Time-varying Bias Estimation for Asynchronous Multi-sensor Multi-target Tracking Systems Using STF

Time-varying bias estimation problem was studied for multi-target tracking systems with asynchronous sensors without knowing bias dynamics. We considered general situations where the number of sensors was arbitrary as well as their sampling rates and initial sampling instants. A two-layer fusion structure was adopted. For each target, a pseudo-measurement of sensor bias was generated by fusing sensor measurements of this target. To make the pseudo-measurement decoupled from the target states the fusion coefficient matrix was determined to be a basis for the left null space of an augmented observation matrix. The bias estimation algorithm was proposed based on the Strong tracking filter （STF） by fusing pseudomeasurements. The proposed algorithm makes use of all available sensor information, has strong tracking ability to abrupt changes and avoids the matrix inversion for large dimensional matrices. Finally, the performance of the proposed algorithm is illustrated by the numerical simulation.     

MIS-Grid for Future Mobile Communications

The ultimate target of mobile communications is to afford any service for anyone anywhere at anytime. The developments for this target have been receiving close attentions during the past decade. At present, many countries and communications unions all open out their standards and productions in order to occupy the future communications market. Meanwhile, China has independently developed the 3rd generation mobile communications standard TD-SCDMA. The demands of consumers have been increas…     

Effect of burn-in on shear strength of 63Sn-37Pb solder joints on an Au/Ni/Cu substrate

A study was performed to examine the effect of burn-in and Au-plating thickness on the shear strength of 63Sn-37Pb solder joints in ball grid array (BGA) packages. The Au-plating thicknesses of 0.3 μm, 0.6 μm, 0.9 μm, and 1.4 μm were evaluated. An isothermal aging temperature of 150°C was employed to simulate burn-in conditions. The evolution of the bulk solder microstructure and intermetallic compounds at the solder joint interface were characterized and correlated to the measured shear strength. The strength of the solder joints with 0.3-μm Au plating was approximately three times higher than the thicker platings after aging. Solder joints with 0.3-μm Au plating failed within the solder matrix, and their strength was dependent upon the bulk solder microstructure and composition. The weakness of the solder joints with thicker Au platings was attributed to the formation of a brittle AuSn₄/Ni₃Sn₄ interface and a ductile Pb-rich layer at the interface.     

Study on AlSb Polycrystalline Films Prepared by Magnetron Sputtering

AlSb polycrystalline thin films were prepared by magnetron sputtering with an improved geometric target, and their structural,electrical and optical properties were studied. The results of XRD measurements suggest that the annealed AlSb thin films are Zinc-blende structure with the average size of about 23～31 nm, and the higher temperature promotes the crystallization of the films. The morphology obtained from the AFM measurements reveals that the surfaces of the films are smooth and the particles are unifo...     

Non-Linearity of Visual Sensitivity and Pursuit Velocity during Smooth Pursuit Eye Movements

During pursuit eye movements, whether the relationships among the visual sensitivity, pursuit velocity, and target velocity are linear or non-linear is an old issue. In this study, we reexamined their relationships with seven speeds by a simple character discrimination task using an infrared eye tracker. Our results found that the pursuit velocity and accuracy were non-linearly related with the target velocity. Besides, the perceptual sensitivity was not linearly related with the pursuit velocity either. A significant difference existed between lower （less than 20 deg/s） and higher speeds （greater than 20 deg/s）. In addition, we found there was no position bias of visual sensitivity between ahead of and behind the pursuit target, but there was a significant perceptual dissymmetry between horizontal and vertical directions at lower pursuit speeds.     

Ultrawide band radar signal detection, estimation and experiment

With reference to the air target detection of ultra-wide band (UWB)/impulse radar(IR), the transient signal processing techniques was discussed. In weak UWB signal detection, the wavelet transforms and high order spectrum estimation techniques were preferred. In target characteristic analysis, a time domain bispectrum estimation algorithm was used to analyze the target impulse response, which could estimate accurately local scattering distribution of complex target. A free field IR experimental system installed in an anechoic chamber was used. With this system, experiments to several target models were made. The results of these experiments verified the signal processing method efficiency.     

DETECTION ON MICRO-DOPPLER EFFECT BASED ON LASER COHERENT RADAR

A laser coherent detection system of 1550 nm wavelength was presented, and experimental research on detecting micro-Doppler effect in a dynamic target was developed. In the study, the return signal in the time domain is decomposed into a set of components in different wavelet scales by multi-resolution wavelet analysis, and the components are associated with the vibrational motions in a target. Then micro-Doppler signatures are extracted by applying the reconstruction. During the course of the final data processing frequency analysis and time-frequency analysis are applied to analyze the vibrational signals and estimate the motion parameters successfully. The experimental results indicate that the system can effectively detect micro-Doppler information in a moving target, and the tiny vibrational signatures also can be acquired effectively by wavelet multi-resolution analysis and time-frequency analysis.     

Ac-electronic and dielectric properties of semiconducting Phthalocyanine compounds: A comparative study

The AC-electronic and dielectric properties of different phthalocyanine films(ZnPc,CuPc,FePc,and H2Pc)were investigated over a wide range of temperature.Both real and imaginary parts of the dielectric constant("D"1–i"2/were found to be influenced by temperature and frequency.Qualitatively the behavior was the same for those compounds;however,the central atom,film thickness,and the electrode type play an important role in the variation of their values.Therelaxationtime,,wasstronglyfrequency-dependentatalltemperaturesandlowfrequencies,whileaweak dependency is observed at higher frequencies.The relaxation activation energy was derived from the slopes of the fitted lines of ln and the reciprocal of the temperature(1/T).The values of the activation energy were accounted forthehoppingprocessatlowtemperatures,whileathermallyactivatedconductionprocesswasdominantathigher temperatures.Themaximumbarrierheight,Wm,wasfoundtobetemperatureandfrequencydependentforallphthalocyanine compounds.The value Wm depends greatly on the nature of the central atom and electrode material type.The correlated barrier hopping model was found to be the appropriate mechanism to describe the charge carrier’s transport in phthalocyanine films.     

The nonlinear optical properties of P3HT under picosecond laser irradiation

The nonlinear optical properties of P3HT in orthodichlorobenzene were investigated by Z-scan technique using second harmonic generation(532 nm) of mode-locked Nd:YAG laser in the picosecond domain. The experimental results show the magnitude of their nonlinear refraction indices was up to the order of 10^-11 esu. The reverse saturable absorption of P3HT solution was observed and their nonlinear absorption coefficients reach up to 3.4 cm/GW. The strong optical nonlinearity of P3HT may find its new application in the photoclectric field.     

提取悬挂的p型硅纳米梁的界面态密度和电阻率

The evaluation of the influence of the bending deformation of silicon nanobridges on their electrical properties is crucial for sensing and actuating applications.A combined theory/experimental approach for determining the resistivity and the density of interface states of the bending silicon nanobridges is presented.The suspended p-type silicon nanobridge test structures were fabricated from silicon-on-insulator wafers by using a standard CMOS lithography and anisotropic wet etching release process.After that,we measured the resistance of a set of silicon nanobridges versus their length and width under different bias voltages.In conjunction with a theoretical model,we have finally extracted both the interface state density of and resistivity suspended silicon nanobridges under different bending deformations,and found that the resistivity of silicon nanobridges without bending was 9.45 mΩ·cm and the corresponding interface charge density was around 1.7445×10¹³ cm^-2.The bending deformation due to the bias voltage slightly changed the resistivity of the silicon nanobridge,however, it significantly changed the distribution of interface state charges,which strongly depends on the intensity of the stress induced by bending deformation.