Dynamic model orbits and Earth system parameters from combined GPS and LEO data

2005 ◽  
Vol 36 (3) ◽  
pp. 431-437 ◽  
Author(s):  
R. König ◽  
Ch. Reigber ◽  
S.Y. Zhu
Keyword(s):  
Dynamic Model ◽  
Earth System ◽  
System Parameters

scholarly journals Nonlinear modeling and stability analysis of a pilot-operated valve-control hydraulic system

2018 ◽  
Vol 10 (11) ◽  
pp. 168781401881066 ◽  
Author(s):  
Wei Wei ◽  
Hongchao Jian ◽  
Qingdong Yan ◽  
Xiaomei Luo ◽  
Xuhong Wu
Keyword(s):  
Dynamic Model ◽  
Hydraulic System ◽  
Nonlinear Modeling ◽  
Orifice Diameter ◽  
Operating Pressure ◽  
Nonlinear Dynamic Model ◽  
System Parameters ◽  
Excited Vibration ◽  
The Stability ◽  
Valve Control

A nonlinear dynamic model is developed to analyze the stability of a pilot-operated valve-control hydraulic system. The dynamic model includes motion of the valve spool and fluid dynamics in the system. Characteristics such as pressure flow across the valve port and orifices, pressure, and flow rate in valve chambers are taken into consideration. Bifurcation analysis is proposed and examined by numerical simulation results when the feedback orifice diameter changes. The effects of different system parameters such as pilot-operating pressure, spring stiffness, and overlap of inlet port on the stability border of the system are studied by two-dimensional bifurcation analyses. The study identifies that bifurcation can occur in the system and lead to sustained self-excited vibration with parameters in certain region of the parameter space. It suggests that the vibration can be effectively predicted and prevented by selecting system parameters from the asymptotic stable parameter region.

Optimum Design of Elastically Supported Gyroscopes for Ship Stabilization

1984 ◽  
Vol 106 (4) ◽  
pp. 387-392
Author(s):  
K.-N. Lee ◽  
A. Seireg
Keyword(s):  
Optimal Design ◽  
Dynamic Model ◽  
Optimum Design ◽  
Design Procedures ◽  
System Parameters ◽  
Ship Roll ◽  
Elastically Supported ◽  
Elastic Spring

The study reported in this paper deals with the development of a dynamic model for the analysis of elastically supported gyroscopic absorber systems for ship stabilization. The gryoscopes are mounted on elastically supported platforms at the fore and aft ends of the ship to minimize both the roll and pitch movements. Springs and dampers are also utilized between the gyroscope gimbal and the platform. Several design configurations of the absorber are considered. Optimal design procedures are utilized to find the system parameters for best performance in each case. The performance of the resulting optimum absorber shows that introducing the elastic spring and damper between the gimbal and platform has a significant effect on reducing the ship-roll action.

scholarly journals Experimental Active Vibration Control in Truss Structures Considering Uncertainties in System Parameters

2008 ◽  
Vol 2008 ◽  
pp. 1-14 ◽  
Author(s):  
Douglas Domingues Bueno ◽  
Clayton Rodrigo Marqui ◽  
Rodrigo Borges Santos ◽  
Camilo Mesquita Neto ◽  
Vicente Lopes
Keyword(s):  
Vibration Control ◽  
Dynamic Model ◽  
Electromechanical Coupling ◽  
Active Vibration Control ◽  
Experimental Methodology ◽  
Truss Structures ◽  
Linear Matrix ◽  
System Parameters ◽  
Identification Method ◽  
Active Vibration

This paper deals with the study of algorithms for robust active vibration control in flexible structures considering uncertainties in system parameters. It became an area of enormous interest, mainly due to the countless demands of optimal performance in mechanical systems as aircraft, aerospace, and automotive structures. An important and difficult problem for designing active vibration control is to get a representative dynamic model. Generally, this model can be obtained using finite element method (FEM) or an identification method using experimental data. Actuators and sensors may affect the dynamics properties of the structure, for instance, electromechanical coupling of piezoelectric material must be considered in FEM formulation for flexible and lightly damping structure. The nonlinearities and uncertainties involved in these structures make it a difficult task, mainly for complex structures as spatial truss structures. On the other hand, by using an identification method, it is possible to obtain the dynamic model represented through a state space realization considering this coupling. This paper proposes an experimental methodology for vibration control in a 3D truss structure using PZT wafer stacks and a robust control algorithm solved by linear matrix inequalities.

Vibration-Induced Loosening and Tightening of Threaded Fasteners

1995 ◽  
Author(s):  
Daniel P. Hess
Keyword(s):  
Dynamic Model ◽  
Nonlinear Interaction ◽  
Low Frequency ◽  
Harmonic Vibration ◽  
Static Equilibrium ◽  
Equilibrium Conditions ◽  
System Parameters ◽  
Threaded Fasteners

Abstract Previous analyses of threaded fasteners under vibration are based on static equilibrium conditions with supporting data limited to low frequency loading. Such analyses predict only a net loosening action. This paper presents a dynamic model of a single-bolt assembly with moderate pre-load subjected to axial harmonic vibration. Simulations with this model predict that threaded fasteners can, on the average, loosen or tighten in the presence of vibration; and that the applied vibration, as well as other system parameters, can be tuned so that either action occurs. The model elucidates the nonlinear interaction of friction and vibration of such systems. Measurements from a single-bolt assembly apparatus are presented and compared with the simulations.

Research and Design of a Novel Mobile Police Station

2012 ◽  
Vol 605-607 ◽  
pp. 341-345
Author(s):  
Xiang Yang Zhao ◽  
Xia Yuan ◽  
Yun Lou
Keyword(s):  
Dynamic Model ◽  
Design Theory ◽  
Performance Test ◽  
Vehicle Design ◽  
Electrical System ◽  
Vehicle Performance ◽  
Police Station ◽  
System Parameters ◽  
Calculation Results ◽  
Research And Design

By studying the design theory of the mobile police station (MPS), the dynamic model of the MPS basic computing has been built then a novel MPS is designed. This kind of MPS, which consists of battery, chassis, body and electrical system, uses electric vehicle as the carrier and in combination with police needs is equipped with a variety of police equipment to meet the needs of establishing a modern police. The vehicle performance test has been done. The results prove that the performance of the MPS has reached the technical level of the Ministry of Science and Technology, showing the vehicle design is reasonable, and the matching calculation results of the electrical system parameters are basically the same as the experimental results.

Dynamic Loosening and Tightening of a Single-Bolt Assembly

1997 ◽  
Vol 119 (3) ◽  
pp. 311-316 ◽  
Author(s):  
D. P. Hess ◽  
S. V. Sudhirkashyap
Keyword(s):  
Dynamic Model ◽  
Low Frequency ◽  
Harmonic Vibration ◽  
Static Equilibrium ◽  
Equilibrium Conditions ◽  
System Parameters ◽  
Threaded Fasteners

Previous analyses of threaded fasteners under vibration are based on static equilibrium conditions with supporting data limited to low frequency loading. Such analyses predict only a net loosening action. This paper presents a dynamic model of a single-bolt assembly with moderate pre-load subjected to axial harmonic vibration. Simulations with this model predict that threaded fasteners can, on the average, loosen or tighten in the presence of vibration; and that the applied vibration, as well as other system parameters, can be tuned so that either action occurs. Measurements from a single-bolt assembly apparatus are presented and compared with the simulations.

Analysis of Friction Effect on Dynamic Characteristics of Artificial Feel System

2013 ◽  
Vol 401-403 ◽  
pp. 460-464
Author(s):  
Hong Jun Xue ◽  
Huo Gen Wu ◽  
Xiao Yan Zhang
Keyword(s):  
Mathematical Model ◽  
Dynamic Model ◽  
Dynamic Characteristics ◽  
Flight Control ◽  
Trial Data ◽  
Equivalent Model ◽  
Flight Control System ◽  
System Parameters ◽  
Model Method ◽  
The Mathematical Model

A complete mathematical model of artificial feel system of a vehicle fly by wire flight control system was established after analyzing the heading mechanical structure of it. Modeling it by means of centralizing the distributed system parameters and establishing it to dynamic model, the nonlinear factors such as clearance and friction in the system were simplified reasonably. To establish a corresponding mathematical model, the dynamic model was established by means of dynamic equivalent model method resulting in a multi-freedom model. The mathematical model was simulated in Matlab/Simulink by modular way, and results were consistent to trial data. Friction as an important nonlinear factor have impact on system performance, analysis of its effect on dynamic characteristics of human feel system were in the condition of inputting different forms and amplitude signal . This provided guidance for designing system.

A method for selecting driving system parameters of a new electric shovel's excavating mechanism with three-DOF

2011 ◽  
Vol 225 (11) ◽  
pp. 2661-2672 ◽  
Author(s):  
B Wei ◽  
F Gao ◽  
J Chen ◽  
J He ◽  
X Zhao
Keyword(s):  
Dynamic Model ◽  
Degrees Of Freedom ◽  
Virtual Work ◽  
Transmission Ratio ◽  
Principle Of Virtual Work ◽  
Driving System ◽  
Generalized Coordinates ◽  
System Parameters ◽  
Three Degrees Of Freedom ◽  
Selection Of

Driving system parameters include motor parameters and transmission ratio of the reducer. In this study, a new three-degrees-of-freedom parallel excavating mechanism of electric shovel is analysed for the selection of its driving system which consists of three sub-driving parts. Based on the principle of virtual work in the form of generalized coordinates, the dynamic model of the excavating mechanism is established to calculate the external inertia loads and force (or torque) loads. For this parallel excavating mechanism which has three sub-drives, the external inertia loads cannot be fully divided into three independent parts with respect to these three sub-driving systems. Hence, the dynamic model of the system is employed to get loads characteristic of three sub-driving systems in the excavating process. Thus, the parameters' range of the motors can be obtained and then the best transmission ratio of every reducer can be obtained.

A Parameter Sensitivity Analysis for the Dynamic Model of a Variable Displacement Axial Piston Pump

1987 ◽  
Vol 201 (4) ◽  
pp. 235-243 ◽  
Author(s):  
S D Kim ◽  
H S Cho ◽  
C O Lee
Keyword(s):  
Sensitivity Analysis ◽  
Dynamic Model ◽  
Parameter Sensitivity ◽  
Piston Pump ◽  
Axial Piston Pump ◽  
Parameter Sensitivity Analysis ◽  
System Parameters ◽  
Non Linear ◽  
Variable Displacement ◽  
Axial Piston

Sensitivity analysis is applied to an investigation of the influence of parameters on the dynamics of a variable displacement axial piston pump. Since an exact mathematical model of piston pump is complex and highly non-linear, the investigation of its dynamic characteristics for the variation of the system parameters by changing separate parameter values in sequence becomes very ineffective. In this paper a parameter sensitivity analysis was employed to analyse the effects of the system parameters systematically. The analysis was done on the exact non-linear dynamic model of the pump system which is represented by fourth-order dynamics. Based upon the simulation results, the degree of influence of each parameter and the justification of order reduction are discussed in some detail.

scholarly journals System description of the defect creation and elimination in the buildings

2018 ◽  
Vol 146 ◽  
pp. 01011 ◽  
Author(s):  
Dalibor Vytlačil
Keyword(s):  
System Dynamics ◽  
Dynamic Model ◽  
Facility Management ◽  
System Description ◽  
System Parameters ◽  
Running Cost ◽  
Defect Elimination ◽  
Dynamics Method ◽  
Parameters Calculation ◽  
Flow Element

The paper deals with the dynamics of the system of defects creation in the buildings and also with the possibilities of the defects elimination. The problem is described by the dynamic model that includes key elements influencing the system behaviour. The model is based on the system dynamics method that uses the stock elements and the flow elements which change the stock element values. In the described problem the main stock is the number of the equipment defects. This parameter can be increased by the flow element that depends on the time of using and the load. For the defect elimination are two possibilities: the planned maintenance and the repair of broken parts. Other elements are number of workers available for the elimination of defects and the running cost depending on the maintenance effort. The case of the main system parameters calculation is presented. The model can be used for understanding the importance of the maintenance in the field of facility management.

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