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GIS-Constrained Multi-scale Coastal SAR Image Segmentation ZHU Jun-jie1,2, DU Xiao-ping1,2, FAN Xiang-tao1,2, GUO Hua-dong1,2 Journal of Applied Sciences    2013, 31 (1): 79-83.   DOI: 10.3969/j.issn.0255-8297.2013.01.013 Abstract （2768）      PDF（pc） （10346KB）（9935）       Knowledge map    Save Both geographic information system (GIS) data and remote sensing imagery are spatial data with multi-scale features although they are concerned with different types of information. This paper discusses the multi-scale segmentation of high-resolution synthetic aperture radar (SAR) images near coastal zones constrained by GIS vector data. To obtain the first level segmentation results at the county-level scale, the high-resolution SAR image is segmented using the fractal network evolution method with the constraint of GIS data. Then, at the province-level scale, the first level results are aggregated to obtain the second level segmentation results. This segmentation results satisfy both the constraint of GIS vector data and the scattering characteristics of SAR images. False coastlines in the SAR images are eliminated. Experimental results show that the proposed method is effective, and the segmentation results can be used for further image statistics and analyses. Related Articles | Metrics | Comments（0） Cited: Baidu(1)

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Automatic Detection of Bridge over Water in High-Resolution Remote-Sensing Image PENG Bi-fa1;2, TAN Yi-hua1;2, TAO Chao1;2, TIAN Jin-wen1;2 Journal of Applied Sciences    2010, 28 (4): 354-360.   DOI: 10.3969/j.issn.0255-8297.2010.04.005 Abstract （2626）      PDF（pc） （11893KB）（6414）       Knowledge map    Save An automatic detection method to identify bridges over water in high-resolution remote-sensing images is proposed. The input image is first segmented into two water and non-water areas according to homogeneity of the water area. The image is scanned, and the bridge is extracted from the non-water area. The orientation of the bridge is determined using region growing and multiple-direction scanning. The bridge is then accurately outlined from the coarse extraction by extension along its orientation. Experimental results show that the proposed method can automatically detect bridge over water in high-resolution remote-sensing images. Performance evaluation indicates that the proposed method is robust and accurate. Related Articles | Metrics | Comments（0） Cited: Baidu(9)

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Wireless Handoff Scheme in IEEE802.11 MAC Layer for High-Speed Mobile Communications ZHAO Li-fang, CHEN Bing Journal of Applied Sciences    2010, 28 (2): 123-128.   Abstract （3286）      PDF（pc） （1192KB）（6346）       Knowledge map    Save Mobile station performs a handoff when it moves out of the range of one access point and tries to connect to the next. The delay and lost packets caused by the handoff process affect the network quality of service. Taking subway wireless communication system as an application scenario, the number of channels used is reduced, which decreases the scan delay effectively. An algorithm called Layer2-Buff is proposed to solve the problem of lost packets, which sets up buffers for STA, and used to save data that cannot be sent successfully. Test results show that Layer2-Buff reduces the packet loss rate to zero in an automatic train control system, and extra delay to the network is tolerable. This algorithm has been applied to a pre-research project of subway signal systems. Related Articles | Metrics | Comments（0） Cited: Baidu(1)

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Image Self-Embedding Based on EZW Coding and Fountain Codes LIAO Chun, QIAN Zhen-xing, NI Jing, WANG Shuo-zhong Journal of Applied Sciences    2014, 32 (1): 65-73.   DOI: 10.3969/j.issn.0255-8297.2014.01.011 Abstract （2327）      PDF（pc） （14781KB）（4458）       Knowledge map    Save We first utilize EZW to encode the wavelet coefficients of the image, and then the fountain encoding to generate the reference data. By extracting forensic data and reference data which is self-embedded into the image, tampered area is detected and reference data is also reconstructed. Comparing to block-based DCT,we overcome the blocking artifact of the recovered image. Besides this, we propose a method which makes the data embedding and image quality dynamic by adjusting the parameters. A balance between the recovered area and recovered quality is also achievable. Reference | Related Articles | Metrics | Comments（0）

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Compressed Sensing Based Sparse Channel Estimation in MIMO Systems WANG Ni-na1, GUI Guan2;3, ZHANG Zhi1, TANG Tian1 Journal of Applied Sciences    2011, 29 (4): 347-352.   DOI: 10.3969/j.issn.0255-8297.2011.04.003 Abstract （2934）      PDF（pc） （1912KB）（3960）       Knowledge map    Save Abstract: In MIMO systems, channel state information (CSI) is necessary for coherent detection and channel equalization at the receiver. Traditional channel estimation methods such as least squares (LS) and minimum mean square error (MMSE) are based on the rich multipath assumption which leads to low frequency spectrum utilization. This paper studies sparse channel estimation for single carrier MIMO systems. A novel method based on compressed sensing is proposed by using sparsity, which can obtain accurate CSI with fewer pilots so as to improve frequency spectrum utilization. Simulation and theoretical analysis show that the compressive sampling matching pursuit (CoSaMP) estimation is the best choice for MIMO sparse multipath channel estimation. Related Articles | Metrics | Comments（0） Cited: Baidu(21)

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Uniform Color Processing of Scanned Topographic Maps Using FFTW-Based Retinex FU Zhong-liang, TONG Chun-ya, SHAO Shi-wei Journal of Applied Sciences    2010, 28 (3): 297-300.   Abstract （2379）      PDF（pc） （6131KB）（3618）       Knowledge map    Save This paper analyzes the appearance of creases and light non-uniformity in scanned topographic maps, and applies the Retinex theory to process the maps. A processing method and a single-scale Retinex algorithm (SSR) are proposed based on the faster Fourier transform in the west (FFTW) and the Retinex theory. Experimental results show that the proposed method can overcome disadvantages of the mathematical model and effectively remove creases and light non-uniformity in scanned topographic maps. Related Articles | Metrics | Comments（0） Cited: Baidu(1)

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Parallel Signal Processing for GPS Software Receiver MIAO Jian-feng1, SUN Yong-rong1, CHEN Wu2, LIU Jian-ye1, HU Cong-wei3 Journal of Applied Sciences    2009, 27 (2): 203-209.   Abstract （2794）      PDF（pc） （1393KB）（3506）       Knowledge map    Save In view of the inability of real time processing in conventional GPS software receivers, a GPS signal parallel processing algorithm is proposed based on dual core processors. Algorithmic modules in GPS software receivers including signal acquisition, tracking loop and pseudo-range position are analyzed. A parallel processing acquisition algorithm which includes a parallel processing and real-time optimization is studied. In the tracking loop, a separate carrier and CA code phase tracking loop are designed. An optimized bandwidth algorithm is described based on a mathematical analysis, which leads to better dynamic performance and less noise vulnerability of the receiver. The GPS software receiver is validated in computer simulation. Comparison with real testing data shows that the proposed method can improve processing ability at least by 30%, satisfying the requirements of the single point pseudo-range positioning approach. Related Articles | Metrics | Comments（0） Cited: Baidu(3)

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Vertical Tilt Correction for Vehicle License Plate Based on Minimizing Variance of Coordinates of Projection Points WU Yi-quan, DING Jian Journal of Applied Sciences    2009, 27 (2): 177-181.   Abstract （2773）      PDF（pc） （669KB）（3223）       Knowledge map    Save In order to facilitate character segmentation and recognition in a license plate recognition system, the tilting license plates in the located images should be corrected in both the horizontal and vertical directions. A vertical tilt correction method by minimizing variance of coordinates of the projection points is proposed. Coarse character segmentation is performed after horizontal correction and upper and lower border delineation. The character points are projected along the vertical direction after shear transform. Two closed-form expressions of the shear angle are derived based on minimizing variance of coordinates of the projection points. Thus the vertical tilt angle is directly determined and the license plate images corrected using the vertical tilt angle. Experimental results show that, compared to the vertical tilt correction methods of the license plate based on rotation projection and line fitting, the proposed method has high accuracy, requires less computation, and is robust. The proposed method has been applied in practical engineering system. Related Articles | Metrics | Comments（0） Cited: Baidu(3)

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Conflict Matrix Random Sort Based Channel Allocation for Multi-channel Wireless Networks YU Xu-tao1, BI Guang-guo2, ZHANG Zai-chen2 Journal of Applied Sciences    2013, 31 (4): 338-344.   DOI: 10.3969/j.issn.0255-8297.2013.04.002 Abstract （2279）      PDF（pc） （1872KB）（3182）       Knowledge map    Save  Multi-channel wireless network improves network capacity by using multiple channels. Channel allocation is a key in a multi-channel network. This paper presents a conflict matrix random sort (CMRS) based channel allocation algorithm. According to the number of available channels, the CMRS channel allocation algorithm divides a multi-channel network into several subnets based on the number of available channels. Links are sorted randomly and a conflict matrix is obtained from the contention graph of the network. To reduce conflicts in subnets, channels are allocated to each link based on conflict matrix. Analysis and simulation results show that the CMRS channel allocation algorithm effectively decreases the number of conflicts in the network, and increases the normalized network throughput. Reference | Related Articles | Metrics | Comments（0）

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Adaptive Despeckling Filter with Edge-Preservation for SAR Image XUE Cun-jin1;2, WEN Xiao-yang1;2, DONG Qing1;2 Journal of Applied Sciences    2011, 29 (1): 44-50.   DOI: 10.3969/j.issn.0255-8297.2011.01.008 Abstract （2517）      PDF（pc） （7838KB）（3121）       Knowledge map    Save To deal with the conflict between speckle removal and edge preservation in the SAR despeckling operations, we propose an adaptive despeckling filter that can preserve edges based on noise identification and edge detection oriented to SAR images. In the filter, the template’s size and shape are adaptively changed according to the noise characteristics, and the edge position and direction in homogeneous and edge regions. This way, noise in the SAR image is reduced, while edges are sharpened, and texture and fine structures preserved. RADARSAT-2 SAR HH images covering the North Arctic Pole obtained on August 25, 2010 are used in the experiment. The results show validation and practicability of the method. Related Articles | Metrics | Comments（0） Cited: Baidu(1)

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Error Calibration for Redundancy Collocation of Six MEMS-IMU HUANG Hui;LIU Jian-ye;LI Rong-bing Journal of Applied Sciences    2009, 27 (1): 106-110.   Abstract （3022）      PDF（pc） （580KB）（3116）       Knowledge map    Save System calibration techniques are discussed for strap-down redundant inertial measurement units. The measuring principle and calculation formulation are introduced. A new static calibration approach is discussed for non-orthogonal inertial sensor configuration, with which model parameters can be calculated with high precision. The procedure of parameter calculation and the solution is given. Simulation results show that the new approach can improve navigation precision. Related Articles | Metrics | Comments（0） Cited: Baidu(2)

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Time-Scale Modification of Audio Signal Using Improved WSOLA Algorithm XU Xue-qiong, YU Xiao-qing, LI Chang-lian, WAN Wang-gen Journal of Applied Sciences    2009, 27 (5): 514-519.   Abstract （2501）      PDF（pc） （821KB）（3113）       Knowledge map    Save To improve efficiency of the waveform similarity overlap-and-add (WSOLA) algorithm in audio signal processing at high sampling rate, this paper proposes a matching method that is progressively performed from the short time mean envelop to the signal waveform. We compute a rough matching envelop based on short time mean envelop, and then perform an exact waveform matching for time-scale modification of the audio signal. The algorithm reduces computation complexity, and improves efficiency with good outcome. In addition, the length of analysis windows is dynamically adjusted based on the modified low energy ratio parameter. Experiments show that it significantly improves processing results of mixed audio. Related Articles | Metrics | Comments（0） Cited: Baidu(2)

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Human Tracking Algorithm Robust against Sudden Changes of Illumination YUAN Xue, SONG Yong-duan Journal of Applied Sciences    2011, 29 (6): 592-597.   DOI: 10.3969/j.issn.0255-8297.2011.06.007 Abstract （2119）      PDF（pc） （10056KB）（3107）       Knowledge map    Save Abstract: This paper presents a robust human tracking algorithm. As human detection and tracking are important to intelligent surveillance, it is essential to ensure that the system can adapt to any environmental changes and track the objects without interruption. This paper proposes a human tracking algorithm robust against sudden changes of illumination. Sudden illumination changes are automatically detected. The camera’s exposure time is adjusted to compensate the changes. A mean shift algorithm is developed to continuously track the same object before and after the sudden change so as to achieve reliable tracking. Experiments verify effectiveness of the proposed algorithm. Related Articles | Metrics | Comments（0） Cited: Baidu(6)

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Fast Acquisition of Primary Synchronization Signal in LTE Systems YANG Xiu-mei1;2, XIONG Yong1;2, JIA Guo-qing1;2 Journal of Applied Sciences    2012, 30 (1): 14-18.   DOI: 10.3969/j.issn.0255-8297.2012.01.003 Abstract （1939）      PDF（pc） （706KB）（3083）       Knowledge map    Save A method is proposed to fast acquire primary synchronization signal (PSS) for cell edge users in long term evolution (LTE) systems. In this method, signals are received in the configured bandwidths of LTE networks, and the sliding mirror is then correlated. The PSS index is achieved from the local PSS correlation at peak position after a clear peak value is observed. Analysis and simulation results show that it is applicable especially to cell edge users in synchronized multi-cell networks to fast acquire PSS with low complexity. Keywords: Related Articles | Metrics | Comments（0） Cited: Baidu(2)

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Vehicle License Plate Location Based on Machine Learning ZHANG Pin-zheng, WANG Jian-hong Journal of Applied Sciences    2011, 29 (2): 147-152.   DOI: 10.3969/j.issn.0255-8297.2011.02.007 Abstract （2473）      PDF（pc） （3134KB）（3022）       Knowledge map    Save This paper proposes a vehicle license plate locating method based on the Adaboost algorithm and smallest univalue segment assimilating nucleus(SUSAN) corner validation. The Adaboost algorithm is applied for initial classification in order to select target license plate region and reduce the number of candidate areas. SUSAN corner validation is then used to calculate and sort probability of each area belonging to the vehicle license. The area with the highest probability is taken as the detection result. Experimental results show that the proposed method is robust to different illumination conditions, and the preset parameters produce satisfactory results in different experiments. Related Articles | Metrics | Comments（0） Cited: Baidu(2)

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Metamaterial Antenna Based on Anisotropic Permittivity SUN Yong-zhi, RAN Li-xin, WANG Wei-guang, CHEN Qiu-lin, ZHU Wei-qiang Journal of Applied Sciences    2010, 28 (4): 413-416.   DOI: 10.3969/j.issn.0255-8297.2010.04.014 Abstract （2543）      PDF（pc） （934KB）（2985）       Knowledge map    Save  We present an equation of dispersion characteristics for anisotropic metamaterial in this paper. In a particular direction, the dielectric constant of the material is zero at certain frequency. This property is used to produce the high-directional antenna. We develop a new metamaterial with a metallic cross-sectional structure, and simulate the radiated field of an omni-directional dipole antenna placed in the metamaterial. The radiated field is concentrated around the normal to the interface between the metamaterial and the air so that to give highly directional radiation. The gain of the antenna is 17.68 dB at 11.5 GHz, and the half power beam width is 5 degrees. The experimental results are consistent with the simulation. Related Articles | Metrics | Comments（0）

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A New Adaptive Bilateral Filtering YU Bo, GUO Lei, QIAN Xiao-liang, ZHAO Tian-yun Journal of Applied Sciences    2012, 30 (5): 517-523.   DOI: 10.3969/j.issn.0255-8297.2012.05.013 Abstract （5002）      PDF（pc） （3956KB）（2865）       Knowledge map    Save In the existing bilateral filtering algorithm, the domain parameters and range parameters need to be predefined. Parameters of a bilateral filter are fixed and cannot guarantee to be optimal. A new adaptive bilateral filtering (ABF) is proposed in this paper. The ABF obtains the domain parameters by estimating the local object scale to minimize edge blurring. The range parameters are set adaptively according to noise variance estimated in smooth areas of a sub image. The method can improve the filtering performance. To filter out strong noise, the value of domain parameters is increased. ABF avoids setting parameters solely by experience, and the domain parameters are set adaptively according to the local image features. ABF can improve the noise filtering ability and reserves edges. Experiments show that the adaptive bilateral filter is superior to traditional bilateral filters, anisotropic diffusion filters, and modified bilateral filters in both subjective and objective evaluations. Reference | Related Articles | Metrics | Comments（0）

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Eigenvalues of Incidence Matrices Applied to the Analysis of Petri Net Structures LIAO Jing-jing, WANG Ming-zhe Journal of Applied Sciences    2010, 28 (4): 417-423.   DOI: 10.3969/j.issn.0255-8297.2010.04.015 Abstract （3322）      PDF（pc） （2421KB）（2834）       Knowledge map    Save By computing eigenvalues of special square matrices derived from the incidence matrices of Petri net models, some important structural properties of Petri nets are analyzed. According to the differences between two types of nets, i.e., choice-free and link-free nets, and non-choice-free and non-link-free nets, two methods are used to transform them into the same class of square matrices. We then obtain sufficient conditions for structure boundedness, conservativeness, repetitiveness and consistency based on the theory of M-matrices. An example of radar model is given to show application in analyzing Petri net structures. Related Articles | Metrics | Comments（0） Cited: Baidu(2)

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MAC Layer Cooperative Multicast Strategy Based on IEEE 802.11 Protocol SONG Liu-bin1, XU You-yun1;2, XIE Wei2, YU Jiang1 Journal of Applied Sciences    2011, 29 (6): 559-564.   DOI: 10.3969/j.issn.0255-8297.2011.06.002 Abstract （1900）      PDF（pc） （745KB）（2800）       Knowledge map    Save In this paper, we propose a MAC layer cooperative multicast strategy based on the IEEE 802.11 protocol, in which correctly received data can serve as a temporary relay if the user locates a right position. We analyze the outage probability and throughput performance of the proposed strategy, and present a simulation method in NS2. Simulation results show that the new strategy has a better throughput and lower packet loss performance compared to the original MAC protocol. Related Articles | Metrics | Comments（0）

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Urban Spatial Form Analysis of GBA Based on “LJ1-01” Nighttime Light Remote Sensing Images ZHANG Yuxin, LI Xi, SONG Yang, LI Changhui Journal of Applied Sciences    2020, 38 (3): 466-477.   DOI: 10.3969/j.issn.0255-8297.2020.03.012 Abstract （21856）      PDF（pc） （15211KB）（2753）       Knowledge map    Save In this paper, “LJ1-01” nighttime light (NTL) images are used to extract urban built-up areas of Guangdong-Hong Kong-Macao greater bay area (GBA) by employing simple threshold method and vegetation adjusted NTL urban index (VANUI). Comparing the two methods, VANUI is capable of reducing the over-saturations in LJ1-01 images, thus reducing misclassifications caused by “blooming”. The landscape indices of the urban builtup areas in GBA are calculated and analyzed. It is found that there are different patterns in distribution of built-up areas in different cities. As the cores of the development of GBA, Guangzhou, Shenzhen and Hong Kong have expanding urban areas. The urban built-up areas, like Dongguan, Foshan, Macao, Zhongshan and Zhuhai, are highly compact and integrated in spatial distribution. And the urban built-up areas of less developed cities, including Zhaoqing, Jiangmen and Huizhou, are small and separated. This study proves that the LJ1-01 nighttime light images can effectively reveal the urban spatial form of GBA, providing a basis for urban planning policy of GBA. Reference | Related Articles | Metrics | Comments（0）