Applied Mechanics and Materials Vols. 284-287

Abstract: A wind-power generation system uses wind turbine blades to convert the kinetic energy of wind to drive a generator which in turn yields electricity, the aerodynamic performance of the wind turbine blades has decisive effect on the cost benefit of the whole system. The aerodynamic analysis and the optimization of design parameters for the wind turbine blades are key techniques in the early stage of the development of a wind-power generation system. It influences the size selection of connecting mechanisms and the specification of parts in the design steps that follows. A computational procedure and method for aerodynamics optimization was established in this study for three-dimensional blades and the rotor design of a wind turbine. The procedure was applied to improving a previously studied 25kW wind turbine rotor design. Results show that the aerodynamic performance of the new three-dimensional blades has remarkable improvement after optimization.

Abstract: An accurate, high sensitivity and rapid identification assay of bacterial and virus is extremely important in areas such as medical diagnosis, biological research, and environmental monitoring. Raman spectra generates from the molecular species often referred to as ‘whole-organism fingerprinting’ being able to give comprehensive quantitative information about the overall biochemical composition of a microbial sample. Rapid discrimination of bacteria and bacteriaphage can be great important for food, environment and clinical diagnosis. Raman spectra of bacteria stains (Salmonella, Acinetobacter baumannii, Klebsiella pneumoniae) and their related bacteriaphages were analyzed. Raman pattern indicated the characteristic peaks and intensity difference between either bacteria nor phages. Barcode analysis, the intensity of 21 majority peaks summarized from the spectral interval 400–1200 nm showed the distinguishable data code for those cells. The present results suggest that both bacteria (micron) and phages (sub micron) can be directly discriminated by their Raman fingerprint and the barcode analysis method may help us transfer the complex spectra into easily and readability data

Abstract: Numerical analysis has been performed to investigate the seawater flow characteristics and drag force variation on tidal current turbine system with the direction of tidal current. Seawater velocity distribution is largely affected by the current direction flowing into the turbine system including shroud. Wake flow near the unshrouded turbine is generated and the wake region becomes wider in the tidal current direction. Drag force on the system also increases with the inflow angle. The vortex generated from the turbine system continuously moves outward from the shroud inside while the force increases before reaching a peak and then decrease. These results of the seawater flow characteristics with drag force variation according to tidal current direction can be applied to optimal design of tidal current power generation systems.

Abstract: Delamination-free hole is expected for composite parts using optimized drilling parameters due to an increase in composite structures production and in the need for higher quality machining. The influence of the various machining parameters (step angle, stage ratio, feed rate and spindle speed) on thrust force and equivalent delamination factor in step drilling composites was investigated in this study. The use of membership function based on Taguchi method to obtain the optimization of the process parameters by considering multiple performance characteristics has been reported. Finds based on the membership function show that the lowest thrust force of step drilling composites to be about 25.6 N and equivalent delamination factor about 1.005 pixel/pixel.

Abstract: The increased instantaneous speed in signal patterns which generated by the mechanical equipment are largely non-stationary. The signal features are averaged in correspondence with the length of analysis time, thus making it impossible to highlight the signal characteristics and caused the difficulties in identifying or diagnosing faults. In this paper, the wavelet order spectrum method using a combination of wavelet transform (WT) and speed frequency ordering. The feature order does not change with variations in speed, thus can effectively identify non-stationary faults in mechanical equipment. In addition, Principal Components Analysis (PCA) is used to extract the main features of the wavelet order spectrum and reduce the volume of data. This is combined with self-organizing maps (SOM) to devise an artificial intelligence method for fault diagnosis in non-stationary states. Lastly, the wavelet order spectrum method is verified by using a gear-rotor test platform that proofs the feasibility for the theory.

Abstract: Fluorescence is widely used to detect the biochemical effect and some substance containing certain dye. In general, the formation of fluorescent reaction is that an organism or dye, excited by UV light, emits a specific frequency of light; the light is usually a visible or near infrared light. Practically, the fluorescence of object can be excited by continued UV light, but the contrast and sharpness of fluorescence image decrease readily with stray light from the surrounding. In this study, we connect a trigger LED light module to a portable camera system and to perform the fluorescence inspection. When the fluorescent object is excited by asynchronous trigger UV-LED light, the extra intensity of fluorescence can be obtained. In the experiment of security organic dye (BL-ORT), the relative intensity of fluorescence acquired by 30 fps CCD can be increased by more than 11 %. In addition, when the fluorescent dye (chlorine e6) is injected into the tail vein of nude mouse, if its tail excited by the 375nm asynchronous trigger and continuous UV-LED are processed, the average relative intensity is 56.5 % and 49 %, respectively. Therefore, an added relative fluorescence of 15.3 % can be obtained from asynchronous triggering method. Furthermore, the ratio of extra intensity increases with the increase of frame rate of camera.

Abstract: Electronic products have become lighter and thinner nowadays. SMT includes three basic steps, namely solder paste print, electronic component adhesion and reflow[1]. This research tends to capture the image of fringe projection based on CCD with optical grating and reconstruct the 3D surface image of solder paste use triangulation measurement. The main ideal is using fringe projection method to observe the distortion of the fringe phenomenon caused by different heights of the surface. Last, the depth of the surface is computed under test variation and the 3D image is reconstructed.

Abstract: The two-degrees-of-freedom VIV of the circular cylinder with high mass-ratio is numerically simulated with the software ANSYS/CFX. The VIV characteristic is analyzed in the different conditions (Ur=3, 5, 6, 8, 10). When Ur is 5, 6, 8 and 10, the conclusion which is different from the cylinder with low mass-ratio can be obtained. When Ur is 3, the frequency of in-line VIV is twice of that of cross-flow VIV which is equal to the frequency ratio between drag force and lift force, and the in-line amplitude is much smaller than the cross-flow amplitude. The motion trace is the crescent. When Ur is 5 and 6, the frequency ratio between the drag force and lift force is still 2, but the main frequency of in-line VIV is mainly the same as that of cross-flow VIV and the secondary frequency of in-line VIV is equal to the frequency of the drag force. The in-line amplitude is still very small compared with the cross-flow amplitude. When Ur is up to 8 and 10, the frequency of in-line VIV is the same as the main frequency of cross-flow VIV which is close to the inherent frequency of the cylinder and is different from the frequency of drag force or lift force. But the secondary frequency of cross-flow VIV is equal to the frequency of the lift force. The amplitude ratio of the VIV between in-line and cross-flow direction is about 0.5. When Ur is 5, 6, 8 and 10, the motion trace is mainly the oval.

Abstract: The main purpose of this paper is to study the mechanisms of a new computer model of five-axis CNC machine tool developing process, including the kinematics of the spindle for both vertically and horizontally and its build process by simulation. According to the better process, let designer or user understands the characteristics of these particular machine tools. Through the computer simulation and graphic animation, users can observe the relationships of each movement on these new model multi-axis CNC machine tools. During the process of kinematics simulation, the forward and inverse kinematics are discussed and verified by simulation of software ADAMS. A control interface using Matlab is proposed to realize the motion commands and coordinate the kinematics. The simulated prototype demonstrates the feasibility in design through kinematics analysis of the new five axis CNC model in replace of conventional real prototype machine design.

Abstract: A theoretical model is proposed to investigate premixed combustion characteristics of Nano aluminum particles - water mixture. The effects of particle size, initial pressure, and temperature were considered as well. Computational domain is divided into 3 regions; preheat zone 1, preheat zone 2, and reaction zone. No reaction occurs in either of the preheat zones. Reaction zone, consisting of nano aluminum particles–steam mixture and the combustion products, is the region where reaction and heat-release occurs. Energy conservation is considered separately at each zones. The flame speed and temperature distribution are derived by solving the energy equation in each regime and matching the temperature and heat flux at the interfacial boundaries. Combustion time correlation of nano aluminum particle is also considered to imply complex aluminum combustion kinetics. Normalized flame speed is calculated as a function of pressure, initial particle diameter, and equivalence ratio and compared with experimental data.