During the 1988/1989 influenza season, five antigenic reassortant influenza A (H 1N2) viruses not previously isolated from man were isolated in Hebei province, People's Republic of China. All isolates contained haemagglutinins (HAs) and neuraminidases (NAs) which were antigenically similar to those of the recent Russian (H1N1) and Hong Kong influenza A (H3N2) viruses, respectively. The results of antigenic and nucleotide sequence analyses revealed that the genes encoding the polymerase, nucleoprotein, NA, matrix and non-structural proteins of the reassortant A/Hebei/24/89 (H1N2) virus were derived from the H3N2 parent virus, whereas its HA gene was from the H1N1 parent virus. The nucleotide sequences of the HA (encoding the HA1 subunit) and NA genes of the reassortant viruses were also determined. Phylogenetic trees constructed from these data by the neighbourjoining method revealed that the HA gene of the reassortant virus was cl6sely related to those of recent human H 1N 1 viruses, whereas the NA gene was related to a recent human Hong Kong (H3N2) virus lineage.

This paper proposes a novel three degrees of freedom parallel machine tool. The parallel machine tool consists of three serial chains and a fixed base and a moving platform which can be moved in a pose space corresponding to the three degrees of freedom. By using matrix methods, a error model of the parallel machine was developed. The explicit solution of the error of joint and the stroke error of telescopic link were solved for analysis of influence factors of error on the position of moving platform. It provided a theoretical foundation for error compensation of parallel machine tool.

In order to improve the performance of end face grinding wheel, the phyllotaxis theory is introduced into the design of the wheel. Meanwhile the movement track equation of the end grinding is established, and the effects of the phyllotactic coefficient on the grinding surface roughness are studied. The simulation results show that the lower surface roughness values can be obtained when choosing reasonable phyllotactic coefficient. It will provide theoretical basis for the ordered abrasive patterns of the end grinding wheel.

In order to improve the grinding performance of end face grinding wheel, the ordered theory is applied to the design of grinding wheel. Based on the track equation of the end grinding, the effects of grinding parameters on the surface roughness are studied and compared with the workpiece appearance by grinding wheel with different abrasive patterns. The simulation results show that the surface roughness values are lower by the grinding wheel with phyllotactic pattern than other patterns. It will provide theoretical basis for designing abrasive ordered pattern of grinding wheel.

This paper proposes a new 2PTT-TPT parallel machine tool, solves the kinematics equation and analyzes the actuating force and maneuverability. In order to simulate the movement trajectory and pose, the model of virtual prototype is built in Solidworks and visualNastran. As a result, the mechanism is featured by compact construction, no singularity and good maneuverability, which provides the theoretical foundation for the design of parallel machine tool.