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Spectra (UV-Visible, IR transmission) of Sc3+, Fe3+ and Cu2+ tri-doped LiNbO <sub/>3</sub> crystals with various [Li]/[Nb] ratios
摘要： The Sc:Fe:Cu:LiNbO3 crystals were grown with Fe3+(0.3 wt.%), Cu2+(0.1 wt.%) and Sc3+(1 mol.%) by the Czochralski method with various [Li]/[Nb] ratios (0.946, 1.05, 1.20 and 1.38). The influence of the [Li]/[Nb] ratios on the defect structure of Sc:Fe:Cu:LiNbO3 crystals was analyzed by the UV-Visible spectra and IR transmission spectra. The spectra show that the absorption edge shift to the red with [Li]/[Nb] ratios enhancing. The Sc:Fe:Cu:LiNbO3 crystals with [Li]/[Nb] ratio of 1.05 is nearly stoichiometric. A new narrow OH- associated vibrational peak at 3505 cm-1 was revealed in Sc:Fe:Cu:LiNbO3 crystals with the ratio of [Li]/[Nb] = 1.38. It is attributed to the (Sc2-Nb)-(OH)-. The results show that the defect structure changes with the [Li]/[Nb] ratios variation.
关键词： IR transmission spectrum,Sc:Fe:Cu:LiNbO3 crystal,UV-Visible spectrum
更新于2025-09-23 15:22:29
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Method for Combined Observation of Serial Sections of Stented Arteries Embedded in Resin by Light Microscopy and Transmission Electron Microscopy
摘要： We have developed a new method for obtaining information on whole tissues by light microscopy (LM) and ultrastructural features by transmission electron microscopy (TEM). This method uses serial sections of a stented artery embedded in resin. Stents were implanted in porcine coronary arteries in this study. The heart was perfusion fixed in a 2% paraformaldehyde and 1.25% glutaraldehyde mixed solution. The stented artery was then removed, fixed in 1% osmium, embedded in Quetol 651 resin, and sectioned serially. For LM, the black color of osmium was removed from the section by immersion in periodic acid and hydrogen peroxide after deplasticization. These sections were stained with hematoxylin and eosin and Elastica–Masson trichrome stain. For TEM, thin sections were re-embedded in Quetol 812 resin by the resupinate method and cut into ultrathin sections. A clear, fine structure was obtained, and organelles, microvilli, and cell junctions in the endothelium were easily observed. The combined observation of adjacent specimens by LM and TEM enabled us to relate histopathological changes in the millimeter scale to those in the nanometer scale.
关键词： porcine,stent,resupinate method,coronary artery,epoxy resin,transmission electron microscopy,light microscopy
更新于2025-09-23 15:22:29
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A monocular vision–based perception approach for unmanned aerial vehicle close proximity transmission tower inspection
摘要： Employing unmanned aerial vehicles to conduct close proximity inspection of transmission tower is becoming increasingly common. This article aims to solve the two key problems of close proximity navigation—localizing tower and simultaneously estimating the unmanned aerial vehicle positions. To this end, we propose a novel monocular vision–based environmental perception approach and implement it in a hierarchical embedded unmanned aerial vehicle system. The proposed framework comprises tower localization and an improved point–line-based simultaneous localization and mapping framework consisting of feature matching, frame tracking, local mapping, loop closure, and nonlinear optimization. To enhance frame association, the prominent line feature of tower is heuristically extracted and matched followed by the intersections of lines are processed as the point feature. Then, the bundle adjustment optimization leverages the intersections of lines and the point-to-line distance to improve the accuracy of unmanned aerial vehicle localization. For tower localization, a transmission tower data set is created and a concise deep learning-based neural network is designed to perform real-time and accurate tower detection. Then, it is in combination with a keyframe-based semi-dense mapping to locate the tower with a clear line-shaped structure in 3-D space. Additionally, two reasonable paths are planned for the refined inspection. In experiments, the whole unmanned aerial vehicle system developed on Robot Operating System framework is evaluated along the paths both in a synthetic scene and in a real-world inspection environment. The final results show that the accuracy of unmanned aerial vehicle localization is improved, and the tower reconstruction is fast and clear. Based on our approach, the safe and autonomous unmanned aerial vehicle close proximity inspection of transmission tower can be realized.
关键词： Close proximity inspection of transmission tower,monocular vision,UAV self-positioning,tower localization
更新于2025-09-23 15:22:29
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Area-Efficient Analog FIR Filter for Multi-Level Optical Transmission; 多値光伝送歪み補償に用いる小面積アナログFIRフィルタ;
摘要： The transmission of waveforms through optical fiber usually results in some waveform distortion. To smoothen this distortion, digital finite-impulse response (FIR) filters are commonly employed. Digital FIR filters require a relatively large area for digital signal processing (DSP) on IC chip, so an analog FIR filter is adopted. According to past researches, it is possible to realize a small area circuit by using a CMOS inverter as a delay circuit. However, number of delay circuits employing CMOS inverter increases N/2 for Multi-Level optical transmission. Therefore, we propose a new multiplier and attempted to reduce the circuit area of 4 PAM analog FIR filter. According to the estimation using SPICE simulation, it can be expected to reduce the area by 25% by using the proposed configuration.
关键词： analog FIR filter,CMOS inverter,gilbert cell,multi-level,28 nm FDSOI,optical transmission
更新于2025-09-23 15:22:29
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A facile route to diatoms decorated with gold nanoparticles and their optical properties
摘要： This paper presents a facile route for the decoration of biogenic silica from diatoms with gold nanoparticles (AuNPs) with dimensions from 10 to 40 nm. The AuNP decoration on the diatoms is performed through initial attachment of colloidal AuNPs (2 nm) followed by enhancement of the size of the AuNPs by mild reduction of tetrachloroauric (III) acid from solution. The samples were characterised by transmission electron microscopy (TEM), energy-dispersive X-ray analysis, Fourier transform infrared spectroscopy and light spectroscopy in the ultraviolet and visible (UV/Vis) range. The size of the isolated AuNPs on unmodified acid-cleaned diatoms was 10 nm according to TEM micrograph analysis. The measured UV/Vis spectrum showed an absorption peak at 525 nm, which corresponds well to the optical properties of AuNPs of the same size. The extent of decoration with AuNPs of the diatoms was significantly improved after functionalisation with 3-aminopropyltriethoxysilane of the biogenic silica. The absorption peak in the visible range was redshifted to 590 nm due to enlargement of the AuNPs up to 40 nm and clustering of the AuNPs. The AuNP decoration on the hierarchical and complex structured biogenic silica of diatoms might be interesting for biodiagnostic and surface-enhanced Raman spectroscopic applications.
关键词： transmission electron microscopy,optical properties,nanoparticles
更新于2025-09-23 15:22:29
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Impact Analysis of DSSC on Distance Relay Performance under Fault Conditions
摘要： This paper demonstrates the impact analysis of the Distributed Static Series Compensator (DSSC), on the performance of distance relay protection of high voltage transmission lines. The concept of DSSC model with its control circuit and distance relay are described. A five bus test system with DSSC and distance relay is designed with the help of MATLAB/SIMULINK software. The impact of DSSC on distance protection relay for different fault conditions and various fault locations is analyzed. The results of simulation show that the connection of DSSC in the transmission system changes the transmission line impedance greatly as estimated by the distance relay to be less or greater than the actual impedance in fault conditions. Hence, the distance relay performance changes, either over reaches or under reaches.
关键词： FACTS Controller,Distributed FACTS Devices,Distributed Static Series Compensator,High Voltage Transmission Line,Distance Relay
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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All-Optical Transmission Modulation Due to Inelastic Interactions of Ultrashort Pulses in a Disordered Resonant Medium
摘要： Random resonant media being one of the possible realizations of disordered metamaterials open a room of opportunities for achieving new fundamental effects and designing advanced nanophotonic devices. Strongly nonlinear optical properties of such media attract ever increasing attention nowadays from both theoretical and experimental points of view. Hereinafter, the case of the photonic-crystal-like structure with a randomly varying light–matter coupling provided by the random density of quantum particles is considered. Using numerical solution of the Maxwell–Bloch equations, the effects of the pulse collisions in the medium are studied. It is shown that disorder enables the qualitative changes of the system’s response for co-propagating pulses, whereas this is not the case for the counter-propagating ones. The scheme for an all-optical transmission modulation due to the disorder-induced inelasticity of collisions of co-propagating pulses is proposed. The ability of precise tuning the modulation via the inter-pulse distance and background refractive index adjustment is revealed. This novel approach for light control can be utilized for some high demand applications, such as modulation and switching of a pulsed radiation.
关键词： disordered metamaterials,transmission modulation,ultrashort pulses,localization of light,resonant medium
更新于2025-09-23 15:22:29
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22.3: Low cost fabrication of high contrast ratio and high transmission wire grid polarizer by nanoimprint lithography
摘要： This paper proposes a novel approach for low cost fabrication of large area wire grid polarizer (WGP). WGPs regarded as one potential alternative to traditional rear polarizer and DBEF possess the advantages of large contrast ratio (CR), high transmission. To date WGPs can be fabricated through electron beam direct write, which is slow and expensive, therefore not suitable for large area application. With the development of nano-fabrication methods, for instance, nanoimprint lithography (NIL), large area WGP can be made at low cost and fast speed. Furthermore, flexible polarizer can also be made through roll-to-roll (R2R) NIL. In this paper, a WGP with high TM transmission of around 85% and low TE transmission down to 0.2% through the visible light spectra will be realized through nanofabrication. The contrast ratio of the WGP can reach >450 with peak value >3000. For the fabrication process, atom layer deposition (ALD) will be utilized to prepare imprint mask which can achieve highly precise control of expected structure. In this paper, characterization of the designed WGP will also be narrated in the back part, including transmission, CR and the SEM schematic diagram. We believe that low cost fabrication method shows the potential to be adopted for industrial fabrication of polarizer in the future.
关键词： atom layer deposition (ALD),large area fabrication,low cost fabrication,wire grid polarizer (WGP),high contrast ratio,nanoimprint lithography (NIL),high TM transmission
更新于2025-09-23 15:22:29
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Microwave transmission performance of fused silica ceramics in microwave high-temperature heating
摘要： Compared with traditional heating methods, microwave heating is widely used in many industrial heating fields because of its advantages, such as material-selective heating, volumetric heating and high-efficiency heating. However, previous studies have shown that the heating mode depends on the transmission performance of refractory insulation materials. In this study, a commonly used refractory material (fused silica ceramics) for microwave heating was studied, according to the law of electromagnetic wave propagation in a single-layer plate, the power transmission coefficient (PTC) of the material at different thickness, temperature and frequency (915 MHz and 2360 MHz) was calculated and analysed, in order to design the refractory structure which has good microwave transmission performance in the whole microwave heating process. The results show that the transmission performance of fused silica ceramics fluctuates regularly with increasing thickness, and there are several microwave transmission peaks in the PTC patterns, the thicknesses corresponding to the transmission peaks at frequency 2360 MHz are in order 0.033 m, 0.065 m and 0.098 m; as the temperature increases, the position of the transmission peaks will shift to a smaller thickness, the transmission performance of fused silica ceramics decreases slightly with increasing temperature. Comparing the transmission performance of mullite, alumina (Al2O3) and fused silica ceramics, it was found that the fused silica ceramics have excellent transmission properties; especially it is at high temperature. The results of this study can provide guidance for the selection of refractory structure materials and sizes as well as the optimization of heating process parameters in high-temperature microwave heating.
关键词： A. Microwave heating,D. Transmission performance,B. Fused silica ceramic,C. High temperature wave transmitting material
更新于2025-09-23 15:22:29