for the reduction of microorganisms in food. The present study aimed to evaluate the effect of γ irradiation on black tea quality and microbial load, during storage. Irradiation had a significant effect on reducing the microbial load, while untreated samples had a high microbial load. Untreated samples absorbed moisture up to 8.65% in 12 months time, whereas it was 6.0% in the case of irradiated samples. The quality of the irradiated teas exhibited stability in major parameters like theaflavin (TF), thearubigin (TR), highly polymerized substances (HPS), and total liquor colour (TLC). There was no significant difference among the quality characteristics of 7 kGy and 10 kGy irradiated samples during the entire period of storage when compared with 0 day control. Results indicated a deterioration in quality of well packed, but untreated control samples during storage. Irradiation resulted in complete removal of microbes and extended the shelf life of black tea.     

Exergy analysis of direct expansion solar‐assisted heat pumps using artificial neural networks

Artificial neural network (ANN) is applied for exergy analysis of a direct expansion solar‐assisted heat pump (DXSAHP) in the present study. The experiments were conducted in a DXSAHP under the meteorological conditions of Calicut city in India. An ANN model was developed based on backpropagation learning algorithm for predicting the exergy destruction and exergy efficiency of each component of the system at different ambient conditions (ambient temperature and solar intensity). The experimental data acquired are used for training the network. The results showed that the network yields a maximum correlation coefficient with minimum coefficient of variance and root mean square values. The results confirmed that the use of an ANN analysis for the exergy evolution of DXSAHP is quite suitable. Copyright © 2009 John Wiley & Sons, Ltd.     

Performance prediction of a direct expansion solar assisted heat pump using artificial neural networks

This paper presents the suitability of artificial neural network (ANN) to predict the performance of a direct expansion solar assisted heat pump (DXSAHP). The experiments were performed under the meteorological conditions of Calicut city (latitude of 11.15 °N, longitude of 75.49 °E) in India. The performance parameters such as power consumption, heating capacity, energy performance ratio and compressor discharge temperature of a DXSAHP obtained from the experimentation at different solar intensities and ambient temperatures are used as training data for the network. The back propagation learning algorithm with three different variants (such as, Lavenberg–Marguardt (LM), scaled conjugate gradient (SCG) and Pola-Ribiere conjugate gradient (CGP)) and logistic sigmoid transfer function were used in the network. The results showed that LM with 10 neurons in the hidden layer is the most suitable algorithm with maximum correlation coefficients (R²) of 0.999, minimum root mean square (RMS) value and low coefficient of variance (COV). The reported results conformed that the use of ANN for performance prediction of DXSAHP is acceptable.     

A comparative study of vegetable oil methyl esters (biodiesels)

In the present study, rubber seed oil, coconut oil and palm kernel oil, which are locally available especially in Kerala (India), are chosen and their transesterification processes have been investigated. The various process variables like temperature, catalyst concentration, amount of methanol and reaction time were optimized. Biodiesel from rubber seed oil (with high free fatty acid) was produced by employing two-step pretreatment process (acid esterification) to reduce acid value from 48 to 1.72 mg KOH/g with 0.40 and 0.35 v/v methanol-oil ratio and 1.0% v/v H₂SO₄ as catalyst at a temperature of 63(±2) °C with 1 h reaction time followed by transesterification using methanol-oil ratio of 0.30 v/v, 0.5 w/v KOH as alkaline catalyst at 55(±2) °C with 40 min reaction time to yield 98-99% biodiesel. Coconut oil and palm oil, being edible oils, transesterification with 0.25 v/v methanol-oil ratio, 0.50% w/v KOH as at 58(±2) °C, 20 min reaction time for coconut oil and 0.25% v/v methanol-oil ratio, 0.50% w/v KOH as alkaline catalyst at 60(±2) °C for palm kernel oil will convert them to 98-99% biodiesel. The brake thermal efficiency of palm oil biodiesel was higher with lower brake specific fuel consumption, but rubber seed oil biodiesel(ROB) showed less emission (CO and NO_x) compared to other biodiesels.     

Applications of artificial neural networks for refrigeration, air-conditioning and heat pump systems—A review

In this paper, an attempt has been made to review the applications of artificial neural networks (ANN) for energy and exergy analysis of refrigeration, air conditioning and heat pump (RACHP) systems. The studies reported are categorized into eight groups as follows: (i) vapour compression systems (ii) RACHP systems components, (iii) vapour absorption systems, (iv) prediction of refrigerant properties (v) control of RACHP systems, (vi) phase change characteristics of refrigerants, (vii) heat ventilation air conditioning (HVAC) systems and (viii) other special purpose heating and cooling applications. More than 90 published articles in this area are reviewed. Additionally, the limitations with ANN models are highlighted. This paper concludes that ANN can be successfully applied in the field of RACHP systems with acceptable accuracy.     

Non-nutritive functional agents in rattan-shoots, a food consumed by native people in the Philippines

The tender shoots of Calamus ornatus, one of the food items consumed by the native people, Kanawan Aytas, in the Bataan region of the Philippines, have not been studied before. A bioassay-guided investigation of its methanolic extract afforded non-nutritive functional agents (NFAs), steroidal saponins 1–3, along with its aglycone (4). The NFAs 1–4 inhibited cyclooxygenase enzymes, COX-1 and -2, by 47%, 43%, 33%, and 53% and 71%, 75%, 78%, and 73%, respectively, at 28.2, 24.2, 21.2 and 60.4 μM. Treatment of breast (MCF-7), CNS (SF-268), lung (NCI-H460), colon (HCT-116) and gastric (AGS) cancer cell lines with the extract at 100 μg/ml reduced cell proliferation. Similarly, the pure NFAs 2 and 3 reduced the cell viability of breast, CNS, lung, colon and gastric cancer cell lines by 37.5%, 22.4%, 53.3%, 58.2%, 40.3% and 29.8%, 21.3%, 45.6%, 37.1%, 25.0%, respectively, at 24.2 and 21.2 μM. The 50% reduction in cell viability (IC₅₀) concentrations of 2 and 3 against these cancer cell lines were 8.8, 6.1, 7.5, 23.8, 12.1 and 3.8, 7.1, 3.3, 14.3, 12.1 μM, respectively. This is the first report on the isolation of steroidal saponins from C. ornatus shoots and their antiinflammatory and tumor cell proliferation inhibitory activities. Therefore, our results suggest that the Kanawan Aytas may yield health benefits from rattan-shoots in their diet.     

Residual deposits in green tea shoots and black tea after individual and combined application of propiconazole and copper oxychloride

BACKGROUND: A combination of propiconazole and copper oxychloride is commonly used for controlling blister blight disease caused by the fungus Exobasidium vexans Massee of tea in south India. Field trials were conducted in wet and dry seasons to determine the rate of dissipation of propiconazole and copper oxychloride (COC) in green tea shoots and black tea. High‐performance liquid chromatography was used to quantify propiconazole residues in these matrices. Copper was analysed using atomic absorption spectrometry. RESULTS: The rate of dissipation of propiconazole in both seasons followed first‐order kinetics. Dissipation was faster in the wet than in the dry season. Factors such as rainfall elution and leaf growth dilution lead to faster residual decline in the wet season. However, even in wet season 0.10 mg kg^?1 of propiconazole residues were noted in black tea on the seventh day after fungicide application because of its systemic nature. Thus good control over the disease could be achieved. CONCLUSION: The recommended safe harvest interval and half‐life for the combined application of propiconazole and COC from this study is 5.39 and 2.43 days respectively in green tea shoots during the dry season. Moreover, the residues of propiconazole in green tea shoots on the seventh day is the same as the maximum residue limit (MRL) proposed by the European Union (EU), indicating that combined application of the two chemicals does not leave significant residues on seventh day or thereafter. Hence, upon harvest, which is usually between 8 and 10 days after fungicide application, the green tea shoots are safer from fungicide residues and pose less risk to human consumption. Copyright © 2009 Society of Chemical Industry     

A study on landslides and subsurface piping,facilitated by dykes,using vertical electrical sounding and δO<Superscript>18</Superscript> and δH<Superscript>2</Superscript> stable isotopes

A combination of vertical electrical sounding (VES) and δO¹⁸ and δH² stable isotope geochemistry is used in this study to trace out the extension of a dyke and for deciphering the subsurface piping phenomena in a landslide-affected hamlet, Pasukadavu, in the Western Ghats of Kerala, India. VES was successful in extracting three to four different subsurface layers characterized by differing resistivity. Two VES sections were prepared from 24 different VES locations, each one for understanding the dyke extension and for delineating subsurface conduits. The dyke was characterized by high resistivity of 800–5000 Ω.m and shows varying thickness. In the second profile, the void zone, which is characteristic of piping, is delineated through a low resistivity zone (75 to 350 Ω.m). δO¹⁸ and δH² stable isotopes collected along the second VES profile show the same chemistry, indicating that it is the same water which flows all along the VES profile 2. A four-stage conceptual model was developed to illustrate and narrate the sequence of development of the piping phenomena and landslide activity.