Logo detection with extendibility and discrimination

Logos are specially designed marks that identify goods, services, and organizations using distinguished characters, graphs, signals, and colors. Identifying logos can facilitate scene understanding, intelligent navigation, and object recognition. Although numerous logo recognition methods have been proposed for printed logos, a few methods have been specifically designed for logos in photos. Furthermore, most recognition methods use codebook-based approaches for the logos in photos. A codebook-based method is concerned with the generation of visual words for all the logo models. When new logos are added, the codebook reconstruction is required if effectiveness is a crucial factor. Moreover, logo detection in natural scenes is difficult because of perspective tilt and non-rigid deformation. Therefore, this study develops an extendable, but discriminating, model-based logo detection method. The proposed logo detection method is based on a support vector machine (SVM) using edge-based histograms of oriented gradient (HOGE) as features through multi-scale sliding window scanning. Thereafter, anti-distortion affine scale invariant feature transform (ASIFT) is used for logo verification with constraints on the ASIFT matching pairs and neighbors. The experimental results using the public Flickr-Logo database confirm that the proposed method has a higher retrieval and precision accuracy compared to existing model-based methods.

     

Microstructural characteristics in Ni/zirconia bonding

Zirconia with various dopants of Y₂O₃ and CeO₂ was employed in the solid state bonding of an Ni/ceramic assembly. The interfacial microstructure of the bonding assembly was examined by electron microscopy and X-ray diffraction and the bonding strength was evaluated with a tensile test under constant pressure. An intermediate layer was observed in the interface of the 3Y₂O₃-10CeO₂-ZrO₂/Ni bonding assembly which revealed that the solid state bonding of Ni/zirconia required the formation of a thin oxide layer to wet the ceramics. In the Ni/zirconia bonding, the growth of NiO was influenced by the dopants in the zirconia. This would, in turn, result in different bonding strengths between ZrO₂ and nickel. The highest bonding strength occurred in the 12CeO₂-ZrO₂/Ni assembly.     

Formation and growth morphology of oxidation-induced ferrite layer in Fe-Mn-Al-Cr-C alloys

Three austenitic Fe-31 Mn-9Al-xCr-0.87C alloys (x=0, 3 and 6) have been oxidized in dry air at 800 to 1100 ° C. An oxidation-induced ferrite layer is observed between the oxide layer and the austenite matrix. The ferrite layer is formed due to the selective oxidation of manganese. Qualitative and quantitative electron microscopic techniques are employed to investigate the morphological development and elemental redistribution in the alloy system. The mechanism of the formation and growth of the ferrite layer and the diffusion path of the carbon due to austenitic decomposition are explored.     

Effects of characteristics of image quality in an immersive environment

Image quality issues such as field of view (FOV) and resolution are important for evaluating "presence" and simulator sickness (SS) in virtual environments (VEs). This research examined effects on postural stability of varying FOV, image resolution, and scene content in an immersive visual display. Two different scenes (a photograph of a fountain and a simple radial pattern) at two different resolutions were tested using six FOVs (30, 60, 90, 120, 150, and 180 deg.). Both postural stability, recorded by force plates, and subjective difficulty ratings varied as a function of FOV, scene content, and image resolution. Subjects exhibited more balance disturbance and reported more difficulty in maintaining posture in the wide-FOV, high-resolution, and natural scene conditions.     

Subjective and objective evaluation of visual fatigue caused by continuous and discontinuous use of HMDs

During continuous use of displays, a short rest can relax users' eyes and relieve visual fatigue. As one of the most important devices of virtual reality, head‐mounted displays (HMDs) can create an immersive 3D virtual world. When users have a short rest during the using of HMDs, they will experience a transition from virtual world to real world. In order to investigate how this change affects users' eye condition, we designed a 2 × 2 experiment to explore the effects of short rest during continuous using of HMDs and compared the results with those of 2D displays. The Visual Fatigue Scale, critical flicker frequency, visual acuity, pupillary diameter, and accommodation response of 80 participants were measured to assess the subject's performance. The experimental results indicated that a short rest during the using of 2D displays could significantly reduce users' visual fatigue. However, the experimental results of using HMDs showed that short rest during continuous using of HMD induced more severe symptoms of subjectively visual discomfort, but reduced the objectively visual fatigue.     

"Conflicting" motion cues to the visual and vestibular self-motion systems around 0.06 Hz evoke simulator sickness

The basic question this research addressed was, how does simulator sickness vary with simulated motion frequency? Participants were 11 women and 19 men, 20 to 63 years of age. A visual self-motion frequency response curve was determined using a Chattecx posture platform with a VR4 head-mounted display (HMD) or a back-projected dome. That curve and one for vestibular self-motion specify a frequency range in which vestibular and visual motion stimuli could produce conflicting self-motion cues. Using a rotating chair and the HMD, a third experiment supported (p < .01) the hypothesis that conflicting cues at the frequency of maximum "crossover" between the curves (about 0.06 Hz) would be more likely to evoke simulator sickness than would conflicting cues at a higher frequency. Actual or potential applications of this work include a preliminary design guidance curve that indicates the frequency range of simulated motion that is likely to evoke simulator or virtual reality sickness; for simulators intended to operate in this frequency range, appropriate simulator sickness interventions should be considered during the design process.     

Synthesis and sintering behaviour in CeO2-ZrO2 ceramics

The co-precipitation method has been employed to prepare CeO₂-ZrO₂ ceramics. The application of a wet chemical method is expected to yield highly sinterable material at lower sintering temperatures. The characteristics of the synthesized powders are evaluated with respect to the particle size distribution, calcination step, and the degree of agglomeration. The sintering behaviour of the prepared powder is studied at various temperatures to obtain different phase distributions and grain sizes. The amount of the monoclinic phase in the as-sintered specimen is decreased with increasing CeO₂ contents in CeO₂-ZrO₂. 13.7 mol% CeO₂ is sufficient to achieve a tetragonal phase in the CeO₂-ZrO₂ system. In addition, Y₂O₃ and MgO dopants in CeO₂-ZrO₃ reduce the grain size and result in a fully tetragonal phase for the 10 mol% CeO₂ matrix.     

Nitriding in the high temperature oxidation of Fe-31Mn-9AI-6Cr alloy

An alloy, of Fe-31.3Mn-8.92AI-5.96Cr-0.86C composition, was heated from 800 to 1000° C in atmospheres of oxygen, nitrogen and dry air respectively. A needle-like structure was observed between the alloy matrix and the external oxidation layer in the nitrogen-containing atmosphere at temperatures higher than 800° C. The needle-like phase was identified as AIN by both X-ray and STEM diffraction methods. Nitriding first occurred in the austenitic grains adjacent to the free surface, with subsequent AIN growth towards the alloy matrix. The ferrite phase, formed due to the precipitation of chromium carbide, prevented the growth of AIN. For the alloy oxidized in air, AIN formed and the growth front of AIN was ahead of the oxides. The aluminium content of the alloy matrix in the nitrided region was depleted by the formation of AIN. Due to the rapid nitriding of AI, the formation of a protective oxide layer was retarded and the oxidation resistance became less promising.Will be on leave to the Department of Materials Science and Engineering, Cornell University, as visiting scientist, after 1 October 1987.     

The effect of carbon on the high temperature oxidation of Fe-31 Mn-9Al-0.87C alloy

The alloy with the composition Fe-31Mn-9Al-0.87C was employed to investigate the effects of carbon on the oxidation behaviour at 800, 900 and 1000° C in dry air. Electron and optical microscopy were applied to examine the morphology and elemental redistribution in the oxide scale. Oxidation kinetics of the alloy oxidized at 800 and 900° C exhibited three-stage and two-stage parabolic rate laws, respectively. For the alloy oxidized at 1000° C, a carbon-induced breakaway three-stage oxidation mechanism developed. The carbon addition had a detrimental effect on the oxidation resistance and resulted in a porous initial oxide layer, which was favourable to the oxidation of manganese as well as the formation of a uniform and bulky oxide. As the oxidation temperature was increased, the diffusion rates of the metallic elements and the healing ability of oxide scales were enhanced. However, when the carbon content in alloy was above the saturation value, a breakaway scaling may have occurred due to the carbon-induced oxidation.     

Napiergrass (Pennisetum purpureum S.) protects oxidative damage of biomolecules and modulates antioxidant enzyme activity

The effects of water extract of napiergrass (Pennisetum purpureum S.) (WEN) on oxidative damage of biomolecules and modulation of antioxidant enzyme activity were investigated. The results showed that WEN displayed marked free radical scavenging, reducing power, as well as ferrous ions chelating effects. WEN has a dose-dependent response for protective action on oxidation of phospholipid, deoxyribose and low-density lipoprotein (LDL) in the range of 0–0.5 mg/ml, indicating that WEN had in vitro protective action on oxidative damage of biomolecules. Oxidative stress induced by H₂O₂ significantly decreased the viability of BNL cells. However, addition of WEN in the medium protected cells from H₂O₂-induced cytotoxicity. Furthermore, treatment of cells with WEN in the range of 0–0.2 mg/ml displayed protective effect from H₂O₂ induced oxidation in a concentration dependent manner. With respect to the effect of WEN on antioxidant enzymes, the results showed the WEN at 0.2 mg/ml enhanced activities of glutathione peroxidase (GPX), glutathione reductase (GR), glutathione transferase (GST) and catalase (CAT) in BNL cells by 2.93-, 35.8-, 4.23-, and 2.78-fold, respectively, compared to the control; WEN increased the GSH content by 3.2-fold, implying that WEN may up-regulate the levels of GSH and antioxidant enzymes in BNL cells. WEN scavenged NO generated by a NO donor, sodium nitroprusside (SNP) and suppressed NO production in lipopolysaccharide (LPS)-activated macrophage RAW 264.7 cells. The determination of ascorbic acid and total anthocyanins as well as HPLC analysis revealed that ascorbic acid, rutin, epicatechin, anthocyanins, p-coumaric acid, quercetin and catechin were present in WEN, which function as in vitro antioxidants by virtue of their ability to scavenge ROS and RNS. Overall, the results obtained showed that WEN is rich in antioxidant components and they can serve as an excellent potential for use as a natural phytochemicals source.