Editor in chief：Jun-Hao CHU
International standard number：ISSN 1001-9014
Unified domestic issue：CN 31-1577
Domestic postal code：4-335
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Abstract:A W-band planar injection-locked harmonic oscillator (ILHO) based on substrate integrated waveguide (SIW) was implemented. Using the technique of harmonic extraction from diodes as a frequency multiplier, this ILHO has a free-running output frequency around 90.2 GHz under the condition of strong coupling for high injection power. When injecting a signal near 45.08 GHz in the fundamental injection-locked mode, it has an output power more than 6.5 dBm with a locking bandwidth of more than 120 MHz. The combination of the simple synchronization with a low-frequency reference signal allows the generation of stable and low phase-noise W-band signals with a fully integrated planar source.
Abstract:This paper demonstrates a novel highly integrated LTCC MMW passive receiving front-end which consists of antenna array, feed network and embedded band pass filter. The above passive components were co-designed as an antenna-in-package (AIP) solution for millimeter wave wireless system. Firstly, 2×2 linear patch antenna array with air cavity had been designed. Its maximum gain was increased 2.9dB by adopting a novel embedded air cavity. Secondly, a 3-pole miniaturized hairpin filter which was composed of three double layer resonators had been co-designed with the feed network. The filter exhibits an insertion loss of 1.9 dB and a 3 dB bandwidth about 8.1% at the center frequency of 34 GHz. Finally, the above antenna and filtering network were co-designed as a 3-D wireless receiving front-end. In the integrated structure, via fences were introduced to suppress parasitic modes. The measured maximum gain of the array antenna is 14.3dB and its impedance bandwidth (VSWR＜2) is 2.8GHz(32.9～35.7GHz)with the filtering feed network. The excellent overall performance of the novel array antenna shows great potential as a fully integrated passive front-end solution for a Ka-band wireless system.
Abstract:The band structure of InAs/GaSb superlattice was calculated using K.P theory under the envelope-function approach. The electro effective mass and absorption coefficient with different material structure were also calculated. Four-layer structure model considering two interfaces was investigated and used to modify the calculation. Comparing with the experiment results, this four layer model has closer cutoff wavelength than standard model. The results showed that different interface structure can also influence the band structure, leading to the changes of cutoff wavelength. For the same InAs/GaSb superlattice material fully compensated with InSb interface, one with symmetric InSb interfaces has shorter cutoff wavelength than superlattice with asymmetric interfaces.
Abstract:The poly(vinylidenefluoride-trifluoroethylene)/Ag composite films are derived by spin-coating and annealed at hydrogen atmosphere. Ag(111) phase labeled at the diffraction peak 2θ=38.1 is observed from X-ray diffraction (XRD) pattern, and it was also proved from scanning electron microscope (SEM) images. A blue shift was observed in the infrared transmission spectrum of the composite films, which suggests the interaction of dipole and silver nanoparticles. The ferroelectric polarization and dielectric constant of P(VDF-TrFE)/Ag composite thin films increase by 32.5% and 13.3%, respectively, compared with the pure polymer films under air annealing. The dielectric loss tangent of the P(VDF-TrFE)/Ag composite films is independent of Ag doping ratios, which violates the percolation theory.
Abstract:A 16-element focal plane linear array (FPLA) operating at 84～94GHz for passive millimeter-wave imaging was designed. The parabolic reflector with 500mm diameter was used to obtain an angular resolution of 0.47?. The 16 feed-horns are arranged as 4×4 array and the adjacent feed-horns are stagger at vertical direction, which doubles the scene sampling density in vertical direction and satisfies Nyquist theorem. The radiation field of the antenna was calculated in MATLAB by using current distribution method, and the location of the feed horns was optimized based on the results. Imaging results indicate that the full sampling imaging data of scene can be obtained when the FPLA scanning is done in horizontal direction for only one time and imaging time is reduced to half that of the traditional scanning way.
Abstract:A dual-layer dielectric film of Ge/GeO2 hollow-core mid-infrared fiber was proposed. The capillaries with single circle air holes are made by stack-draw method, which are then covered by a layer of silica gel in the following procedure to increase the mechanical strength of the structure. The dual-layer dielectric reflection films of GeO2-Ge on inner wall of the quartz capillary were deposited by CVD and hydrogen reduction. The reflection efficiency at the short wave band is raised in this way. From the spectrum analysis, the fiber transmission wavelength spreads from 3 to 12 μm without apparent absorption.
Abstract:An investigation of the mechanism of extraordinary transmission through metal hole array at THz range was presented. The experiments and simulations verified that the metal film perforated with rectangular arrays had a peak which related with the length of the rectangular. Furthermore, by composing rectangular holes with different length to form an array, the transmission spectra exhibit two individual peaks or a broaden peak. This composed array has potential applications in THz filter, polarizer, and reflector.
Abstract:A system for the measurement of Terahertz-wave scattering was set up. It includes 0.2THz BWO, pyroelectric detector and an automatic optical table. With this system, THz wave scattered by two copper plates with different surface roughness were measured. The result showed that electromagnetic scattering produced by the terahertz wave induced current and lambert scattering caused by the rough surface of the conductor exist at the same time. The metal rough surface approximated to lambert body could be considered as mirror when terahertz wave was obliquely incident. However, with the increase of roughness, the reflection gets weaker while the scattering becomes stronger, and the main peak shifts toward the angle smaller than that of reflection. Under the situation of normal incidence, the scattering curve decreased more quickly at the scattering angle less than 40?and changed slowly when the angel was more than 40?. For many materials, scattering peak appeared when the scattering angle was around 50?.
Abstract:Artificial sprays can be used in the fire safety and infrared stealth because that they can strongly attenuate the heat radiation through the scattering and absorbing effect. A model is established to calculate infrared radiation attenuated in the spray by coupling the radiation transfer equation and energy conservation equation. Taken the sprays as an absorbing, emitting, anisotropic scattering non-gray medium, the medium radiation, multiple scattering of the sprays, target radiation flux, and environment are taken into account. The radiative coefficients are calculated through Mie law and narrow bands approximation. The hemispherical spectral transmissivity is calculated with this model. By comparing with the Lambert-Beer's law, it was found that medium radiation, multiple scattering, and target radiation flux can weaken the spray shielding efficiency.
Abstract:This paper studied the variation of the stress-related thermal infrared spectrum of the rock under pressure. The thermal infrared spectrum radiation from two kinds of granites under uniaxial compression at room temperature was monitored with a spectroradiometer (8～14 μm). The experimental results show that the infrared radiance (amount of increase) of rock varies linearly with the stress. The stress sensitive waveband is determined by the mineral component and structures of the rock. The correlation coefficient between infrared radiance and load was analyzed comprehensively, so was the ratio of maximal variation to standard deviation. The results show that sensitive waveband to stress is in the range of 8.4～10.6μm for rich-feldspar porphyritic granite with central band at 8.75 μm; while for rich-plagioclase and equigranular granite, the sensitive waveband to stress is 8.2～11.7 μm, and centered at 10.25 μm. These wavebands can be used as reference for monitoring of the stress and catastrophe of the rock with infrared remote sensing.
Abstract:The field of view (FOV) of the 8 mm band synthetic aperture radiometer with regular Y-shaped array is small due to the relative large electronic scale of the RF front. To overcome this disadvantage, a kind of star-shaped array is presented. In the star-shaped array, the visible distance is only half of that of the antennas, so it doubles the imaging FOV. To deal with the missing visibilities of the star-shaped array, an image restoration method based on back-dropping and projecting onto convex set (POCS) is presented. Imaging simulations were carried out. The simulations validate the effectivity of the presented method.
Abstract:Spectral unmixing is one of the important techniques for hyperspectral data analysis. Full constrained (i.e., non-negative and sum to one constrained) least squares linear spectral mixture modeling (FCLS-LSMM) is widely used for its conciseness and clarity of physical meaning. Unfortunately, the traditional iterative processing for solving FCLS-LSMM is of heavy computational burden. The recently developed geometric analysis method of LSMM provided a new way for decreasing the complexity of LSMM. The unmixing results, however, are not in line with the FCLS requirements. In this case, a new geometric unmixing method is constructed to completely meet the FCLS requirements. The method is of very low complexity and has the capability to obtain the theoretically optimal solution. Experiments show the effectiveness of the proposed method.
Abstract:Hyperspectral image classification is an important research aspect of hyperspectral data analysis. Relevance vector machine (RVM) is widely utilized since it is not restricted to Mercer condition and does not have to set the penalty factor. Due to the high dimension of hyperspectral data, the classification accuracy is severely affected when there are few training samples. Feature reduction is a common method to deal with this phenomenon. However, most of the filter model based feature selection methods can not provide optimal feature selection number. This paper proposes to utilize the statistic estimation characteristic of Monte Carlo random experiments to calculate optimal feature reduction number and conduct hyperspectral image classification with relevance vector machine. Experimental results show the reliability of the feature reduction number calculated by Monte Carlo method. Compared with the classification of original data, there is a significant improvement in the classification accuracy with the feature reduction data.
Abstract:In a traditional scanning imaging system, energy from target is usually weakened by the crossing-pixels phenomenon, and false alarms may happen because of random high intensity noise and peaks in a point target detection. To solve these problems the temporal-spatial over-sampling detection system was proposed. To evaluating its performance, the signal to noise ratio of image obtained by this system was compared with that obtained by single sampling in the same optical system. The results show that the signal to noise ratio can meet the requirement of applications by centralizing the target energy into a pixel in over-sampling system. The target scale can be larger than noise and peaks scale after high-resolution fusion and the target scale can be extended up to 3×3 pixels. Then the false alarm probability can be decreased effectively.
Abstract:A modified algorithm of marker-based watershed segmentation was proposed by combining spectral similarity with phase congruency model in this paper. The performance of segmentation using marker-based watershed algorithm was decided by the result of edge detection from remotely sensed imagery. Thus we use spectral similarity of the same type ground object from remotely sensed imagery to suppress fake edges and noises to retrieve good segmentation results. In this paper, a spectral similarity model defined by the sum of distance of spectral curve between the target pixel and adjacent pixels was introduced into phase congruency model for edge detection. Then segmentation of remotely sensed imagery was obtained by using auto marker-based watershed algorithm. Finally, an unsupervised evaluation and comparison of the image segmentation from the proposed algorithm and some other existing algorithms was implemented using information entropy. Furthermore, the computation time of the proposed algorithm was also compared with other algorithms. The experimental segmentation results show that the proposed algorithm can reduce the over-segmentation phenomenon efficiently and it is readily to obtain better segmentation results by using this algorithm.
Abstract:Extracting the novel signal parameters is an effective means to solve the sorting problems of complex radar emitter signals. The features of the slice of ambiguity function main ridge are one of the most feasible parameters among various characteristics. To search the slice of ambiguity function main ridge of signal more quickly, a smart search algorithm based on superiority inheritance was constructed and statistical hypothesis testing theory was used to analyze and test the obtained data. The results of simulation show that, the proposed method can reduce the search time to 28.6% that of original method while obtaining the right slice with higher success rate and higher accuracy.
Abstract:The optical filtering principles of AOTF and system architecture of AOTF hyperspectral imager have been presented. A field hyperspectral imaging system has been setup and been applied in the multi-scale remote sensing in Tibetan Plateau. Hyperspectral images of different scale have been collected in the experimental area for plateau vegetation, and more abundant field supporting and comparative data have been provided. By data processing, the engineering feasibility of the technique has been validated, and a novel method has been introduced for unmixing the mixed pixel in remote sensing images.
Abstract:Mathematical expression was established for evaluating anticancer efficacy of samples of Z. nitidum to human tumor cells based on their infrared fingerprints. Chloroform extracts of the root of Z. nitidum from different habitats in China were used as subject samples to do anticancer experiments on two strains of human tumor cells, 7901 and Hela cells. Meanwhile, their fingerprints of infrared spectra were obtained. Screening arguments of backward elimination method was adopted to establish the spectra-effect correlation between infrared fingerprint and pharmacology data. The results showed that deviations of the predictive values from the true values were within ?10% for the two kinds of tumor cells, suggested that there was close correlation between infrared fingerprint and biological activity of Z. nitidum. The model implied that alkaloids in Z. nitidum have main effect on tumor cells.
Editor in chief：Jun-Hao CHU
International standard number：ISSN 1001-9014
Unified domestic issue：CN 31-1577
Domestic postal code：4-335