Simulation of water entry of an elastic wedge using the FDS scheme and HCIB method

The hydroelasticity of water entry of an elastic wedge is simulated using a code developed using the flux-difference splitting scheme for immiscible and incompressible fluids and the hybrid Cartesian/immersed boundary method. The free surface is regarded as a moving contact discontinuity and is captured without any additional treatment along the interface. Immersed boundary nodes are distributed inside a fluid domain based on the edges that cross an instantaneous body boundary. Dependent variables are reconstructed at each immersed boundary node with the help of an interpolation along a local normal line for providing a boundary condition for a discretized flow problem. A dynamic beam equation is used for modeling the elastic deformation of a wedge. The developed code is validated through comparisons with other experimental and computational results for a free-falling wedge. The effects of the elastic deformation of the wedge on the pressure fields and time histories of the impact force are investigated in relation to the stiffness and density of the structure. Grid independence test is carried out for the computed time history of the force acting on an elastic wedge.     

A Terrain Rendering Method Using Vertical Ray Coherence

Ray casting may be applied to the terrain rendering from DTMs (digital terrain models). In this paper we propose a ray casting method which exploits exact vertical ray coherence. This method not only achieves a good performance, but also allows any set of viewing parameters. To analyse the vertical ray coherence property, we define the following terms: a ray plane which is perpendicular to the sea-level plane and passes through the COP (centre of projection), and the corresponding ray line which is the line of intersection of the ray plane and the projection plane. Vertical ray coherence can be stated as: if two rays pass through the same ray line, they pass over the identical set of points on the DTM base plane. After a ray is cast on the DTM, we can get a good starting point to cast another ray using this property. Our method tries to cover the projection plane with ray lines. Since ray lines are not parallel to each other, it is a difficult task to cover the entire plane. In fact all ray lines intersect at a point (COP′). We first generate a set of ray lines sufficient to cover the projection plane near COP′. As pixels get further from COP′, more ray lines are generated to fill most of the gaps between pixels covered by the previous set of ray lines. Rays passing through the same ray line are effectively cast using vertical ray coherence. To fill remaining pixels not covered by ray lines, pixel values of vertical/horizontal neighbours are interpolated. To cast rays efficiently, successive points generated by a line algorithm are followed along the projection of the rays on the DTM base plane. © 1997 by John Wiley & Sons, Ltd.     

A Compact Differential Formula for the First Derivative of a Unit Quaternion Curve

This paper presents a compact differential formula for the first derivative of a unit quaternion curve defined on SO(3) or S³. The formula provides a convenient way to compute the angular velocity of a rotating 3D solid. We demonstrate the effectiveness of this formula by deriving the differential properties of various unit quaternion curves^1–5 at the curve end points.     

Mechanical and electrical properties of In-Bi solder at Bi2212 superconductor interface with annealed Ag spray layers and Ag precoating layers

The electrical properties of solder contact layers between Cu-Ni shunt metal and tube type Bi₂₂₁₂ superconductor that is applied in superconducting fault current limiter were studied. The contact properties of the solders are improved not only by Ag precoating layers, but also by the pre-sprayed Ag layer and subsequent Ag precoating layers. The annealed Ag sprayed layers onto Bi₂₂₁₂ superconductor prior to Ag electroplating work as protecting layers for the superconductor from plating solutions. The contact angle of the electroplated Ag layer is 42.91° and decreases to 15.25° and 5.88° with Ag sprayed layer and additional Ag electroplated layers. The Ag sprayed layer with suitable annealing prior to Ag electroplating improves contact strength of the Ag electroplated layer by about 12% due to denser microstructure of the Ag electroplated layers.     

Operator Based Two Loop Nonlinear Forced Vibration Control of a Flexible Plate

A nonlinear forced vibration control method for a flexible plate with piezoelectric actuators is proposed in this paper. A model of a flexible plate, taking into account the hysteresis of the piezoelectric actuator, is given. In addition, the design of nonlinear control system is given by using the operator theory. Finally, the effectiveness of the proposed nonlinear control system is confirmed by simulation and experimental results.     

Development and Experimental Evaluation of Strip Shape Prediction Model for Sendzimir Rolling Mills

It is difficult to obtain the desired strip shape using Sendzimir rolling mills because small diameter work rolls can be easily deformed by the rolling force. To control the strip shape effectively, it is important to understand the relationship between the behavior of the shape actuator and the variation of the strip shape. A numerical model based on the contact element method was proposed for the prediction of strip shape. In this numerical model, the relationships between the actuating forces, the roll deflections, the thickness profiles of the entry and exit sides, and the strip shape were considered. The proposed numerical model for strip shape prediction was evaluated by computer simulation and experiment with respect to various AS-U roll and first intermediate roll positions.     

Limonoid Glucosides in Commercial Citrus Juices

Commercial citrus juices were found to contain very high concentrations of limonoid glucosides. TLC analyses showed the presence of these compounds averaging 320, 190 and 82 ppm in orange, grapefruit and lemon juices, respectively. The major glucoside in citrus juices was limonin 17-O-β-D-glucopyianoside, which constituted over 50% of the total limonoid glucosides in the juices.     

Micro parts assembly system with micro gripper and RCC unit

This paper presents a new micro assembly system, which is composed of a micro gripper, a micro remote center compliance (RCC) unit, a voice coil motor-driving mechanism and precision motion stages. The micro gripper is actuated by two shape memory alloy (SMA) wires, and its grip is 1 mm. The micro RCC unit has low translational and rotational stiffness sufficient for micro parts assembly. The voice coil motor-driving mechanism can generate linear motion with an adjustable stiffness, and it can also measure external force in the moving direction. An algorithm for the automatic assembly of micro parts is also proposed, and assembly experiments are performed.     

An Evaluation of the Machinability of Nitinol SMA Using Combined Process of EP and MR Polishing

Nitinol,a shape memory alloy(SMA),is manufactured from titanium and nickel.It is employed in various fields for use in devices such as micro sensors,ultra-precision devices and satellite wings.It is highly recommended as a material in medical stents for insertion into the body because it has excellent organic compatibility.However,because they are intended to be inserted into the human body,products such as medical stents require a high-quality surface.Because nitinol has more of the characteristics of titanium than of nickel,one of its drawbacks is that heat generated in nitinol during machining is not discharged smoothly,leading to areas of inner stress which occur when traditional machining methods are used.To overcome this difficulty,various non-traditional machining methods,including non-contact machining,have been investigated for use with nitinol.This study is focused on the application of an effective fabrication method that combines electrolytic polishing(EP)and MR polishing to improve the surface integrity of nitinol through a series of experiments.Surface roughness variations of the polished nitinol were investigated by changing the imposed polishing conditions of EP and MR polishing,respectively.Finally,the variations in the surface roughness were observed with polished previously performed via the EP process.