Abstract:Seeking in a field of view (FOV) is influenced by the existence of jammers, noise, shine background or flying perturbations. All these factors may push the target out of the FOV and cause missing the target. In all the seekers the FOV is not fully exploited which means the target can be missed before becoming out of the FOV, this results of the nonlinearity of the reticle structure. In this paper, a novel method of the target position detection a crossed four slits or crossed array trackers (CAT) seeker will be designed, simulated and evaluated. The idea of this method depends on dividing the FOV into main regions up to a certain parameter, which is the pulses number; then, each main region will be divided into sub-regions up to a second parameter which will be the pulses distribution a spin period. The errors sources will be discussed and evaluated. Other new idea will be applied which is exploiting some area of the FOV where a part of the position data is missed in the information signal by pushing the target to the region where the information signal carries the total position data.

Abstract:Transmitted terahertz time-domain spectroscopy (THz-TDS) using dipole-antenna on LT-GaAs was applied to determine the THz spectral characteristics of single-crystal ZnO, pure-and Mg-doped ZnO nanopowders (NPs) at room temperature. The power absorption and refractive index were measured in the frequency range from 0.2 to 2 THz. Mg doping increases the absorption coefficient, while decreases the refractive index of the compound ZnO NPs. The THz dielectric properties of pure-and Mg-doped ZnO NPs exhibit similar behaviors with that of the ZnO single crystal, which are found to be associated with the transverse optical E1 (TO) phonon mode.

Abstract:With the importance of automotive drive assistance system of intelligent vehicle, vehicle detection fusing millimeter wave (MMW) radar data and vision multi-features is presented. The vehicle detection algorithm can be divided into three steps. Firstly, a space alignment algorithm between MMW radar and vision was proposed to get space alignment point according to the space transformation matrix of image coordinate and radar coordinate. The second step obtains region of interest (ROI) according to the space aligned point and search strategy. At last, vehicle detection was realized through features of vehicle including bottom shadow, symmetry, left and right edges; in this step, an improved segmentation algorithm of bottom shadow of vehicle was described in order to obtain accurate vehicle width. The performance of the algorithm was verified under different scenarios. The results show the vehicle detection algorithm is effective and feasible.

Abstract:Several etching methods for mesa of InAs/GaSb superlattice in IR FPA were investigated. The InAs/GaSb superlattices used here were prepared by molecular beam epitaxy. A standard PIN device structure was applied in all samples with a period of 8ML InAs/8ML GaSb. Inductively coupled plasma etching with CH4, Cl2 and Ar as reactive gases and wet etching with solution including orthophosphoric acid and tartaric acid were compared. The mesa height was measured by α-step meter system, while surface morphology was evaluated by microscope and scanning electron microscopy. The results shows that CH4 based etching can give a smooth surface and slippery lateral with an 80 degree angle. Furthermore, the mesa depth was easy to control. This method is suitable for fabricating deep mesa device. It has also been found that etching with the solution based on orthophosphoric acid can obtain a smoother, clear surface and low in the longitudinal. It is a better way to fabricate IR FPA.

Abstract:After different loopholes are produced by Ar+ ion-beam in p-HgCdTe, width of n-type layer has been defined by the electron beam induced current measurement. It can be observed that under the same milling condition, the width of n-type layer depends on both of the mercury vacancy concentration and the volume of the milled-HgCdTe. Further study shows that the width of n-type layer linearly decreases with an increase of the mercury vacancy concentration if volume of the milled-HgCdTe is equal. Meanwhile, the width of n-type layer will linearly increases with volume of the milled-HgCdTe increasing if the mercury vacancy concentration is kept unchanged.

Abstract:The third satellite of new generation polar orbit meteorological satellite of China(FY-3C)was successfully launched on September 2013. In order to analyze the capability of the microwave humidity and temperature sounder’s sounding channels in atmospheric parameters detection, the basic atmospheric parameters data of Katrina provided by the “University of Wisconsin-Non-hydrostatic Model System”(UW-NMS)were combined with the microwave radiative transfer model to simulate the radiometric characteristics of 118GHz and 183GHz. The results show that fine structure of atmosphere humidity and temperature profile can be achieved by using 118GHz and 183GHz which are the millimeter-submillimeter sounding channels. The brightness temperature of(118.75±5.0)GHz and(183.31±7.0)GHz decrease about 108K and 76K, respectively, due to the scattering of frozen hydrometeors. This result indicates that these channels data can be used to detect the cloudy atmosphere. The different kinds of hydrometeors can significantly affect the brightness temperature of 118GHz and 183GHz channels and it will be used in hydrometeors retrieval. When mixing ratios of rain drops increase, only the brightness temperature of(118.75±5.0)GHz decreases about 4.5K. The responsiveness reveals that 118GHz is an important band for precipitation retrieval. The brightness temperature of(118.75±5.0)GHz decreases about 10K when mixing radio of snow at middle layers increase. This result shows the channel can be used to detect the snow particle.

Abstract:The selection of detection band is fundamental to the design of infrared warning satellites. An approach adopting point target radiation flux apparent contrast spectrum to select the detection band was proposed in this paper. A relatively complete model calculating the apparent contrast spectrum of rocket plume was founded at first. Then the infrared radiation spectral characteristics of typical liquid and solid rockets at various altitudes were obtained by modeling and simulating. Finally, the infrared radiation of background and the transmittances and path radiation of atmosphere were calculated using the combined atmospheric radiative transfer(CART). Based on the above results, the apparent contrasts spectral of typical liquid and solid rockets at various altitudes were gained. Results of both liquid and solid rockets show that, the apparent contrast at 2.55～2.85μm and 4.19～4.48μm are higher than other bands, and might be suitable for the infrared warning satellites detection band chosen by the space based infrared system.

Abstract:The traditional target detection methods suffer from the quality of target and background training samples, attitude of target, visual angle of target and noise, etc. In order to overcome these limits, a novel method of data-driven quadratic correlation filter based on sparse coding was proposed, in which the dictionary of target autocorrelation matrix is built. This model not only detects target with multiple attitudes and visual angles, but also is insensitive to noise and the quality of training samples. This model is independent of the randomness in different backgrounds. The experimental results on pedestrian and vehicle show that the proposed algorithm is effective. The idea of proposed algorithm is a good reference for improving the methods of filtering.

Abstract:Aiming at the elements of infrared polarization imaging system based on metal wire-grid polarizer, a lot of affecting factors such as target, atmosphere, sky, polarizer reflect and radiate itself should be take into accounted, which is favorable for analyzing the infrared polarization radiation constitutes entering into the imaging system. Based on the bidirectional reflectance distribution function model, the paper establishes transmission equation of infrared polarized radiation that includes reflection and emission, and we deduces the mathematical model with respect to a lot of factors of the degree and the angle of polarization. By simplifying the formula of degree of polarization reasonable, the simulated curves of degree of polarization are consistent with the measured date in references. The result of this paper can afford gist theory and techno-gsustain for improving the detection capability of infrared polarization imaging system.

Abstract:Short-wavelength infrared(SWIR)focal plane array detector suffers from problems including intrinsic non-uniformity, low signal-to-noise ratio(SNR), and relatively high cost. To overcome these difficulties, a staring-mode frame imaging scheme was proposed based on Hadamard transform(HT), using single element detector and digital micro-mirror device(DMD)spatial light modulator. Experimental study has been carried out to verify the validity of this method in SWIR imaging. The results demonstrate that this scheme is a promising approach to achieving low cost, high SNR SWIR imaging.

Abstract:A novel scheme for the generation of photonic millimeter-wave was proposed, which is applicable to optical/wireless hybrid access network. Based on the characteristic that a wide spectrum signal can be produced by modulating a distributive feedback semiconductor laser, a laser is directly modulated with low-frequency sinusoidal signal. The laser’s spectrum is broadened and then injected into a series of phase-locked semiconductor lasers to make themselves coherent light sources. The light sources are used to load different signals at different wavelengths for transmission. At the receiving end, optical filters with different passband characteristics are used for signal processing, selectively receiving the baseband signal, optical microwave clock signal, and the uplink light sources or up conversion signals modulated with different subcarrier frequency. As verification, the generation and reception of subcarrier-modulated optical signal for 2.5Gbps baseband signal, 20GHz and 40GHz are completed. Due to the limited experimental conditions, only the theoretical verification was conducted. Though, as the system can be integrated with waveguide design, an optical microwave signal with higher carrying frequency can be generated. It is very beneficial to future optical/wireless hybrid access and the system of ultra-dense wavelength division multiplexing.

Abstract:A new sub-pixel mapping method is presented in this paper, which makes use of multiple shifted remote sensing images to enhance the back-propagation neural network(BPNN)-based sub-pixel mapping method. Different from the original BPNN method that uses a single observed coarse spatial resolution image, the new method integrates multiple coarse spatial resolution images that are shifted from each other to determine the probability of a sub-pixel belonging to each class. The probabilities and land cover fractions are then used to allocate classes for sub-pixels. The proposed method can decrease the uncertainty and errors in BPNN-based sub-pixel mapping. Experimental results show that with both visual and quantitative evaluation, the proposed method can obtain more accurate sub-pixel mapping results.

Abstract:Quantitative estimation of emerged plant water content with multi-spectral remote sensing technique is of great significance for emerged plant physiological status and growth trend monitoring. The hyperspectral reflectance of canopy of wetland typical emerged plant(reed and cattail)was measured by Field-Spec 3 wild high-spectrum radiometer. The leaf water content and leaf area index(LAI)of corresponding samples were also measured. First of all, the ground spectral data(reed and cattail)were resampled to simulate the spectral of WorldView-2 imagery, then the simple ratio vegetation index(SR)and normalized difference vegetation index(NDVI)were constructed with arbitrary two band combination from the simulated WorldView-2 spectra, respectively. The correlation between canopy water content(CWC )and vegetation index were analyzed. The estimation models were obtained by using regression and correlation analysis for different emerged plant community. In addition, the research result of ground data was applied to WorldView-2 high resolution multispectral imagery covering the study area, and the CWC of emerged plant community was estimation in spatial scale. The results show that the SR and NDVI constructed by the simulated WorldView-2 spectra had a good overall correlation with CWC. The SR(8, 3)reedwas selected as the optimal vegetation index to estimate the CWCreed, the best models are evaluated and validated as y=0.005x+0.003. The NDVI(8, 3)cattailwas selected as the optimal vegetation index to estimate the CWCcattail, the best models were evaluated and validated as y=2.461x2-0.313x 0.032. According to two K-fold cross validation examination, these estimation models have the satisfactory prediction accuracy. The prediction accuracy of CWCreedwas 87.42% and the prediction accuracy of CWCcattailwas 82.12%. Furthermore, based on the research result of ground data, we made use of WorldView-2 high resolution multispectral imagery to map the CWC of different emerged plant community. According to the examination of measured data, the estimation RMSE of CWCreedand CWCcattailfrom imagery were 0.0048 and 0.0052, respectively. The estimation accuracy were 83.56% and 80.31%, respectively. It was demonstrated that using WorldView-2 high resolution multispectral imagery to estimate the CWC of wetland emerged plant community has a high feasibility.

Abstract:Split Bregman method, which can converge quickly and denoise very well, is considered to be an extremely efficient method for total variation denosing model. By studying Split Bregman method, an adaptive Split Bregman method which can adjust Lagerange multiplier and penalty parameter automatically was proposed. Experimental results show that the new method can not only converge faster than the traditional Split Bregman method, but also preserve the edge information while removing noises.

Abstract:Hyperspectral unmixing is an important issue to analyze hyperspectral data. Based on the present mixing models, a new nonlinear unmixing algorithm for hyperspectral imagery was proposed. By introducing the abundance nonnegative constraint, abundance sum-to-one constraint and the bound constraints of nonlinear parameters, the proposed algorithm transforms the hyperspectral unmixing problem into a constrained nonlinear least squares problem. It consists of two sub-problems which obtain alternately the abundance vectors and nonlinear parameters of the observation pixels. Then, the alternating iterative optimization technique was used to solve this problem. The experimental results on synthetic and real hyperspectral dataset demonstrated that the proposed algorithm can effectively overcome the inherent limitations of the linear mixing model. Meanwhile, the proposed algorithm performs well for noisy data, and can also be used as an effective technique for the nonlinear unmixing of hyperspectral imagery.

Abstract:In hyperspectral remote sensing imagery, material usually present two spatial distribution characteristics: one is its dominance in some special areas, another is its consistency on the land surface. By utilizing this two prior information, we propose an algorithm named nonnegative matrix factorization (NMF) with abundance constraint, which introduces both orthogonality and smoothness into abundance. To further improve the algorithm performance, we also propose a new stop criterion and an adjusting method of adapting weight factor to the varying signal-to-noise (SNR) and mixing degree. Experimental results based on synthetic and real hyperspectral data show that our algorithm not only represents material distribution characteristics very well, but also increases the unmixing accuracy. Meanwhile, the algorithm can lead to satisfactory unmixing results under the conditions of low SNR and no pure pixels.