Use of system identification techniques for improving airframe finite element models using test data

A method for using system identification techniques to improve airframe finite element models using test data was developed and demonstrated. The method uses linear sensitivity matrices to relate changes in selected physical parameters to changes in the total system matrices. The values for these physical parameters were determined using constrained optimization with singular value decomposition. The method was confirmed using both simple and complex finite element models for which pseudo-experimental data was synthesized directly from the finite element model. The method was then applied to a real airframe model which incorporated all of the complexities and details of a large finite element model and for which extensive test data was available. The method was shown to work, and the differences between the identified model and the measured results were considered satisfactory

Use of system identification techniques for improving airframe finite element models using test data

A method for using system identification techniques to improve airframe finite element models was developed and demonstrated. The method uses linear sensitivity matrices to relate changes in selected physical parameters to changes in total system matrices. The values for these physical parameters were determined using constrained optimization with singular value decomposition. The method was confirmed using both simple and complex finite element models for which pseudo-experimental data was synthesized directly from the finite element model. The method was then applied to a real airframe model which incorporated all the complexities and details of a large finite element model and for which extensive test data was available. The method was shown to work, and the differences between the identified model and the measured results were considered satisfactory

Experimental Environmental Profiles and Sloshing Dynamics Aboard Zero-G Aircraft

This study presents the results of a parabolic flight experiment to study the sloshing dynamics of the magneto-active propellant management device experiment. This device utilizes a magnetoactive membrane and magnets located external to the tank to effectively damp the liquid free surface motion. This research work establishes a benchmark with sloshing analytical formulation and sensor calibration methods that can be used to characterize future research parabolic flights while providing important environmental profiles measured during flight, such as accelerations, pitch angle, velocity, temperature, total volatile content, carbon dioxide, relative humidity, magnetic field, and radiation. Correlation between these flight variables and the sloshing experiment are suggested to improve suppression of sloshing. Preliminary postflight analysis suggests a close correlation between high peaks of carbon dioxide and total volatile compound levels during the parabolas – levels sustained for up to one hour combined during cruise in some parabolic flights

Effectiveness of pelvic girdle exercise on pelvic girdle pain and specific activities among primigravida mothers attending antenatal OPD at selected hospitals, Salem.

A Study was done to assess the effectiveness of Pelvic girdle exercise on Pelvic Girdle Pain and specific activities among primigravida mothers attending antenatal OPD in selected hospitals, Salem. A Quasi experimental pre-test and post-test control group design was adopted. Non probability purposive sampling technique was used to select 60 primigravida mothers with Pelvic Girdle Pain among which 30 were assigned to experimental group and 30 were assigned to control group. Data was collected over a period of 4 weeks from 31.08.15 to 27.09.15. Pre-test was done for both experimental and control groups by using Modified Pelvic Girdle Questionnaire and Patient Specific Functional Scale. The researcher demonstrated Pelvic girdle exercise for 3-5 mothers for 30 minutes. After demonstration the mothers instructed to redemonstrate the exercise and the investigator checked their performance also insisted to perform this exercise program 2 times daily for a period of 2 weeks and a logbook was given to record the exercise were performed in their home. Along with this experimental group received a pamphlet which contains Pelvic girdle exercise and contact numbers of samples collected for follow up. All the samples instructed to come at the end of 1st and 2nd week of their antenatal visit after implementation of Pelvic girdle exercise and the post test conducted by using same tools to assess the effectiveness of Pelvic girdle exercise on Pelvic Girdle Pain and specific activities. Data analysis done by using descriptive and inferential statistics. The result showed that, in pretest majority of mothers had moderate pain in both experimental and control group (66% & 73%) respectively, whereas in post test majority of the experimental group mothers had mild pain in both post test- I (66%) and post test – II (97%) and majority of the control group mothers had moderate pain (66%) in both post test – I and post test – II respectively. In pretest the experimental group mothers had mean Pelvic Girdle Pain score of 35.30±12.13 whereas in post test I & II mean score was 22.33± 7.31 & 12.83± 5.33. The calculated ‘t’ values were 11.98 in post test – I & 12.08 in post test-II which was highly significant at

Isolation, identification and screening of potential xylanolytic enzyme from litter degrading fungi

Consortia of litter degrading fungal species were developed from different baiting substrates collected in and around Western ghat forest ecosystem, Coimbatore, Tamilnadu, India. Fifty-three litter degradingfungal species were isolated by nylon litterbag technique. The production of endo-b-1,4-xylanase (1,4-b-D-xylan xylanohydrolase, E.C. 3.2.1.8), b-D-xylosidase (1,4-b-xylan xylanohydrolase, E.C. 3.2.1.37) and protease was studied using oat spelt xylan as carbon source. Results showed that all fifty-three fungal species isolated from various litter samples produced fairly good xylanolytic enzyme activity. The xylanase and b-D-xylosidase activity ranges from 4.41 to 132.20 U and 48.72 to 1510.32 U, respectively. Growth was determined in terms of mycelial dry weight, which ranged between 0.209 and 1.047 mg/ml. The protease enzyme activity was from 19.7 to 60.8 U. This is the first report concerning xylanolyticenzyme production by the litter degrading fungi, isolated from litter samples

In Vitro Anti-plasmodial activity of Trigonella foenum–graecum L.

Developing countries, where malaria is one of the most prevalent diseases, still rely on traditional medicine as a source for the treatment of this disease. For the present study, Trigonella foenum-graecum L. (fenugreek) were collected from Coimbatore, Tamilnadu, India. The test plant has been used in India by traditional healers for the treatment of fever as well as other diseases. The active principle was extracted out in different solvent systems to assess the anti-plasmodial potential, with an aim that they can further be utilized to formulate drugs. In vitro anti-plasmodial assay of the extracted fractions of fenugreek leaves was carried out using laboratory adapted chloroquine sensitive and resistant Plasmodium falciparum isolates. Schizont maturation inhibition assay was adopted to analyze the potential of the extracts. Ethanol extract (50%) seemed to possess profound anti-plasmodial activity with IC50 value of 8.75 ± 0.35 µg ml−1 and 10.25 ± 0.35 µg ml−1 against chloroquine sensitive and resistant P. falciparum isolates, respectively. Among the investigated six fractions of the plant extracts, two were found to have significant anti-plasmodial activity with IC50 values <10 µg ml−1, namely ethanol and butanol extracts. Two extracts chloroform and ethyl acetate showed moderate activity with IC50 values ranging from 10 to 20 µg ml−1, and the other two extracts, hexane and water appeared to be inactive with IC50 values >85 µg ml−1. In addition, preliminary phytochemical screening of the various extracts indicated the presence of alkaloids, saponin, tannin like phenolic compounds, flavonoids and steroids

CFD Fuel Slosh Modeling of Fluid-Structure Interaction in Spacecraft Propellant Tanks with Diaphragms

Liquid sloshing within spacecraft propellant tanks causes rapid energy dissipation at resonant modes, which can result in attitude destabilization of the vehicle. Identifying resonant slosh modes currently requires experimental testing and mechanical pendulum analogs to characterize the slosh dynamics. Computational Fluid Dynamics (CFD) techniques have recently been validated as an effective tool for simulating fuel slosh within free-surface propellant tanks. Propellant tanks often incorporate an internal flexible diaphragm to separate ullage and propellant which increases modeling complexity. A coupled fluid-structure CFD model is required to capture the damping effects of a flexible diaphragm on the propellant. ANSYS multidisciplinary engineering software employs a coupled solver for analyzing two-way Fluid Structure Interaction (FSI) cases such as the diaphragm propellant tank system. Slosh models generated by ANSYS software are validated by experimental lateral slosh test results. Accurate data correlation would produce an innovative technique for modeling fuel slosh within diaphragm tanks and provide an accurate and efficient tool for identifying resonant modes and the slosh dynamic response