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111.
In this paper, a reversible data hiding scheme based on modification of prediction errors (MPE) is proposed. For the existing histogram-shifting based reversible data hiding techniques, though the distortion caused by embedding is low, the embedding capacity is limited by the frequency of the most frequent pixel. To remedy this problem, the proposed method modifies the histogram of prediction errors to prepare vacant positions for data embedding. The PSNR of the stego image produced by MPE is guaranteed to be above 48 dB, while the embedding capacity is, on average, almost five times higher than that of the well-known Ni et al. techniques with the same PSNR. Besides, MPE not only has the capability to control the capacity-PSNR, where fewer data bits need less error modification, but also can be applied to images with flat histogram. Experimental results indicate that MPE, which innovatively exploits the modification of prediction errors, outperforms the prior works not only in terms of larger payload, but also in terms of stego image quality.  相似文献   
112.
113.
This paper evaluates laser-assisted machining (LAM) as an economically viable process for manufacturing precision aluminum oxide ceramic parts. Because it is locally heated by an intense laser source prior to material removal, LAM leads to higher material removal rates, as well as improved control of workpiece properties and geometry. To assess the feasibility of the LAM process and better understand its governing physical phenomena, experiments were conducted to obtain different measures of surface roughness for Al2O3 workpieces machined by laser-assisted turning using a Nd:YAG laser.The experimental results were analyzed using the Taguchi method, which facilitated identification of optimum machining conditions. The findings indicate that rotational speed, with a contribution percentage as high as 42.68%, had the most dominant effect on LAM system performance, followed by feed, depth of cut, and pulsed frequency. LAM's most important advantage is its ability to produce much better workpiece surface quality than does conventional machining, together with larger material removal rates (MRR) and moderate tool wear.  相似文献   
114.
An investigation of cold extruding hollow flanged parts from sheet metals   总被引:1,自引:0,他引:1  
Hole flanging with cold extrusion can avoid necking or fracture as encountered in conventional sheet metal-forming operations. Substantial flange height and lip thickness can be achieved with flange extrusion because the forming load is compressive. Using a hydraulic press, flange extrusions of 5 and 10 mm inner diameters were produced in pieces of cup-shaped galvanized steel, as well as aluminum 5052 workpieces with a thickness of 0.8 mm, both of which had a pre-hole on the cup bottom. As the punch load was exerted on the cup rim, a clamping force was applied to suppress dilation on the cup bottom.The experiments showed that with sufficient clamping force, significant flange height could be extruded. The utmost extruded flange of 5 mm i.d. was 6 times larger than that drawn from the conventional method, whereas that of 10 mm i.d. was 3.8 times larger than that drawn from the conventional method. However, no flange was extruded and buckling occurred on the cup bottom when the clamping force was insufficient. The experiments confirmed the results predicted by the FE simulation. For a selected flange inner diameter, the ratio of the extruded flange height to the increase in cup bottom thickness was directly related to the normalized clamping pressure, i.e. the ratio of clamping pressure to workpiece yield strength. Therefore, both the application of a larger clamping force or the use of low-strength workpiece materials facilitated the extrusion of flange while suppressing the dilation of the cup bottom. Flange extrusions with a larger diameter correspond to a smaller extrusion ratio or reduction of area. Experiments showed that a significant flange height could be extruded with a 10 mm inner diameter for both galvanized-steel and aluminum 5052, while results for extrusions with a 5 mm inner diameter were unfavorable when using galvanized-steel. High-strength materials and a high extrusion ratio required greater clamping force for the flange extrusion process, and consequently caused excessive forming load on the forming dies as well as on the hydraulic press, thus rendering the process less effective.  相似文献   
115.
In addition to operating the imaging ellipsometric measurements by four-specific temporal phases in the photoelastic modulated ellipsometry, we added the fifth one to solve the initial phase of the photoelastic modulator. This methodology has been developed to conquer the slow imaging processing of charge-coupled device camera for the stroboscopic illumination in the polarization modulated imaging ellipsometry. Without any calibration in its initial phase, we can perform the ellipsometric measurement by the measurements of intensity at five-specific temporal phases. The intensities of a full cycle for a point on SiO(2)∕Si thin film were measured and analyzed for verifying this algorithm. The five stroboscopic illuminations were performed to measure the two-dimensional distribution of the same SiO(2)∕Si thin film.  相似文献   
116.
The materials science and engineering related to the fabrication of conducting polymer thin films and the progress in the development of devices integrated with organic transparent electrodes based on conducting polymers for display applications are reviewed. Transparent electrodes are essential components for many display modules. With the evolution of display technologies, conducting polymers are recently emerging as important alternative materials for the fabrication of transparent electrodes. Conducting polymers offer some advantages, such as light weight, low cost, mechanical flexibility and excellent compatibility with plastic substrates for the development of next-generation display technologies and, in particular, are expected to play an important role in the development of flexible display technologies.  相似文献   
117.
Research has suggested that the most typical and catastrophic automobile–motorcycle crash takes place when an automobile manoeuvres into the path of an oncoming motorcycle at intersection, which involves a motorist infringing upon the motorcycle's right of way (ROW). In Taiwan, motorcycles, on the other hand, are the one that has been observed to violate the ROW of approaching automobiles at intersections. Such a ROW-violation by left-turn motorcyclists in front of approaching traffic is a safety problem in terms of its frequency and accident consequence. Using high-definition video cameras to capture motorcycles’ behaviours, the present study empirically analyses the determinants of motorcyclists violating the hook-turn area (HTA) that has been implemented in Taiwan to deter motorcyclists from violating the ROW of approaching vehicles. Mixed (random parameters) logit models are found to be superior in fitting the data to traditional binary logit models. Main findings include that there was an increased likelihood of HTA-violation at T/Y intersections, in rural areas, during non rush hours, when the riders were females, younger, when riders were travelling on mopeds or heavier motorcycles, when traffic volume was less, and when riders were with half-style helmets. Implications of the research findings, the concluding remarks, and recommendations for future research are finally provided.  相似文献   
118.
The transparent conducting oxide (TCO) film is a significant component in flat panel display industry, applied for flexible display, e-paper, and touch panel. The TCO materials have high refractive index, so the phenomenon of high reflectance is the major issue and needs solved in present and future market. In this study, the structure and process of new lower reflection TCO hybrid film is introduced. The laser interference lithography and UV nanoimprint are combined for fabrication of sub-wavelength structures on PET film, then the tin-doped indium oxide (ITO) deposited on structures. Finally, the best result of this hybrid film is reflectance reduced to 3.3% at wavelength 550nm, just 13% of the original film, and the resistance of ITO layer is 1.05×10−3 Ω-cm. This result is useful for the TCO film applied in low reflection demand products in the future.  相似文献   
119.
A triple-bounded dichotomous choice (TBDC) structure and Spike models are applied to investigate the amount of money Taiwan automobile drivers are willing to pay for five types of moving violations, including local street speeding, expressway and freeway speeding, red light running, right turn on red, and drink-driving. Face-to-face survey was conducted at freeway rest areas by targeting passenger car drivers. The Spike model, superior to other tradition models by capturing excessive zero responses, is applied and the estimated results show that speeders would accept willingness to pay (WTP) of US$37 and US$48,1 respectively, for local roads and expressways and highways, while red-light runners would accept a WTP of US$44, drivers who turn right on red would accept a lower WTP of US$9, and drunk drivers will accept a WTP as high as US$597. Interestingly, the difference in WTP for drunk driving between drivers and motorcyclists is significant, while others are not.  相似文献   
120.
ABSTRACT

A friction stir processing (FSP) method has been developed to fabricate a locally reinforced aluminum matrix composite (AMC) by stirring electroless-copper-coated SiC particles into AA6061 matrix. The interfacial bonding between particulate reinforcement and the matrix was enhanced by the copper coating. Effective improvement in hardness and in tensile strengths has been proved. Microstructural investigation and analyses were conducted to correlate the microstructural evidences with the possible strengthening mechanisms. The effect of copper coating on the bonding between SiC particles and Al-matrix; the role of the dispersed Cu debris and the increased Cu content in solid solution on the strengthening; and the effect of friction stir on dislocation density and on the recrystallization behavior were analyzed. Multiple strengthening mechanisms due to diffusion between copper film and matrix; dispersion of fine copper debris and Al-Cu intermetallic compounds (IMCs) in the matrix; solid solution due to increased copper content and dislocation punching were four major mechanisms in interpreting the strengthening phenomena in AMC containing copper coated SiC reinforcements.  相似文献   
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