共查询到10条相似文献，搜索用时 140 毫秒
1.
Peng Guangzheng Chen Ping Zhao Tong 《北京理工大学学报》1999,19(3):71
Aim To present a new kind of
pneumatic position control system based on the analysis of the disadvantages of
conventional pneumatic position control systems. Methods The new kind of pneumatic
position control system used a new kind of actuator-cylinder with a built-in brake and a
displacement sensor. And PWM control method and fuzzy control algorithm were utilized in
the system to control the position of the cylinder, and the brake was used to fix the
cylinder to its target position after it reached the position.Results The stiffness of the system was
experimentally proved to be greatly improved and the position precision to be within
0.15mm. In addition, the system is free of great shock and wear. Conclusions The new kind of pneumatic
position control system is free of the disadvantages of conventional systems, and is of
practical value. 相似文献
2.
Aim To research the interpolation
algorithm of parallel connected machine tool based on stewart mechanism.Methods
The common idea of time-discrete interpolation algorithm and the inverse kinematics model
of parallel connected machine tool were used to evaluate the relation between tool motion
path and six telescopic legs and to derive one kind of interpolation algorithm.Object
oriented program design method was adopted to work out the simulation software and the
availability of the interpolation algorithm was testified by computer simulation.Results
and Conclusion Simulation results of machining process of sphere parts and
one-sheet-hyperboloid parts show that the interpolation algorithm proposed is correct and
practical, providing a new and feasible interpolation algorithm for parallel connected
machine tool. 相似文献
3.
Yang Shuchang Wei Ping 《北京理工大学学报》1999,19(3)
Aim To study a real-time traffic flow
measurement system providing necessary statistics of traffic flow parameters for traffic
departments through measuring vehicle number, velocity and other traffic parameters.Methods
The real-time traffic flow measurement was processed through image difference method.
Because of its capability for data processing at high speed, the RISC (reduced instruction
set computer) was used to carry out real-time and practical research on the whole system. Results
Experiment devices of real-time traffic flow measurement was developed and the practical
algorithm of image processing was designed and debugged. Conclusion In
practical traffic flow measurement, the precision of measuring vehicle number is over 95%.
The system work robustly under various conditions, it can automatically cope with the
gradual and sudden changes of the environment light. 相似文献
4.
The isothermal oxidation behavior
of two kinds of alloying Ti-Al alloyTi-48Al-2Cr-2Nb and Ti-47Al-1Cr-1V-2.5Nb at 800℃ and 900℃
is investigated.Their high temperature
oxidation character and the influence of the alloying element upon the oxida－tion behavior are discussed.The
study shows that the oxidation resistance of two alloying Ti-Al alloy at 800℃ is poorer than that of
48Al.However,their oxidation properties at 900℃ are considerably improved,and the oxidation speed is much
lower than that of 48 Alalloy.At the two oxidation temperatures,Ti-48Al-2Cr-2Nb alloy
shows better oxidation resistance than that of Ti-47Al-1Cr-1V- 相似文献
5.
According to observed Gamma-ray
fit spectrum,Gamma-ray emission mechanism is analyzed.The upper limit of electron energy
that causes Gamma-ray emission is determined.The electrons obtain energy from synchrotron
absorption acceleration.Theconclusion is that high energy Gamma-ray is the result of
inverse-Compton scattering,and Gamma-rays with different energies radiate from different
regions in the crab nebula. 相似文献
6.
Ma
Siyu 《北京师范大学学报(自然科学版)》2000,36(2):209-212
The optical
nonlinear coefficient of nonlinear glasses is studied by transmission coefficient in a
nonabsorption region or when absorption can be ignored. Numerical relations between
nonlinear coefficient and transmission coefficient are presented. As nonlinear coefficient
increases, the transmission coefficient decreases. The results can be used to analyze the
nonlinearity of glasses embedded with semiconductor quantum dots. 相似文献
7.
黑洞熵公式的简单推导 总被引：4，自引：3，他引：1
Black hole is
treated as 2-D membrane. Starting from the usual state equation of thermal radiation, the
black hole entropy is technically computed, and the result that is proportional to the
area of horizon is briefly obtained. 相似文献
8.
Based on the previous works of
the second author,a kind of finite difference scheme with third-order accuracy for the
homogeneous diffusion equation on non-uniform grid is presented.The proposed scheme is
unconditionally stable. 相似文献
9.
Two models of
molecular cloud in disk galaxies are proposed to investigate the formation of giant
molecular clouds (GMCs) under the gravitational instability and random collision using
PP(Particle-Particle) simulation. Some conclusions can be drawn: 1) The gravitational
instability can make small clouds form large clouds faster than random collision. 2) The
differential rotation in the gravitational instability model plays a positive role in the
agglomeration of molecular clouds. 相似文献
10.
A generalized
formulation of dynamical real-space renormalization-group is suggested. The new version
replaces the single-spin flipping Glauber dynamics with the single-spin transition
dynamics so that it suits for arbitrary spin systems. 相似文献