2014
2014
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Record 457 of
Title:Visual measurement of the pulse laser ablation process on liquid surface by using digital holography
Author(s):Wang, J.(1); Zhao, J.L.(1); Di, J.L.(1); Rauf, A.(1); Yang, W.Z.(2); Wang, X.L.(2)Source: Journal of Applied Physics Volume: 115 Issue: 17 DOI: 10.1063/1.4874742 Published: May 7, 2014Abstract:We present a visual method to dynamically and quantitatively measure the ablation process on liquid surface induced by pulse laser based on digital holography. Taking deionized water as a liquid example, the quantitative data of the evolution of cavity, jet, and pressure in ablation process are experimentally obtained. According to Abel inversion, the refractive index and the thickness contained in the phase information of the axisymmetric jet are decoupled. The temporal resolution, temporal stability, and measurement accuracy of this method are analyzed based on digital holographic theory. In addition, a numerical simulation is performed to calculate the maximum cavity depth, and the results are in good agreement with the experimental data. ? 2014 AIP Publishing LLC.Accession Number: 20142817935402 -
Record 458 of
Title:Visibility enhancement of hazy images based on a universal polarimetric imaging method
Author(s):Liang, Jian(1,2); Ren, Li-Yong(1); Ju, Hai-Juan(1); Qu, En-Shi(1); Wang, Ying-Li(1)Source: Journal of Applied Physics Volume: 116 Issue: 17 DOI: 10.1063/1.4901244 Published: November 7, 2014Abstract:Enhancing the visibility of images taken in the hazy weather is important in many applications. Among many dehazing methods, those based on polarimetric imaging techniques have several advantages, such as ease of keeping detailed information, low cost, and high efficiency. In this paper, we propose a novel and robust dehazing algorithm based on polarimetric imaging. By introducing the orientation-angle information from the Stokes matrix, all the parameters used in dehazing performance can be effectively, precisely and automatically estimated, and no additional human-computer interaction is needed. Besides, this method can also be used in handling hazy images without sky region. Experimental results show that such a method can greatly enhance the visibility of hazy images. ? 2014 AIP Publishing LLC.Accession Number: 20144600196283 -
Record 459 of
Title:Seal designing of theodolite used in seaside environment
Author(s):Jin, Humin(1); Yan, Xiaoxu(1); Hao, Wei(1); Zhou, Sizhong(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9285 Issue: DOI: 10.1117/12.2068710 Published: 2014Abstract:Based on the environment requirements in seaside there exists static and dynamic seal designing for the photoelectric Theodolite. Static seal designing emphatically includes the designing of o-ring size and mechanical property analysis of o-ring seal, which is difficult to adopt conventional dynamic seal to meet the requirements. According to practical application, the combination of the radial labyrinth seal and high quality felt seal are designed. The combination seal which better solves the seal problem of narrow radial size is a good way of dynamic seal. At the same time, there is engineering practice needing to proof the radial labyrinth seal.Accession Number: 20150800545509 -
Record 460 of
Title:Standoff two-color quantum ghost imaging through turbulence
Author(s):Xue, Yu-Lang(1,2); Wan, Ren-Gang(1); Feng, Fei(1,2); Zhang, Tong-Yi(1)Source: Applied Optics Volume: Issue: 14 DOI: 10.1364/AO.53.003035 Published: May 10, 2014Abstract:Recently, a two-color quantum ghost imaging configuration was proposed by Karmakar et al. [Phys. Rev. A 81, 033845 (2010)]. By illuminating an object located far away from the source and detector, with a signal beam of long wavelength to avoid absorptionofshort wavelengths in the atmosphere while a reference beam of short wavelength is detected locally, this imaging configuration can be appropriate for standoff sensing. In practice, the signal beam must propagate through atmosphere in the presence of serious turbulence. We analyzed theoretically the performance of this ghost imaging configuration through turbulence. Based on the Gaussian state source model and extended Huygens-Fresnel integral, a formula is derived to depict the ghost image formed through turbulence of a standoff reflective object. Numerical calculations are also given according to the formula. The results show that the image quality will be degraded by the turbulence, but the resolution can be improved by means of optimizing the wavelengths of the reference and signal beams even when the turbulence is very serious. ? 2014 Optical Society of America.Accession Number: 20141200000630 -
Record 461 of
Title:Hierarchical incorporation of shape and shape dynamics for flying bird detection
Author(s):Zhang, Jun(1); Xu, Qunyu(1); Cao, Xianbin(1); Yan, Pingkun(2); Li, Xuelong(2)Source: Neurocomputing Volume: 131 Issue: DOI: 10.1016/j.neucom.2013.10.026 Published: May 5, 2014Abstract:Flying bird detection (FBD) is critical in avoiding bird-aircraft collisions. Most existing approaches rely on motion detection to identify the flying bird, since it is a typical moving object. However, when there exist other moving objects, those methods often fail to distinguish flying birds from those objects due to the insufficiency of feature description. In this paper, we introduce a novel hierarchical feature model exploiting shape and shape dynamics to improve the ability of representing a flying bird, and then apply it to the FBD problem. As the shape of a flying bird is very distinctive in geometric structures and could provide discriminating spatial information, an improved shape context feature descriptor is proposed at the lower level to capture the spatial relations in bird shape. Then the shape descriptor is extended into the spatio-temporal domain and a shape dynamics description is built at the higher level, in which a 4-state Markovian model is adopted and is learned from training sequences. Moreover, to build a mapping from the lower level to the higher level of the hierarchy, a shape similarity index (SSI) based matching mechanism is designed. We apply these two-level features for detecting flying bird for improved safety of aircrafts flying at low-altitude. The experimental results show that the proposed method is effective and outperforms three other existing vision-based FBD approaches. ? 2013 Elsevier B.V.Accession Number: 20140817363950 -
Record 462 of
Title:Research on shared anode used for the large area array MCP detector
Author(s):Song, Juan(1,2); Zhao, Bao-Sheng(1); Sheng, Li-Zhi(1); Liu, Zhe(1); Dai, Jin-Fei(1,2); Liu, Yong-An(1); Zhou, Yan-Nan(1)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 43 Issue: 8 DOI: 10.3788/gzxb20144308.0823002 Published: August 1, 2014Abstract:The development of signal acquisition system used for the large area array of microchannel plate detector is very difficult. Multi-channel shared anode was put forward to solve this technical issue. Dual-channel shared anode and four-channel shared anode were designed. According to the basic standard that multi-channel Shared anode instead of single channel anode, signal transmission characteristics and collection efficiency were tested. Simulation experiment results show that signal transmission in multi-channel shared anode without attenuation and distortion, and the experimental results and simulation results are identical with each other; dual-channel shared anode's total count rate and four-channel shared anode's count rate are approximately equal to the sum of single channel anode count rate, the relative error of the count rate are 5.2%, 7.4% respectively. Four-channel shared anode can replace single channel anode and dual-channel shared anode, and the number of channels about electronics acquisition system is reduced to 1/4 of the original. So, the volume, weight and power of the whole acquisition system are reduced effectively.Accession Number: 20143900077221 -
Record 463 of
Title:A probabilistic associative model for segmenting weakly supervised images
Author(s):Zhang, Luming(1); Yang, Yi(2); Gao, Yue(3); Yu, Yi(1); Wang, Changbo(4); Li, Xuelong(5)Source: IEEE Transactions on Image Processing Volume: 23 Issue: 9 DOI: 10.1109/TIP.2014.2344433 Published: September 2014Abstract:Weakly supervised image segmentation is an important yet challenging task in image processing and pattern recognition fields. It is defined as: in the training stage, semantic labels are only at the image-level, without regard to their specific object/scene location within the image. Given a test image, the goal is to predict the semantics of every pixel/superpixel. In this paper, we propose a new weakly supervised image segmentation model, focusing on learning the semantic associations between superpixel sets (graphlets in this paper). In particular, we first extract graphlets from each image, where a graphlet is a small-sized graph measures the potential of multiple spatially neighboring superpixels (i.e., the probability of these superpixels sharing a common semantic label, such as the sky or the sea). To compare different-sized graphlets and to incorporate image-level labels, a manifold embedding algorithm is designed to transform all graphlets into equal-length feature vectors. Finally, we present a hierarchical Bayesian network to capture the semantic associations between postembedding graphlets, based on which the semantics of each superpixel is inferred accordingly. Experimental results demonstrate that: 1) our approach performs competitively compared with the state-of-the-art approaches on three public data sets and 2) considerable performance enhancement is achieved when using our approach on segmentation-based photo cropping and image categorization. ? 2014 IEEE.Accession Number: 20143518120093