Search

For this paper, we analyze the achievable sum rate of zero-forcing (ZF) pre-coding and Maximum Ratio Transmission (MRT) pre-coding with Matrix Normalization in massive MIMO system with Imperfect CSIT. We compare the performances of these two pre-codings and find that ZF pre-coding outperforming MRT pre-coding in the high SNR region while MRT pre-coding outperforming ZF pre-coding in the low SNR region. Then we derive the threshold of the pre-coding selection and provide the procedure of pre-coding schemes selection.

The user scheduling and precoding schemes in Multi-User Multiple Input Multiple Output (MU-MIMO) system have the problem of high complexity and the performance of traditional criteria is not good. This paper analysis the advantages of Signal to Leakage plus Noise Ratio (SLNR) criteria firstly, then propose a cross-layer design of user scheduling and precoding scheme based on SLNR criteria. The design only uses SLNR criteria and includes an improved SLNR user scheduling scheme which is accomplished by iteration procedure. Numerical results verify the improved user scheduling scheme can improve the performance of sum capacity and average BER and the cross-layer design has lower complexity.

The pool fire mathematical model of hermetically closed room is built by different plume models, the time of smoke filling and smoke layer temperature are calculated combined with experimental heat release rate. Theoretical calculations are compared with the experimental results to verify the usefulness of different plume models. The results indicate that: in initial period of fire, the smoke filling speeds of four plume models are similar, and McCaffrey plume model is most close to physical processes; in later period of fire, Zukoski plume model is most close to physical processes of smoke filling; during the fire, the results of Thomas plume model and Zukoski plume model are almost identical, and Thomas model is more suitable for engineering application; the smoke layer temperature discrepancy between theoretical calculation and experimental data is huge, and the theoretical calculation method of temperature is not recommended for predicting temperature in engineering.

Three radiation models are discussed in the present paper. The heat fluxes vary considerably between different methods. In all models, fluxes vary highly on the position of nearing the flame and are almost identical on the far away position. Heat fluxes calculated from point source model is less than other two models, and Shokri-Beyler model is highest. Shokri-Beyler method is most applicable at heat fluxes greater than 5 KW/m2 and recommended in engineering design, and Mudan model is not applicable for calculating the heat flux nearing the flame.

Considering the two-wheel auto-balance vehicle system is complex and difficult to control, study on control system and assembly way of the vehicle have been made. The control system can be divided into balance control, speed control and steering control, and solutions to key issues of control system are proposed. Based on rollover prevention, a two-wheel vehicle is designed with low center of gravity. The results indicate that the solutions have increased speed and stability of the vehicle.

This paper presents the design of a bilateral tracing intelligent car based on photoelectric sensors. The control system selects the 16-bit MC9S12XS128 microprocessor as the core controller; employs laser tube and receiving tube to detect the location and movement direction; applies fuzzy self-adaptive PD controller to control the servos; makes use of photoelectric encoder to examine the cars speed. Experimental results indicate that the intelligent car can run along the track steadily and rapidly.