Damage and failure in carbon fiber-reinforced epoxy filament-wound shape memory polymer composite tubes under compression loading

In this paper, axial and radial compression tests of carbon fiber/epoxy filament wound shape memory polymer (SMP) composite tubes were carried out to investigate the corresponding mechanical response. Carbon fibers impregnated with epoxy resin matrix were wound with ±45° layers. The effects of temperature, compression times, defect hole area, shape, and distribution on the mechanical properties of composite tubes were studied and analyzed, respectively. Meanwhile, the mechanical model of stress distribution about the defect hole, under axial compression loading, was established via using the method of complex function. Furthermore, the failure factors of specimens were analyzed. As a result, the defect with sharp angle would result in lower buckling load and Young's modulus. In addition, the failure area, where the delamination of materials, was predominantly located in the middle of specimen. The more times of compression to failure would result in the lower buckling load and Young's modulus of specimens, and the relationship was mainly in form of a specific power function. According to Hashin failure criteria, the effect of axial compression times on buckling load and equivalent modulus was investigated.     

嵌入式linux-F多线程视频监控的设计和实现

使用多任务操作系统linux的多线程技术设计和实现了一个民用领域的远程视频监控系统,实验证明该系统有良好的灵活性,较好的可扩展性,而且节省成本。     

A Bayesian network modeling approach for cross media analysis

Existing methods for the semantic analysis of multimedia, although effective for single-medium scenarios, are inherently flawed in cases where knowledge is spread over different media types. In this work we implement a cross media analysis scheme that takes advantage of both visual and textual information for detecting high-level concepts. The novel aspect of this scheme is the definition and use of a conceptual space where information originating from heterogeneous media types can be meaningfully combined and facilitate analysis decisions. More specifically, our contribution is on proposing a modeling approach for Bayesian Networks that defines this conceptual space and allows evidence originating from the domain knowledge, the application context and different content modalities to support or disproof a certain hypothesis. Using this scheme we have performed experiments on a set of 162 compound documents taken from the domain of car manufacturing industry and 118 581 video shots taken from the TRECVID2010 competition. The obtained results have shown that the proposed modeling approach exploits the complementary effect of evidence extracted across different media and delivers performance improvements compared to the single-medium cases. Moreover, by comparing the performance of the proposed approach with an approach using Support Vector Machines (SVM), we have verified that in a cross media setting the use of generative rather than discriminative models are more suited, mainly due to their ability to smoothly incorporate explicit knowledge and learn from a few examples.     

Large-scale measurement experiments of P2P-TV systems insights on fairness and locality

P2P-TV is an emerging alternative to classical television broadcast systems. Leveraging possibilities offered by the Internet, several companies offer P2P-TV services to their customers. The overwhelming majority of these systems, however, is of closed nature, offering little insight on their traffic properties. For a better understanding of the P2P-TV landscape, we performed measurement experiments in France, Japan, Spain, and Romania, using different commercial applications. By using multiple measurement points in different locations of the world, our results can paint a global picture of the measured networks, inferring their main properties. More precisely, we focus on the level of collaboration between peers, their location and the effect of the traffic on the networks. Our results show that there is no fairness between peers and that is an important issue for the scalability of P2P-TV systems. Moreover, hundreds of Autonomous Systems are involved in the P2P-TV traffic and it points out the lack of locality-aware mechanisms for these systems. The geographic location of peers testifies the wide spread of these applications in Asia and highlights their worldwide usage.     

Novel adaptive color space transform and application to image compression

Various contemporary standards by Joint Picture Expert Group, which is used for compression, exploited the correlation among the color components using a component color space transform before the subband transform stage. The transforms used to de-correlate the colors are primarily the fixed kernel transforms, which are not suitable for large class of images. In this paper an image dependent color space transform (ID-CCT), exploiting the inter-channel redundancy optimally and which is very much suitable for compression has been proposed. Also the comparative performance has been evaluated and a significant improvement has been observed, objectively as well as subjectively over other quantifiable methods.     

Efficient compression of rearranged time-multiplexed elemental image arrays in MALT-based three-dimensional integral imaging

In this paper, an approach to efficiently compress the time-multiplexed EIAs picked up from the MALT-based integral imaging system is proposed. In this method, the time-multiplexed EIAs are rearranged by collecting the elemental images occupied at the same position in each EIA to enhance the similarity among the elemental images. Then, MPEG-4 is applied to these rearranged elemental images for compression. From the experimental results, it is shown that the average correlation quality (ACQ) value representing a degree of similarity between the elemental images, and the resultant compression efficiency have been enhanced by 11.50% and 9.97%, respectively on the average for three kinds of test scenarios in the proposed method, compared to those of the conventional method. Good experimental results finally confirmed the feasibility of the proposed scheme.     

Approximate reasoning and finite state machines to the detection of actions in video sequences

In this paper a novel approach for recognizing actions in video sequences is presented, where the information obtained from the segmentation and tracking algorithms is used as input data. First of all, the fuzzification of input data is done and this process allows to successfully manage the uncertainty inherent to the information obtained from low-level and medium-level vision tasks, to unify the information obtained from different vision algorithms into a homogeneous representation and to aggregate the characteristics of the analyzed scenario and the objects in motion. Another contribution is the novelty of representing actions by means of an automaton and the generation of input symbols for the finite automaton depending on the comparison process between objects and actions, i.e., the main reasoning process is based on the operation of automata with capability to manage fuzzy representations of all video data. The experiments on several real traffic video sequences demonstrate encouraging results, especially when no training algorithms to obtain predefined actions to be identified are required.     

Dazzling effect of repetitive short pulse laser on TDI CCD camera

A dazzling experiment was performed on a 64-stage TDI CCD camera using a 20 Hz repetition frequency picoseconds pulse laser, during which we found a new dazzling effect in which the fringes appeared in the video of the camera beside the saturation spot induced by the laser. We considered it to be the scattered light of the repetition frequency laser pulse to have induced the phenomenon. Width and visibility of the fringes recorded the information of the scattered light, such as repetitive frequency, pulse width and intensity distribution. With the assumption that the laser pulse width is less than one stage integral time of TDI CCD, width expressions for the fringes and space between the fringes were given using the repetitive frequency of laser pulse, row output frequency and integral stage number of the TDI CCD camera.     

Comparison of recovery behaviors of thermally aged SBR composite from compressed and circular deformations

Recovery behaviors of the SBR composite from the compressed and circular deformations after thermal aging were compared. Instantaneous recovery and target recovery time to describe the sealing properties of a sealant were obtained from the recovery variation with the measuring time. For the compressed deformation, the recovery decreased at the initial measurement time and then increased. Since the recovery from the compressed deformation showed a local minimum and the minimum point varied in accordance to the thermal aging conditions, the linearity of the recovery variation was very low. For the circular deformation, the recovery continuously increased as the measurement time elapsed, the linearity was very high, and the instantaneous recovery of less than 0.1 s could be obtained from the extrapolation method. The circular deformation method was found to be suitable for study of recovery behaviors of a rubber article. The recovery behaviors varied with the thermal aging conditions and the difference was explained with the crosslink density change by the thermal aging.     

基于ADV611的质量窗提高监控视频图像压缩率的方法

ADV611是美国Analog公司生产的一种最新的小波视频压缩芯片，它具有的质量窗特性为提高视频图像的压缩率提供了可能。介绍一种基于ADV611的质量窗来提高监控视频图像压缩率的方法。