Analysis of Acoustic Emission Signals using WaveletTransformation Technique

Acoustic emission (AE) monitoring is carried out during proof pressure testing of pressurevessels to find the occurrence of any crack growth-related phenomenon. While carrying out AEmonitoring, it is often found that the background noise is very high. Along with the noise, thesignal includes various phenomena related to crack growth, rubbing of fasteners, leaks, etc. Dueto the presence of noise, it becomes difficult to identify signature of the original signals related to the above phenomenon. Through various filtering/ thresholding techniques, it was found that the original signals were getting filtered out along with noise. Wavelet transformation technique is found to be more appropriate to analyse the AE signals under such situations. Wavelet transformation technique is used to de-noise the AE data. The de-noised signal is classified to identify a signature based on the type of phenomena.Defence Science Journal, 2008, 58(4), pp.559-564, DOI:http://dx.doi.org/10.14429/dsj.58.167

Development of Technology for Large Scale Production of Titanium Sponge

Intensive investigations on the development of titanium metal production technology had been carried out during 1965-1975 at the Bhabha Atomic Research Centre, Bombay and at the Nuclear Fuel Complex, Hyderabad. The Defence Metallurgical Research Laboratory, Hyderabad has set up a ‘Titanium Sponge Experimental Facility’ with a capacity to produce 100 tonnes of sponge per annum in 2000 kg batches by the Kroll’s process with a view to optimising technology for large scale production.The paper presents an outline of the experimental facility and discusses the various considerations that have gone into the design of equipment, materials of construction, process selection, etc. The facility has gone into operation in March,1985. The results obtained so far are encouraging

Comparison of leakage rates of methyl bromide and sulfuryl fluoride during structural fumigations

In structural fumigations, half-loss time (HLT) is the most frequently used indicator for comparing fumigant leakage rates. In practical situations where gas leakage rates during structural fumigations are compared, environmental conditions generally are not analyzed in detail and sealing quality is assumed to be constant or fixed. This gives a false impression that a certain gas fumigant might be contained in a structure better than another fumigant. During commercial structural fumigations at the Hal Ross Flour Mill, Department of Grain Science and Industry, Kansas State University, Manhattan, Kansas, USA, leakage characteristics of Methyl bromide (MB) and Sulfuryl fluoride (SF) were compared by taking internal and external environmental conditions into consideration. Two sets of one 24-h MB and one 24-h SF fumigation experiments were conducted in May and August 2009. Mill sealing and fumigations were conducted by two separate commercial fumigators. After sealing, sealing quality prior to a fumigation was verified by a building pressurization test. The mill was subjected to different pressure levels generated by a specially made fan. At each pressure level, the air flow rate through a calibrated fan was measured. The observed air flow rate plotted as a function of pressure quantified leakage characteristics of the mill. In two MB and SF fumigations, gas concentrations were continuously monitored during the entire fumigation period. A weather station was installed on the roof of the mill to monitor outside barometric pressure, wind speed and direction, temperature, and relative humidity. Inside the mill, a temperature and relative humidity data logger was placed on each of the five floors of the mill. Results of this study provided a quantitative side-by-side comparison between MB and SF in the same facility. The pressurization test showed that sealing effectiveness can be quantitatively determined ahead of fumigation. It also confirmed the sealing quality for all fumigations was essentially similar. MB and SF sowed similar gas distribution and leakage characteristics. Although the observed HLTs of the fumigations were different, those differences could be explained by the differences in environmental conditions, primarily wind speed, and to a certain extent mill temperature, rather than inherent properties of MB and SF gases.Keywords: Structural fumigation, Half-loss time, Grain-processing facility, Sulfuryl fluoride, Methyl bromid

A simplified and improved modeling approach for the structural fumigation process using computational fluid dynamics

A 3D Computational fluid dynamics (CFD) model of the fumigation process in the Hal Ross Flour Mill of Kansas State University, Manhattan, Kansas, USA, was formulated for prediction of the gas leakage rate to approximate the gas Half-loss time (HLT) during fumigation with Methyl bromide (MB) and Sulfuryl fluoride (SF). The model consisted of external and internal flow domains. The external domain was used to predict stagnation pressures generated by wind impinging on the mill’s walls. The internal domain was used to predict fumigant leakage rates in terms of HLT. Cracks on the mill’s walls represented the effective leakage areas on the internal flow domain. This modeling approach had been used by the authors (Chayaprasert and Maier) in a previous study, but it was simplified and improved in the present study. The primary simplification in the modeling approach was exclusion of the flour mill’s interior details (e.g., milling equipment), reducing the model formulation and simulation computing times. In the previous study, the gas-tightness of the internal flow domain was identified by varying the flow resistance coefficient of the effective leakage areas until the model yielded a HLT value that was close to the one observed from the experimental fumigant concentration data. In the present study, the domain gas-tightness was verified by building pressurization tests. The model was validated using data from one MB and one SF fumigation experiments. The HLTs provided by simulated fumigations were in good agreement with those determined from the experiments. The result of the present study provides further validation to the modeling approach and emphasizes the importance of building pressurization test for accurate HLT prediction. Keywords: Structural fumigation, Half-loss time, Pilot flour mill, Computational Fluid Dynamics (CFD), Building pressurization tes

C-band superconductor/semiconductor hybrid field-effect transistor amplifier on a LaAlO3 substrate

A single-stage C-band superconductor/semiconductor hybrid field-effect transistor amplifier was designed, fabricated, and tested at 77 K. The large area (1 inch x 0.5 inches) high temperature superconducting Tl-Ba-Ca-Cu-O (TBCCO) thin film was rf magnetron sputtered onto a LaAlO3 substrate. The film had a transition temperature of about 92 K after it was patterned and etched. The amplifier showed a gain of 6 dB and a 3 dB bandwidth of 100 MHz centered at 7.9 GHz. An identical gold amplifier circuit was tested at 77 K, and these results are compared with those from the hybrid amplifier

Development of Single Serum ELISA and Flow Through Assay for Infectious Bursal Disease of Poultry

The infectious bursal disease (IBD) is an age-limiting viral disease of chicken affecting both broiler and layer chicks between 3 – 6 weeks of age characterized by severe immunosuppression and high mortality. The maternally derived antibodies protect chicks till they develop age – resistance, hence breeder flocks immune status monitoring regularly helps in ensuring adequate levels of maternal antibodies transfer to hatchlings and fine tuning of vaccination schedule. The conventional virus neutralization test (VNT) though gold standard, is time consuming and cumbersome. Hence, alternate immunodiagnostic tests which are simple and relatively easy to perform viz., single serum dilution enzyme linked immunosorbent assay (ELISA) for antibody titre and flow through assay (FTA) for antigen detection were developed. A standard curve was constructed by using regression analysis which helped in derivation of an equation and that allowed to demonstrate correlation between observed titre and predicted titre. At a dilution of 1:2000 of serum there was a linear relationship between predicted titres at single serum dilution and observed titre. The FTA was able to detect 200 ng / µl concentrations of IBDV. The FTA can be performed as, on spot test for detection of IBDV in suspected cases

Structural heat treatments against Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae): effect of flour depth, life stage and floor.

The effect of high temperatures (50-60°C) and two levels of sanitation (~0.5 and 43 g of flour), on mortality of eggs, young larvae, old larvae, pupae, and adults of the red flour beetle, Tribolium castaneum, were evaluated during heat treatment of a pilot flour mill at Kansas State University. The mill was heated once during 13-14 May 2009 and once during 25-26 August 2009. Each of the heat treatments lasted 24 h. Bioassay boxes, with life stages of T. castaneum and temperature sensors confined in small compartments, were placed in 25 locations across all five mill floors. Temperature data showed that the mean time to 50°C based on the two treatments ranged from 10.39 to 17.18 h, and the mean time above 50°C ranged from 6.01 to 13.63 h. The mean maximum temperatures attained ranged from 50.7 to 61.4°C. In general, temperatures were lower in compartments with 43 g of flour when compared with compartments with 0.5 g of flour. Temperatures were also lower on the first floor than on the remaining floors. In box bioassays, essentially none of the life stages survived the 24 h heat treatment (99-100% mortality), except on the first floor. The survival of insects, especially on the first floor, is related to how quickly temperatures reached 50°C and how long temperatures were held between 50 and 60°C, and the maximum temperatures attained at a given location. There were only small differences in mortality between the two levels of sanitation. These results show that heat treatment of flour mills can control all life stages of T. castaneum in 24 h. Keywords: Tribolium castaneum, Heat treatment, Sanitation, Life stages, Methyl bromide alternative

Heat treatment: A viable methyl bromide alternative for managing stored-product insects in food-processing facilities

Heat treatment involves raising and maintaining temperatures of grain storage structures, warehouses, and food-processing facilities between 50 to 60°C to manage stored-product insect species. The duration of heat treatment is application-specific and may vary from 6 h for an empty storage facility to 24 h for an entire food-processing facility. Laboratory and commercial trials with high temperatures during the last decade, especially with forced air gas heaters, have resulted in a wealth of information on (1) understanding responses of insect species and life stages to heat, (2) heat distribution within a treated area, and (3) techniques necessary for gauging effectiveness of commercial heat treatments. Insect responses vary with the temperature, among species, and within a species among life stages. Air movement and strategic placement of fans are important for eliminating cool spots.Keywords: Heat, Forced air, Flour mills, Methyl bromide alternativ

Equilibrium Moisture Content of Kabuli, Chickpea, Black Sesame, and White Sesame Seeds

Sesame and chickpea are important crops in Ethiopia because both are major export crops that generate much revenue for both small farmers and the country as a whole. However, there is a lack of information about the fundamental equilibrium moisture content (EMC) relationships among these crops, which would help facilitate better monitoring and storage. Therefore, EMC adsorption and desorption prediction models based on temperature (T) and relative humidity (RH) were developed for the modified Chung-Pfost and modified Henderson models for Kabuli chickpea (KC), black sesame (BS), and white sesame (WS) seeds. The samples for conducting the adsorption and desorption tests were conditioned to various moisture content (MC) levels for the EMC test models. The samples (~500 g) were placed in multiple sealed enclosures equipped with T and RH sensors, which were placed in an environmental chamber where they were exposed to three temperatures (15°C, 25°C, and 35°C). The MCdb ranges used for model development for adsorption and desorption were, respectively, 11.6% to 19.5% and 8.9% to 16.9% for KC samples, 5.0% to 8.7% and 4.3% to 6.9% for BS, and 4.2% to 8.7% and 3.5% to 7.6% for WS. Nonlinear regression was used to determine the model coefficients for the modified Henderson and modified Chung-Pfost equations. The prediction statistics for the adsorption and desorption models yielded an SEE of, respectively, 0.53% and 0.68% MCdb for KC, 0.23% and 0.13% for BS, and 0.28% and 0.25% for WS. The model coefficients obtained in this study will be used in a moisture meter based on EMC measurement, which is currently being used as part of a USAID postharvest project in various African and Asian countries. These EMC models may also be important for other grain operations, which include harvesting, drying, storage, conditioning, and processing