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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 - Two-dimensional Spectrum for Diving Stage SAR Processing with High-order Equivalent Range Model
摘要： For airborne synthetic aperture radar (SAR) processing in its diving stage, the diving velocity brings additional range variance to the range history in the synthetic aperture time. The traditional hyperbolic range model is not accurate enough to approximate the actual range equation and the precise two-dimensional spectrum cannot be achieved. In order to address this problem, a highly accurate spectrum deduction based on high-order equivalent range model is proposed in this paper. By introducing the high-order terms, more degrees-of-freedom are obtained for the equivalent range model and the actual range history can be accurately fitted. Based on the achieved range model, the two-dimensional spectrum for diving stage SAR can be accessed. Simulation experiments are carried out to validate the effectiveness of proposed spectrum.
关键词： two-dimensional spectrum,diving stage,range model,Synthetic aperture radar (SAR)
更新于2025-09-23 15:22:29
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A Method for Determining the Length of FBG Sensors Accurately
摘要： In this study we propose a method for estimating the length of single mode fibre Bragg grating type sensors with high accuracy. Our method is based on calculating the maximum oscillation frequency of the side-lobes of the FBG reflection spectrum. We show that this frequency is independent of the stress field to which the sensor is subjected, and is dependent on the length of the sensor. This method can be used to characterise the gauge length of already installed FBG sensors so that they can provide useful data for engineering models of structural integrity. All the analyses are based on the approximated transfer matrix model, which is a newly developed numerical method for analysis of the FBG reflection spectrum under various stress fields.
关键词： Fiber Bragg grating,structural integrity,reflection spectrum,FBG,length determination
更新于2025-09-23 15:22:29
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[IEEE 2018 OCEANS - MTS/IEEE Kobe Techno-Ocean (OTO) - Kobe, Japan (2018.5.28-2018.5.31)] 2018 OCEANS - MTS/IEEE Kobe Techno-Oceans (OTO) - Modeling Reflection Loss of the Gaussian Rough Ocean Surface
摘要： Modeling the acoustic reflection loss at the rough ocean surface is a necessary component of a sonar transmission model when the scattering field is mainly forward scattering and focuses on the specular direction. To modeling the reflection loss at small angles is of great significance for acoustic field predictions at meduim-to-long ranges ,especially for shallow oceans or oceans with a surface duct. Firstly, based on the rough ocean surface of Gaussian spectrum, the validity of Ramsurf acoustic propagation model under rough surface conditions is demonstrated through comparison with the trial data in high state. Moreover, using the modified PE code—Ramsurf as a benchmark, Kirchhoff Approximation (KA) Reflection Loss (RL) model and Small Slope Approximation (SSA) RL model are compared and analyzed. The numerical simulation implies that the SSA model and results by Ramsurf match well.
关键词： rough sea surface,Small slope Approximation,reflection loss,Kirchhoff Approxiamtion,Gaussian spectrum
更新于2025-09-23 15:22:29
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Geometry error analysis in solar Doppler difference navigation for the capture phase
摘要： Deep space exploration missions continue to become more ambitious, driving the need to investigate autonomous navigation systems that are accurate and timely. The solar Doppler difference navigation is a newly-developed and promising celestial autonomous navigation method for use, particularly in the crucial capture period. In this paper, we present novel analyses for three error sources for the solar Doppler difference navigation from the perspective of geometry, motivated with a Mars Deep Space Exploration example. The geometry error sources include the area overlap rate of the direct and the reflected solar light sources, the spread effects related to the time difference of arrival (TDOA) of light, and the solar rotation Doppler difference error. The area overlap rate and the spread effects of TDOA can be utilized to assess the overlap degree of the direct source and the reflected source in both space and time. Theoretical analyses and simulation results demonstrate that the direct and the reflected light sources can be accurately approximated as the same source. The solar rotation Doppler difference error is explored using a velocity error model. This model forms a hemi-ellipsoid that can be utilized to compensate the Doppler error caused by the solar rotation. The three errors decline with the deep space explorer approaching Mars, which means that the performance of the solar Doppler difference navigation method continuously improves in the critical capture period. These results can offer a reference for the system design of the solar Doppler difference navigation.
关键词： error analysis,solar spectrum,Doppler effects,navigation,geometry error
更新于2025-09-23 15:22:29
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Effect of Nb-doping on the structural and electrical properties of Ba0.97La0.02Ti1-xNb4x/5O3 ceramics at room temperature synthesized by molten-salt method
摘要： We, herein, report on the structural and electrical properties of Ba0,97La0.02Ti1-xNb4x/5O3 ceramics prepared by the molten-salt method. The XRD patterns of the samples at room temperature showed a single perovskite phase having a tetragonal structure with a P4/mmm space group. The electrical properties were studied by complex impedance spectroscopy in the frequency range (1–107Hz) at room temperature. The real and imaginary parts of impedance decreased with increasing Nb concentration. The complex impedance plot exhibited a single impedance semicircle for each compound, identified over the high and medium frequencies followed by a linear section, at low frequency, is explained by Warburg’s element. The study of the normalization curves of impedance and electrical modulus showed a mismatch of both peaks, which suggests the presence of short-range motion of charge carriers. The electrical conductivity decreased with increasing niobium amount and the experimental data were fitted using Jonscher’s universal power law. The exponent n is slightly superior to 1, indicating that the hopping occurs between neighboring sites.
关键词： molten-salt,conductivity,Ba0.97La0.02Ti1-xNb4x/5O3,EIS spectrum,impedance spectroscopy,Warburg element
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE 38th International Conference on Electronics and Nanotechnology (ELNANO) - Kiev (2018.4.24-2018.4.26)] 2018 IEEE 38th International Conference on Electronics and Nanotechnology (ELNANO) - Influence of Spin-Orbit Interaction on the Magneto-Optical Spectra of InSb Quantum Rings
摘要： The theoretical calculations of dependences of energy levels and absorption spectra of electrons in the quantum ring by a quasi-parabolic shape on the applied external magnetic field were carried out. The influence of spin-orbit interaction was taken into account in these calculations. Spin-orbit interaction leads to appearance of change in the dependence of absorption frequency of quantum rings on applied magnetic field.
关键词： spin-orbit interaction,absorption spectrum,quantum ring
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 - Dection and Health Analysis of Individual Tree in Urban Environment with Multi-Sensor Platform
摘要： With the technology enhanced, 3D mobile light detection and ranging (LiDAR) can produce more accurate 3D information for the objects. Meanwhile, hyperspectral remote sensing has more number of wavelengths and provides a higher resolution spectrum of objects. This paper proposes a multi-sensor platform to provide these two data for health detection at the individual tree level in urban environments. We firstly locate and segment the suspected tree objects by ground removal and Euclidean distance clustering. Then we take use of spectrum to remove non-tree objects, e.g., buildings, light poles. After that, we use LiDAR data to compute the geometric parameters of each tree and hyperspectral data to analyze its health situation.
关键词： point cloud,hyperspectral,spectrum,LiDAR,individual tree detection,health monitoring
更新于2025-09-23 15:22:29
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Real-Time Demonstration of Optimized Spectrum Usage with LSA Carrier Aggregation
摘要： Mobile broadband networks will face a tremendous growth in data traffic demand over the next 20 years. A key requirement for the evolution of radio access networks is the increase in the amount of spectrum and optimized spectrum usage, in order to meet future service demands. More efficient spectrum use will come with evolving technology features and novel spectrum sharing models. Candidates for technology improvements are higher order and massive MIMO systems, cooperative base stations and CoMP techniques, highly optimized resource allocation algorithms, network densification with inter-cell interference management and highly flexible carrier aggregation techniques to extend spectrum. In this paper, we will highlight carrier aggregation combined with flexible spectrum assignment and use of spectrum databases following novel licensing schemes. We give an overview of LSA activities, present a 3CA demonstration platform enabling the LSA concept and discuss its implementation constraints.
关键词： carrier aggregation,real-time demonstrator,authorized shared access,licensed shared access,spectrum sharing
更新于2025-09-23 15:22:29
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Secure Point-to-Multipoint Communication Using the Spread Spectrum Assisted Orthogonal Frequency Diverse Array in Free Space
摘要： Wireless communication security has been increasingly important nowadays. Directional modulation (DM) is seen as a promising wireless physical layer security technology. Traditional DM is a transmit-side technology that projects digitally modulated information signals in the desired directions (or at the desired locations) while simultaneously distorting the constellation formats of the same signals in other directions (or at all other locations). However, these directly exposed digitally modulated information signals are easily intercepted by eavesdroppers along the desired directions (or around the desired locations). A new DM scheme for secure point-to-multipoint communication based on the spread spectrum assisted orthogonal frequency diverse array (short for SS-OFDA-M-DM) is proposed in this paper. It can achieve point-to-multipoint secure communication for multiple cooperative receivers at different locations. In the proposed SS-OFDA-M-DM scheme, only cooperative users that use specific DM receivers with right spread spectrum parameters can retrieve right symbols. Eavesdroppers without knowledge of spread spectrum parameters cannot intercept useful signals directly at the desired locations. Moreover, they cannot receive normal symbols at other locations either even if the right spread spectrum parameters are known. Numerical simulation results verify the validity of our proposed scheme.
关键词： Frequency diverse array,Spread spectrum,Directional modulation,Secure point-to-multipoint communication
更新于2025-09-23 15:22:29
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Pulsed light treatment for the reduction of Salmonella Typhimurium and Yersinia enterocolitica on pork skin and pork loin
摘要： The aim of the presented study was to investigate the impact of pulsed light on the reduction of Salmonella Typhimurium and Yersinia enterocolitica on pork skin and loin. Fluences of 0.52 to 19.11 J/cm2 were applied to the pathogen-inoculated products to perform microbiological studies, as well as analyses of color, temperature, lipid peroxidation and odor. Reductions on pork skin ranged from 1.73 to 3.16 log for Salmonella and from 1.48 to 4.37 log for Yersinia. Microbial reduction was significantly lower on pork loin, varying between a minimum of 0.4 and a maximum of 1.7 log for both pathogens. Treatments ≥7.36 J/cm2 modified the color parameters of pork skin and fluences ≥9.66 J/cm2 rendered pork loin samples less red. All studies with pulsed light resulted in odor changes, except for the experiment on pork skin at 0.52 J/cm2. Despite significant microbiological reduction on pork skin, further studies should be carried out to optimize this promising technology.
关键词： Pulsed broad spectrum light,Lipid peroxidation,Microbial reduction,Pork,Sensory analysis
更新于2025-09-23 15:22:29