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[IEEE 2018 Conference on Design and Architectures for Signal and Image Processing (DASIP) - Porto, Portugal (2018.10.10-2018.10.12)] 2018 Conference on Design and Architectures for Signal and Image Processing (DASIP) - GPU Based Quarter Spectral Correlation Density Function
摘要： In this study we investigate the parallelization of a key feature extraction method called spectral correlation density (SCD) function, which is used in signal classification systems particularly under low signal-to-noise ratio conditions for classifying numerous signals. In order to reduce the computation complexity of the SCD function, we introduce a method called Quarter SCD (QSCD) that allows extracting features of a given signal by processing only quarter of the input signal data. We then parallelize the QSCD by targeting general purpose graphics processing unit (GPU) through architecture specific optimization strategies. We present experimental evaluations on identifying the parallelization configuration for maximizing the efficiency of the program architecture in utilizing the threading power of the GPU architecture. We show that algorithmic and architecture specific optimization strategies result with improving the throughput of the state of the art GPU based Full SCD from 120 signals/second to 2719 signals/second.
关键词： GPGPU,spectral correlation density,signal classification
更新于2025-09-23 15:22:29
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Consistency in XCO2 Retrievals from Sciamachy, Gosat and OCO-2 for Spatio-Temporal Characteristics at a Global Scale
摘要： Long-term XCO2 retrievals, which are obtained by the three measurements including SCIAMACHY, GOSAT and OCO-2, are publicly available from 2003 to date. These XCO2 data can help us better understanding the underlying processes of uptake and release of CO2 in biosphere and anthropogenic emissions at global scales via probing into the characteristics of the spatio-temporal variations of XCO2. We investigated the inconsistency of the spatio-temporal variations of XCO2 in these three measurements by combining with NDVI data. We apply a global land mapping XCO2 datasets generated by data-driven spatio-temporal geostatistics method to the correlation analysis with NDVI. As a result, XCO2 demonstrate smooth variations in time without jumping in the time node between the three measurements. They demonstrate similar patterns of correlation coefficients with NDVI which could indicate the process of CO2 interchange in biosphere-atmosphere.
关键词： XCO2,spatio-temporal variations,correlation,inconsistency
更新于2025-09-23 15:22:29
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OPTICAL CHARACTER RECOGNITION MENGGUNAKAN ALGORITMA TEMPLATE MATCHING CORRELATION
摘要： OCR (Optical Character Recognition) adalah suatu solusi yang efektif untuk proses konversi dokumen cetak ke dokumen digital. Permasalahan yang timbul dalam proses pengenalan dokumen komputer adalah bagaimana teknik pengenalan untuk mengidentifikasi berbagai jenis karakter dengan berbagai ukuran dan bentuk. Metode pengenalan yang digunakan dalam tugas akhir ini adalah metode Template Matching Correlation. Sebelum proses pengenalan, citra masukan dengan format * bmp atau jpg * diolah terlebih dahulu di proses preprocessing, yang meliputi binerisasi, segmentasi, dan normalisasi gambar. Rata-rata tingkat keberhasilan pengenalan yang dihasilkan oleh sistem ini adalah 92,90%. Hasil akhir menunjukkan bahwa penggunaan metode Template Matching Correlation cukup untuk membangun sebuah sistem OCR dengan akurasi yang baik efektif.
关键词： Template Matching Correlation,preprocessing,Optical Character Recognition,OCR
更新于2025-09-23 15:22:29
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Signal degradation due to finite integration time for correlation detection in Nyquist OTDM scheme
摘要： Integration time of the correlation receiver for a Nyquist optical time-division multiplexing (OTDM) scheme is limited by the multiplicity of the OTDM scheme. We investigate the signal degradation caused by the finite integration time of the correlation receiver. The signal degradation factor is analyzed by separating it into noise resistance degradation and inter-symbol interference. We also conduct numerical simulations to estimate the required multiplicity number and roll-off factor for suppressing the signal degradation.
关键词： optical Nyquist pulse,OTDM,correlation receiver
更新于2025-09-23 15:22:29
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Characteristic Mode Analysis and Design of Wide Band MIMO Antenna Consisting of Metamaterial Unit Cell
摘要： This paper presents a full wave simulation and characteristic mode-based design of a multiple-input-multiple-output (MIMO) antenna at 5.8 GHz for wireless local area network applications. The driven analysis comprises two antennas that are placed orthogonal to each other. A metamaterial unit structure in the form of a rectangular loop resonator is placed around the antenna element to reduce the electromagnetic interference and to increase the isolation between the two monopoles. A characteristic mode technique is employed to find out the dominant mode of the proposed antenna without a feeding port. It was revealed that mode 1 was the dominant mode among the three modes used. The MIMO antenna is constructed and measured using a vector network analyzer. A good isolation of less than 25 dB was attained with a wide impedance bandwidth of 65.5%.
关键词： rectangular loop resonator,multiple-input-multiple-output (MIMO),envelope correlation coefficient,mutual coupling
更新于2025-09-23 15:22:29
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Precisely Automatic Time Window Locating for an Interferometric Fiber-Optic Sensor Array Based on a TDM Scheme
摘要： Interferometric fiber-optic sensors are often organized in the form of large-scale arrays by lending the technique of time division multiplexing (TDM) to reduce the system cost. Discriminating the time windows for different sensor units is the prerequisite to successfully demodulate the sensing message, but it traditionally calls for a very time-consuming manual calibration process. To combat this problem, a novel automatic time window locating method is proposed in this paper. It introduces the concept of shape function and carries out the cross-correlation operation between the shape function and the sensor signal. The shape function is defined as the function whose curve profile reflects the main data characteristics of the sensor signal. The time window information is then extracted from the correlation result. This whole process is carried out automatically by the interrogation controller of the sensor system without any manual intervene. Experiments are conducted to validate this method. The proposed method can greatly reduce the complexity of locating time windows in large-scale TDM sensor arrays, and make the practical use of the TDM scheme much more convenient.
关键词： fiber-optic sensor,interrogation controller,time division multiplexing (TDM),time window,cross correlation
更新于2025-09-23 15:22:29
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[IEEE 2018 14th Symposium on Neural Networks and Applications (NEUREL) - Belgrade, Serbia (2018.11.20-2018.11.21)] 2018 14th Symposium on Neural Networks and Applications (NEUREL) - Deep Features in Correlation Filters for Thermal Image Tracking
摘要： Object tracking using thermal infrared cameras has specific properties and challenges which distinguish it from the commonly used visual tracking. Recently, correlation filters (CF) based on deep features have been successfully applied in certain visual tracking scenarios. In this paper, we demonstrate that the success of these methods essentially depends on the way of how the deep features have been obtained. Indeed, the trackers based on CF and deep features use the pre-trained networks, originally trained for the object classification problem; hence, the obtained features are not invariant to changes of object appearance which may result from the change of camera type. We show that CF trackers based on deep features obtained from a convolutional architecture, pre-trained for visual object classification problem, have relatively poor performance when applied to the thermal tracking problem. Specifically, we test the performance of Kernelized Correlation Filter (KCF) on several chosen thermal video datasets, and demonstrate that the tracking results, when using simple feature representations (HOG features), are better than when using the pre-trained deep features. The results suggest that improved architectures and training methods for deep features should be developed in order to get more robust CF trackers.
关键词： Object Tracking,Deep Features,Correlation Filter,Thermal Imaging
更新于2025-09-23 15:22:29
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An Extension of Phase Correlation-Based Image Registration to Estimate Similarity Transform Using Multiple Polar Fourier Transform
摘要： Image registration is a core technology of many different image processing areas and is widely used in the remote sensing community. The accuracy of image registration largely determines the effect of subsequent applications. In recent years, phase correlation-based image registration has drawn much attention because of its high accuracy and ef?ciency as well as its robustness to gray difference and even slight changes in content. Many researchers have reported that the phase correlation method can acquire a sub-pixel accuracy of 1/10 or even 1/100. However, its performance is acquired only in the case of translation, which limits the scope of the application of the method. However, there are few reports on the estimation of scales and angles based on the phase correlation method. To take advantage of the high accuracy property and other merits of phase correlation-based image registration and extend it to estimate the similarity transform, we proposed a novel algorithm, the Multilayer Polar Fourier Transform (MPFT), which uses a fast and accurate polar Fourier transform with different scaling factors to calculate the log-polar Fourier transform. The structure of the polar grids of MPFT is more similar to the one of the log-polar grid. In particular, for rotation estimation only, the polar grid of MPFT is the calculation grid. To validate its effectiveness and high accuracy in estimating angles and scales, both qualitative and quantitative experiments were carried out. The quantitative experiments included a numerical simulation as well as synthetic and real data experiments. The experimental results showed that the proposed method, MPFT, performs better than the existing phase correlation-based similarity transform estimation methods, the Pseudo-polar Fourier Transform (PPFT) and the Multilayer Fractional Fourier Transform method (MLFFT), and the classical feature-based registration method, Scale-Invariant Feature Transform (SIFT), and its variant, ms-SIFT.
关键词： similarity transform,image registration,Polar Fourier Transform,phase correlation,Log-polar Fourier Transform
更新于2025-09-23 15:22:29
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In-situ 3D shape and recession measurements of ablative materials in an arc-heated wind tunnel by UV stereo-digital image correlation
摘要： In-situ three-dimensional (3D) ablation shape and recession measurements of ablative materials of hypersonic vehicles in high-temperature wind tunnel tests are essential to understand the ablation performance of these materials, which can provide necessary information for better thermal protection system (TPS) design. In this work, a novel ultraviolet stereo-digital image correlation (UV stereo-DIC) technique is proposed for in-situ measurements of 3D ablation shapes and recession in ablation tests. Specifically, a self-developed UV stereo-DIC system, combing a monochromatic UV illumination, two bandpass filters and two UV cameras, is first established. Using the UV stereo-DIC system, strong thermal radiation emitted from the heated sample and the heating device can be effectively suppressed. Natural textures formed from illuminating the rough sample surface by UV light are used as speckle patterns in stereo-correlation. In-situ 3D ablation shapes of a blunt cone subjected to arc heating were measured with a temperature range of 1000 °C to 1868 °C, and the UV stereo-DIC measurements showed good agreement with post-test measurement of the recession of the test articles. Based on the experimentally measured 3D shapes, several key parameters, such as full-field recession, dynamic recession rate, were calculated. The results demonstrate the efficacy and potential of UV stereo-DIC for 3D shape and recession measurements in ablation tests.
关键词： Recession,High temperature,UV stereo-digital image correlation,Ablation shape
更新于2025-09-23 15:22:29
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[IEEE 2018 International Conference on Current Trends towards Converging Technologies (ICCTCT) - Coimbatore (2018.3.1-2018.3.3)] 2018 International Conference on Current Trends towards Converging Technologies (ICCTCT) - Generation and Analyzation of Spectral Density for IRNSS SPS PRN Code
摘要： The Indian Regional Navigational Satellite System (IRNSS) satellites provide two services namely standard Positioning Service (SPS) and Restricted Service (RS). L5 and S are the frequency bands from which both the services are utilized. To transmit the navigational information in SPS downlink gold codes are used. Most of the GNSS will work on the principle of CDMA where PRN sequences are the heart of the system. In this paper Pseudo Random Noise (PRN) codes are generated for an SPS signal which is called as SPS PRN code. A CDMA signal is generated using these sequences by using BPSK modulation. The analysis is done based on a time domain signal basis and is used to derive the Power Spectral Density of a CDMA signal. The spectrum analyser optimal operating conditions are observed by using the analytical results. To generate these codes, the polynomials G1 & G2 are selected, which are similar to ones used by GPS C/A signal and are as per the pre-conditions provided in IRNSS_SPS_ICD_June 2014. This paper also covers the process of selection of codes to be computed and the properties of PN-sequence are also analysed. The Xilinx ISE test system and Mat lab apparatus were used for the simulation of SPS PRN codes and additionally the implementation of PRN code is done on FPGA hardware wherein positive results have been obtained. These obtained simulated test results are within the theoretical limits.
关键词： ISE SIMULATOR,FPGA,CDMA,CORRELATION,PRN CODE
更新于2025-09-23 15:22:29