- 标题
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- 实验方案
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Cu-Doped ZnO Electronic Structure and Optical Properties Studied by First-Principles Calculations and Experiments
摘要： The band structure, the density of states and optical absorption properties of Cu-doped ZnO were studied by the ?rst-principles generalized gradient approximation plane-wave pseudopotential method based on density functional theory. For the Zn1-xCuxO (x = 0, x = 0.0278, x = 0.0417) original structure, geometric optimization and energy calculations were performed and compared with experimental results. With increasing Cu concentration, the band gap of the Zn1-xCuxO decreased due to the shift of the conduction band. Since the impurity level was introduced after Cu doping, the conduction band was moved downwards. Additionally, it was shown that the insertion of a Cu atom leads to a red shift of the optical absorption edge, which was consistent with the experimental results.
关键词： absorption spectrum,electronic structure,?rst-principles calculations,Cu doped ZnO
更新于2025-09-23 15:22:29
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Statistical classification of contamination in glass insulators by reading its spectrum
摘要： This paper proposes to use a statistical approach for classifying the contamination level of insulators used in high voltage transmission lines. This studied case considers the voltage applied on glass insulators used in a chain of six elements of a 69 kV power line. When submitted to high voltage, the insulators radiate radio frequency signals up to frequencies of some GHz. In this frequency range the signal can be detected using portable antennas, and then be applied to post processing. These received spectra are analyzed by statistical methods, mean and standard deviation, and the cross relation between them is used to classify the pollution level in insulators. To reduce complexity and cost a simple data processing using the mean and the standard deviation are used. Two types of glass insulators are considered: clean or polluted, and to cover the entire frequency range from 30 MHz to 1 GHz two types of antennas were needed. The results obtained with the mean and the standard deviation show that the first 100 MHz bandwidth can be used for statistical of the insulator pollution level.
关键词： radio frequency spectrum,mean value,High voltage transmission lines insulators,statistical classification methods,standard deviation
更新于2025-09-23 15:22:29
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Investigation on Near-Infrared Quantitative Detection based on Heteromorphic Sample Pool
摘要： To enhance the detection precision of samples with scattering characteristics by near infrared spectroscopy (NIRS), this study developed a heteromorphic sample pool and established the related 2D light intensity acquisition system, which can simultaneously acquire multi-path exit light adsorption and scattering information of the samples under test. The Intralipid-20% phantom solutions in 34 samples with different concentrations were detected, while one-dimensional (1D) exit light intensity distributions and two-dimensional (2D) exit light intensity distributions on the surface of the samples were analyzed and modeled using partial least squares. In contrast with the prediction results based on the modeling method of 1D exit light intensity distribution, the modeling method of 2D exit light intensity distribution exhibits more favorable results; specifically, correlation coefficient enhanced by 2.48%, while root mean square error reduced by 6.89%. The experimental results demonstrate that using heteromorphic sample pool can effectively achieve NIRS-based detection precision and speed of chemical components in the solutions with scattering characteristics, which can provide important references for high-throughput and high-precision detection of turbid media in analytical chemistry.
关键词： two-dimensional (2D) light intensity distribution,heteromorphic sample pool,near-infrared spectrum
更新于2025-09-23 15:22:29
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Spin-Hamiltonian parameters and tetragonal distortion for the (WO6)7? octahedral centers in the WO3-doped Zn(PO4)2 ZnO nanopowders
摘要： The spin-Hamiltonian parameters (g factors g//, g⊥ and hyperfine structure constants A//, A⊥) of the tetragonal (WO6)7? octahedral center in the WO3-doped Zn3(PO4)2ZnO nanopowders are investigated from the high-order perturbation formulas resting on the two-mechanism (crystal-field and charge-transfer mechanisms) model with a suitable assignment of the absorption band at about 14,370 cm?1. The calculated results are in keeping with the experimental values. The tetragonal distortion of the (WO6)7? octahedral center is also achieved on the basis of the calculation. The outcomes are discussed.
关键词： W5+,Optical spectrum,Zn3(PO4)2ZnO,Crystal-and ligand-field theory,Spin-Hamiltonian parameters
更新于2025-09-23 15:22:29
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Facile in situ synthesis of Ag and Bi co-decorated BiOCl heterojunction with high photocatalytic performance over the full solar spectrum
摘要： Full-spectrum-responsive Ag/Bi/BiOCl hierarchical micro-flower heterojunction via a facile in-situ solvothermal route. The samples were characterized by XRD, SEM, TEM, XPS, BET and UV–Vis–NIR. The in-situ incorporation of Bi into the semiconductor BiOCl nanosheets with oxygen vacancies could be regulated efficiently by the Ag+ additive content. The samples presented a strong optical absorption in the whole region of 200–2400 nm and displayed excellent photocatalytic performance over the full solar spectrum. The presence of metallic Ag, Bi and oxygen vacancies strengthened the light absorption and promoted the charge-carrier separation of BiOCl, resulted in higher photocatalytic activity than that of pure BiOCl and P25 under UV and visible light irradiation. Furthermore, the photocatalytic responsiveness of Ag/Bi/BiOCl was successfully extended to the NIR region. On the basis of the radical species trapping experiments, h+, (cid:129)O2-, and (cid:129)OH were confirmed to be the mainly active species involved in the degradation of organic pollutants in the NIR region.
关键词： Full-spectrum,Near-infrared,Photocatalysis,Ag/Bi/BiOCl,Heterojunction
更新于2025-09-23 15:22:29
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Caracterización y simulación de ruido en las imágenes de PET reconstruidas con OSEM: desarrollo de un método para la generación de imágenes sintéticas
摘要： Introduction: The goals of the study are to characterize imaging properties in 2D PET images reconstructed with the iterative algorithm ordered-subset expectation maximization (OSEM) and to propose a new method for the generation of synthetic images. Material and methods: The noise is analyzed in terms of its magnitude, spatial correlation, and spectral distribution through standard deviation, autocorrelation function, and noise power spectrum (NPS), respectively. Their variations with position and activity level are also analyzed. This noise analysis is based on phantom images acquired from 18F uniform distributions. Experimental recovery coefficients of hot spheres in different backgrounds are employed to study the spatial resolution of the system through point spread function (PSF). The NPS and PSF functions provide the baseline for the proposed simulation method: convolution with PSF as kernel and noise addition from NPS. Results: The noise spectral analysis shows that the main contribution is of random nature. It is also proven that attenuation correction does not alter noise texture but it modifies its magnitude. Finally, synthetic images of 2 phantoms, one of them an anatomical brain, are quantitatively compared with experimental images showing a good agreement in terms of pixel values and pixel correlations. Thus, the contrast to noise ratio for the biggest sphere in the NEMA IEC phantom is 10.7 for the synthetic image and 8.8 for the experimental image. Conclusions: The properties of the analyzed OSEM-PET images can be described by NPS and PSF functions. Synthetic images, even anatomical ones, are successfully generated by the proposed method based on the NPS and PSF.
关键词： PET,Autocorrelation function,OSEM,Iterative reconstruction,Noise power spectrum,Point spread function
更新于2025-09-23 15:22:29
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[IEEE 2018 Asia Communications and Photonics Conference (ACP) - Hangzhou, China (2018.10.26-2018.10.29)] 2018 Asia Communications and Photonics Conference (ACP) - A code-free optical undersampling technique for broadband microwave spectrum measurement
摘要： A novel broadband microwave (MW) spectrum measurement (BMSM) scheme based on code-free optical undersampling and homodyne detection is proposed. The fully analog generation of optical pulses with a far-less-than-Nyquist rate is only through modulating cascaded electrooptical modulators by a single RF tone instead of any high-speed coding sequence modulation. Homodyne detection will reduce the analysis bandwidth of BMSM and enhance the detection performance of weak signal. A multi-band signal with 20 GHz spectral range and SNR = 61 dB is used to investigate the BMSM performance of this scheme, and the results show good performance for BMSM. The potentials for further optimization in practice are also discussed.
关键词： homodyne detection,optical undersampling,microwave spectrum measurement
更新于2025-09-23 15:22:29
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A Novel Whole Spectrum-based Non-invasive Screening Device for Neonatal Hyperbilirubinemia
摘要： Objective: Careful screening of bilirubin level in newborns is mandatory as per American Academy of Pediatrics (2004), to reduce incidents of kernicterus and acute bilirubin encephalopathy. Although invasive capillary collection of blood and subsequent biochemical test is considered a gold standard for jaundice detection in neonates, transcutaneous bilirubin (TcB) measurement using various non-invasive instruments is also used sporadically across the globe. The major aim of this study was to develop a non-invasive spectrometry-based technique for measurement of neonatal bilirubin level as an alternative of total serum bilirubin (TSB) test without limitations of other available bilirubinometers. Methods: The instrument comprised of a light source and a spectroscopic detector. A light beam from source incident on the neonatal nail plate through optical fibers. The retro reflected light is acquired using the detector. An indigenously developed software used to acquire and analyze the optical signal and to calculate the bilirubin value. The instrument was calibrated and validated in reference to TSB on 1033 subjects. Major results: The result (r=0.95 and P<0.001), indicates a strong correlation between the bilirubin value obtained from our method and TSB. Time variant analysis of the subjects undergoing phototherapy provided a good correlation (r = 0.98). The repeatability test, result shows the mean coefficient of variation less than 5.0%. Conclusions: The indigenously developed non-invasive technique, successfully detects the bilirubin under various physiological conditions with high accuracy and precision.
关键词： non-invasive optical method,LabVIEW,diffuse reflection,Neonatal jaundice,whole spectrum-based diagnosis
更新于2025-09-23 15:22:29
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[IEEE 2018 China International SAR Symposium (CISS) - Shanghai (2018.10.10-2018.10.12)] 2018 China International SAR Symposium (CISS) - A Novel Algorithm for Spacebome SAR DBF Based on Sparse Spatial Spectrum Estimation
摘要： A novel method of digital beam forming (DBF) based on sparse spatial spectrum estimation for spaceborne synthetic aperture radar (SAR) is proposed in this paper. This method converts the estimation of target scene elevation into the estimation of sparse spatial spectrum, which reduces the impact of the number of signal samples. Finally, the simulated results confirm the validity of the method.
关键词： Sparse Spatial Spectrum Estimation,Synthetic Aperture Radar (SAR),Digital Beamforming (DBF)
更新于2025-09-23 15:22:29
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[ACM Press the 3rd International Conference - Seoul, Republic of Korea (2018.08.22-2018.08.24)] Proceedings of the 3rd International Conference on Biomedical Signal and Image Processing - ICBIP '18 - Noise and Resolution Performance Evaluation for Statistical and Non-Statistical Iterative CBCT Reconstruction Methods
摘要： Non-statistical iterative and statistical iterative reconstruction (SIR) methods establish different models for Cone-beam computed tomography (CBCT) image reconstruction, which possibly produce different performance outcomes in reconstructed images. This paper presents a method to evaluate the noise and resolution properties of statistical and non-statistical iterative conditions. An algorithms EGSnrc/BEAMnrc Monte Carlo (MC) system was built for generating CBCT projections of a digital water phantom. SIR based OSC-TV (ordered subsets convex via total variation minimization) algorithm was selected to compare with non-statistical ASD-POCS (adaptive steepest descent-projection onto convex sets) algorithm and conventional FDK algorithm. The results demonstrate that ASD-POCS algorithm achieved a higher modulation transfer function than SIR based OSC-TV algorithm at the price of a higher image noise, while OSC-TV algorithm yielded best noise equivalent quanta performance among the three algorithms. The results of our study could guide a better evaluation and optimization of reconstruction algorithms for CBCT imaging.
关键词： Noise equivalent quanta,Image quality assessment,Noise power spectrum,Modulation transfer function,Computed tomography
更新于2025-09-23 15:22:29