Large-eddy simulation of spectral coherence in a wind turbine wake

This work is mainly dedicated to the study of the characteristics of spectral coherence of turbulence fluctuations in wind turbine wakes. A computational fluid dynamics (CFD) code has been implemented using a large-eddy simulation (LES) approach, which is thought to be conceptually more suitable for studying the turbulence evolution in a wind turbine wake. Comparisons with experimental data from the Nørrekær Enge II Windfarm, in Denmark, and with an analytical model proposed by Panofsky and Dutton have been performed, and the results are found to be in reasonable agreement with both

Thermo-Mixed Hydrodynamics of Piston Compression Ring Conjunction

The final publication is available at http://link.springer.com.A new method, comprising Navier-Stokes equations, Rayleigh-Plesset volume fraction equation, an analytical control-volume thermal mixed approach and asperity interactions is reported. The method is employed for prediction of lubricant flow and assessment of friction in the compression ring-cylinder liner conjunction. The results are compared with Reynolds-based laminar flow with Elrod cavitation algorithm. Good conformance is observed for medium load intensity part of the engine cycle. At lighter loads and higher sliding velocity, the new method shows more complex fluid flow, possessing layered flow characteristics on account of pressure and temperature gradient into the depth of the lubricant film, which leads to a cavitation region with vapour content at varied volume fractions. Predictions also conform well to experimental measurements reported by other authors

Sinonasal pathology and headaches

Primary headaches or other chronic headaches can be triggered by sinonasal pathologies, or variations within the sinonasal tract. Establishing a cause and effect relationship between certain sinonasal conditions and chronic headaches can justify sinonasal surgery for the relief of headaches and provide considerable relief to a subgroup of patients with chronic headaches resistant to medical treatment. A prospective study on 204 patients undergoing sinonasal surgery for an apperent symptomatic sinonasal pathology was conducted to determine the incidence and types of headaches in sinonasal patients preoperatively, the presence of potential sinonasal triggering mechanisms, and postoperative headache relief when such triggers are removed. The relationship between potential triggers and postoperative relief is analysed to determine a possible link. Headache was a major complaint in 50% of these patients and the overall incidence of primary type headaches was 25.5% (52 of 204 patients). Postoperatively, 83.4% of the patients expressed improvement of the headaches (85/102). High scores of preoperative Sinonasal Headache Quotient (SNHQ), obtained through a general questionnaire and endoscopic/radiologic work up seems to correlate well with postoperative relief of headaches (p<0.0001), as well as a well defined lesion site and an ipsilateral pain localization (P<0.02). A detailed sinonasal analysis of chronic headache patients may help identify a subgroup with potential sinonasal triggers and these patients may experience considerable relief of headache following surgery

Sinonasal distribution of topically applied particles: Computerized tomographic detection and the effects of topical decongestion

OBJECTIVE: Determine the efficacy of computerized tomography (CT) in detecting the intranasal distribution of sprayed radio-enhanced particles and the effects of topical decongestion on particle distribution

Lung parenchyma changes in ankylosing spondylitis: demonstration with high resolution CT and correlation with disease duration

Objective: To analyze the spectrum of the lung parenchyma changes in ankylosing spondylitis (AS) with high resolution computed tomography (HRCT) and correlate the findings with disease duration. Material and methods., Twenty patients (18 male, 2 female) with the diagnosis of AS according to New York criteria were included in the study. None of the patients had history of tuberculosis, prolonged inorganic dust exposure and hospitalization for pneumonia. Seven of the patients were smokers, three patients were exsmokers, and 10 patients were nonsmokers. The patients were assigned to three groups depending on disease duration. Group 1: patients with disease duration less than or equal to 5 years (it: four patients), group 2: patients with disease duration greater than or equal to 6 years but less than or equal to10 years (n: four patients), group 3: patients with disease duration greater than or equal to 11 years (n: 12 patients). HRCT and pulmonary function tests (PFT) were performed in all patients. Results: HRCT demonstrated pathology in 17 patients (85%). Two patients in group 1, 4 patients in group 2 and 11 patients in group 3 had pulmonary parenchyma changes. Emphysema (9/20), septal thickening (9/20) and pleural thickening (9/20) were the most common changes followed by nodule (8/20) and subpleural band formation (7/20). Three patients had apical fibrosis (AF). Septal and pleural thickening (both 4/10) were the most common changes when only nonsmokers were considered. Among nine patients with emphysema three were nonsmokers. Conclusion: There is a wide spectrum in pulmonary parenchyma changes in AS. These changes begin in early stages of the disease and increase with disease duration. Although smoking complicates the spectrum of changes in pulmonary parenchyma, they are predominately in the form of interstitial inflammation. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved

LONG-TERM PROGNOSIS AFTER A FIRST MYOCARDIAL-INFARCTION IN TURKEY - DETERMINANTS OF MORTALITY AND REINFARCTION

Long-term prognosis of a first myocardial infarction and factors associated with late cardiac mortality and reinfarction were studied in 718 survivors. Patients have been followed up for 1-10 years (mean 57.6 +/- 39.6 months). None of the patients underwent coronary bypass surgery in the follow-up period. Cumulative mortality rates were 8.6% in the first year, 17.9% in 3 years, 26.4% in 5 years and 36.5% in 10 years. The type and site of myocardial infarction (Q-wave versus non-Q-wave and anterior versus infero-posterior) were found to have no independent prognostic importance. The cardiac mortality was best predicted by the occurrence of congestive heart failure in the coronary care unit. Other determinants of late outcome were the presence of ventricular arrhythmias, left bundle branch block, and the occurrence of stable or unstable angina pectoris or reinfarction during the follow-up period. Usage of antiplatelet or anticoagulant drugs was not found to affect mortality. Reinfarction rates were 4, 9.9, 15.5 and 28% in 1, 3, 5 and 10 years, respectively, and no relation was found between the type and location of myocardial infarction and reinfarction rate. Reinfarction was higher in patients receiving anticoagulants and in patients with postmyocardial infarction angina. Our findings suggest that the prognosis of patients with a first acute myocardial infarction in Turkey is not different from that in Western populations and factors influencing prognosis are similar to those previously reported