trogen species. Although we cannot definitively separate the contributions of the PACN and soot to the yield of gtiseous nitrogen, the data suggest that, in the PAC conversion regime of our measurements, the net effect of the conversion of the nitrogen in PAC is the production of gaseous nitrogen species, most probably HCN.
Though computer technology has brought about virtual manufacturing to expedite design and analysis through simulation and visualization, machines remain essential, as ultimately products need to be made. This paper presents a new type of 5-axis parallel machine tool based on a 3 degrees of freedom parallel platform manipulator with base mounted prismatic actuators. This machine tool is different from the Stewart platform type parallel machine tool in that its feed motion in X-direction is realized by the worktable on which work-piece is fixed and the parallel manipulator sliding on the gantry structure of the machine tool is responsible for the translation along Y-direction instead of the movable platform of the manipulator. Due to this special architecture, the workspace in X-direction and Y-direction of the new machine tool is enlarged greatly. And its rigidity is higher because of the adaptation of gantry structure. This machine tool is controlled by a PC based NC system in simultaneous 5 axes control mode.
Based on the idea of integrated design, a drive-transmission integrated linear electromechanical actuator is developed. The actuator consists of a permanent magnet synchronous motor (PMSM), a ball-screw and shells. By using coaxial assemblage, the ball-screw is inserted into the hole of the hollow motor rotor and the nut of the ball-screw connects with the motor rotor. In order to restrict the ball-screw rotating relatively to the shell, splines machined respectively on ball-screw and the shell come into being a spline pair. A driver based on a DSP processor and IGBTs plus a position feedback resolver forms a precise servo system.
In-suit β-Ti (Zr,Nb) dendrite/amorphous matrix composites were prepared by copper injection casting, specimens (1.5:1 aspect ratio) with different diameters were tested under quasi-static compressive loading at different strain rate. The results show that the structure of amorphous composites is amorphous matrix and in-suit β dendritic crystal phase; for 3mm and 4mm specimens, with the change of strain rate, the compressive strength and the fracture strain have no obvious changes. however, positive strain rate sensitivity was observed to 5mm specimens; in the same strain rate, with the decrease of the diameters, compressive strength and fracture strain all have great increases, which indicate the amorphous composites has obvious size effect.
Automatic Dynamic Analysis of Mechanical System (ADAMS) provides a powerful modeling and simulating environment that helps people to build, simulate, refine, and ultimately optimize any mechanical system. In the classroom teaching of mechanism course, to use ADAMS to show the establishment and movement of all kinds of mechanisms and their simulation process of kinematics and kinetics as a demonstration will significantly enrich students' perceptual knowledge, enlighten and guide students cogitation, stimulate their interests in mechanism thereby enhance the effectiveness of course teaching.
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