Foxlink (Taiwan)

ABSTRACTPolycarbonate (PC)/polybutylene terephthalate (PBT) blends (CBs) represent a good compromise between the properties of PC and PBT and are among the most popular engineering plastics today. To evaluate the capability of recycled and reprocessed CBs, the physical and mechanical properties of 0 to 20 times reprocessed CBs were characterized, and an attempt was made to modify a 20-time reprocessed CB to reach ≥85% of the functionality of a virgin CB. Generally, the thermal weight loss (30% at 300–450°C and 40% at ~470°C) of the CBs varied little with the reprocessing cycles, reflecting their high thermal stability. The increased melting index (from 18.7 to 92.0 g (10 min)–1) but decreased stress values (from 6.08 to 4.99 kgf mm–2), strains (from 79.0 to 29.1%), impact strength (from 144 to 14.7 J m–1) and torque values (from 82 to 60 N m–1) with reprocessing cycles suggest that the CBs undergo thermal/mechanical decomposition when reprocessing and become thereafter stiffer. Satisfactory modification of the 20 times reprocessed CB succeeded simply via adding ~30% (w/w) virgin PC and PBT. Adding styrene maleic anhydride and a chain extender failed to improve the stress values of reprocessed CBs, probably due to their weak interaction with the PC and PBT molecules.

With the advances in the technologies of lens modules, image sensors and integrated circuits, commercial high-end cameras have shrunk to a smaller size and lighter weight. However, improving the camera’s portability results in problems such as unstable imageand video capture. The images or videos taken by miniature cameras usually have larger vibrations than those taken by bulky cameras. Image stabilization therefore becomes a necessary capability in many consumer digital cameras [1], [2], [3], [4], [5]. It is particularly important in situations where the user takes video in moving vehicles, records and tracks moving objects, or uses the camera in automatic machine vision applications in order to ensure desired visual quality and performance of processing solutions.

The fixed tap-length and step-size filtered-X least mean-square (FxLMS) algorithm is conventionally used in active noise control (ANC) systems. A tradeoff between the performance and the convergence rate is a well-known problem due to the choice of the step size. Although the variable-step-size FxLMS algorithms have been proposed for fast convergence, a long tap-length filter is frequently required in order to deal with different environments such that the convergence rate is still subject to a small step size for the long tap length. In this paper, we study a new ANC system with a variable tap-length and step-size FxLMS algorithm. Based on the assumption of an unsymmetric and two-sided exponential decay response model for the ANC control filter, the new FxLMS algorithm has the minimum mean-square deviation for the optimal filter coefficients. In the online secondary path modeling ANC system, simulation results show that the new algorithm with different kind of variable step sizes can provide significant improvements of convergence rate and noise reduction ratio, compared to the fixed-tap-length FxLMS algorithms.

The beauty of the golden sky at sunset, the splendor of peacock feathers, and the glorious spectacle of fireworks are displays of changing color. Our visual sense is greatly enriched by our perception and appreciation of colors. Although our color perception seems to be direct and effortless, it is a very interesting subject of immense complexity, as are other aspects of our visual perception. In the last 70 years, we have made a lot of progress in understanding the physics, chemistry, optics, physiology, psychophysics, anatomy, neural science, and molecular biology of human color vision, but we are still very far from being able to describe exactly how it works. Therefore, practical use of color requires certain empirical rules. These rules, which are by no means perfect, are based on many years of experimentation and observation, and they form the empirical foundation of colorimetry, the science of measuring color.

Although our interest in the human visual system is mainly in the role it plays as the observer in a color imaging system, we cannot completely treat it as a big black box, because the system is nonlinear and far too complicated to be characterized as such. There have been many attempts to apply linear system theory to the human visual system and characterize it with a system transfer function. That approach may serve some purposes in a few applications, but it is inadequate for most color imaging applications. Another possible approach is to treat it as many medium-sized black boxes, one for each special aspect in image perception. This is a more practical approach and it has been used very well for many applications. For example, we can measure the human contrast sensitivity as a function of luminance, field size, viewing distance, noise level, and chromatic contents, and the results can be used to design the DCT quantization tables for color image compression. However, the medium-sized black box approach does not give us much insight or guidance when our problem becomes more complicated or when we have a new problem. The size of the black boxes has to be reduced. An extreme limit is when each box corresponds to a single neuron in the visual pathway. Even then, some details inside the neuron may still be important to know. In general, how much detail we need to know is highly application-dependent, but the more we know the better we are equipped to deal with image perception related questions.

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Abstract Wear rates (μgm/s) versus rotor speed for carbon samples sliding against smooth and wavy copper rotors (250 μm thick copper sheets were attached to smooth and wavy steel and polycarbonate backings) were identical at some speeds, but at other speeds wear rates for the wavy rotors were almost half those of the smooth rotors. Slider vibrations (periodic, with period set by rotation) perpendicular to the sliding surface were measured and Fourier analyzed. Comparison of vibration spectral amplitudes to spectral amplitudes derived from surface profiles identified vibration modes dynamically enhanced by surface waviness on the wavy rotor. At speeds where wear rates on the wavy rotor were most reduced, amplitudes of certain modes in the vibration spectrum were most enhanced. For all these cases, the product of mode number times speed was nearly constant, suggesting resonance. Contact forces and contact voltage drop (due to a mA current flowing from slider to rotor) were measured and plotted versus time during all experiments. Friction coefficients rapidly varied between 0.1 and 0.4, but averaged 0.2. Traces of friction coefficient versus time for both wavy and smooth rotors were similar, even when wear rates plunged on the wavy rotor. There were no large jumps in the contact voltage drop data, suggesting that the slider never disconnected from any of the rotors. Photoelastic visualizations (Bryant and Lin, 1993) of slider-rotor interfaces revealed concentrated contact on the smooth rotors, but none on the wavy rotors. The absence (induced by vibration) of concentrated contact may have caused differences in wear rates. Appreciable reductions (up to 50 percent) in wear rate are possible by adding small surface waves to a rotor that induce micro-vibrations of the slider-spring-rotor contact system. The effect appears most pronounced at resonance.