DETC2005-84974 STRESS ANALYSIS AND LIFE ASSESSMENT OF ROTOR AND RETAINING RING OF GENERATOR FOR FOSSIL POWER PLANT

Increased rating of the generator capacity can be achieved by either increasing length or diameter of generator rotor body. Increasing the length of the rotor diameter should ensure the dynamic stability. On the other hand, increasing rotor diameter should satisfy the strength limit of current rotor material. ABSTRACT In addition to the higher centrifugal forces during normal operation in 3600 rpm, a generator rotor body is subjected to the contact pressures from shrink-fit between generator rotor and retaining ring. To obtain the structural reliability and life assessment of the generator, the finite element models were developed and structural analyses were carried out. The stress distributions and the critical locations of the rotor body were identified. Further, the fatigue life is performed to estimate the remaining life of generator. The critical crack size and probability of failure are also evaluated based on the analysis results. The critical sizes of a crack of generator are predicted using linear elastic fracture mechanics. These results will be applied to the development of a larger 1000MW capacity generator. This paper presents both stress analysis and life assessment results of the new 1000MW generator rotor assembly. The baseline design of the 800MW generator rotor was also evaluated for verifying the reliability of the analysis results. Two load cases, the contact pressures from shrink-fit between rotor and retaining ring and the centrifugal forces during normal operation in 3600 rpm, were considered. To obtain the structural reliability and life assessment of the generator, the finite element models were developed and structural analyses were carried out. The stress distributions and the critical locations of the rotor body were identified. Further, the fatigue life is performed to estimate the remaining life of generator. The critical crack size and probability of failure are also evaluated based on the analysis results INTRODUCTION In rapid technology advancement of the fossil power plant, it is inevitable that the output of a given turbine generator frame size will be increased from time to time. This has required redesign of the generator to keep pace with the increased rating. For turbine generators, increased rating presents challenges for designer. The designers to ensure that the new design can be satisfied the performance capabilities and electrical rating requirements, while maintaining mechanical, thermal and magnetic limits. These challenges come out largely as a result of increasing stresses, vibrational instability, fatigue and stress corrosion crack. To obtain the structural reliability and life assessment of the new generator, stress analyses, fatigue life assessment, and critical crack evaluation are required and the finite element analysis for the generator rotor assembly is used for this purpose

Minimally Invasive Irrigation for Lumbar Spinal Epidural Abscess using a Trans-Sacral Epiduroscopic Laser Decompression Catheter

We describe a case of a spinal epidural abscess that was successfully treated with minimally invasive irrigation using trans-sacral epiduroscopic laser decompression (SELD) catheter. A 66-year-old man experienced aggravating right leg pain and lower back pain for 1 month despite receiving several pain blocks at a local hospital. Magnetic resonance imaging scans showed annular fissure and bulging disc at the L4/5 level. Therefore, we decided to treat the L4/5 lesion using SELD. Laboratory studies demonstrated leukocytosis and elevated C-reactive protein level. However, we did not pay attention to the abnormal laboratory values before SELD. During SELD, we found a yellowish epidural abscess and pus drainage. Therefore, we irrigated the epidural abscess using an SELD catheter. His low back pain was relieved dramatically immediately after the procedure. The spinal epidural abscess completely resolved after 20 days of antibiotic treatment. Minimally invasive irrigation and drainage using a SELD catheter and intravenous antibiotic therapy are helpful for the treatment of spinal epidural abscess

Urachal Actinomycosis Mimicking a Urachal Tumor

A 26-year-old man presented with lower abdominal discomfort and a palpable mass in the right lower quadrant. An abdominal computed tomography (CT) scan revealed an abdominal wall mass that extended from the dome of the bladder. Fluorine-18 fluorodeoxyglucose (FDG) positron-emission tomography/CT (PET/CT) showed hypermetabolic wall thickening around the bladder dome area that extended to the abdominal wall and hypermetabolic mesenteric infiltration. Differential diagnosis included a urachal tumor with invasion into adjacent organs and chronic inflammatory disease. Partial cystectomy with abdominal wall mass excision was performed, and the final pathologic report was consistent with urachal actinomycosis

Association between periodontitis and hemorrhagic stroke among Koreans: A case-control study

Background: Several studies suggested that periodontitis is a risk factor for stroke, but the relationship between periodontitis and hemorrhagic stroke has not been widely reported. This study aims to evaluate the association between periodontitis and hemorrhagic stroke and to identify the risk group for this association. Methods: We recruited 165 patients who were diagnosed via computed tomography brain imaging as having had a hemorrhagic stroke and 214 non-stroke control subjects for a case-control study. All participants underwent a clinical periodontal examination using clinical attachment level (CAL) as amarker. Information about sociodemographic factors, behavioral factors, systemic health, and a familial history of systemic health was gathered through an interview using structured questionnaires. The association between periodontitis and hemorrhagic stroke was evaluated using multivariate logistic regression analyses with adjustment for age, gender, income, education, hypertension, diabetes, body mass index, cardiac disease, familial hypertension history, familial diabetes history, familial cardiac disease history, smoking, and alcohol consumption. Subgroup analyses were also performed to investigate potential risk groups. Results: After controlling for potential confounders, periodontitis (CAL ≥6 mm) was found to be significantly associated with hemorrhagic stroke (odds ratio: 2.5; 95% confidence interval: 1.1 to 5.6), but this association did not exhibit a dose-dependent response for periodontitis (percentile of sites of periodontal pockets with CAL ≥5 mm among total probed pockets). The association between periodontitis (CAL ≥6 mm) and hemorrhagic stroke was significant for males, patients who had a lower income than control subjects, obese patients, and patients without diabetes. Conclusions: Periodontitis may be an independent risk factor for hemorrhagic stroke. Risk groups include males, patients without diabetes, and obese subjects

A Case of Amblyomma testudinarium Tick Bite in a Korean Woman

A case of tick bite was found in the inguinal region of a 74-year-old Korean woman. She was attacked by the tick while working in her vegetable garden in the vicinity of mountain located in Suncheon City, the southern coastal area of the Korean Peninsula. On admission she complained of mild discomfort and itching around the bite area. The causative tick was 23 mm long and had slender pedipalps. The scutum was quite ornate and had eyes at the edge. The genital aperture was located anterior to the level of the coxa II. The spiracular plate was comma-shaped and the anus was surrounded posteriorly by the anal groove. The coxa I had subequal 2 spurs; the external one slightly larger. The spur of coxa IV was slightly longer than those of coxae II and III. The tarsus IV had 2 distinct subapical ventral spurs. It was identified as the fully engorged adult female of Amblyomma testudinarium. This is the first human case of Amblyomma bite in Korea

Lactobacillus plantarum DK119 as a Probiotic Confers Protection against Influenza Virus by Modulating Innate Immunity

Lactobacillus plantarum DK119 (DK119) isolated from the fermented Korean cabbage food was used as a probiotic to determine its antiviral effects on influenza virus. DK119 intranasal or oral administration conferred 100% protection against subsequent lethal infection with influenza A viruses, prevented significant weight loss, and lowered lung viral loads in a mouse model. The antiviral protective efficacy was observed in a dose and route dependent manner of DK119 administration. Mice that were treated with DK119 showed high levels of cytokines IL-12 and IFN-c in bronchoalveolar lavage fluids, and a low degree of inflammation upon infection with influenza virus. Depletion of alveolar macrophage cells in lungs and bronchoalveolar lavages completely abrogated the DK119-mediated protection. Modulating host innate immunity of dendritic and macrophage cells, and cytokine production pattern appeared to be possible mechanisms by which DK119 exhibited antiviral effects on influenza virus infection. These results indicate that DK119 can be developed as a beneficial antiviral probiotic microorganism