THEORETICAL DESIGN STUDY ON SHAFTING ALIGNMENT CALCULATION FOR HIGH SPEED CRAFT

The design reliability of the theory applied when calculating the sensitivity of shafting alignment must be determined especially at the initial design stage of shafting arrangement and calculation for the vertical static bearing loads (reaction forces) and pressures in order to obtain positive uniform values, which have to comply with the design requirements of the High Speed Craft Code of Classification Society. Any poor design of shafting arrangement for each vertical static bearing location and/or bearing off-set design value may cause a failed shafting alignment calculation and a non-uniform bearing load or over excessive bearing load and pressure on the propulsion shaft stern tube/strut supporting bearing and possible further damage, for example, excessive wastage and/or crack on a damaged aft shaft strut bearing for a high speed craft. The objective of this study was to find and verify the design reliability of the applied theoretical method for calculating the suitable design values of each vertical static bearing load and pressure on the propulsion shafting system at the initial design stage of shafting arrangement. The design values for each vertical static bearing load and pressure calculated by theoretical design methodologies of the finite element method (FEM) and the three moment equation method (TMEM) were compared with the shipyard original design values for the same design case of propulsion shafting system. The design deviation of the vertical static bearing from the shipyard original design values was determined in order to decide which design methodology (TMEM or FEM) would be adopted and developed for further numerical algorithm design on shafting alignment optimization. According to the obtained results, both the FEM and the TMEM theoretical design accuracy and reliability were well matched with the shipyard original design values. In addition, the TMEM design results for each static bearing load and pressure proved to be more close to the shipyard original design values

THEORETICAL DESIGN STUDY ON SHAFTING ALIGNMENT CALCULATION FOR HIGH SPEED CRAFT

The design reliability of the theory applied when calculating the sensitivity of shafting alignment must be determined especially at the initial design stage of shafting arrangement and calculation for the vertical static bearing loads (reaction forces) and pressures in order to obtain positive uniform values, which have to comply with the design requirements of the High Speed Craft Code of Classification Society. Any poor design of shafting arrangement for each vertical static bearing location and/or bearing off-set design value may cause a failed shafting alignment calculation and a non-uniform bearing load or over excessive bearing load and pressure on the propulsion shaft stern tube/strut supporting bearing and possible further damage, for example, excessive wastage and/or crack on a damaged aft shaft strut bearing for a high speed craft. The objective of this study was to find and verify the design reliability of the applied theoretical method for calculating the suitable design values of each vertical static bearing load and pressure on the propulsion shafting system at the initial design stage of shafting arrangement. The design values for each vertical static bearing load and pressure calculated by theoretical design methodologies of the finite element method (FEM) and the three moment equation method (TMEM) were compared with the shipyard original design values for the same design case of propulsion shafting system. The design deviation of the vertical static bearing from the shipyard original design values was determined in order to decide which design methodology (TMEM or FEM) would be adopted and developed for further numerical algorithm design on shafting alignment optimization. According to the obtained results, both the FEM and the TMEM theoretical design accuracy and reliability were well matched with the shipyard original design values. In addition, the TMEM design results for each static bearing load and pressure proved to be more close to the shipyard original design values

Quasiparticle dynamics and phonon softening in FeSe superconductors

Quasiparticle dynamics of FeSe single crystals revealed by dual-color transient reflectivity measurements ({\Delta}R/R) provides unprecedented information on Fe-based superconductors. The amplitude of fast component in {\Delta}R/R clearly tells a competing scenario between spin fluctuations and superconductivity. Together with the transport measurements, the relaxation time analysis further exhibits anomalous changes at 90 K and 230 K. The former manifests a structure phase transition as well as the associated phonon softening. The latter suggests a previously overlooked phase transition or crossover in FeSe. The electron-phonon coupling constant {\lambda} is found to be 0.16, identical to the value of theoretical calculations. Such a small {\lambda} demonstrates an unconventional origin of superconductivity in FeSe.Comment: Final published version; 5 pages; 4 figure

Spatially-resolved relaxation dynamics of photoinduced quasiparticles in underdoped YBasub2sub 2Cusub3sub 3Osub7−deltasub {7-delta}

The spatially-resolved relaxation characteristics of photoinduced quasiparticles (QPs) in CuO$sub 2$ planes of underdoped YBCO are disclosed by polarized fs time-resolved spectroscopy. The relaxation time (tau) along b axis diverges at Tc, and appears to be governed by a temperature-dependent gap Delta(T) at T Tc, a monotonic increase of tau with decreasing T along the b axis and ab diagonal was observed and can be attributed to a temperature-independent gap Delta$sub p$. The results lend support to recombination dominant scenario of QP dynamics. However, the QP thermalization may take part along the nodal direction in the highly underdoped samples.Comment: 16 pages, 4 figures. To be published in Physical Review B, Brief Repor

Spatial Symmetry of Superconducting Gap in YBa2Cu3O7-\delta Obtained from Femtosecond Spectroscopy

The polarized femtosecond spectroscopies obtained from well characterized (100) and (110) YBa2Cu3O7-\delta thin films are reported. This bulk-sensitive spectroscopy, combining with the well-textured samples, serves as an effective probe to quasiparticle relaxation dynamics in different crystalline orientations. The significant anisotropy in both the magnitude of the photoinduced transient reflectivity change and the characteristic relaxation time indicates that the nature of the relaxation channel is intrinsically different in various axes and planes. By the orientation-dependent analysis, d-wave symmetry of the bulk-superconducting gap in cuprate superconductors emerges naturally.Comment: 8 pages, 4 figures. To be published in Physical Review B, Rapid Communication

Fabrication and Low Temperature Thermoelectric Properties of Na_xCoO_2 (x = 0.68 and 0.75) Epitaxial Films by the Reactive Solid-Phase Epitaxy

We have fabricated Na_xCoO_2 thin films via lateral diffusion of sodium into Co_3O_4 (111) epitaxial films (reactive solid-phase epitaxy: Ref. 4). The environment of thermal diffusion is key to the control of the sodium content in thin films. From the results of x-ray diffraction and in-plane resistivity, the epitaxial growth and the sodium contents of these films were identified. The thermoelectric measurements show a large thermoelectric power similar to that observed in single crystals. The quasiparticle scattering rate is found to approach zero at low temperatures, consistent with the small residual resistivity, indicating high quality of the Na_xCoO_2 thin films.Comment: 16 pages. 4 figures. To appear in Applied Physics Letter

A comparative review of dynamic neural networks and hidden Markov model methods for mobile on-device speech recognition

The adoption of high-accuracy speech recognition algorithms without an effective evaluation of their impact on the target computational resource is impractical for mobile and embedded systems. In this paper, techniques are adopted to minimise the required computational resource for an effective mobile-based speech recognition system. A Dynamic Multi-Layer Perceptron speech recognition technique, capable of running in real time on a state-of-the-art mobile device, has been introduced. Even though a conventional hidden Markov model when applied to the same dataset slightly outperformed our approach, its processing time is much higher. The Dynamic Multi-layer Perceptron presented here has an accuracy level of 96.94% and runs significantly faster than similar techniques