Tactile whole-field imaging sensor on photoelasticity

The paper describes a whole-field imaging sensor developed on the principles of photoelasticity. The sensor produces colored fringe patterns when load is applied on the contacting surface. These fringes can be analyzed using conventional photoelastic techniques, however, as the loading in the present case is not conventional some new strategies need to be devised to analyze the load imprint. The loading is unconventional in the sense that low modulus photoelastic material is deformed under vertical load in the direction of light travel to induce the photoelastic effect. The paper discusses the efficacy of both RGB calibration and phase shifting techniques in sensing applications. The characteristics of fringe patterns obtained under vertical and shear loads have been studied and the results obtained under these conditions are discussed with their limitations specifically when this is applied for sensing applications. Finally a case study has been conducted to analyze a foot image and conclusions drawn from this have been presented. Copyright © 2007 by ASME

Photoelastic stress analysis under unconventional loading

This paper presents use of conventional photoelastic techniques under unconventional loading situations to evaluate their efficacy in sensing applications. The loading is unconventional in the sense that low modulus photoelastic material is deformed under vertical load in the direction of light travel to induce the photoelastic effect. This is atypical of conventional methods where loading is across the light travel. Both RGB calibration and phase shining techniques have been used to study the characteristics of fringe patterns obtained under vertical and shear loads. The results obtained under these conditions are discussed with their limitations specially when this is applied for sensing applications. Finally a case study has been conducted to analyze the foot image and conclusions drawn from this have been presented. Copyright © 2007 by ASME

Load estimation from photoelastic fringe patterns under combined normal and shear forces

Recently there has been some spurt of interests to use photoelastic materials for sensing applications. This has been successfully applied for designing a number of signal-based sensors, however, there have been limited efforts to design image-based sensors on photoelasticity which can have wider applications in term of actual loading and visualisation. The main difficulty in achieving this is the infinite loading conditions that may generate same image on the material surface. This, however, can be useful for known loading situations as this can provide dynamic and actual conditions of loading in real time. This is particularly useful for separating components of forces in and out of the loading plane. One such application is the separation of normal and shear forces acting on the plantar surface of foot of diabetic patients for predicting ulceration. In our earlier work we have used neural networks to extract normal force information from the fringe patterns using image intensity. This paper considers geometric and various other statistical parameters in addition to the image intensity to extract normal as well as shear force information from the fringe pattern in a controlled experimental environment. The results of neural network output with the above parameters and their combinations are compared and discussed. The aim is to generalise the technique for a range of loading conditions that can be exploited for whole-field load visualisation and sensing applications in biomedical field

Effect of oxidative stress on ABC transporters: contribution to epilepsy pharmacoresistance

Epilepsy is a neurological disorder affecting around 1%-2% of population worldwide and its treatment includes use of antiepileptic drugs to control seizures. Failure to respond to antiepileptic drug therapy is a major clinical problem and over expression of ATP-binding cassette transporters is considered one of the major reasons for pharmacoresistance. In this review, we have summarized the regulation of ABC transporters in response to oxidative stress due to disease and antiepileptic drugs. Further, ketogenic diet and antioxidants were examined for their role in pharmacoresistance. The understanding of signalling pathways and mechanism involved may help in identifying potential therapeutic targets and improving drug response

Research on mechanisms of alloy strengthening. Part 1 - Strengthening through fine particle dispersion. Part 2 - Control of structure and properties by means of rapid quenching of liquid metals /splat cooling/ Semiannual report

Alloy strengthening mechanisms - strengthening by fine particle dispersion, and structure and properties control by rapid quenching or splat cooling of liquid metal

Molecular Mechanisms of Persistence of Mutualistic Bacteria Photorhabdus in the Entomopathogenic Nematode Host

Symbioses between microbes and animals are ubiquitous, yet little is known about the intricate mechanisms maintaining such associations. In an emerging mutualistic model system, insect-pathogenic bacteria Photorhabdus and their insect-parasitic nematode partner Heterorhabditis, we found that the bacteria undergo major transcriptional reshaping in the nematode intestine. Besides general starvation mechanisms, the bacteria induce cellular acidification to slow down growth, switch to pentose phosphate pathway to overcome oxidative stress and nutrition limitation, and shed motility but develop biofilm to persist in the nematode intestine until being released into the insect hemolymph. These findings demonstrate how the symbiotic bacteria reduce their nutritional dependence on the enduring nematode partner to ensure successful transmission of the couple to the next insect host

Aortopathy in patients with a bicuspid aortic valve : determining susceptibility for aortic complications

The prevalence of aortic dilation and related complications as rupture and dissection is higher in patients with a bicuspid aortic valve (BAV) as compared to patients with a tricuspid aortic valve (TAV), although not every individual carries this increased risk. It is therefore essential to identify those patients who are less susceptible for aortic wall pathology, as preventive ascending aortic surgery would not be necessary in this group. Since aortic diameter as a criterion for surgery is only decisive at population level, it would be very valuable to have tailored risk stratification at patient level. The purpose of this thesis was therefore to investigate the possibility to identify patients with BAV, without apparent dilation, with an increased susceptibility for future complications as aortic dilation and dissection. Furthermore the biological mechanism underlying aortic wall pathology in BAV was compared to a known genetically determined syndrome with an increased risk of aortopathy being Marfan syndrome.UBL - phd migration 201

NUMERICAL TRANSIENT HEAT TRANSFER ANALYSIS OF REACTOR FOR MAGNESIUM BASED ALLOY FOR HYDROGEN STORAGE APPLICATION

Metal hydrides are potential hydrogen storage media. They release hydrogen at moderate temperatures and pressures. Magnesium hydride is a promising approach for stationary power system application, due to high hydrogen storage capacity by weight. Magnesium hydride based reactor design is more complex due to high thermal energy release and absorption during hydriding reaction and dehydriding reaction, respectively. In this study, results of a numerical modeling study are presented for a 1.5 kg Magnesium alloy based hydriding reactor. Temperature profile in the reactor is computed by FEM analysis using ANSYS software for hydriding and dehydriding reaction. FEM analysis indicates that the reactor temperature is raised from 200 C to 422 ºC in 20 minutes during the hydriding process. Hence, a “cooling system” is required for maintaining temperature during the hydriding process. During the dehydriding process, maximum temperature drop occurs from 350 C to 189 ºC in 20 minutes. Therefore, an external heat source of 2 kW is required for maintaining the temperature during dehydriding. Details are presented