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A new method of applying the solid wall boundary condition in a weakly compressible Smooth Particle Hydrodynamics (SPH) method is proposed and tested in a few basic benchmark flows. It makes use of approximate equations of motion and the wall similarity for the pressure and the velocity of the flow near solid walls avoiding the use of the particle interpolation formula which otherwise require special treatment for the truncated smoothing region near the boundary. It is intended to be used in the calculation and the simulation of turbulent flows and test calculations have been done with the Reynolds Averaged Navier Stokes (RANS) equations and spatially-filtered equations of motion and continuity equation with appropriate treatment of turbulence effects. The test calculations of fully developed open channel flow without resolving the viscous sublayer and the transient dam break flows without fully resolving the turbulent fluctuations show that the behaviour seen in the corresponding experimental results is reproduced. The present formulation appears to be an alternative boundary condition formulation to be used in the SPH calculation of practical engineering and environmental flows. [ABSTRACT FROM AUTHOR]

A large-eddy simulation method of calculating the flow past an elastically-supported body, has been constructed based on the finite difference method formulated in the coordinates fixed on the moving body. The boundary conditions on the body can be applied in the same way as on a fixed body. Reconstruction of computational mesh or interpolation of the computational points is not needed as the body moves. The coding of the method is simple and the computation is efficient, but the equations of motion must be written in the non-inertial coordinates and the boundary conditions on the outer boundaries of the flow domain that also move must be adjusted as the orientation of the body changes. The method has been tested in the computation of the flow past a rectangular cylinder supported by a spring and dashpot and the motion of the cylinder for which experimental data are available. Comparison with experimental data in the case of a rectangular cylinder of depth to breadth ratio of D/B =2 indicates that the characteristics of the translational oscillation corresponding to the heaving of long beams and the rotational oscillation corresponding to the torsional deformation are reproduced well. [ABSTRACT FROM AUTHOR]

PTFE (polytetrafluoroethylene) has superior characteristics such as low dielectric constant, low dielectric tangent, and chemical stability. However, it has a low adhesion force. In order to improve the adhesion force, we have studied the surface modification of PTFE by using a discharge under high E/ n ( E is the electric field, n is the particle density) conditions in nitrogen. Under high E/ n conditions, electrons and ions achieve energies up to and exceeding 100 eV. It is inferred that improvement of adhesion is brought about by the introduction of polar groups at the surface. However, it is not clear which particles (ions, atoms, excited molecules, etc.) in the discharge space promote the introduction of polar groups into the PTFE surface. We assume that ions with high kinetic energies rather than the binding energy of PTFE contribute to the formation of chemical bonds by breaking C-C or C-F bonds. It is expected that bond cleavage is the rate-determining step in surface modification. We measured the contact angle of samples irradiated at various ion energies and exposure doses. The results indicate that increasing the exposure dose accelerates the introduction of polar groups. In addition, it is inferred that an ion energy of about 40 eV is effective for the introduction of polar groups. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 179(1): 1-7, 2012; Published online in Wiley Online Library (). DOI 10.1002/eej.21226 [ABSTRACT FROM AUTHOR]

Three-dimensional unsteady flow in the intake channel of a small-scale hydroelectric power facility has been simulated numerically using a large eddy simulation technique. The basic numerical method is the highly simplified MAC iteration method modified for the free-surface flow. The standard Smagorinsky model with near-wall damping and correction for irrotational strain was used to evaluate the sub-grid scale stresses. Using the numerical grid that marginally resolves the near-wall flow of laboratory-scale Reynolds number, the complex and unsteady nature of the vortical flow can be reproduced well. The free-surface depression associated with the formation of a free-surface vortex and its time development, which have so far been difficult to be reproduced numerically, are particularly well captured. The present study shows that this method is relevant for predicting the intake flows with possible air entrainment. [ABSTRACT FROM AUTHOR]

Instantaneous velocity distributions in the viscous and roughness sublayers and in the lower parts of the logarithmic-law region of flat-plate boundary layers over smooth and rough surfaces are measured using a hot-wire rake consisting of two X-wire and nine single-sensor probes in order to investigate the turbulence structure and similarity of the instantaneous and filtered velocity profiles near the wall. The results can provide useful information as to the treatment of flow in this region in a large-eddy type simulation of high Reynolds-number flows over smooth and rough walls. The instantaneous velocity profiles feature large-scale structures but random fluctuations of considerable amplitude are superimposed and no similarity that is applicable to instantaneous unconditioned profiles can be derived. Conditionally averaged profiles based on the magnitudes of the wall shear and normal velocity in the buffer layer, however, show trends related to the sweep-ejection type events. The filtered profiles normalized by the filtered instantaneous friction velocity show similarity that progressively extends its region from the immediate neighborhood of the wall to the log layer as the filter size is increased. The minimum streamwise length of the filter size required to show logarithmic similarity is found to be as large as 1800 wall units. Similar results are obtained for rough-wall boundary layers if the instantaneous friction velocity is replaced by the equivalent velocity scale implied by the velocity just outside the roughness-influenced sublayer at about 10 viscous units from the wall, or about 1.5 times the height of the roughness bars from the wall. The sub-grid stress components have are obtained from the data and implication for modeling is discussed. [Copyright &y& Elsevier]

The gene encoding malate dehydrogenase (MDH) of the obligately piezophilic deep-sea bacterium Moritella sp. strain 2D2 was cloned and sequenced. There were two positions [close to the active site (Ala-180) and in the subunit interaction site (His-229)] with 2D2-specific substitutions. The MDH genes of strain 2D2 and a psychrophilic bacterium Moritella sp. strain 5710 exhibiting the highest sequence similarity were overexpressed in Escherichia coli. The 2D2 MDH was more heat-stable than the 5710 MDH. The apparent Km value at 62.1 MPa for NADH of the 2D2 MDH was higher than that of the 5710 MDH. The 2D2 MDH in which a His–Gln substitution was introduced at position 229 decreased the thermal stability and Km value at 62.1 MPa. The 5710 MDH that was substituted Gln-229 with His increased the thermal stability and Km value at 62.1 MPa. These results indicate that the His residue at position 229 of the 2D2 MDH may play a role in the thermal stability and the MDH function at high pressure. [Copyright &y& Elsevier]

Presents information on the lipid composition of barophilic bacterial strains. What the strains contained; Information on an examination of the strains; Results of the examinations; Details on fatty acids.

Presents a study which determined the lipid and fatty acid compositions in nine obligate and facultative barophilic bacteria, isolated from the intestinal contents of seven deep-sea fish. Methodology of study; Level at which docosahexaenoic acid was found in eight strains; Other findings of experiments conducted; What the results suggest.

Examines the pressure resistances of the spores of six Bacillus strains at 5 to 10 degrees Celsius and compares their heat resistances. Bacterial strains and culture conditions; Preparation of spore suspensions; Determination of heat resistance; Determination of pressure resistance of the spores.

The mean-velocity and turbulence quantities in a few qualitatively different types of asymmetric two-dimensional turbulent near wakes in nearly zero-pressure gradient have been experimentally studied. In all cases, the log-law similarity of the boundary layers was found to continue into the initial part of the wake, with the same similarity variables as in the boundary layers on the same side, provided the origin of the normal distance is taken at the smooth extension of the respective surfaces. The Reynolds stress profiles show sharp peaks just downstream of the trailing edge, and the magnitudes of the peaks are found to be related to the values of the surface friction at the trailing edge. These peaks grow into the full width of the wake to form the far wake profiles. In this process, the turbulent diffusions of the Reynolds stresses are very important, and when the size asymmetry is severe, is not clearly of the gradient-transport type [ABSTRACT FROM AUTHOR]

Herein, scour depth measurements are compared with theoretical and empirical estimates obtained at four sites in Chiba and Fukushima Prefectures impacted by the 2011 Tohoku Tsunami. At sites where scour was caused by either floodwall overtopping or acceleration of flow around building foundation footings, results of published scour experiments are compared with measured scour depths. [ABSTRACT FROM PUBLISHER]

Optimization of mooring line design parameters including line azimuth angles, line diameter, line length and mooring radius is presented for a turret-moored FPSO. The optimization procedure is implemented using a Mooring Optimization Tool for FPSO (MooOpT4FPSO), which is an in-house optimization tool purposely developed for this purpose. The tool is a synchronisation of the Regrouping Particle Swarm Optimization (RegPSO) algorithm with commercial software, OrcaFlex. Case studies using a validated numerical FPSO model moored with multicomponent mooring lines acted upon by non-collinear wave, wind and current were analysed using the developed tool. To take into consideration the interaction of the riser system in the optimization procedure, the integrated design methodology was adopted where the riser safe operation (SAFOP) zone diagram combined with the offset diagram is used for the verification/assessment of the design criteria of the risers and mooring lines. The optimized FPSO model offsets in eight directions are found to be within the riser safe operation zone. Based on the results, the tool was able to simultaneously optimise the mooring line diameter, line length, mooring radius, and azimuth angles of the turret FPSO to achieve a specific offset. Application of the tool can help the industry save material (by reduction of line diameter and length) and consequently the overall project cost, in addition to the reduction of structural payload exerted on the platform. Furthermore, the tool has an automatic search capability, which is an improvement to the conventional mooring design approach that is based on a trial-and-error approach. • A novel numerical optimization tool for FPSO mooring line parameters for (MooOpT4FPSO) have been developed. The tool has the capability of simultaneously optimizing azimuth angles, line lenght, line diameter and mooring radius of turret FPSO. • Application of the tool in mooring design can bring a reduction in line material and consequently the overall project cost, in addition to the reduction of payload exerted on the platform. • Application of the tool brings a direct industrial solution to the conventional trial and error approach. [ABSTRACT FROM AUTHOR]

The increased application of Information and Communications Technology in automation and digitization is the driving concept towards the actualization of the Industrial Revolution 4.0. Many aspects of industrial design and operations including offshore engineering have been automated. However, the selection procedure of mooring design parameters including azimuth angle, pretension, diameter, fairlead slope, and mooring radius, which is a critical aspect of mooring system design has remained heavily based on a manual approach despite the availability of sophisticated hydrodynamic analysis software. Up to date, there is no proper review on optimisation techniques that have the potential of automating these procedures. In the past, some of the few available mooring optimisation procedures consider only the mooring lines for the prediction of optimal platform offset without due consideration to the integrity of the risers. Thus, the significance of adopting an integrated riser-mooring design methodology in the optimisation of mooring design variables is discussed in this paper where the integrity of the riser is adequately represented using a Safe Operation (SAFOP) zone polar diagram. We also review the developmental transition from the use of classical to Evolutionary Algorithms (EA) in the optimisation procedure. EA has been acknowledged as a practical alternative for solving mooring optimisation problems. Hence, some of the EA techniques are presented and their computational capabilities explored. In the last part, a concise review of the application of optimisation techniques for mooring optimisation of the different offshore floating platforms is presented based on their capabilities in minimizing platform offset and efficiency in terms of simulation time. So far, EA techniques like the Differential Evolution (DE), variants of Genetic Algorithms (GA) and Particle Swarm Optimisation (PSO) have been used to optimize mooring line design variables. Based on the discussions, the potentials of DE, RegPSO and other variants of PSO can be further explored for better efficiency. • Previous studies addressing differential evolution (DE), genetic algorithm (GE) and particle swarm optimisation (PSO) techniques used for optimisation of mooring parameters have been critically reviewed. • The integrated riser -mooring design methodology is effective in accounting for integrity of riser and mooring systems. • The application of evolutionary algorithms, particularly the variants and hybrids of DE ,PSO and GA, have proven to be efficient optimisation of mooring systems. • Some variants of PSO like the RegPSO have demonstrated improved capability in terms of escaping premature convergence , thereby resulting in better computational efficiency. [ABSTRACT FROM AUTHOR]

PIV measurements near a wall are generally difficult due to low seeding density, low velocity, high velocity gradient, and strong reflections. Such problems are often compounded by curved boundaries, which are commonly found in many industrial and medical applications. To systematically solve these problems, this paper presents two novel techniques for near-wall measurement, together named Interfacial PIV, which extracts both wall-shear gradient and near-wall tangential velocity profiles at one-pixel resolution. To deal with curved walls, image strips at a curved wall are stretched into rectangles by means of conformal transformation. To extract the maximal spatial information on the near-wall tangential velocity field, a novel 1D correlation function is performed on each horizontal pixel line of the transformed image template to form a “correlation stack”. This 1D correlation function requires that the wall-normal displacement component of the particles be smaller than the particle image diameter in order to produce a correlation signal. Within the image regions satisfying this condition, the correlation function yields peaks that form a tangential velocity profile. To determine this profile robustly, we propose to integrate gradients of tangential velocity outward from the wall, wherein the gradient at each wall-normal position is measured by fitting a straight line to the correlation peaks. The capability of Interfacial PIV was validated against Particle Image Distortion using synthetic image pairs generated from a DNS velocity field over a sinusoidal bed. Different velocity measurement schemes performed on the same correlation stacks were also demonstrated. The results suggest that Interfacial PIV using line fitting and gradient integration provides the best accuracy of all cases in the measurements of velocity gradient and velocity profile near wall surfaces. [ABSTRACT FROM AUTHOR]