Evaluation and Comparison of the Principal Component Analysis (PCA) and Isometric Feature Mapping (Isomap) Techniques on Gas Turbine Engine Data

This paper performs a comparative analysis of the results of PCA and ISOMAP for the purpose of reducing or eliminating erratic failure of the Gas Turbine Engine (GTE) system. We employ Nearest-neighbour classification for GTE fault diagnosis and M-fold cross validation to test the performance of our models. Comparison evaluation of performance indicates that, with PCA, 80% of good GTE is classified as good GTE, 77% of the average GTE is classified as average GTE and 67.6% of bad GTE is classified as bad GTE. With ISOMAP, 67% of good GTE is classified as good GTE, 70.8% of the average GTE is classified as average GTE and 81% of bad GTE is classified as bad GTE. PCA produces 26% error rate with nearest neighbour classification and 17% error rate with M-fold cross validation. While ISOMAP produces 35% error rate with nearest neighbour classification, and 26.5% error rate with M-fold cross validation. Results indicate that PCA is more effective in analyzing the GTE data set, giving the best classification for fault diagnosis. This enhances the reliability of the turbine engine during wear out phase, through predictive maintenance strategies

Pattern of Presentation of Newly Diagnosed Persons living with HIV/AIDS Infection in Uyo, South-South Nigeria

HIV/AIDS is a significant cause of morbidity and mortality worldwide. In countries with poor healthcare infrastructure facility development and services, symptoms at initial presentation may be non-specific leading to poor decision-making and management. The objective of this study was to determine the pattern of presentation of newly diagnosed persons with retroviral infection in Uyo, South-South Nigeria. Between January and June 2010, a total of 1024 new patients attending the general outpatient clinic of the University of Uyo Teaching Hospital, Akwa Ibom State, were screened for retroviral infection and pattern of presentation using rapid immunoassay method based on the principle of immunochromatography as well as pattern of presentation of those who tested positive. Of the 1024 patients attending the clinic, 315 (30.8%), consisting of 107 (34.0%) males and 208 (66.0%) females tested positive. The patients ranged in age from 15 years to greater than 40 years. All the teenagers were female patients (1.9 %).The majority of the patients were between 25-29 years (28.6%). A total of 78 patients (24.8%) only knew of their HIV status while conducting voluntary counseling and testing (VCT) for some other medical reasons. Major reasons for presentation was weight loss in 18.1 % of patients, prolonged unexplained fever,14.9%; diarrhoea, 6.7%; skin rashes, 6.7 %; cough, 2.9 % and a combination of 2 or more symptoms in 26.0 % of the patients. HIV infection is common among patients attending primary care clinics. Although many of the patients presented with primary symptoms of weight loss, prolonged fever, diarrhoea, skin rashes and cough, a significant number of them came with apparently non-specific health concern. This strongly highlights the need for high index of suspicion of HIV infection in persons attending clinics for other medical conditions especially when the symptoms are multi- systemic. Key words: HIV; Newly Diagnosed; Patients; Pattern of Presentation; Nigeria