- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Segmented and non-segmented stacked denoising autoencoder for hyperspectral band reduction
摘要： Hyperspectral image (HSI) analysis often requires selecting the most informative bands instead of processing the whole data without losing the key information. Existing band reduction (BR) methods have the capability to reveal the nonlinear properties exhibited in the data but at the expense of losing its original representation. To cope with the said issue, an unsupervised non-linear segmented and non-segmented stacked denoising autoencoder (UDAE)-based BR method is proposed. Our aim is to find an optimal mapping and construct a lower-dimensional space that has a similar structure to the original data with least reconstruction error. The proposed method first confronts the original HS data into smaller regions in the spatial domain and then each region is processed by UDAE individually. This results in reduced complexity and improved efficiency of BR for classification. Our experiments on publicly available HS datasets with various types of classifiers demonstrate the effectiveness of UDAE method which equates favorably with other state-of-the-art dimensionality reduction and BR methods.
关键词： Autoencoder (AE),Hyperspectral imaging (HSI),Classification,Clustering,Band reduction (BR)
更新于2025-09-23 15:23:52
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Skeletal tailoring of two-dimensional π-conjugated polymer (g-C3N4) through sodium salt for solar-light driven photocatalysis
摘要： Structural modi?cation of graphitic carbon nitride (g-C3N4) by addition of sodium salt has been investigated for solar light-driven photocatalysis. The results from optical study indicates that the incorporation of sodium ions decreases band gap energy along with upward shifts of conduction and valence band. However, no substantial increment in surface area was observed, but morphological and optical studies con?rm that the structural deformation of g-C3N4 through sodium salt activates the ?n π * electronic transition, which can extend the absorption range to the red region attributing towards a reduced charge recombination, narrow band gap, and high conduction band edge. Furthermore, the photocatalytic activity of sodium doped g-C3N4 (0.6Na-g-C3N4) was examined under solar light for di?erent operational conditions in terms of phenol degradation of real tannery e?uent, and it was found that under optimum experimental conditions, i.e., 5 h solar irradiance, pH 5, H2O2 concentration 800 mg/L with a ?ow rate of 4 L/h, 0.6 Na- g-C3N4 exhibits 84.22% reduction in phenol while for g-C3N4 only 63.53% was observed.
关键词： Graphitic carbon nitride,Photocatalytic activity,Charge recombination,Solar irradiance,Band gap,Sodium salt
更新于2025-09-23 15:23:52
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3D Band-Absorptive Frequency Selective Rasorber: Concept and Analysis
摘要： This paper presents a 3D band-absorptive frequency selective rasorber (FSR). Such an FSR is absorptive within a specific band and almost transparent below the absorption band. The definition and evaluation of the band-absorptive FSR is initially provided and followed by the design concept of 3D FSR. An example is then proposed, whose unit cell is composed of 3D absorber and 3D band-stop FSS. An equivalent circuit model is established for understanding its operating principle. A prototype of the proposed 3D band-absorptive FSR is fabricated. The measured results show that it has an absorption band (|S11| ≤ ?10 dB and |S21| ≤ ?10 dB) from 4.21 to 6.51 GHz, with a thickness of 0.17 wavelength at 4.21 GHz. Moreover, |S21| is higher than ?1 dB at the frequencies below 1.28 GHz. The proposed band-absorptive FSR can be used as radomes for low-frequency antennas in military communications or spectrum monitoring systems.
关键词： band-absorptive,Frequency selective rasorber (FSR),absorptive frequency selective structure
更新于2025-09-23 15:23:52
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[IEEE 2018 18th International Symposium on Antenna Technology and Applied Electromagnetics (ANTEM) - Waterloo, ON (2018.8.19-2018.8.22)] 2018 18th International Symposium on Antenna Technology and Applied Electromagnetics (ANTEM) - Cavity Perturbation Technique to Characterize Dielectric Materials at Ka-band
摘要： The characterization of permittivity and dielectric loss of dielectric materials using a perturbation technique is conducted in simulation. The working frequency of this technique has been extended to the Ka-band. Simulation results demonstrate this perturbation technique is suitable for characterization of high permittivity dielectric materials for mm-wave and maintains good accuracy.
关键词： dielectric loss measurement,permittivity measurement,cavity perturbation technique,dielectric materials,Ka-band
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE Industry Applications Society Annual Meeting (IAS) - Portland, OR, USA (2018.9.23-2018.9.27)] 2018 IEEE Industry Applications Society Annual Meeting (IAS) - Design and Optimization of a Solar Power Conversion System for Space Applications
摘要： This manuscript details a design method for a 500kW solar power based microgrid system for space applications. The design method utilizes multi-objective optimization with the Genetic Algorithm considering four parameters that characterize solar power based microgrids (battery voltage, PV maximum power, PV maximum power point voltage, and number of panels per string). The final optimization metric is the ratio of daily average deliverable power to total system mass (W/kg) metric. The microgrid system is composed of a number of modular DC-DC micro-converters, of which four topologies (buck, boost, buck-boost and non-inverting buck-boost) are evaluated and compared. The non-inverting buck-boost converter is determined to be the best candidate, and the optimal system characteristics are provided and analyzed. The final system design achieves a specific power of 35.56W/kg, with optimized result of 743.7V battery voltage, 439.5W PV maximum power, 182.7V PV maximum voltage, and three panels per string. Based on the optimizations results, a prototype is designed, tested, and analyzed in terms of efficiency and low temperature reliability. The converter achieved a peak efficiency of 98.4%, a power density of 3.54W/cm3, a specific power of 3.76W/g, and operated for over 267 hours of 11-minute low temperature cycles from 0oC to -140oC.
关键词： wide band gap semiconductors,microgrids,non-inverting buck-boost,maximum power point trackers,space exploration,photovoltaic systems,design optimization,DC-DC power converters,system-level design,low temperature testing
更新于2025-09-23 15:23:52
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Simultaneously achieving a large negative dispersion and a high birefringence over Er and Tm dual gain bands in a square lattice photonic crystal fiber
摘要： We proposed a novel photonic crystal fiber composed of a double-cladding square lattice that could be used in dual-band, Er and Tm optical gain bands, simultaneously supporting a large negative dispersion and a high birefringence. We theoretically investigated the light guiding property through the proposed PCF by using a vectorial finite element method (FEM) with a perfectly matched layer (PML). By optimizing the structural parameters, we obtained an ultra-large negative dispersion of -20,186ps/(nm?km) and a very high birefringence of 9.27 ×10-3 at the wavelength of 1.55μm in the Er gain band and a very large negative dispersion of -8,067ps/(nm?km) and a high birefringence of 1.0 ×10-3 at the wavelength of 1.87μm in the Tm band. We further discussed the roles of waveguide parameters on the chromatic dispersion, its slope, and the birefringence of the fiber as well as the mode field diameter. The proposed fiber could be directly applied for dual-band dispersion and polarization control in fiber laser cavities as well as optical communications and sensors in the dual bands.
关键词： Thulium band,Erbium band,Negative dispersion,High birefringence,Photonic crystal fiber
更新于2025-09-23 15:22:29
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DESIGN OF DUAL- AND QUAD-BAND E-CRLH-TLS WITH ARBITRARY PHASE CHARACTERISTICS
摘要： In this paper, extended composite right/left-handed (E-CRLH) transmission line (TL) metamaterial structures, with two left-handed (backward) and two right-handed (forward) pass bands, are investigated. Also, design procedures in order to design dual- and quad-band E-CRLH-TLs are presented in detail and the parameters of these structures are extracted by clean formulas, while satisfying arbitrary phase shifts at the operating frequencies. Finally, the dispersion and characteristic impedances of these transmission lines are derived and plotted. The results of this paper can be applied to any type of TL-based dual- and quad-band microwave component.
关键词： microwave component,metamaterial,phase shift,dual-band,E-CRLH,quad-band,transmission line
更新于2025-09-23 15:22:29
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Regional Manufacturing Cost Structures and Supply Chain Considerations for SiC Power Electronics in Medium Voltage Motor Drives
摘要： With the growth in wide bandgap (WBG) semiconductors, specifically Silicon Carbide (SiC), the technology has matured enough to highlight a need to understand the drivers of manufacturing cost, regional manufacturing costs, and plant location decisions. Further, ongoing research and investment, necessitates analytical analysis to help inform development of wide bandgap technologies. The paper explores the anticipated device, module, and motor drive cost at volume manufacturing. It additionally outlines the current regional contributors to the supply chain and proposes how the base models can be used to evaluate the cost reduction potential of proposed research advances.
关键词： Wide bandgap,Supply chain,SiC,Wide-band gap,Wideband gap,Techno-economic,WBG,bottoms-up,Medium voltage,Motor drive,Wide band-gap,Analysis,Power electronics,Cost model
更新于2025-09-23 15:22:29
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[Communications in Computer and Information Science] Advances in Signal Processing and Intelligent Recognition Systems Volume 968 (4th International Symposium SIRS 2018, Bangalore, India, September 19–22, 2018, Revised Selected Papers) || Design of a Compact High Gain Wide Band Ψ Shaped Patch Antenna on Slotted Circular Ground Plane
摘要： A compact wideband high gain W shaped patch antenna on circular ground plane is proposed. The patch is designed and fabricated on FR4 substrate with a thickness of 1.6 mm and is compact in size as 122.7 mm2 including ground plane. The SMA connector with a center radius of 0.36 mm is connected at a coordinate (x = 5 mm, y = 3.3125 mm) as a feeding line to give RF signal as input. A wide impedance bandwidth is obtained due to the slots on the radiating element and by placing shorting post near zero potential ?elds makes the structure compact. An impedance bandwidth is further enhanced by placing an inverted U-slot on ground plane. The proposed structure is resonating at ?ve different frequencies 1.924 GHz, 2.88 GHz, 5.29 GHz, 8.58 GHz and 12.27 GHz yields an impedance bandwidth of 345 MHz, 92 MHz, 200 MHz and 4.77 GHz respectively. Re?ection coef?cient (S11) at 8.58 GHz & 12.27 GHz is ?36.37 dB and ?44.61 dB respectively. The proposed antenna is giving a maximum gain of 6.1 dB and has a stable radiation pattern with in the resonating band. The designed antenna is fabricated and is experimentally validated for the results. It reveals that the proposed antenna is suitable for WLAN and X band applications.
关键词： X band,Circular ground plane,WLAN band,Shorting post,Inverted U slot
更新于2025-09-23 15:22:29
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[IEEE 2018 XXIIIrd International Seminar/Workshop on Direct and Inverse Problems of Electromagnetic and Acoustic Wave Theory (DIPED) - Tbilisi (2018.9.24-2018.9.27)] 2018 XXIIIrd International Seminar/Workshop on Direct and Inverse Problems of Electromagnetic and Acoustic Wave Theory (DIPED) - Dual – Band Microtrip Quasi – Yagi Antenna Design for Free Band and 5G Mobile Communication
摘要： In this work, numerical and experimental analyses of a dual-band microstrip patch dipole-loop antenna are done. This design operates at amateur radio, amateur satellite (2.3-2.4 GHz) band and planned 5G mobile communication band; 3.4-3.8 GHz frequencies. There are two different radiating structures and regions in this antenna. One of the radiating structure is a rectangle shaped loop which is responsible for operation at lower frequency (2.3-2.4 GHz) and the other structure is a printed dipole which is responsible for operation of the upper (3.4-3.6 Hz) frequency. Apart from different operation frequencies, these structures also illustrates different radiation characteristics. The loop shaped region radiates bi-directional broadside radiation while the dipole part radiates with higher gain (peak gain 5 dBi). Proposed design is validated by High Frequency Structure Simulator (HFSS) and also measurements are carried out on fabricated prototype.
关键词： compact low cost and profile antennas,dual band,microstrip antenna,free band,5G
更新于2025-09-23 15:22:29