Laboratory Stand for Simplified Verification of Missile Dynamics for Didactic Purposes

The purpose of this study was to describe dynamics of missile based on bibliography, simplify the model to the easiest form, and verify it with the use of a designed laboratory stand. Next, a simple control system of the missile was designed. The stand is prepared for didactic purposes. A mathematical model was derived by applying Newton's second law together with the earth's coordinate system and the base coordinate system. Parameters of the actual rocket model were determined using the created laboratory stand. Synthesis of the rocket roll system was designed using Simulink PID Tuner application (MathWorks, Inc. Natick, Massachusetts, USA). A control system was based on a proportional-integral (PI) regulator. The designed control system was subjected to simulated tests in MATLAB Simulink (MathWorks, Inc. Natick, Massachusetts, USA).

Quasi-Periodic Oscillations of Roll System in Corrugated Rolling Mill in Resonance

This paper investigates quasi-periodic oscillations of roll system in corrugated rolling mill in resonance. The two-degree of freedom vertical nonlinear mathematical model of roller system is established by considering the nonlinear damping and nonlinear stiffness within corrugated interface of corrugated rolling mill. In order to investigate the quasi-periodic oscillations at the resonance points, the Poincaré map is established by solving the power series solution of dynamic equations. Based on the Poincaré map, the existence and stability of quasi-periodic oscillations from the Neimark-Sacker bifurcation in the case of resonance are analyzed. The numerical simulation further verifies the correctness of the theoretical analysis.

Nonlinear Roll Damping With Coupling Effect in Regular Beam-Wave

Despite of numbers of method to estimate and predict the nonlinear roll damping, it is the mode least understood and the most difficult to determine so far. Reviewing the existing methods reveals that the coupling effects of other modes on roll motion are ignored by assuming just one degree of freedom (1DOF) roll in experiments. The new concept of Most Often Instantaneous Rotation Center - MOIRC proposed by Fernandes and Asgari has brough other parameters, which can help us to improve the roll damping analysis by including the coupling (roll-sway) that results in asymmetric roll responses. This paper, by describing experiments, aims to confirm this roll-sway effect on roll damping coefficient by taking a well posed 3DOF, which allows to follow the instantaneous rotation centers - IRCs. The regular beam-waves experiments were conducted for different frequencies and wave amplitudes. A 3DOF (sway, heave and roll) system identification is used to extract roll damping from the model test. It is shown that the locus of the IRCs follows a straight line and it has a statistical behavior whose probability density function of IRCs with a Cauchy probability density function. For the first time this characteristic is provided experimentally, well matching with the analytical Cauchy distribution.

Adaptive Learning-based Method for Nitrate Sensor Quality Assessment in On-line Scenarios

Nitrate sensors are commonly used to reflect the nitrate levels of soil conditions in agriculture. In a roll-to-roll system, for manufacturing Thin-Film nitrate sensors, varying characteristics of the ion-selective membrane on screen-printed electrodes are inevitable and affect sensor performance. It is essential to monitor the sensor performance in real-time to guarantee the quality of the products. We applied image processing techniques and offline learning to realize the performance assessment. However, a large variation of the sensor’s data with dynamic manufacturing factors will defeat the accuracy of the prediction system. In this work, our key contribution is to propose a system for predicting the sensor performance in on-line scenarios and making the neural networks efficiently adapt to the new data. We leverage residual learning and Hedge Back-Propagation to the on-line settings and make the predicting network more adaptive for input data coming sequentially. Our results show that our method achieves a highly accurate prediction performance with compact time consumption.

Review on Main Drive Torsional Vibration and Roller Coupling Vibration of Rolling Mill

Background: Rolling mill vibration has become one of the most widespread and unsolved problems in rolling industry, which is called "Ghost" vibration. The research on the starting mechanism, vibration characteristics and vibration suppression measures of high-speed tandem rolling mill has always been a hot spot and difficult point in the field of rolling at home and abroad. However, up to now, the research on rolling mill vibration has not formed a relatively complete and widely accepted theoretical system, experimental means and solutions. In production, vibration is often controlled by experience and test, which has high cost and low efficiency. Methods: In this paper, the research history and achievements of vibration phenomena, vibration mechanism, stability of rolling process and vibration control theory of high-speed tandem rolling mill in recent years are summarized. The aim is to reveal the mechanism of rolling mill vibration in continuous rolling process, the mechanism of rolling mill non-linear vibration instability and its changing law, and to explore the optimization of rolling process and the control method of rolling mill structure so as to improve the rolling process. Results: The evolution of non-linear random torsional / bending vibration and its transfer mechanism to the space coupling vibration of the roll system, the unsteady dynamic friction characteristics of the rolling interface and the mechanism of induced roll chatter, and the non-linear random dynamic behavior of the space coupling vibration of the roll system are revealed. Conclusion: The stability of rolling process can realize the research and development of high-end products considering the stability of rolling process, and also provide reference for further research by industry experts.

Calculation and exploitation of active anti-roll system

Today, more and more control systems of motion, are applied to different ships. Between the movement of the ship, the movement by rotation causes serious damage to the ship's equipment and their performance. There have been many efforts to invent or create certain equipment in order to eliminate these adverse effects. However, few types of equipment have had the same impact on the stabilization of the rollers and systems with active wings stabilizers. In the recent years have been carried out more research for the improvement of systems of the stabilizer fins. The anti-roll fins are a stabilization, reducing the rolling in the hull of the vessel using the elevator fin general designed on both borders of the keel.