Abstract:设计并研制了一种新型复合沟道Al0.3Ga0.7N/Al0.05Ga0.95N/GaN HEMT(CC-HEMT)微波单片集成压控振荡器(VCO),且测试了电路的性能.CC-HEMT的栅长为1μm,栅宽为100μm.叉指金属-半导体-金属(MSM)变容二极管被设计用于调谐VCO频率.为提高螺旋电感的Q值,聚酰亚胺介质被插入在电感金属层与外延在蓝宝石上GaN层之间.当CC-HEMT的直流偏置为Vgs=-3V,Vds=6V,变容二极管的调谐电压从5.5V到8.5V时,VCO的频率变化从7.04GHz到7.29GHz,平均输出功率为10dBm,平均功率附加效率为10.4%.当加在变容二极管上电压为6.7V时,测得的相位噪声为-86.25dBc/Hz(在频偏100KHz时)和-108dB/Hz(在频偏1MHz时),这个结果也是整个调谐范围的平均值.据我们所知,这个相位噪声测试结果是文献报道中基于GaN HEMT单片VCO的最好结果.

Abstract:The relationship of IRFPA between response characteristic and incidence radiation,integral time was analyzed by using the practical response data.The essence of two point blackbody radiometric calibration non-uniformity correction algorithm was proposed by using different response data of high and low temperature to calculate gain coefficient and bias coefficient.Resembling to this,different response data could also be gathered by adjusting integral time.Therefore,non-uniformity correction(NUC) algorithm based on integral time regulation was studied,one and two point calibration correction algorithm was first proposed,then combined with multi-resolution wavelet decomposition,a new adaptive NUC algorithm was presented.Experiments show that the proposed scheme achieves good performance when applied in real imaging system.

Abstract:The second-harmonic generation(SHG) susceptibility of a wurtzite GaN/InxGa1-xN coupling quantum well(CQW) with strong built-in electric field was theoretically investigated.The calculated results reveal that the resonant SHG coefficients reach the order of magnitude of 10-7 m/V and the SHG coefficients are not monotonic functions of the well width,barrier width and the doped concentration of the CQW systems.Our results also show that a strong SHG coefficient can be obtained in the nitride CQW by choosing optimized structural parameters and doped fraction.

Abstract:It is well known that there exists an optimal angle magnification which can make the thermal imaging systems and human eye matching optimally, thus, the thermal imaging systems attain the optimal performance. Anew optimal performance evaluation method was proposed to find the optimal angle magnification on the basis of SNR model. Based on MRTD channel width, a new evaluation parameter was presented for thermal imaging systems performance testing and evaluating. The optimal angle magnification or the optimal viewing distance can be acquired by using the new evaluation parameter through the experimental analysis for the thermal image systems. The new theory is of great significance for developing the evaluation theory of photoelectronic imaging systems, and it provides potential theory guidance for the design of practice systems.

Abstract:采用分子束外延(MBE)方法在BaF2(111)衬底上生长了不同Mn组分的Pb1-xMnxTe(0≤x≤0.012)稀磁半导体薄膜.通过波长为3.0～11.0 μm中红外透射谱的分析并应用透射光谱上干涉峰峰值的位置计算获得了Pb1-xMnxTe薄膜的折射率,由最小平方根拟合得到折射率的一阶Sellmeier色散关系.在吸收边附近,通过直接跃迁吸收系数与光子能量的关系外推得到其光学带隙.结果表明,在中红外区域其折射率随着Mn含量的增加而减小,其光学带隙则随着Mn含量的增加而增大,在温度T=295K时,随着Mn含量x由0变化到0.012,其光学带隙Eg由0.320eV增加到0.370eV.

Abstract:利用红外光谱和渐进因子分析(Evolving factor analysis,EFA)对水溶液中牛血清白蛋白(Boyine serum albumin,BSA)的热动力学过程进行了研究.三因子EFA的结果表明加热导致了牛血清白蛋白的结构变化经历了轻微变化和剧烈变化两个阶段,它们分别发生在温度区间56～76℃和68～82℃.研究显示了渐进因子分析在解析水溶液中蛋白质温度相关红外光谱中的重大作用.

Abstract:Visible and near-infrared reflectance spectroscopy(Vis/NIRS) technique was applied in the early detection of grey mold(cinerea) on eggplant leaves while the symptom had not appeared.Chemometrics was used to build the early detection model.In order to decrease the amount of calculation and improving the accuracy,principle component analysis(PCA) was executed to reduce numerous wavebands into several principle components(PCs) as input variables of BPNNS while the PCs plot of three primary PCs was failed.The performance of the BPNNS model is good with 100% recognition rate and 88% correct rate.Thus,it is concluded that the spectra technology is an available one for the early detection of grey mold on eggplant leaves while the symptom has not appeared and it provides a new method for the early detection of grey mold.

Abstract:Based on the data processing technologies of interferential spectrometer,a sort of real-time data processing system on chip of interferential imaging spectrometer was studied based on large capacitance and high speed field programmable gate array(FPGA) device.The system integrates both interferogram sampling and spectrum rebuilding on a single chip of FPGA and makes them being accomplished in real-time with advantages such as small cubage,fast speed and high reliability.It establishes a good technical foundation in the applications of imaging spectrometer on target detection and recognition in real-time.

Abstract:Aiming at the Stokes scattering matrix of smoke particles, an experimental setup was designed and built with an electro-optic modulation, a quarter waveplate, polarizers and a lock-in amplifier. Through the setup, the angular distributions of the Stokes scattering matrix were measured for the smoke particles generated from smoldering cottons, flaming heptane and smoldering sandals. The results show that the non-sphericity of smoke particles, especially the gray smoke particles, plays an important role on the light scattering. There are some shortcomings for Lorenz-Mie theory, which is based on a spherical model, to analyze the light scattering by smoke particles. In this case, it is suggested that non-spherical models are required to analyze the characteristics, e.g. intensity and polarization ere, of light scattering by smoke particles.

Abstract:There is some quantitative relationship between polarized reflection and bidirectional reflection. In this study, the specular reflection and diffuse reflection components were computed by measuring the polarized reflection of granite surfaces that were different in roughness, And then it was quantitatively analysed how the roughness of granite surface influenced the two kinds of components in hotspot and non-hotspot. Meanwhile, through the analysis, it was found that incidence angle would influence the components, and this kind of influence was controled by the roughness of the granite surface.

Abstract:Two-point calibration technique of microwave radiometer receiver was presented and its errors were analyzed. 23.8GHz digital auto gain compensative microwave radiometer was calibrated and the calibration error range was calculated then. The accuracy of the calibration equation was verified by experiment. The results show that two-point calibration has favorable veracity for microwave radiometer receiver calibration.

Abstract:Based on analyzing optical parametric oscillator(OPO) in the quasi-phase-matched condition,the relationship between the grating period and parametric gain was discussed in singly-resonant optical parametric oscillators.Then,the dependence of threshold energy on the cavity length,the crystal length,the pump pulsewidth and the signal wave output coupling was analyzed in detail.Finally,the theory was proved applicable by our experiments.

Abstract:To get a high-ratio compression of remote sensing images,a neural network(NN)-based compression method was advanced.By using the characteristics of self-learning,parallel processing and distributed storage of NN,a single hidden layer feed-forward NN was constructed for getting high-ratio compression of remote sensing images.Moreover,we employ ridgelet,which is a new geometrical multiscale analysis(GMA) tool and is powerful in dealing with linear singularities(and curvilinear singularities with a localized version),as the activation function in the hidden layer of the network.Therefore the network has both the advantages of NN-based image compression method and more effective representation of edges and contours for the localization properties of ridgelet in scale,location and direction.The simulation results show that the proposed network can not only get high compression ratio but also present promising results,such as high reconstruction quality,fast learning and robustness,as compared to available techniques in the literature.

Abstract:Feature extraction is a crucial technology in advanced radar emitter signal deinterleaving and recognition.A time-frequency atom approach to extract the features of radar emitter signals was presented in this study.Based on the over-complete multiscale dictionary of Gaussian Chirplet atoms,the signals were decomposed into a linear expansion of atoms by the method of marching pursuit(MP).Then,the improved quantum genetic algorithm was applied to effectively reduce the time-complexity at each search step of MP,and thus some intrinsic Chirplet atoms describing features of signals were obtained.Experiment results show that the Chirplet atom is better than the Gabor atom in extracting the feature parameters,which confirms the validity and feasibility of the approach.

Abstract:The calculation method of seawater density by the multi-angle and polarized information was advanced here.The function between the properties of polarization of seawater and the seawater density was inferred from the angle of multi-angle remote sensing and polarized remote sensing.The seawater density was calculated by the polarized property of seawater and refraction index of seawater.The work will be helpful to extend the available application scope of remote sensing and exploit a new idea of ocean basic parameters' inversion.

Abstract:The connection between coherent structure in turbulence and the aero-optical distortions was studied through proper orthogonal decomposition(POD).The computational fluid dynamics(CFD) solutions of high speed turbulence around a missile IR window were used as resource data.Singular vector decomposition was adopted to achieve POD for the spatial-dependent mean flow field.As optical path difference(OPD) is often used to describe optical performance,the low-order singular value of the refractive index fields has good agreement with OPD caused by the source data.Then a plain method for simulating aero-optical distortions was proposed,in which only singular values of refractive index were used.By using the first order singular value,the method can represent the characters of aberrated wave-front,and the relative error of OPD is no more than 2%.The results also validate the argumentation that most aero-optical distortions are caused by coherent structure.

Abstract:The chemical oxygen demand(COD) in wastewater can be determined by near-infrared spectra(NIRs),however it is strongly influenced by the water absorbance.It is then very important to choose proper pathlength for improving measurement sensitivity and thus minimize the measurement error. In this study,we presented a series of experiments to determine the optimum pathlength for COD determination using a Fourier transform near infrared instrument with transmission measurement.Sixty wastewater samples for this study were collected from hoggery.Partial least squares(PLS) models were developed based on the spectral data which had been collected by using the cell pathlength of 1mm, 2mm,5mm,and 10mm.The performances of the differents models were compared.The results show that the pathlength of 10mm developes the optimal performance in the spectral range 800-1350nm and that of 1mm or 2mm of pathlength can be obtained in the spectral range of 1350~2500nm.In addition,our results suggest that two pathlength combination can improve the reliability and accuracy of the model in the region of 800~2500nm.This method of two pathlength combination may also be applied to the quantitative analysis of complex components in aqueous solutions.