Papers by Keyword: Dynamic Model

Abstract: The melting process in the glass industry is an energy-intensive process that uses fossil fuels to maintain melting temperatures between 1600°C and 1700°C. The process is carried out in the Glass Furnace. Obtained the high temperature also of flue gas is around 1350 °C – 1500 °C. Hence with the high temperature is potential to heat recovery in the form of combustion air pre-heating using a regenerator to increase the efficiency in Glass Furnace. This phenomenon gave rise to an idea to create a modelling mathematic to know the optimum process in Glass Furnace. Many studies on Glass furnace regenerator have been carried out but only for one cyclic of heat transfer in regenerator. Therefore, in this study, dynamic modeling of the regenerator will be made, namely a mathematical model that describes quantitatively the dynamic behavior during the process of reversing the direction between the regenerators, which will later explain the effect of air flow rate and the selection of the optimal transition time value for the demonstration, regenerator work and regenerator heat stability, by observing the dynamic behavior of the regenerator temperature profile using the FlexPDE software version 7. The simulation results show that the longer the switching time of regenerator is linier to inclining temperature in the regenerator with the optimum switching time (ST) at 10 minutes. The regenerator heat stability greatly influenced by air flow rate and heat propagation by heat transfer convection. However, the dimension selection of the regenerator plays a crucial role in heat utilization in glass furnaces.

Abstract: In the work, a variant of mathematical modeling of the solution of the heat transfer problem was developed, analytical analysis of the dependencies of the parameters of technological parameters was carried out to determine the parameters of current pulses that ensure a uniform distribution of current density over the treated surface. A diagram of the stages of constructing a complete mathematical model of the ECDP process (electrochemical dimensional processing) of titanium, aluminum, and their alloys is given. The above equations reflect the theory of mass transfer processes, include the temperature parameter. The limitations of the possibility of carrying out the treatment process are modeled, the peculiarities of formation and development of the gas-liquid layer, changes in its physical properties, and violation of the treatment stability are taken into account. It has been found that to eliminate the processing instability associated with the appearance of turbulence in the electrode reaction zone due to the large gas filling of the interelectrode gap, a series of relationships must be considered DT = f (i, Q, t_imp) to determine optimal parameters of pulse current.

Abstract: In this study, the nonlinear dynamic analysis of the motion and control of the lower limb exoskeleton using differential transform method is presented. Devices for medical processes are continuously undergoing improvement such as enhancing and assisting automatic therapies with flexible and configurable programs for treating people with partial disability in lower limbs as applied in lower-limb exoskeleton. The configurable programs in this exoskeleton can be applied to observe and control the motion of the exoskeleton for effective physiotherapy and reduced rehabilitation time for patients with such disability. Hence, a two degree of freedom nonlinear dynamic model for the motion and control of the lower limb exoskeletons was developed for two links. The nonlinear dynamic models are solved by applying the differential transform method (DTM) and verified with the forth order Runge-Kutta numerical method (RK4). The effects of the applied torque on the two links are investigated and it is observed that Link 1 has large negative deflection amplitude that drives link 2 towards the opposite positive direction. An increase in the applied torque resulted in increase in the amplitude of the system for all initial condition considered. This in turns increases the nonlinear dynamic behavior of link 2 due to its lower mass value. The speed of both links dampens out over the history due to the presence of damping term. At equilibrium, both links are in phase and have the same amplitude over the time history. This study provides an analytical tool for observing and controlling the motions of the lower limb exoskeleton and for improving the designs of the medical device.

Abstract: The paper gives a general description of the dynamic model of the blast-furnace process that enables to calculate transition processes of the blast furnace thermal state, evaluated by the content of silicon in hot metal. It provides calculation results of the transition processes to be subjected to changes in control actions: ore load from the top and oxygen concentration in blast, natural gas flow rate and hot blast temperature from the bottom. Specific features of these transition processes during blast-furnace smelting are analyzed. The paper shows that the dynamic characteristics of blast furnaces change are subjected to control actions and depend significantly on properties of melted raw materials and operating parameters of blast furnaces. The oscillatory transition process in the blast furnace is observed in the case after disturbance it has an opposite influence on the thermal state of the lower and uppers stages of heat exchange. The paper presents prediction results of the silicon content in hot metal. It gives practical recommendations for selection of control actions.

Abstract: Due to the problems that the rolling force of seamless steel tube during tandem rolling process is affected by many factors, the calculation is complex and the accuracy is not enough. In order to improve the rolling force calculation accuracy of the tandem rolling mill, analyze the metal flow, stress distribution rules and cross section deformation characteristics during the rolling process of seamless steel tube, calculation of the rolling force was divided into the reduced-diameter area and the reduction of wall area, and a new calculation method was proposed, which concerns the rolling force in reduced-diameter area related to the material yield stress, friction coefficient and the crushing stress of the tube, while the rolling force in the reduction of wall area is only related to the material yield stress and the friction coefficient. The results show that the calculated rolling force is in agreement with the measured values with errors less than ±10%. The model satisfies the actual conditions and is applicable to engineering application.

Abstract: This paper dedicated of introduction of dynamic model of improved mechanical system of sensor of atomic force microscope. The subject of the research is enhancement of dynamic characteristics of cantilever - main mechanical part of sensor. These characteristics defines frequency of oscillations of mentioned cantilever and are main limitations of the speed of scanning procedure of the microscope. Modification of original dynamic system of atomic force microscope made adding nonlinear additional stiffness, created by stream of compressed air. In order to determine dynamic characteristics of modified system there are necessary to create corresponding dynamic model. Parameters of such model were defined using experimental research and theoretically from 3-D model of microscope cantilever. Solution of this model brings dependencies between air gap, pressure of compressed air and oscillation frequency of cantilever. Finally, results there are presented and conclusions are drawn.

Abstract: In the long-term monitoring period, the structural health monitoring (SHM) system produces a huge amount of monitoring data. It becomes a very important thing that how to real-timely predict structural reliability indices from such huge number of monitored data. In this paper, To real-timely predict reliability of bridge members with real-time monitoring information, with the long-term mass monitored data of health monitoring system, the data-based dynamic model including observation equation and state equation is built, and then the mixed Gaussian particle filter (MGPF) is introduced. With particle filter method, Bayesian method and dynamic model, the posteriori distribution parameters of state variable and one-step forward prediction distribution parameters of monitored data are predicted. Through resampling technique, with MGPF, the prediction precision of dynamic model can generally increase. Based on the dynamic monitored data, the weights of resampled particles can be constantly updated. Therefore the problem of particle degradation is solved. Finally based on the real-time predicted distribution parameters, with the first order second moment (FOSM) method, the dynamic reliability of bridge member is predicted, and an actual example is provided to illustrate the application and feasibility of the proposed models and methods.

Abstract: The increase of transverse contact ratio (ε_α) value usually allows reducing general level of gear vibroactivity. Article put to the test influence of coefficient ε_α value on dynamic forces in mesh zone with use of dynamic model of toothed gear. From theoretical point of view, the optimum value of transverse contact ratio is equal 2, what mean, that in mesh are always two pair of teeth. Obtainment such value of coefficient ε_α requires another construction of toothed wheels – wheels with HCR (High Contact Ratio) profile teeth. On result of occurrence of different deviations in toothed gears, as well as the dynamic phenomena, obtainment of continuous two-pair cooperation of gear pair is impossible and when this necessary is, solutions with near or exceed optimum value of coefficient are applied.

Abstract: The paper deals with quadrocopter stability in vertical axis. At first, dynamic model of quadrocopter is introduced. In the paper are derived relations for control error in steady state for PD and PID controller. Based on dynamic model the PID controller is designed by optimizing method. Using designed controller the quadrocopter stability in vertical axis was simulated in software Matlab. In the conclusion the results of the simulation are shown.

Abstract: The paper brings into attention the dynamic analysis of a bi-mobile mechanism selected from the literature and used for the leg of a mobile platform. Two solutions of bi-mobile mechanical systems applied in such purpose are found. In the classic theory of mechanisms the dynamic models for the mono-mobile mechanisms are known. Through the motion equation these put into evidence the variation of the reduced moment or reduced force applied to the input link for an entire cycle in the permanent regime functioning of the mechanism. In the case of the leg bi-mobile mechanism the approached dynamic model is based on the bi-mobile RTRTR active group firstly applied for a real technique solution in robotics. The mechanism may be also used for robot arms.