The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
The accurate measurements for fiber propagation delay is the prerequisite of timing accuracy in high precision optical fiber timing system. A certain of processing is needed for measurements because the original measurements generally cannot meet the accuracy requirement. The commonly used methods such as Adjacent-averaging method and modeling method based on the measurement have low efficiency or...
Atmospheric duct is an anomalous structure with a high probability in the sea. Rough sea surface exists as an air-sea boundary, which can enable electromagnetic wave propagation more complex in atmospheric duct due to scattering. By the Fourier split-step algorithm of the standard parabolic equation and the impedance boundary conditions, the transmission loss in atmospheric duct for different kind...
In the visible light communication (VLC) orthogonal frequency-division multiplexing (OFDM) systems, the peak-to-average power ratio (PAPR) of OFDM signals is the primary concern of the transmission performance. In order to obtain low PAPR signals, we report and experimentally demonstrate a phase modulated OFDM system. The system can be reach 1.2Gbit/s under the standard illuminance level. And the...
A middleware software used to connect radar scanning unit based on multicast mechanism and display unit based on unicast mechanism is designed and implemented, and by using the cooperation mechanism of ARM and DSP Dual-Core in DM3730, DSP core processes the realization of radar coordinate conversion algorithm to solve the problem of single-core ARM processor in data processing (packet loss). As can...
Multibeam satellite communication systems (MSC-Ss) have been applied to provide efficiently power and bandwidth utilization for broadband service by employing frequency reuse. However, bandwidth for each beam is divied by frequency reuse which is used to mitigate the adjacent beam interference. Recently researchers resorted precoding as a novel interference mitigation technique to achieve full frequency...
In this paper, we propose an efficient identity-based authentication and key agreement protocol for wireless roaming. In the protocol, a roaming user only needs one message transmission to achieve authentication and session key establishment with the roaming server. We then demonstrate that the protocol ensures the privacy of roaming users, by providing anonymity and untraceability.
In order to address the matching problems of oblique remote sensing image with viewpoint change, geometric deformation and radiometric distortion, this paper presents a new point-based matching method which conducts feature extraction by building nonlinear space on simulation images derived from a full-range resample of the origin image. All distortions caused by the position change of camera are...
The binocular visual collaborative video tracking method can simultaneously obtain Far-Range image in global field of view and Close-Range image in following field of view with which can track the target, but the error of PTZ(Pan Tilt and Zoom) motion parameters of the following camera is relatively large and the calibration algorithm is relatively complex. Thus, a new strategy for PTZ calibration...
In order to strengthen the robustness of video object tracking and overcome the drastic appearance changes caused by diverse challenges, a generative algorithm based on sparse histogram was proposed. Firstly, the image was partitioned into patches by using overlapped sliding window. Secondly, the local features of the object were extracted, and the sparse representation was exploited to achieve the...
This paper proposes a block-based least squares thresholding algorithm, according to the analysis and comparison of the shortcomings of Otsu and maximum entropy methods. The proposed algorithm deals with images by least squares processing methods, which stretch the gray level of images and make the gray values more uniform. In this way, the images can be more suitable for binarization.
The paper is focused on the ambiguity problem in pose estimation of circle feature and a new method is proposed based on the concentric circle constraint. The pose of a single circle feature, in general, can be determined from its projection in the image plane with a pre-calibrated camera, but there are generally two possible sets of pose parameters. By introducing the concentric circle constraint,...
A human body modelling and its contour feature point positioning approach based on the Point Distribution Model (PDM) and Active Shape Model (ASM) is proposed in this paper. We establish the training sample set of the human body data which obtained via 3D body scanner. The feature points of human body image are extracted, the training sample set registration and principal component analysis is done...
Most traditional network anomalies and attacks detection systems tend to employ supervised strategies, which require labeled training dataset that is arduous and expensive to obtain and fails to detect unknown attacks jeopardizing the system security and reliability. In this paper we present a new unsupervised approach based on abnormality weights rendering and subspace clustering techniques to detect...
Vehicle logo recognition (VLR) is a main issue in vehicle identification system. Logo recognition is still a challenge technique since VLR methods suffer from the large within-class variations due to the different illumination conditions, different viewpoints et al. In this paper, motivated by the excellent performance of the collaborative representation based classification (CRC), we formulate VLR...
With the development of multimedia technology and Internet, the amount of videos in the Internet is increasing quickly. Among the large amount of videos in the Internet, a considerable number of them are copies of original videos, which are simply revised versions of the original ones. The purpose of video copy detection technology is to detect copy videos, which has important applications in video...
Impressive achievements have been achieved over the years in object recognition and 3D pose estimation while detecting objects and estimating their 3D poses reliably is still a very challenging problem, especially for texture-less objects in heavily cluttered scenes. In this paper, we introduce an improved approach based on multi-stage feature learning to identify object as well as their 3D orientation...
With the increase of spreading distance, the light energy decays rapidly in water. Simultaneously, the light will reflect and deflect multiple times in its travel path. Underwater image typically suffers from poor visibility, low contrast and color distortion due to light scattering and attenuation. In this paper, we put forward a novel algorithm to restore the image based on dark channel prior. The...
Gaze-tracking is a hot technology of human-computer interaction, which requires an explicit personal calibration process before every use for the sake of higher accuracy. When a number of different gaze interactive systems are used continuously, the calibration process would take the trouble. Due to the accuracy of interaction relying on the calibration of the camera which is used, in this paper,...
Ultrasonic ranging system has been used in many applications. In order to realize precisely positioning motion objects, ultrasonic sensors are adopted to measure their motions, and then their 2D coordinates should be positioned. This will lead to complicated calculations and then yield to measurement errors with improperly designed programs. This study addresses a method to realize automatically tracking...
Image segmentation approaches have contributed a lot to help people interpret Synthetic aperture radar (SAR) images well. Fuzzy C-means (FCM), as a clustering method, is the most popular one of SAR image segmentation. However, classical FCM is quite sensitive to speckle noises included in the SAR images, and adding the spectral information is still not enough to improve the performance. Hence, there...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.