Filters








23 Hits in 1.7 sec

Using Dual-Polarization Interferograms to Correct Atmospheric Effects for InSAR Topographic Mapping

Zhiwei Liu, Haiqiang Fu, Jianjun Zhu, Cui Zhou, Tingying Zuo
2018 Remote Sensing  
Atmospheric effect represents one of the major error sources for interferometric synthetic aperture radar (InSAR), particularly for the repeat-pass InSAR data. In order to further improve the practicability of InSAR technology, it is essential to study how to estimate and eliminate the undesired impact of atmospheric effects. In this paper, we propose the multi-resolution weighted correlation analysis (MRWCA) method between the dual-polarization InSAR data to estimate and correct atmospheric
more » ... ects for InSAR topographic mapping. The study is based on the a priori knowledge that atmospheric effects is independent of the polarization. To find the identical atmospheric phase (ATP) signals of interferograms in different polarizations, we need to remove the other same or similar phase components. Using two different topographic data, differential interferometry was firstly performed so that the obtained differential interferograms (D-Infs) have different topographic error phases. A polynomial fitting method is then used to remove the orbit error phases. Thus, the ATP signals are the only identical components in the final obtained D-Infs. By using a forward wavelet transform, we break down the obtained D-Infs into building blocks based on their frequency properties. We then applied weighted correlation analysis to estimate the wavelet coefficients attributed to the atmospheric effects. Thus, the ATP signals can be obtained by the refined wavelet coefficients during inverse wavelet transform (IWT). Lastly, we tested the proposed method by the L-band Advanced Land Observing Satellite (ALOS)-1 PALSAR dual-polarization SAR data pairs covering the San Francisco (USA) and Moron (Mongolia) regions. By using Ice, Cloud, and land Elevation Satellite (ICESat) data as the reference data, we evaluated the vertical accuracy of the InSAR digital elevation models (DEMs) with and without atmospheric effects correction, which shows that, for the San Francisco test site, the corrected interferogram could provide a DEM with a root-mean-square error (RMSE) of 7.79 m, which is an improvement of 40.5% with respect to the DEM without atmospheric effects correction. For the Moron test site, the corrected interferogram could provide a DEM with an RMSE of 10.74 m, which is an improvement of 30.2% with respect to the DEM without atmospheric effects correction.
doi:10.3390/rs10081310 fatcat:jqu5sozpjrgsta4ds6p6k7ghjq

Recognition of blue movies by fusion of audio and video

Haiqiang Zuo, Ou Wu, Weiming Hu, Bo Xu
2008 2008 IEEE International Conference on Multimedia and Expo  
Along with the explosive growth of the Internet, comes the proliferation of pornography. Compared with the pornographic texts and images, blue movies can do much harm to children, due to the greater realism and voyeurism of blue movies. In this paper, a framework for recognizing blue movies by fusing the audio and video information is described. A one-class Gaussian mixture model (GMM) is used to recognize porno-sounds. A generalized contourbased pornographic image recognition algorithm is used
more » ... to detect pornographic image frames of a video shot. Then a fusion algorithm based on the Bayes theory is employed to combine the recognition results from audio and video. Experimental results demonstrate that our framework which exploits both audio and video modalities is more robust and achieves better performance than one which uses either one alone.
doi:10.1109/icme.2008.4607365 dblp:conf/icmcs/ZuoWHX08 fatcat:6cn2cdz7ebaxrar6cseke5prty

A Framework for Correcting Ionospheric Artifacts and Atmospheric Effects to Generate High Accuracy InSAR DEM

Zhiwei Liu, Cui Zhou, Haiqiang Fu, Jianjun Zhu, Tingying Zuo
2020 Remote Sensing  
Repeat-pass interferometric synthetic aperture radar is a well-established technology for generating digital elevation models (DEMs). However, the interferogram usually has ionospheric and atmospheric effects, which reduces the DEM accuracy. In this paper, by introducing dual-polarization interferograms, a new approach is proposed to mitigate the ionospheric and atmospheric errors of the interferometric synthetic aperture radar (InSAR) data. The proposed method consists of two parts. First, the
more » ... range split-spectrum method is applied to compensate for the ionospheric artifacts. Then, a multiresolution correlation analysis between dual-polarization InSAR interferograms is employed to remove the identical atmospheric phases, since the atmospheric delay is independent of SAR polarizations. The corrected interferogram can be used for DEM extraction. Validation experiments, using the ALOS-1 PALSAR interferometric pairs covering the study areas in Hawaii and Lebanon of the U.S.A., show that the proposed method can effectively reduce the ionospheric artifacts and atmospheric effects, and improve the accuracy of the InSAR-derived DEMs by 64.9% and 31.7% for the study sites in Hawaii and Lebanon of the U.S.A., respectively, compared with traditional correction methods. In addition, the assessment of the resulting DEMs also includes comparisons with the high-precision Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) altimetry data. The results show that the selection of reference data will not affect the validation results.
doi:10.3390/rs12020318 fatcat:kw5k6sna3bd6dfuvewem3w732a

Patch-based skin color detection and its application to pornography image filtering

Haiqiang Zuo, Weiming Hu, Ou Wu
2010 Proceedings of the 19th international conference on World wide web - WWW '10  
Along with the explosive growth of the World Wide Web, an immense industry for the production and consumption of pornography has grown. Though the censorship and legal restraints on pornography are discriminating in different historical, cultural and national contexts, selling pornography to minors is not allowed in most cases. Detecting human skin tone is of utmost importance in pornography image filtering algorithms. In this paper, we propose two patch-based skin color detection algorithms:
more » ... gular patch and irregular patch skin color detection algorithms. On the basis of skin detection, we extract 31-dimensional features from the input image, and these features are fed into a random forest classifier. Our algorithm has been incorporated into an adult-content filtering infrastructure, and is now in active use for preventing minors from accessing pornographic images via mobile phones.
doi:10.1145/1772690.1772887 dblp:conf/www/ZuoHW10 fatcat:z2kc2qb4m5gr5ppumrgc25ths4

Image spam filtering using Fourier-Mellin invariant features

Haiqiang Zuo, Xi Li, Ou Wu, Weiming Hu, Guan Luo
2009 2009 IEEE International Conference on Acoustics, Speech and Signal Processing  
Image spam is a new obfuscating method which spammers invented to more effectively bypass conventional text based spam filters. In this paper, a framework for filtering image spams by using the Fourier-Mellin invariant features is described. Fourier-Mellin features are robust for most kinds of image spam variations. A one-class classifier, the support vector data description (SVDD), is exploited to model the boundary of image spam class in the feature space without using information of
more » ... e emails. Experimental results demonstrate that our framework is effective for fighting image spam.
doi:10.1109/icassp.2009.4959717 dblp:conf/icassp/ZuoLWHL09 fatcat:z2oscolisjbvrfz2yyriqqp6xq

HIV/AIDS Knowledge, Attitudes, and Behaviors of Construction Workers in China

Bo Qu, Haiqiang Guo, Gao Sun, Tianming Zuo, Yang Zhang, Brandon Y Li
2008 International Journal of Biomedical Science  
The objective of the study was to describe HIV/AIDS knowledge, attitudes, risk behaviors, and sources of information among construction workers in China. A cross-sectional survey of 458 construction workers was conducted among 4 construction sites in Shenyang city in 2006. All 458 participants were individually interviewed in a private setting by a trained team of medical researchers using a structured questionnaire, which included questions on general personal information and the knowledge,
more » ... itudes, practice questions and the favorable mode of health education. A total of 428 valid questionnaires were collected. Data entry and statistical analyses were performed using the SPSS 13.0. Our results indicated that the majority of construction workers in China are sexually active youths and adults with limited education and poor knowledge of HIV/AIDS. The proportions of correct answers to questions about HIV/AIDS ranged from 4.9% to 70.7%. The score was significantly different by education level (χ(2)=47.51, p<0.01), and marrital status (χ(2)=16.48, p<0.01). More than 60% of the construction workers had a negative attitude toward HIV/AIDS-infected individuals. The source of workers' knowledge toward HIV/AIDS mainly came from TV (35.8%), newspaper (14.3%), family and friend (13.1%) and others (28.2%). Chinese migrant workers in general lack knowledge about HIV/AIDS. Our study suggests prevention programs should be encouraged and these may have the potential role to limit the emergence of China's HIV/AIDS epidemic.
pmid:23675089 pmcid:PMC3614707 fatcat:ptdej2gqu5b23ejv5k3jxznxru

Detecting image spam using local invariant features and pyramid match kernel

Haiqiang Zuo, Weiming Hu, Ou Wu, Yunfei Chen, Guan Luo
2009 Proceedings of the 18th international conference on World wide web - WWW '09  
Image spam is a new obfuscating method which spammers invented to more effectively bypass conventional text based spam filters. In this paper, we extract local invariant features of images and run a one-class SVM classifier which uses the pyramid match kernel as the kernel function to detect image spam. Experimental results demonstrate that our algorithm is effective for fighting image spam.
doi:10.1145/1526709.1526921 dblp:conf/www/ZuoHWCL09 fatcat:tgw5bz5yhbhc5jthqdg7264xpe

Rank Aggregation Based Text Feature Selection

Ou Wu, Haiqiang Zuo, Mingliang Zhu, Weiming Hu, Jun Gao, Hanzi Wang
2009 2009 IEEE/WIC/ACM International Joint Conference on Web Intelligence and Intelligent Agent Technology  
Filtering feature selection method (filtering method, for short) is a well-known feature selection strategy in pattern recognition and data mining. Filtering method outperforms other feature selection methods in many cases when the dimension of features is large. There are so many filtering methods proposed in previous work leading to the "selection trouble" that how to select an appropriate filtering method for a given text data set. Since to find the best filtering method is usually
more » ... e in real application, this paper takes an alternative path. We propose a feature selection framework that fuses the results obtained by different filtering methods. In fact, deriving a better rank list from different rank lists, known as rank aggregation, is a hot topic studied in many disciplines. Based on the proposed framework and Markov chains rank aggregation techniques, in this paper, we present two new feature selection methods: FR-MC1 and FR-MC4. We also introduce a perturbation algorithm to alleviate the drawbacks of Markov chains rank aggregation techniques. Empirical evaluation on two public text data sets shows that the two new feature selection methods achieve better or comparable results than classical filtering methods, which also demonstrate the effectiveness of our framework.
doi:10.1109/wi-iat.2009.32 dblp:conf/webi/WuZZHGW09 fatcat:oyvczukxkfc33j5eimjp2bhoty

Recognition of adult images, videos, and web page bags

Weiming Hu, Haiqiang Zuo, Ou Wu, Yunfei Chen, Zhongfei Zhang, David Suter
2011 ACM Transactions on Multimedia Computing, Communications, and Applications (TOMCCAP)  
[2] Weiming Hu, Haiqiang Zuo, Ou Wu, Yunfei Chen, Zhongfei Zhang, and David Suter. Recognition of adult images, videos, and web page bags. ACM Trans. Multimedia Comput. Commun.  ... 
doi:10.1145/2037676.2037685 fatcat:6fflafayhnbwviiss6x7y7xo4u

Recognizing and Filtering Web Images Based on People's Existence

Ou Wu, Haiqiang Zuo, Weiming Hu, Mingliang Zhu, Shuxiao Li
2008 2008 IEEE/WIC/ACM International Conference on Web Intelligence and Intelligent Agent Technology  
Judging whether a web image contains people is useful in both pornographic image recognition and image filtering when searching for images of people. We proposed an approximate but rapid method to solve this problem. For a web image, three types of probabilities are calculated from the image itself, the image's associated texts and the title of the web page it located, respectively. Then a final probability representing the people's existence is achieved by fusion of the three probabilistic
more » ... es. Based on the probability of people's existence, we proposed a twolayer framework for pornographic image recognition and a solution of image retrieval respectively. In the experiments conducted, our proposed framework and solution demonstrate good performances in the image recognition and filtering respectively. 2008 IEEE/WIC/ACM International Conference on Web Intelligence and Intelligent Agent Technology 978-0-7695-3496-1/08 $25.00
doi:10.1109/wiiat.2008.48 dblp:conf/webi/WuZHZL08 fatcat:pg3o3ej2qjemboon5bax6euwhe

The enhanced photo absorption and carrier transportation of InGaN/GaN Quantum Wells for photodiode detector applications

Haojun Yang, Ziguang Ma, Yang Jiang, Haiyan Wu, Peng Zuo, Bin Zhao, Haiqiang Jia, Hong Chen
2017 Scientific Reports  
We have conducted a series of measurements of resonantly excited photoluminescence, photocurrent and photovoltage on InGaN/GaN quantum wells with and without a p-n junction under reverse bias condition. The results indicate that most of the resonantly excited photo-generated carriers are extracted from the quantum wells when a p-n junction exists, and the photon absorption of quantum wells is enhanced by the p-n junction. Additionally, the carrier extraction becomes more distinct under a
more » ... bias. Our finding brings better understanding of the physical characteristics of quantum wells with p-n junction, which also suggests that the quantum well is suitable for photodiode detectors applications when a p-n junction is used. The light-to-electricity conversion process of III-nitride materials and devices is the essential foundation for visible and ultraviolet photodetectors that are potentially applied in light communication, medical care and smoke alarm 1-4 . However, the conversion efficiency is still low due to difficulties for obtaining low density of dislocations and high conductive of epitaxial films 1,5,6 . Generally, the conversion efficiency is composed of the photo absorption and carrier extraction efficiency. The p-n junction is one of the most important structures for carrier extraction, of which the feature characteristic is collecting the electrons and holes from depletion region. When a p-n junction is under illumination, the photo-excited electrons and holes are drifted to the opposite sides of the p-n junction by the built-in field, thus an electrical response generates for photodiode detectors 7,8 . According to this, the most popular photodetectors are based on p-i-n structures. Extending the absorption region (i-layer) width is a general method of enhancing the absorption efficiency for a photodetector device. However, a large lattice mismatch between InN, GaN and AlN becomes an impediment to the growth of high-quality thick hetero-epitaxial layer due to increased biaxial strain in wurtzite structures 9 . It brings high-density of threading dislocations that can seriously deteriorate the device performance 10 . Comparing with bulk materials, multiple quantum wells (MQW) structure can modulate the interface strain thus improves the crystalline quality. According to established theories, the photo-generated carriers caused by interband absorption of quantum wells will relax to ground state and cannot form the photocurrent owing to the confinement. Hence, to date, most of the III-nitride UV photodetectors have relied on bulk-like epilayers. Recently, some results have been presented about photodetectors made using of quantum wells by interband absorption [11] [12] [13] [14] [15] [16] . It was thought that MQW-based detectors have different advantages over bulk devices, such as flexibility to tune the detection edge 12,15 . Even so, there is yet a big lack in the investigation of multiple-quantum-well photodetectors. Here, we find that when the p-n junction is applied under short circuit, most of the resonantly excited carriers can escape from the wells and form photocurrent rather than relax to ground state for recombination. If a reverse bias is applied on the quantum wells with p-n junction, this carrier extraction effect is enhanced, which may be a new mechanism to use quantum wells for photodetectors applications.
doi:10.1038/srep43357 pmid:28240254 pmcid:PMC5327382 fatcat:4smkl7ixqfhsfgw6aahckpjmyi

Evaluation of the Vertical Accuracy of Open Global DEMs over Steep Terrain Regions Using ICESat Data: A Case Study over Hunan Province, China

Zhiwei Liu, Jianjun Zhu, Haiqiang Fu, Cui Zhou, Tingying Zuo
2020 Sensors  
The global digital elevation model (DEM) is important for various scientific applications. With the recently released TanDEM-X 90-m DEM and AW3D30 version 2.2, the open global or near-global coverage DEM datasets have been further expanded. However, the quality of these DEMs has not yet been fully characterized, especially in the application for regional scale studies. In this study, we assess the quality of five freely available global DEM datasets (SRTM-1 DEM, SRTM-3 DEM, ASTER GDEM2, AW3D30
more » ... EM and TanDEM-X 90-m DEM) and one 30-m resampled TanDEM-X DEM (hereafter called TDX30) over the south-central Chinese province of Hunan. Then, the newly-released high precision ICESat-2 (Ice, Cloud, and land Elevation Satellite-2) altimetry points are introduced to evaluate the accuracy of these DEMs. Results show that the SRTM1 DEM offers the best quality with a Root Mean Square Error (RMSE) of 8.0 m, and ASTER GDEM2 has the worst quality with the RMSE of 10.1 m. We also compared the vertical accuracies of these DEMs with respect to different terrain morphological characteristics (e.g., elevation, slope and aspect) and land cover types. It reveals that the DEM accuracy decreases when the terrain elevation and slope value increase, whereas no relationship was found between DEM error and terrain aspect. Furthermore, the results show that the accuracy increases as the land cover type changes from vegetated to non-vegetated. Overall, the SRTM1 DEM, with high spatial resolution and high vertical accuracy, is currently the most promising dataset among these DEMs and it could, therefore, be utilized for the studies and applications requiring accurate DEMs.
doi:10.3390/s20174865 pmid:32872143 fatcat:nozljvcvondkdfc4jllnjne3hu

Realization of high-luminous-efficiency InGaN light-emitting diodes in the "green gap" range

Yang Jiang, Yangfeng Li, Yueqiao Li, Zhen Deng, Taiping Lu, Ziguang Ma, Peng Zuo, Longgui Dai, Lu Wang, Haiqiang Jia, Wenxin Wang, Junming Zhou (+2 others)
2015 Scientific Reports  
Light-emitting diodes (LEDs) in the wavelength region of 535-570 nm are still inefficient, which is known as the "green gap" problem. Light in this range causes maximum luminous sensation in the human eye and is therefore advantageous for many potential uses. Here, we demonstrate a high-brightness InGaN LED with a normal voltage in the "green gap" range based on hybrid multiquantum wells (MQWs). A yellow-green LED device is successfully fabricated and has a dominant wavelength, light output
more » ... r, luminous efficiency and forward voltage of 560 nm, 2.14 mW, 19.58 lm/W and 3.39 V, respectively. To investigate the light emitting mechanism, a comparative analysis of the hybrid MQW LED and a conventional LED is conducted. The results show a 2.4-fold enhancement of the 540-nm light output power at a 20-mA injection current by the new structure due to the stronger localization effect, and such enhancement becomes larger at longer wavelengths. Our experimental data suggest that the hybrid MQW structure can effectively push the efficient InGaN LED emission toward longer wavelengths, connecting to the lower limit of the AlGaInP LEDs' spectral range, thus enabling completion of the LED product line covering the entire visible spectrum with sufficient luminous efficacy. Light-emitting diode (LED), one of the most important optoelectronic devices, has been used in a wide range of applications 1-3 , such as display backlights and general illumination. Great progress 4-7 has been made since the first candela-class high-brightness InGaN-based LED was realized in 1994 by Shuji Nakamura 8 . A high external quantum efficiency (EQE) of 80% is achieved 9 for InGaN blue LEDs; however, for emissions with wavelengths beyond 535 nm, the EQE of InGaN-based LEDs decreases dramatically as the wavelength increases 10 . AlGaInP LEDs, which have a high efficiency when emitting red and yellow light, are not suitable for wavelengths shorter than 570 nm because of the direct-indirect bandgap transition when the aluminum molar concentration reaches approximately 53% 11 .Commercialized LEDs with emission wavelengths between 535 and 570 nm to match the highest spectral sensitivity of the human visual perception of brightness are still absent, which is known as the "green gap" problem 12 . Because the bandgap of InGaN covers the wide spectral range from near ultraviolet to near infrared, it is possible to realize high-brightness light emission for wavelengths greater than 535 nm. The problem is that the efficiency of InGaN LEDs typically decreases rapidly with the increasing indium content required to achieve longer-wavelength emissions. Generally, two main factors are responsible for the efficiency decrease: (1) the crystal quality deterioration due to the lattice mismatch between InGaN and GaN and indium phase separation 13 and (2) the reduction of the electron-hole wavefunction overlap due to the strong polarization field in InGaN/GaN MQWs, which is also known as the quantum-confined Stark effect 14 (QCSE). Various approaches [15] [16] [17] [18] [19] [20] [21] have been proposed to overcome these problems. The
doi:10.1038/srep10883 pmid:26039353 pmcid:PMC4454147 fatcat:ucs3xpsobzbolbm7kz7nhseloe

Efficacy and safety of Yinchenwuling powder for hyperlipidemia: a systematic review and Meta-analysis

Yao Haiqiang, Zhang Zengliang, Wang Ji, Chen Yu, Zhu Libing, Li Xiaoke, Yang Zheng, Wang Zisong, Sun Ranran, Xu Xuanxuan, Li Changming, Wu Yanling (+3 others)
2016 Journal of Traditional Chinese Medicine  
doi:10.1016/s0254-6272(16)30019-x fatcat:2r6uhlbfxbbjhphfqopr3rqgqm

Modulation of dopamine release in the striatum by physiologically relevant levels of nicotine

Li Wang, Shujiang Shang, Xinjiang Kang, Sasa Teng, Feipeng Zhu, Bin Liu, Qihui Wu, Mingli Li, Wei Liu, Huadong Xu, Li Zhou, Ruiying Jiao (+7 others)
2014 Nature Communications  
Striatal dopamine (DA) release can be independently triggered not only by action potentials (APs) in dopaminergic axons but also APs in cholinergic interneurons (ChIs). Nicotine causes addiction by modulating DA release, but with paradoxical findings. Here, we investigate how physiologically relevant levels of nicotine modulate striatal DA release. The optogenetic stimulation of ChIs elicits DA release, which is potently inhibited by nicotine with an IC 50 of 28 nM in the dorsal striatum slice.
more » ... This ChI-driven DA release is predominantly mediated by a6b2* nAChRs. Local electrical stimulus (Estim) activates both dopaminergic axons and ChIs. Nicotine does not affect the AP DA -dependent DA release (AP DA , AP of dopaminergic axon). During burst Estim, nicotine permits the facilitation of DA release by prevention of DA depletion. Our work indicates that cholinergic stimulation-induced DA release is profoundly modulated by physiologically relevant levels of nicotine and resolves the paradoxical observation of nicotine's effects on striatal DA release.
doi:10.1038/ncomms4925 pmid:24968237 fatcat:vox63xm65vh4jn7qtis5sg2lne
« Previous Showing results 1 — 15 out of 23 results