Applied Mechanics and Materials Vols. 479-480

Abstract: This study presents a compound optical film to improve luminance and uniformity to apply in side-LED (Light-emitting diode) backlight module. LIGA (Lithographie GalVanoformung Abformung) technology, soft lithography and homemade gray scale mask were combined to fabricate micro-lens array. Optical film with variable size micro-lens array embedded with micro-voids was designed and manufactured. FRED software was used to simulate optical performance. Micro-voids were quantitatively embedded in the PDMS (Polydimethylsiloxane) optical film. Under the quantitative control of air pressure, those micro-voids inside the optical film can cause light diffusion. The compound optical film with embedded micro-voids, multi aspect ratio and variable size micro-lens array can be fabricated quickly without substrate. Luminance Colorimeter BM-7A from TOPCON was used to carry out the optical measurement. According to the measured data, the compound optical film with embedded micro-voids can enhance the luminance up to 5% and the uniformity up to 6.5% ~ 8.4%. The optical efficiency can be improved via the compound optical film.

Abstract: This study explores the optimum design of secondary optical element (SOE) for a non-coplanar two-reflector solar concentrator. The non-coplanar solar concentrator comprises a primary parabolic mirror and a secondary hyperbolic mirror. Ray tracing simulation is adopted to investigate the optical performance, including the acceptance angle and the optical efficiency, of the solar concentrator with various designs of SOE. Finally, preliminary optimum designs of SOE are presented and discussed.

Abstract: In this research, a contact lens design for myopia and astigmatism eyes was proposed. With two spherical surfaces assembled in the optical system, the design could take advantage of compacting overall volume size. But in this design, the value of spherical aberration (SA) at wide radius of contact lenses seems lower. If we corrected the design to improve the value of SA, Modulation Transfer Function (MTF) and coma aberration (TCO) value would become lower relatively. In this study, we integrated the Taguchi method and principal component analysis (PCA) to optimize the multiple quality characteristics (SA, TCO and MTF) of the contact lenses. With the combination of the methods, a set of optimum design parameters was well selected to balance the values of SA, TCO and MTF that improve the SA 25.63%, TCO 91.88% and MTF 2.4%. It was concluded that the integration of the Taguchi method and PCA succeeded in optimizing the SA, TCO and MTF values, and the contact lenses could be well designed without sacrificing system performance.

Abstract: This paper presents an improved initial guessing method for the famous Zhang's camera calibration method for a moving camera. Given three or more known points in a scene, we can compute initial guessing values for maximum likelihood estimation for varying focal camera calibration. This method is useful in structure from motion, which needs consecutive video camera calibration using a known camera distortion.

Abstract: This paper addresses a compact framework to matching video sequences through a PSNR-based profile. This simplify video profile is suitable to matching process when apply in disordered undersea videos. As opposed to using color and motion feature across the video sequence, we use the image quality of successive frames to be a feature of videos. We employ the PSNR quality feature to be a video profile rather than the complex contend-based analysis. The experimental results show that the proposed approach permits accurate of matching video. The performance is satisfactory on determine correct video from undersea dataset.

Abstract: The shear plastic deformation behavior of a material during equal channel angular (ECA) extrusion is governed primarily by the die geometry, the material properties, and the process conditions. This paper employs the rigid-plastic finite element (FE) to investigate the plastic deformation behavior of Ti-6Al-4V titanium alloy during ECA extrusion processing. Under various ECA extrusion conditions, the FE analysis investigates the damage factor distribution, the effective stress-strain distribution, and the die load at the exit. The relative influences of the internal angle between the two die channels, the friction factors, the titanium alloy temperature and the strain rate of billet are systematically examined. In addition, the Taguchi method is employed to optimize the ECA process parameters. The simulation results confirm the effectiveness of this robust design methodology in optimizing the ECA processing of the current Ti-6Al-4V titanium alloy.

Abstract: Non-contact magnetic gears have gained significant attention due to no mechanical fatigue, no lubrication, reduced maintenance, improved reliability, overload protection, physical isolation between input and output shafts, and potential for very high efficiency. However, it inherently suffers from a main disadvantage on the ripple of the transmitted torque that may causes vibration of the output shaft. This paper presents an external magnetic gear set with section-shaped magnets with low torque ripple. Finite-element method is used as an assistant tool for the magnetic field analysis and transmitted torque analysis. The effects of number of magnet poles on the maximum transmitted torque and torque ripple of the magnetic gear set are also discussed. It is of benefit to the further design purposes of magnetic gear mechanisms

Abstract: This work experimentally investigated the effect of the oscillating flow on the heat transfer enhancement of the finned heat sink with top bypass clearance. The cooling system of the finned heat sink usually employs the steady flow with fixed flow rate to complete the objective of forced convection. This work designed and manufactured a device to oscillate air flow. The experimental results indicate that it would obtain 10~34% heat-transfer increment for the oscillating-flow cases with sufficiently small bypass clearance. It demonstrates that the oscillating flow does promote the cooling performance of finned heat sink.

Abstract: This paper presents means to minimize the cogging force of a new type of permanent magnet excited transverse flux linear synchronous motor (PMTFLSM). The translator of this linear motor consists of cross-shaped core sets. Varying the parameters of air gap length, magnet dimensions, pole pitch and tooth width of the translator, the cogging force of the PMTFLSM will be analyzed. Taguchi's parameter method including 2D finite element analysis (FEM) is employed to minimize the cogging force. Analytical and simulation results indicate the usefulness of our approach in practice

Abstract: In this paper, based on the previous research experiences in the lumped parameter modeling and study of active control mounts model, a test bench model of ACM in powertrain is described and the vibration model is implemented in MATLAB. In order to validate the implementation of the state equations in this work, a finite element analysis (FEA) method is used in ANSYS and compared with analytical model for validate. After the validation, the control strategy is integrated into the analytical model by using the linear quadratic regulator (LQR) method, which is a well know design technique that provides practical feedback gains. Furthermore, this work examines the application of genetic algorithms (GA) in optimizing the weight matrices of LQR. Finally, this work will be useful in improved prediction and performance of vehicle NVH.