Study on the working state of the five hundred-meter aperture spherical telescope using step-wise assignment method

2014 ◽  
Vol 229 (2) ◽  
pp. 316-324 ◽  
Author(s):  
Yu Liu ◽  
Feng Gao
Keyword(s):  
Nonlinear Equations ◽  
Analytical Solutions ◽  
Driving Mechanism ◽  
Initial Value ◽  
Unknown Parameters ◽  
Support Structure ◽  
Assignment Method ◽  
New Type ◽  
Set Up ◽  
The Mathematical Model

The working state of the five hundred-meter aperture spherical telescope (FAST) is solved using the step-wise assignment method. In this paper, the mathematical model of the cable-net support structure of the FAST is set up by the catenary equation. There are a large number of nonlinear equations and unknown parameters of the model. The nonlinear equations are solved by using the step-wise assignment method. The method is using the analytical solutions of the cable-net equations of one working state as the initial value for the next working state, from which the analytical solutions of the nonlinear equations of the cable-net for each working state of the FAST and the tension and length of each driving cable can be obtained. The suggested algorithm is quite practically well suited to study the working state of the cable-net structures of the FAST. Also, the working state analysis result of the cable-net support structure of a reduced model of the cable-net structure reflector for the FAST is given to verify the reliability of the method. In order to show the validity of the method, comparisons with another algorithm to set the initial value are presented. This method has an important guiding significance to the further study on the control of the new type of flexible cable driving mechanism, especially the FAST.

Theoretical and Experimental Study of the Dynamics of the Tripod-Ball Sliding Joint With Clearance

2001 ◽  
Author(s):  
Jia Xiaohong ◽  
Ji Linhong ◽  
Jin Dewen ◽  
Zhang Jichuan
Keyword(s):  
Mathematical Model ◽  
Equations Of Motion ◽  
Experimental Studies ◽  
Active System ◽  
New Concepts ◽  
Sliding Joint ◽  
New Type ◽  
Set Up ◽  
The Mathematical Model ◽  
Kane Method

Abstract Clearance is inevitable in the kinematic joints of mechanisms. In this paper the dynamic behavior of a crank-slider mechanism with clearance in its tripod-ball sliding joint is investigated theoretically and experimentally. The mathematical model of this new-type joint is established, and the new concepts of basal system and active system are put forward. Based on the mode-change criterion established in this paper, the consistent equations of motion in full-scale are derived by using Kane method. The experimental rig was set up to measure the effects of the clearance on the dynamic response. Corresponding experimental studies verify the theoretical results satisfactorily. In addition, due to the nonlinear elements in the improved mathematical model of the joint with clearance, the chaotic responses are found in numerical simulation.

Research and Design of In-Arm Torsional Electromagnetic Active Suspension

2019 ◽  
Author(s):  
Chengleng Han ◽  
Lin Xu ◽  
Mohamed A. A. Abdelkareem ◽  
Enkang Cui ◽  
Junyi Zou ◽  
...  
Keyword(s):  
Characteristic Curve ◽  
Body Height ◽  
Active Suspension ◽  
Small Scale ◽  
Unknown Parameters ◽  
Body Attitude ◽  
New Type ◽  
Stiffness And Damping ◽  
The Mathematical Model ◽  
Research And Design

Abstract This paper introduced a new type of an active suspension named as In-Arm Torsional Electromagnetic Active Suspension (ITEAS) according to its suspension characteristics. The proposed ITEAS is capable of actively controlling body attitude and adjusting the stiffness and damping of a suspension system in a larger scale. The structure of the ITEAS system is composing of a mechanical displacement adjustment device, a two-chamber vane damper connected by an electromagnetic valve, two torsion bars and necessary connection units such as trailing arms. Based on the hydraulic theory and fluid mechanics, the mathematical model of the vane damper was established and the external characteristic curve of the damper was obtained through the simulations. Regarding to the ITEAS stiffness and damping analysis, a quarter dynamic vehicle model was established and simulated by the AMESim platform. The results showed that the automobile ride based on the ITEAS system was reasonable as well as the functions of body height adjustment and suspension controllability were available. Thereafter, a small-scale prototype has been built to calibrate the unknown parameters for further research on ITEAS.

Dynamics and Stability of Non-Planar Rigid Rotor Equipped with Two Ball-Spring Autobalancers

2019 ◽  
Vol 19 (02) ◽  
pp. 1950001 ◽  
Author(s):  
Mousa Rezaee ◽  
Mir Mohammad Ettefagh ◽  
Reza Fathi
Keyword(s):  
Mathematical Model ◽  
Nonlinear Equations ◽  
Equations Of Motion ◽  
Rigid Rotor ◽  
Out Of Plane ◽  
New Type ◽  
Nonlinear Equations Of Motion ◽  
The Mathematical Model ◽  
System Time

Recently, a new type of automatic ball balancer (ABB), called the ball-spring autobalancer (AB), has been proposed, which substantially eliminates the drawbacks of the traditional ABBs. In previous studies, the dynamics of the Jeffcott planar rotor equipped with ball-spring AB has been investigated. In the Jeffcott model, it is assumed that the ABB is located on the plane of the unbalance disk. However, for the non-planar rigid rotor with distributed imbalances, out-of-plane motions may occur, and the Jeffcott model becomes unreliable as the tilting motion cannot be explained. To this end, the aim of this paper is to analyze the capability of the ball-spring AB in balancing non-planar rotors and to reconfirm its pre-claimed advantages over the traditional ABBs for balancing non-planar rotors. To start, the mathematical model of the rigid rotor with two ball-spring ABs is established, based on which the nonlinear equations of motion are derived. Then, the system time responses are computed numerically and the balanced stable regions are acquired by the Lyapunov’s first method. The results of this study show that the ball-spring ABs can balance the non-planar rotors and the tilting motion does not impair the pre-claimed advantages of the ball-spring AB.

Fixture Optimization for Robotic Belt Grinding System

2011 ◽  
Vol 121-126 ◽  
pp. 2030-2034
Author(s):  
Dong Zhang ◽  
Chao Yun ◽  
Ling Zhang
Keyword(s):  
Mathematical Model ◽  
Optimization Methods ◽  
Belt Grinding ◽  
Robotic Grinding ◽  
The Monte Carlo Method ◽  
New Type ◽  
Set Up ◽  
Robotic Belt Grinding ◽  
The Mathematical Model ◽  
Grinding System

The precision is impacted when the robotic grinding path is discontinuous and the gripper needs to be replaced during manufacturing. In order to solve this problem, a new type PPPRRR grinding robot was proposed. The mathematical model for the robotic grinding paths was set up. The factors including the pose of the workpiece respect to the end joint and the position of contact wheel respect to the robot base frame {O}were analyzed to influence the grinding ability of the system. Base on the Monte Carlo method the posture and position factors above had been optimized, and the grinding ability of the system was increased. The optimization methods were proved right and workable by grinding golf head experiment.

The Study of the Initial State of Cable-Net Structure Reflector for the FAST

2012 ◽  
Author(s):  
Yu Liu ◽  
Feng Gao
Keyword(s):  
Mathematical Model ◽  
Variational Principle ◽  
Nonlinear Equations ◽  
Layer By Layer ◽  
Initial State ◽  
Main Cable ◽  
Highly Nonlinear ◽  
Node Location ◽  
Set Up ◽  
The Mathematical Model

By using the variational principle to set up the mathematical model of the reflector for the FAST, we can get the node location of the cable-net and tension of the main cable by solving highly nonlinear equations of the mathematical model. A new layer-by-layer substitution approach has been proposed for solving the highly nonlinear equations, through the calculation and simulation it verifies the correctness of this method.

Experimental test of vision-based navigation and system identification of an unmanned underwater survey vehicle (SAGA) for the yaw motion

2019 ◽  
Vol 41 (8) ◽  
pp. 2160-2170 ◽  
Author(s):  
Seda Karadeniz Kartal ◽  
M. Kemal Leblebicioglu ◽  
Emre Ege
Keyword(s):  
Mathematical Model ◽  
System Identification ◽  
Navigation System ◽  
Unknown Parameters ◽  
Navigation Data ◽  
State Measurement ◽  
Suitable Combination ◽  
Set Up ◽  
Parameter Values ◽  
The Mathematical Model

In this study, a nonlinear mathematical model for an unmanned underwater survey vehicle (SAGA) is obtained. The structure of the mathematical model of the vehicle comes from a Newton–Euler formulation. The yaw motion is realized by a suitable combination of right and left thrusters. The navigation problem is solved by using the inertial navigation system and vision-based measurements together. These are integrated to more accurately obtain navigation data for the vehicle. In addition, the magnetic compass is used to support the attitude information of the vehicle. A pool experimental set-up is designed to test the navigation system. Performance of the resultant navigation system can be analysed by creating suitable system state, measurement and noise models. The navigational data for the vehicle has been improved using a Kalman filter. The mathematical model of the vehicle includes some unknown parameters such as added mass and damping coefficients. It is not possible to determine all the parameter values as their effects on the state of the system are usually negligible. On the other hand, most of the ‘important’ parameters are obtained based on a system identification study of the vehicle using this estimated navigational data for coupled motion. This study is performed in a MATLAB/Simulink environment.

Mathematical Models of Papermaking

2001 ◽  
Vol 6 (1) ◽  
pp. 9-19 ◽  
Author(s):  
A. Buikis ◽  
J. Cepitis ◽  
H. Kalis ◽  
A. Reinfelds ◽  
A. Ancitis ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Initial Value Problems ◽  
Moisture Transfer ◽  
Bound Water ◽  
Drying Process ◽  
Initial Value ◽  
First Order ◽  
Heat And Moisture ◽  
The Mathematical Model ◽  
The Web

The mathematical model of wood drying based on detailed transport phenomena considering both heat and moisture transfer have been offered in article. The adjustment of this model to the drying process of papermaking is carried out for the range of moisture content corresponding to the period of drying in which vapour movement and bound water diffusion in the web are possible. By averaging as the desired models are obtained sequence of the initial value problems for systems of two nonlinear first order ordinary differential equations. 

Research on Dynamic Balance Method of Precision Centrifuge

2014 ◽  
Vol 945-949 ◽  
pp. 777-780
Author(s):  
Tao Liu ◽  
Yong Xu ◽  
Bo Yuan Mao
Keyword(s):  
Mathematical Model ◽  
Balance Control ◽  
Dynamic Balance ◽  
Dynamic Balancing ◽  
Structure Characteristics ◽  
Balance System ◽  
Simulation Results ◽  
Set Up ◽  
System Controller ◽  
The Mathematical Model

Firstly, according to the structure characteristics of precision centrifuge, the mathematical model of its dynamic balancing system was set up, and the dynamic balancing scheme of double test surfaces, double emendation surfaces were established. Then the dynamic balance system controller of precision centrifuge was designed. Simulation results show that the controller designed can completely meet the requirements of precision centrifuge dynamic balance control system.

Evaluation of a personal professional mentor scheme for newly qualified nurses

2021 ◽  
Vol 30 (11) ◽  
pp. 672-676
Author(s):  
Charlotte Austin ◽  
Yvonne Halpin
Keyword(s):  
Thematic Analysis ◽  
Structured Interview ◽  
Potential Outcomes ◽  
Experienced Nurses ◽  
Support Strategies ◽  
Supportive Role ◽  
New Type ◽  
Experienced Nurse ◽  
Set Up ◽  
Pastoral Support

Background: Newly qualified nurses are known to experience a range of feelings and fears in the first transitional 12 months post-qualifying, with absence and turnover among potential outcomes. Aim: To evaluate the personal professional mentor role and scheme, a new pastoral support initiative, from the perspective of participating newly qualified nurses. Methods: Newly qualified paediatric nurses (n=10), who had been assigned a personal professional mentor (an experienced nurse who worked elsewhere in their employing NHS Trust), completed a semi-structured interview. The data were analysed using thematic analysis. Findings: The personal professional mentor counteracted some aspects of transition isolation for the newly qualified nurses. They were an independent, accessible, experienced confidant and a welcome new supportive role. Conclusion: Pairing experienced nurses with newly qualified nurses provided a new type of workplace support during transition. Inexpensive to set up and run, it is an easy addition to any portfolio of support strategies.

Annihilation Lifetime Spectroscopy Using Positrons from Bremsstrahlung Production

2012 ◽  
Vol 331 ◽  
pp. 41-52 ◽  
Author(s):  
Andreas Wagner ◽  
Wolfgang Anwand ◽  
Maik Butterling ◽  
Thomas E. Cowan ◽  
Fine Fiedler ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Linear Accelerator ◽  
Electron Accelerator ◽  
Positron Annihilation Spectroscopy ◽  
Doppler Broadening ◽  
Electron Linear Accelerator ◽  
Positron Annihilation Lifetime ◽  
Electron Bremsstrahlung ◽  
New Type ◽  
Set Up

A new type of a positron annihilation lifetime spectroscopy (PALS) system has been set up at the superconducting electron accelerator ELBE [ at Helmholtz-Zentrum Dresden-Rossendorf. In contrast to existing source-based PALS systems, the approach described here makes use of an intense photon beam from electron bremsstrahlung which converts through pair production into positrons inside the sample under study. The article focusses on the production of intense bremsstrahlung using a superconducting electron linear accelerator, the production of positrons inside the sample under study, the efficient detector setup which allows for annihilation lifetime and Doppler-broadening spectroscopy simultaneously. Selected examples of positron annihilation spectroscopy are presented.

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