High-Temperature Optoelectronic Device Characterization and Integration Towards Optical Isolation for High-Density Power Modules

Power modules based on wide bandgap (WBG) materials enhance reliability and considerably reduce cooling requirements that lead to a significant reduction in total system cost and weight. Although these innovative properties lead power modules to higher power density, some concerns still need to be addressed to take full advantage of WBG-based modules. For example, the use of bulky transformers as a galvanic isolation system to float the high voltage gate driver limits further size reduction of the high-temperature power modules. Bulky transformers can be replaced by integrating high-temperature optocouplers to scale down power modules further and achieve disrupting performance in terms of thermal management, power efficiency, power density, operating environments, and reliability. However, regular semiconductor optoelectronic materials and devices have significant difficulty functioning in high-temperature environments. Modular integration of optoelectronic devices into high-temperature power modules is restricted due to the significant optical efficiency drop at elevated temperatures. The quantum efficiency and long-term reliability of optoelectronic devices decrease at elevated temperatures. The motivation for this study is to develop optoelectronic devices, specifically optocouplers, that can be integrated into high-density power modules. A detailed study on optoelectronic devices at high temperature enables us to explore the possibility of scaling high-density power modules by integrating high-temperature optoelectronic devices into the power module. The primary goal of this study is to characterize and verify the high-temperature operation of optoelectronic devices, including light-emitting diodes and photodiodes based on WBG materials. The secondary goal is to identify and integrate optoelectronic devices to achieve galvanic isolation in high-density power modules working at elevated temperatures. As part of the study, a high-temperature packaging, based on low temperature co-fired ceramic (LTCC), suitable to accommodate optoelectronic devices, will also be designed and developed

Parallelizing a network intrusion detection system using a GPU.

As network speeds continue to increase and attacks get increasingly more complicated, there is need to improved detection algorithms and improved performance of Network Intrusion Detection Systems (NIDS). Recently, several attempts have been made to use the underutilized parallel processing capabilities of GPUs, to offload the costly NIDS pattern matching algorithms. This thesis presents an interface for NIDS Snort that allows porting of the pattern-matching algorithm to run on a GPU. The analysis show that this system can achieve up to four times speedup over the existing Snort implementation and that GPUs can be effectively utilized to perform intensive computational processes like pattern matching

A framework for cardio-pulmonary resuscitation (CPR) scene retrieval from medical simulation videos based on object and activity detection.

In this thesis, we propose a framework to detect and retrieve CPR activity scenes from medical simulation videos. Medical simulation is a modern training method for medical students, where an emergency patient condition is simulated on human-like mannequins and the students act upon. These simulation sessions are recorded by the physician, for later debriefing. With the increasing number of simulation videos, automatic detection and retrieval of specific scenes became necessary. The proposed framework for CPR scene retrieval, would eliminate the conventional approach of using shot detection and frame segmentation techniques. Firstly, our work explores the application of Histogram of Oriented Gradients in three dimensions (HOG3D) to retrieve the scenes containing CPR activity. Secondly, we investigate the use of Local Binary Patterns in Three Orthogonal Planes (LBPTOP), which is the three dimensional extension of the popular Local Binary Patterns. This technique is a robust feature that can detect specific activities from scenes containing multiple actors and activities. Thirdly, we propose an improvement to the above mentioned methods by a combination of HOG3D and LBP-TOP. We use decision level fusion techniques to combine the features. We prove experimentally that the proposed techniques and their combination out-perform the existing system for CPR scene retrieval. Finally, we devise a method to detect and retrieve the scenes containing the breathing bag activity, from the medical simulation videos. The proposed framework is tested and validated using eight medical simulation videos and the results are presented

The Mullaperiyar conflict (NIAS Backgrounder No. B4-2010)

T he Mullaperiyar project is an inter-state inter-basin scheme which diverts water from the upper reaches of the west flowing Periyar River in Kerala into the eastern plains of Vaigai River Basin in Tamil Nadu for irrigation after power generation. It is one of the earliest trans-basin projects in India and was commissioned in 1895 by the British in the then Travancore State by an agreement signed in 1886 which was ratified after independence by the respective states of Tamil Nadu and Kerala. The project situated in the territory of Kerala benefiting Tamil Nadu has been a source of conflict. The simmering tension took the form of a full-blown conflict between the two neighbouring states after leaks were detected in the Mullaperiyar dam following which the reservoir level was brought down to 136 ft from 152 ft in 1979. Over the years, the two states have been involved in a tussle over the issue of raising the water level back to its original height and related safety concerns. Implicit in these issues are other deeper disquiets that have protracted and aggravated the conflict. The State and Central governments, various scientific and sociopolitical institutions and the media have shaped the conflict and the resolution process during this tumultuous period

Coconut kernel protein in diet protects the heart by beneficially modulating endothelial nitric oxide synthase, tumor necrosis factor-alpha, and nuclear factor-kappaB expressions in experimental myocardial infarction

AbstractPrevious studies conducted in our laboratory revealed that coconut kernel protein has a significant cardioprotective effect on isoproterenol-induced myocardial infarction in rats. In the present study, we explored the possible protective mechanism of coconut kernel protein during acute myocardial infarction. Coconut kernel protein (50 mg/100 g) was administered to Sprague-Dawley rats orally for 45 days. Isoproterenol (20 mg/100 g) was injected subcutaneously at an interval of 24 hours twice to induce myocardial infarction. Myocardial infarction was confirmed by the abnormal activities of cardiac marker enzymes in serum. Activities of antioxidant enzymes such as superoxide dismutase (SOD) and catalase were decreased (p < 0.05) in the heart of isoproterenol-treated rats, whereas pretreatment with coconut kernel protein increased (p < 0.05) these activities. An improved antioxidant status in these rats was further confirmed by the increased level of reduced glutathione and decreased level of lipid peroxidation products. Nitric oxide synthase (NOS) activity in the heart and nitrite level in blood were increased (p < 0.05) in coconut kernel protein-treated rats administered with isoproterenol compared to isoproterenol control rats. Coconut protein pretreatment upregulated the expression of endothelial nitric oxide synthase (eNOS), whereas expressions of nuclear factor-kappaB (NF-κB) and tumor necrosis factor-alpha (TNF-α) were downregulated in isoproterenol-treated rats. These findings suggest that the protective effects of coconut kernel protein may be mediated in part through upregulation of nitric oxide production, antioxidant mechanisms, and its ability to inhibit TNF-α and NF-κB activation

Study of α-transfer reaction 28Si( 7Li, t) 32S

The 28Si( 7Li, t) 32S reaction has been studied at 48 MeV. Using a αt potential overlap based on a microscopic cluster model, the full finite-range distorted wave Born approximation analysis was carried out for nine low-lying states; 0.0 MeV (0+), 2.23 MeV (2+), 3.78 MeV (0+), 4.46 MeV (4+), 5.01 MeV (3-), 5.80 MeV (1-), 6.76 MeV (3-), 7.43 MeV (1-) and 8.49 MeV (1-) of the residual nucleus. A re-analysis was also done for the same states of 32S having an αd overlap for the reaction 28Si (6Li, d) 32S at 75.6 MeV. Theoretical spectroscopic factors have been calculated for the measured even-parity states of 32S using the shell model code OXBASH. The spectroscopic factors were compared for both the reactions

Wide-angle α-t coincidence measurement in the breakup of 7Li on 27Al

We have performed wide-angle in-plane coincidence measurements of the alpha particles and tritons emitted in the 48-MeV 7Li projectile breakup reaction on 27Al. The data have been analyzed using the post-form distorted-wave Born-approximation (DWBA) theory of breakup reactions where Coulomb and nuclear breakup as well as their interference terms are included. The theory is able to provide a good description of the experimental data particularly at large relative angles between the fragments. The interference between the Coulomb and nuclear breakup modes is found to be significant

Inclusive and exclusive measurements in the projectile breakup of 7Li

The inclusive and exclusive measurements were carried out for 7Li projectile breakup on 27Al target at 48 MeV. In the inclusive data we have observed a broad peak around the beam velocity for alphas and tritons. The exclusive data for alpha-triton coincidences show good agreement with the post-form DWBA theory of breakup reactions

Coupled channel description of 16O+142,144,146Nd scattering around the Coulomb barrier using a complex microscopic potential

Angular distributions of elastic scattering and inelastic scattering from 2+ 1 state are measured for 16O+142,144,146Nd systems at several energies in the vicinity of the Coulomb barrier. The angular distributions are systematically analyzed in coupled channel framework. Renormalized double folded real optical and coupling potentials with DDM3Y interaction have been used in the calculation. Relevant nuclear densities needed to generate the potentials are derived from shell model wavefunctions. A truncated shell model calculation has been performed and the calculated energy levels are compared with the experimental ones. To simulate the absorption, a 'hybrid' approach is adopted. The contribution to the imaginary potential of couplings to the inelastic channels, other than the 2+ 1 target excitation channel, is calculated in the Feshbach formalism. This calculated imaginary potential along with a short ranged volume Woods-Saxon potential to simulate the absorption in fusion channel reproduces the angular distributions for 16O+146Nd quite well. But for 16O+142,144Nd systems additional surface absorption is found to be necessary to fit the angular distribution data. The variations of this additional absorption term with incident energy and the mass of the target are explored. © 2003 Elsevier Science B.V. All rights reserved