High-efficiency fast scintillators for "optical" soft x-ray arrays for laboratory plasma diagnostics

Scintillator-based "optical" soft x-ray (OSXR) arrays have been investigated as a replacement for the conventional silicon (Si)-based diode arrays used for imaging, tomographic reconstruction, magnetohydrodynamics, transport, and turbulence studies in magnetically confined fusion plasma research. An experimental survey among several scintillator candidates was performed, measuring the relative and absolute conversion efficiencies of soft x rays to visible light. Further investigations took into account glass and fiber-optic face-plates (FOPs) as substrates, and a thin aluminum foil (150 nm) to reflect the visible light emitted by the scintillator back to the optical detector. Columnar (crystal growth) thallium-doped cesium iodide (CsI:Tl) deposited on an FOP, was found to be the best candidate for the previously mentioned plasma diagnostics. Its luminescence decay time of the order of approximately 1-10 micros is thus suitable for the 10 micros time resolution required for the development of scintillator-based SXR plasma diagnostics. A prototype eight channel OSXR array using CsI:Tl was designed, built, and compared to an absolute extreme ultraviolet diode counterpart: its operation on the National Spherical Torus Experiment showed a lower level of induced noise relative to the Si-based diode arrays, especially during neutral beam injection heated plasma discharges. The OSXR concept can also be implemented in less harsh environments for basic spectroscopic laboratory plasma diagnostics.     

Improved flow pattern map for accurate prediction of the heat transfer coefficients during condensation of R-134a in smooth horizontal tubes and within the low-mass flux range

This paper presents an improved flow pattern map for predicting the heat transfer coefficients during condensation of R-134a inside a smooth horizontal tube. Experimental tests were conducted over the low-mass flux range of 75–300 kg/m² s, at a nominal saturation temperature of 40 °C, and with the test section vapour qualities ranging from 0.76 down to 0.03. This represents points within the annular, intermittent and stratified flow regimes. The results were used to modify the Thome–El Hajal flow pattern map to include a transition region between the stratified-wavy and annular or intermittent flow regimes. The revised flow pattern-based heat transfer correlation predicted the experimental data to a mean deviation of less than 6%.     

Computer Simulation of the Elastic and Fracture Behavior of Sodium Chloride Crystal

Molecular statics calculations of mechanical properties have been carried out for NaCI using the Born–Mayer–Huggins pair potential and periodic boundary conditions. Three truncation techniques are utilized. For each, calculations have been performed as a function of the truncation distance. The stress–strain curve, the fracture strength, and the fracture strain are found to be much more sensitive to the truncation technique and to variations in the truncation distance than other properties such as the elastic constants, the cohesive energy, or the lattice parameter.     

AN EXPERIMENTAL INVESTIGATION OF GUILLOTINING OF ALUMINUM ALLOY 5005

This paper reports on an experimental investigation of the guillotining of aluminum alloy 5005. The effects of clearance and blade sharpness on performance of the guillotining process are investigated and analyzed. Four parameters are measured in the plastic deformation and fracture zones: rollover, burnish, fracture, and the burr height. It is shown that the burnish decreases as the clearance increases, and the burnish is always higher for the relatively dull blades than for sharp blades. On the other hand, fracture behavior is opposite to that of the burnish. Burr height increases as the clearance increases and as the blade gets duller.     

Detection of faulty high speed wind turbine bearing using signal intensity estimator technique

Bearings are typically used in wind turbines to support shafts and gears that increase rotational speed from a low speed rotor to a higher speed electrical generator. For various bearing applications, condition monitoring using vibration measurements has remained a subject of intense study to the present day since several decades. Various signal processing techniques are used to analyse vibration signals and extract features related to defects. Statistical indicators such as Crest Factor (CF) and Kurtosis (KU) were reported as very sensitive indicators when the presence of the defects is pronounced, whilst their values may come down to the level of undamaged components when the damage is well advanced. Further, these indicators were applied to an acquired data from proposed diagnostic models, test rigs, and instrumentations that were specifically used for particular research tests, and thus, it is essential to undertake further investigations and analysis to assess the influence of other factors such as the structural noise and other operating conditions on the real‐world applications. With this in mind, the present work proposes Signal Intensity Estimator (SIE) as a new technique to discriminate individual types of early natural damage in real‐world wind turbine bearings. Comparative results between SIE and conventional indicators such as KU and CF are also presented. It was concluded that SIE has an advantage over the other fault indicators if sufficient data are provided.     

Clinical characteristics determining the mode of presentation in patients with acute coronary syndromes

OBJECTIVES: The purpose of this study was to examine clinical characteristics of patients with acute coronary syndromes to identify factors that influence the mode of presentation. BACKGROUND: In acute coronary syndromes, presentation with myocardial infarction or unstable angina has major prognostic implications, yet clinical factors affecting the mode of presentation are not well defined. METHODS: A prospective cohort study was made of 1,111 patients with acute coronary syndromes. Baseline demographic, clinical and biochemical data were compared in groups with myocardial infarction (n = 633) and unstable angina (n = 478). RESULTS: The risk of myocardial infarction relative to unstable angina was increased by age >70 years (odds ratio [OR] 2.21; 95% confidence interval [CI] 1.33 to 3.66), male gender (OR 1.56; CI 1.13 to 2.16) and cigarette smoking (OR 1.49; CI 1.09 to 2.03). A rise in admission creatinine from the 10th to the 90th centile of the distribution also increased the odds of myocardial infarction (OR 1.30; CI 1.05 to 1.94). Conversely, the risk of myocardial infarction relative to unstable angina was reduced by previous treatment with aspirin (OR 0.37; CI 0.27 to 0.52), hypertension (OR 0.64; CI 0.47 to 0.86) and previous acute coronary syndromes (OR 0.36; CI 0.26 to 0.51) and revascularization procedures (OR 0.36; CI 0.21 to 0.62). CONCLUSIONS: The clinical presentation of acute coronary syndromes may be influenced by various factors that have the potential to influence the coagulability of the blood, the collateralization of the coronary circulation and myocardial mass. Myocardial infarction is favored by cigarette smoking, advanced age and renal impairment, while unstable angina is favored by treatment with aspirin, hypertension, previous revascularization and previous coronary syndromes.     

Kinetic modeling of liquid generation from oil shale in fixed bed retort

Kinetics of shale oil generation in a fixed bed retort is modeled using a second order rate equation. Samples from Ellajjun oil shale deposits are tested in 350–550 °C temperatures range. In each run, 400 g are charged to reactor and heated in a range of 2.2–10 °C min⁻¹. Shale oil liquid is condensed at 0 ± 2 °C and its rate measured as function of time and temperature.     

Effect of Microwave Annealing on the Structure and Magnetic Properties of Co-based Amorphous Ribbons

We investigated the structure and magnetic properties of CoFeSiB amorphous ribbons in the presence of microwave emission. Samples have been emitted onto in the microwave cavity with working frequency of 2.45 GHz at different times of emission. Structure and surface properties of samples emitted to have been investigated by X-ray diffraction and Atomic force microscopy. Also, magnetic properties of samples were investigated by magneto-optical Kerr effect measurement. Our results show that increasing in annealing time may change the crystalline state of samples and also decrease the magnetic coercivity and surface roughness.     

Neural network for the reliability analysis of simplex systems

A new approach to the reliability analysis, based on neural networks, is introduced in this paper. The reliability analysis of a simple nonredundant digital system, Simplex System, with repair is used to illustrate the neural network approach. The discrete-time Markov model of simplex systems is realized using feed-forward recursive neural network. The energy function and update equations for the weights of the neural network are estabilished such that the network converges to the desired reliability of the simplex system under design. The failure rate and repair rate, satisfying the desired reliability, are extracted from the neural weights at convergence. The obtained results are verified by the conventional approach.