Youquan Zhao

Unitary Space-Time Modulation of Turbo Trellis-Coded for Multiple-Antenna Rayleigh Fading Channel

Unitary (USTM) has got more attention for its potential in implementing high data rate transmission in a noncoherent multiple-antenna Rayleigh flat fading channel. In this paper, we have given out a bandwidth efficient turbo trellis-coded modulation scheme for the non-coherent multiple-antenna Rayleigh fading channel, where the channel state information (CSI) is not necessary both at the transmitter and the receiver. In this proposal, we combine USTM as constellations with the turbo trellis-coded modulation, resulting in the turbo trellis-coded USTM (TTC-USTM), with the trellis-coded USTM encoder as the component encoders. We have also applied the iterative maximum a posteriori (MAP) algorithm. According to PC simulations, we demonstrated that without bandwidth expansion, TTC-USTM produces obvious coding gains over its uncoded counterparts.

Analytical methods of microscopic fluorescence spectral imaging

Technology for fluorescence spectral imaging of microscopic has made significant strides advantages in the past several years. These advances have led to the enhanced choice of suitable diagnosis bases. Of course, fluorescence imaging can facilitate the study of disease at the molecular level in vivo. And this type of optical imaging has enabled real-time research to track cell movement, cell growth and other cell functions. With the addition of spectral imaging, fluorescence spectral imaging could complete a so-called 4-dimension imaging for the object. The investigator can obtain either the color imaging information or the information beyond it. The combination of both of them could show the relative completeness message. For evolution of software tools to deal with the resulting high-dimensionality datasets, it is necessary to find some effective and comparative reliable datasets analytical methods. In this paper, it also describes some quantitative fluorescence in tissue and addresses further applications of fluorescence spectral imaging. It includes MSE (Minimum Squared Error), PCA (Principal Components Analysis), ICA (Independent Component Analysis), FEA (Finite-Element Analysis), wavelet theory and their applications. They are useful in intact animals for disease detection, screening, diagnosis, treatment evaluation and drug development.

Laser induced heat source distribution in bio-tissues

During numerical simulation of laser and tissue thermal interaction, the light fluence rate distribution should be formularized and constituted to the source term in the heat transfer equation. Usually the solution of light irradiative transport equation is given in extreme conditions such as full absorption (Lambert-Beer Law), full scattering (Lubelka-Munk theory), most scattering (Diffusion Approximation) et al. But in specific conditions, these solutions will induce different errors. The usually used Monte Carlo simulation (MCS) is more universal and exact but has difficulty to deal with dynamic parameter and fast simulation. Its area partition pattern has limits when applying FEM (finite element method) to solve the bio-heat transfer partial differential coefficient equation. Laser heat source plots of above methods showed much difference with MCS. In order to solve this problem, through analyzing different optical actions such as reflection, scattering and absorption on the laser induced heat generation in bio-tissue, a new attempt was made out which combined the modified beam broaden model and the diffusion approximation model. First the scattering coefficient was replaced by reduced scattering coefficient in the beam broaden model, which is more reasonable when scattering was treated as anisotropic scattering. Secondly the attenuation coefficient was replaced by effective attenuation coefficient in scattering dominating turbid bio-tissue. The computation results of the modified method were compared with Monte Carlo simulation and showed the model provided reasonable predictions of heat source term distribution than past methods. Such a research is useful for explaining the physical characteristics of heat source in the heat transfer equation, establishing effective photo-thermal model, and providing theory contrast for related laser medicine experiments.

Bio-tissue temperature measuring for laser medicine

Temperature is an intuitionistic indicator of laser and tissue thermal interaction. It can be used as verification of theory prediction as well as online clinic indicator. Temperature measuring is an indispensable tool in laser and tissue photo-thermal theory research. A computer-assistant noninvasive or minimally invasive temperature measuring system, which can be used in laser medicine, was introduced. Combined infrared radiation thermometer and miniature thermocouple, the surface irradiating point and inner temperature can be monitored synchronously. This system has some necessary advantages for in vivo tissue temperature measuring. The infrared radiation thermometer temperature range is 0~200°C and 1mV/°C analog voltage output signal can be tntered to computer. Inside LED red light and aiming sound can assure the distance between thermometer and measuring point to be the focus distance of 25mm and measuring circle has the least diameter of 2.5mm. The mini K-thermocouples were made by ourselves, their temperature range is 25~500°C, the diameter of 0.4mm, and the response time is rapid up to 0.1s. They are convenient for precision orientation in the organisms. Multichannel temperature measuring can reduce the measurement error and be able for distribution measuring. Integrated temperature sensor LM35 and numerical computation is used to compensate the cold port temperature of the thermocouples. The numerical computation can also revise the nonlinearity error with the least squares method quintic polynomial fitting, which excels to the circuit method. Calibration results with glycerin and mercury thermometer showed the absolute error value is less than 0.45°C within 26-98°C. The real time temperatures of murine skin tissue irradiated by CO2 and Nd:YAG laser were measured. Such a system is suitable to high precision, large range, minute point, rapid response and real time tissue temperature measuring in laser applications. The saved data can be used for later analysis and compared with the thermal transferring theory model and calculation.