Computer simulation of transient stability analysis of power systems.

Determination of stability characteristics of a power system is considered as a substantial issue with the increasing complexity of power systems. Power system stability is defined as the behavior of the electrical power system under sudden or sequence of disturbances when it is operating in steady state. It could be a problem of voltage stability, frequency stability or rotor angle stability depending of the type of disturbance. Transient stability which is a sub section of rotor angle stability, is concerned with the condition in which the synchronous machines in the system remain in synchronism or \u27in-step\u27 with each other when the system is subjected to severe disturbances. In multi-machine power system, transient stability analysis is an indispensable tool in the areas of planning, design, operation and research. The nonlinear nature under disturbance is not linearised for the purpose of analyzing transient stability. Therefore, the theories and methodologies for transient stability analysis based on approximations and assumptions. This study is to prepare an educational software package to understand the transient stability behavior while understanding the theories and methodologies behind it. (Abstract shortened by UMI.)Dept. of Electrical and Computer Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2004 .J39. Source: Masters Abstracts International, Volume: 43-01, page: 0276. Adviser: G. R. G. Raju. Thesis (M.A.Sc.)--University of Windsor (Canada), 2004

Outcome of surfactant therapy in a tertiary referral centre in Sri Lanka

Objective To assess the outcome of surfactant therapy at a tertiary referral centre in Sri Lanka Design, setting and method All babies treated with surfactant at Sri Jayewardenepura General Hospital during 2007 were included in the study. Data on weight, maturity, age of ventilation, age of surfactant therapy, ventilator settings before and after surfactant, arterial blood gas results before and after surfactant, details regarding pneumothorax and pulmonary haemorrhage, duration of ventilation and chronic lung disease at 28 days, 3 months, and 6 months were collected. Data analysis was done according to maturity groups. Results Forty eight babies had surfactant therapy during the study period. The commonest indication was hyaline membrane disease (HMD) in prematures (45), followed by meconium aspiration syndrome (03). According to maturity, 22 (46%) were in 28-33+ weeks, followed by 12 (25%) in <28 weeks, 11 (23%) in 34-36+ weeks and 3 (6%) were>37 weeks (mature). Only 6 (12%) babies in 34-36+ weeks had transient hypoxia. None of them developed pneumothorax. Four (8%) had features suggestive of pulmonary haemorrhage 12-48 hours after surfactant replacement therapy. Four (8%) babies had chronic lung disease at 28 days of age and two of them were in babies <28 weeks. The reduction in oxygen requirements was seen within 6 hours of therapy in 7/12, 18/22, 6/11 in <28, 28-33+ and 34-36+ weeks babies respectively and in 12-24 hours in babies>37 weeks. There were 14 deaths comprising 5/12 of babies <28 weeks, 5 /22 of 28-33+ weeks, 4/11 of 34-36+ weeks. Duration of ventilation varied among the survivors; 5/7 babies of <28 weeks needed>10 days of ventilation whereas 10/17 of 28-33+ weeks needed <10 days of ventilation

Oligo-microarray analysis and identification of stress-immune response genes from manila clam (Ruditapes philippinarum) exposure to heat and cold stresses

Thermal stress regulates the complex system of gene expression and downstream biochemical and physiological responses in aquatic species. To identify genes involved in heat stress responses in manila clam (Ruditapes philippinarum), microarray analysis was conducted using clam transcriptome generated by pyrosequencing of cDNA library. Manila clams were exposed to heat (30 +/- A 1 A degrees C) and cold (4 +/- A 1 A degrees C) stresses and compared with control animals (18 +/- A 1 A degrees C). Heat stressed animals have changed greater number of transcripts (8,306) than cold stress (7,573). Results of both heat and cold exposure has shown that over 2-fold up-regulated or down regulated (> 2-or < 2-fold) transcripts were higher at 24 h than at 6 h. It suggests that silent and constitutive express genes can activate at critical stage of thermal stress which could be between 6 and 24 h post stresses. We identified wide range of stress-immune response genes such as transcription factors, heat shock proteins, antioxidant and detoxification enzymes, inflammatory and apoptosis related genes, cell adhesion molecules, cytokines, and IFN regulatory proteins. Histological results revealed that non-specific cellular alterations such as lesions, hypertrophy, and necrosis in stressed gills could be due to decrease of gas exchange rate which may cause hypoxia.N