JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY

Estimates of Reliability of Some Failure-Success Compcments Using the Virtual System Method

Dai Ming

1997, 6(2): 101-105.

[Abstract](166)

Abstract:
Using the virtual system method (V5), estirnates of reliability of failure-sumess components that change with store time are disciased, together with their small sample property.

Stability for the Manifold of Equilibrium State of the Autonomous Birkhoff System

Mei Fengxiang

1997, 6(2): 106-109.

[Abstract](181) [PDF 200KB](3)

Abstract:
Studies the stability for them manifold of equilibrium state of the autonomous Birkhoffsystem. Uses the Liapunov's direct method and the first approximation method to obtain thestability criterion for the manifold of equilibrium state of the system. Gives an example toillustrate the application of the result.

A Study on the Double Semi-Active Vibration Isolation System

Li Cuiying, Wang Shuyong

1997, 6(2): 110-117.

[Abstract](174)

Abstract:
This paper puts forward the concept of double semi-active vibration isolation systemutilizing the "on-off" active damper and the "on-off" active spring. Applying KBM Asympto-tic method, the vibration of the system in case of weak semi-active control is studied. ln pcactice, there are two types of vibration isolation. One is to isolate the transmitting of the cyclicunbalanced force generated by the revolving machine to the surroundings. The other is to isolatethe transmitting of the vibration displacement of the surroundings to precise equipment. Deduc-ing the influence of the roadway unflatness on vehicles also belongs to this type. For the firsttype of isolation system, the damper always dissipates energy, and the total work done by the spring in a vibration cycle is zero. For the second type of isolation system, the work done by the damper sometimes is positive, and sometimes negative. The damper dissipates less energy. The work done by the spring in a vibration cycle isn't zero, and it is usually positive. ln thispaper, the vibration isolation is refered to the second type. .

Dynamic Path-Independent J-Integral and Its Dual Form in Elastic-Plastic Solids with Deformation

Wu Xiangfa, Fan Tianyou, Zhang Liangxin

1997, 6(2): 118-123.

[Abstract](191)

Abstract:
This paper presents the dynamic path-independent J-integral and its dual form in elastic-plastic solids with finite deformation (FD). Then based on the basic equations of elastic-plastic solids with FD and the principles of potential and residual, the reasoning of their path-independence is given.On the condition of small deformation (SD) or elastostatics the new integral forms can freturn to the forms of SD or elastostatics. so that the uniform dynamic path-independent J-integral and its dual form suitable to both SD and FD is founded and the applicable domain of dynamic J-integral in fracture is extended.

Motion Stability of a One-Link Torso Model Under Muscular Coactivation

Guo Qiao

1997, 6(2): 124-129.

[Abstract](239)

Abstract:
Stability of movement of a one-link human torso model is discussed. Three pair; of actuators control the model. The actuators hate physiological attributes of muscles with their tension related to excitation, length and locity. Coactivation and intrinsic feedback are used so as to achiey stability of the system, and for optimizing the performance of the system under constraints. The coactivation of muscles can provide robustness of the performance of the system.

Stability of Orifice-Annular and Shallow一Pocket Restricted Floating Ring Gas Bearing

Zhang Ruiqian, Zhang Xisheng

1997, 6(2): 130-137.

[Abstract](209)

Abstract:
The stability of orifice-annular and shallow-pocket restricted floating ring gas journal bearing is theoretically analyzed by use of the modified 8-stiffness and damp coefFcients method. The trends of the rotor dimensionless critical mass, varying with the cleaCanoe ratio C2 / C the ratio m₂/m₁the sing speed ratio cot/co, and the supply pressure PS are presented. The theoretical results are in agreement with Wang Y F's experimental results.

On the Parametric Design of Electromechanical Actuators

Yang Shuxing, Zhong Ping

1997, 6(2): 138-144.

[Abstract](224) [PDF 324KB](13)

Abstract:
The load locus of an electromechaical actuator at yen frequency bandwidth is studied and the influences of some key parameters such as the frequency bandwidth，the gear ratio on the load loots are discussed. Some oonclusiorn on the parametric des of the actuator are drawn out and an example is given to show how to use the conclusions in the later designs.

Control of a Constant Force and Position System

Yao Xiaoxian, Feng Hui

1997, 6(2): 145-152.

[Abstract](247)

Abstract:
Introducing a kind of force and position control system, the paper method to construct the system fuzzy control rules, and disscusses the relations between the membership functions and the characters of digital valves. To improve the control accuracy, a non-linear amplifier is applied to tune membership distrtbutions under conditions that the membership functions are fixed. A number of experiments were carried out with satisfactory results.

Control of Self-Motion and Optimization of Dynamic Performance for Redundant Manipulators

Zhao Zhanfang, Shi Xiaolun, Zhang Qixian, Lu Jilian

1997, 6(2): 153-162.

[Abstract](186)

Abstract:
Problems arise when most existing algorithms of redundant robotic manipulators are used for the optimization of dynamic parameters. One of such problems is the uncontrolled self-motion in the joint space of the manipulator. This paper analyzes the reasons causing undesirable self-motion and presents two approaches which can be used to handle the problem Fectily. In addition, the methods can be used to the norm of joint velocities and optimize applied torque distribution and thus the dynamic performance of redundant robot ran be significantly improved.

A Dual-Space Approach for Optimization of Dynamic and Kinematic Performance of Redundant Manipulators

Zhao Zhanfang, Shi Xiaolun

1997, 6(2): 163-172.

[Abstract](210) [PDF 499KB](2)

Abstract:
One of the problems in most existing algorithms for optimizing dynamic parameters of redundant robotic manipulator; is the inadequate consideration of redundancy-related kine-matics, such as avoidance of obstacle, singular configuration and the joint motion limits. Thispaper introduces a method based on the concept of dual-space of the Jacobian matrix to resolve the problem. Based on the method, lcinematic parameters can be optimized in the lacobian space with a higher priority. In the time, dynamic optimization such as optimization of applied torque distribution can be achieved by adjusting joint movement in the null space of the Jacobian matrix. Implementation through computer simulation demonstrates that the proposed methods are efFective and can be used to optimize simultaneously both the lcinematir and dynamic narametecs of redundant manipulator.

Integrated System Framework Supporting Concurrent Engineeringt

Wu Ruijun, Ning Ruxin

1997, 6(2): 173-179.

[Abstract](223)

Abstract:
This paper presents a concurrent engineeiing framework for CAD/CAPP/CAM inte-grated system, introduces the components of integration tools, integrated product information model, process model of product development, and cooperative work system of the framework.Under the unified user interface of the framework, multi-disciplinary team members can use their tools respectively to conduct concurrent product development. Each related element of product development begins cooperation from the outset, conducts open and real time data exchanging and sharing. To evaluate and refine the product design and manufachue process as well as support activities, the team can hold multimedia meeting through multimedia network meeting system, and negotiate by using project coordination system.

Analysis of Stochastic Response of Rotational Shell Considering Its Constitutive Nonlinearity

Gao Shiqiao, Niemann H J, Qu Kebo

1997, 6(2): 180-186.

[Abstract](177)

Abstract:
A relatively simple nonlinear fracture model of reinforoed concrete was established.To deal with the stochastic nonlinear problem, an iterative statistic linearization method (ISLM)was used and developed.

1997 Vol. 6, No. 2