- 标题
- 摘要
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- 实验方案
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Temperature Dependent Electrical Transport Properties of High Carrier Mobility Reduced Graphene Oxide Thin Film Devices
摘要： We confirm variable electrical transport properties of high mobility reduced graphene oxide (RGO) thin films fabricated by pulse laser deposition. The temperature dependent (5K–350K) four terminal electrical transport property measurements range hopping and thermally activated transport mechanism of the charge carriers at low (5K–210K) and high temperature (210K–350K) regions, respectively. The calculated localization length, the density of states near the Fermi level (EF), hopping energy, and Arrhenius energy gap provide useful information to explain the excellent electrical properties of the RGO films. Hall mobility measurement confirms p-type characteristics of the thin films. The charge carrier Hall mobility can be engineered by tuning the growth parameters, and the measured maximum mobility was 1596 cm2v-1s-1. The optimization of the improved electrical property is well supported by structural properties such as the defect density, average size of sp2 clusters and degree of reduction, which were investigated by Raman spectroscopy and X-ray diffraction analysis.
关键词： PLD,variable range hopping,and Raman spectroscopy,hall mobility,Reduced graphene oxide,localization length
更新于2025-09-23 15:22:29
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Color Noise Reduction Method in Non-constant Luminance Signal for High Dynamic Range Video Service
摘要： A high dynamic range (HDR) video service is an upcoming industry. For compatibility with legacy devices receiving a non-constant luminance (NCL) signal, new tools supporting an HDR video service are required. The current pre-processing chain of HDR video can produce color noise owing to the chroma component down-sampling process for video encoding. Although a luma adjustment method has been proposed to solve this problem, some disadvantages still remain. In this paper, we present an adaptive color noise reduction method for an NCL signal of an HDR video service. The proposed method adjusts the luma component of an NCL signal adaptively according to the information of the luma component from a constant luminance signal and the level of color saturation. Experiment results show that the color noise problem is resolved by applying our proposed method. In addition, the speed of the pre-processing is increased more than two-fold compared to a previous method.
关键词： non-constant luminance,high efficiency video coding,wide color gamut,High dynamic range
更新于2025-09-23 15:22:29
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Prediction of declining solar activity trends during solar cycles 25 and 26 and indication of other solar minimum
摘要： Study of variations in solar activity parameters has its importance in understanding the underlying mechanisms of space weather phenomena and space climate variability. We have used the already observed data of solar parameters viz. sunspot numbers, F10.7 cm index and Lyman alpha index recorded for last seventy years (1947–2017). We have applied the Hodrick Prescott ?ltering method to bifurcate each time series into cyclic and trend parts. The cyclic part of each time series was used to analyse the persistence while the trend part was used to obtain the input data for the study of future predictions. Further, the cyclic component of each parameter was analysed by using the rescaled range analysis and the value of Hurst exponent was obtained for sunspot numbers, F10.7 cm index and Lyman alpha index as 0.90, 0.93 and 0.96 respectively. By using the simplex projection analysis on the values of amplitude and phase of the trend component of each time series, we have reconstructed the future time series representing solar cycles 25 and 26. When extrapolated further in time, the reconstructed series provided the maximum values of sunspot numbers as 89 ± 9 and 78 ± 7; maximum values of F10.7 cm index were 124 ± 11 and 118 ± 9 and Lyman alpha index were 4.61 ± 0.08 and 4.41 ± 0.08 respectively for solar cycles 25 and 26. In our analysis we have found that the solar cycle 25 will start in the year 2021 (January) and will last till 2031 (February) with its maxima in year 2024 (February) while the solar cycle 26 will start in the year 2031 (March) with its maxima in 2036 (June) and will last till the year 2041 (February). We have also compared the activities of solar cycles 5 and 6 (Dalton minima periods) to solar cycles 25 and 26 and have observed that the other solar minimum is underway.
关键词： Rescale range analysis,Sunspot numbers,Solar activity,solar minimum,Hurst exponent,Simplex projection analysis
更新于2025-09-23 15:22:29
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Robust artifact-free high dynamic range imaging of dynamic scenes
摘要： The irradiance range of the real-world scene is often beyond the capability of digital cameras. Therefore, High Dynamic Range (HDR) images can be generated by fusing images with different exposure of the same scene. However, moving objects pose the most severe problem in the HDR imaging, leading to the annoying ghost artifacts in the fused image. In this paper, we present a novel HDR technique to address the moving objects problem. Since the input low dynamic range (LDR) images captured by a camera act as static linear related backgrounds with moving objects during each individual exposures, we formulate the detection of foreground moving objects as a rank minimization problem. Meanwhile, in order to eliminate the image blurring caused by background slightly change of LDR images, we further rectify the background by employing the irradiances alignment. Experiments on image sequences show that the proposed algorithm performs significant gains in synthesized HDR image quality compare to state-of-the-art methods.
关键词： Multi-exposure fusion,High dynamic range imaging,Rank minimization,Motion blur,Optical flow,Ghost removal
更新于2025-09-23 15:22:29
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Reduced Graphene Oxide-Nanostructured Silicon Photosensors With High Photoresponsivity at Room Temperature
摘要： We have created nanostructured Si (~3 nm) with a direct band gap of 1.37 eV on electrically conducting reduced graphene oxide (rGO) for a highly efficient photosensor. This robust photosensor is fabricated using a non-equilibrium processing route, where nanosecond excimer laser pulses melt the alternating layers of Si and amorphous carbon to form micropillars and nanoreceptors of Si on rGO layers. The incident white light generates free carriers in the Si microstructures and nanoreceptors which are ballistically transported (via rGO layers) to the external circuit under the application of a voltage bias. The responsivity of rGO-Si devices to light (resistance vs time) and I-V measurements indicate an exponential drop in resistance with the incidence of white light and non-rectifying nature, respectively. Photoresponsivity of the rGO-Si devices is calculated to be 3.55 A/W at room temperature, which is significantly larger than the previously fabricated graphene-based Ohmic photosensors. Temperature-dependent resistance measurements of rGO-Si structures follow Efros-Shklovoskii variable range hopping (ES-VRH) electrical conduction in the low-temperature region (<100 K) and Arrhenius conduction in the high-temperature region (>100 K). In rGO, the localization length, hopping energy, and activation energy are calculated to be 17.58 μm, 3.15 meV, and 1.67 meV, respectively. The 2D nature of highly reduced and less defective rGO also render an interesting negative magnetoresistance (~2.5 %) at 5 K, thereby indicating potential implications of rGO-Si in opto-spintronics. The large-area integration of rGO-Si structures with sapphire employing nanosecond pulsed laser annealing and its exciting photosensing properties will open a new frontier for further extensive research in these functionalized 2D materials.
关键词： Pulsed laser annealing,Raman spectroscopy,Variable range hopping,Nanostructures,Reduced graphene oxide
更新于2025-09-23 15:22:29
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A Switching Sequence for Unary Digital-to-Analog Converters Based on a Knight's Tour
摘要： This paper proposes a new switching sequence with the asymmetric placement of weighting elements for a unary digital-to-analog converter (DAC). The proposed sequence is based on a so-called knight’s tour according to the modified Warnsdorf’s rule. To estimate the efficiency of the proposed switching sequence, a 10-bit resistive DAC has been designed and fabricated in the UMC 180-nm technology. Experimental results show that in comparison with an array of weighting elements without compensation of the systematic error, the proposed switching sequence reduces the maximal integral (INL) and the mean INL by 20% on the average in the temperature range from ?40 °C to 85 °C. Besides that, the maximal INL does not depend on the temperature, while the mean INL decreases with temperature increase.
关键词： CMOS integrated circuits,digital–analog conversion,nonlinear circuits,dynamic range
更新于2025-09-23 15:22:29
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[IEEE ICASSP 2018 - 2018 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP) - Calgary, AB (2018.4.15-2018.4.20)] 2018 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP) - No-Reference Hdr Image Quality Assessment Method Based on Tensor Space
摘要： The full-reference image quality assessment (IQA) method are limited in practical applications. Here we propose a no-reference quality assessment method for high dynamic range (HDR) images based on tensor space. First, the tensor decomposition is used to generate three feature maps of an HDR image, considering color and structure information of the HDR image. Second, for a given HDR image, the corresponding multi-scale manifold structure features are extracted from the first feature map. For the second and third feature maps of the HDR image, multi-scale contrast features are extracted. Finally, the extracted features are aggregated by support vector regression to obtain the objective quality score of the HDR image. Experimental results show that the proposed method is superior to some representative full and no-reference methods, and even superior to the full-reference HDR IQA method, HDR-VDP-2.2, on the Nantes database. The proposed method has a higher consistency with human visual perception.
关键词： high dynamic range,feature maps,No-reference,image quality assessment,tensor space
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE 3rd International Conference on Signal and Image Processing (ICSIP) - Shenzhen, China (2018.7.13-2018.7.15)] 2018 IEEE 3rd International Conference on Signal and Image Processing (ICSIP) - An Analytical Imaging Algorithm for Parallel Invariant SAR
摘要： This paper discusses the processing method for parallel invariant SAR, and an analytical imaging algorithm based on GLBF is proposed. The bulk focusing is performed by reference function multiplication (RFM), then the range scaling factor is derived and further corrected by Chirp-z transform (CZT). The algorithm can be applied to wide scene imaging with the derived data blocking rules. The proposed imaging algorithm is verified by simulations.
关键词： chirp-z transform (CZT),parallel invariant SAR,range scaling factor
更新于2025-09-23 15:22:29
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Photonic approach for microwave frequency measurement using a silicon microring resonator
摘要： We propose and experimentally demonstrate a photonic measurement approach of microwave frequency with adjustable measurement ranges and low errors based on a silicon microring resonator (MRR). The key factor is that microwave photonic filters (MPFs) with high rejection ratios could be realized by a phase modulator, an optical filter and a silicon MRR. In the experiment, by adjusting the wavelength of the laser diode, tunable MPFs with rejection ratios beyond 60 dB are realized in order to construct different amplitude comparison functions (ACFs) with high frequency resolutions (30dB/GHz). According to the mapping relationships between the microwave frequency and power ratio of the ACF, the unknown microwave frequency could be measured. The experimental results show that microwave frequency could be measured from 10 GHz to 19 GHz with a measurement resolution of 0.08 GHz. In the future, the measurement ranges and frequency resolutions could be manipulated according to practical requirements. The photonic measurement method and compact device are significant in microwave systems.
关键词： on-chip microwave system,Microwave frequency measurement,adjustable measurement range
更新于2025-09-23 15:22:29
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Linearized Single Sideband Modulation Link with High SFDR Performance
摘要： A linearized fiber optic link without dispersion induced power fading is presented. It is based on using a dual-drive dual-polarization modulator to generate a single sideband RF modulated optical signal and an orthogonally linear polarized unmodulated optical signal. The link is linearized and consequently the third order spurious free dynamic range (SFDR3) is largely increased by designing the angle of a linear polarizer connected to the modulator output to suppress the third order intermodulation distortion. The two Mach Zehnder modulators inside the dual-polarization modulator are biased at the quadrature point. Hence there is no degradation in the link second order spurious free dynamic range (SFDR2) performance compared to the conventional quadrature-biased Mach Zehnder modulator link. Experimental results demonstrate a single sideband modulation link without dispersion induced power fading and a record measured SFDR3 of 121.4 dB?Hz4/5.
关键词： optical single sideband,intermodulation distortion,linearization techniques,dynamic range,Analog optical links
更新于2025-09-23 15:22:29