scholarly journals TO THE QUESTION OF OPTIMISING THE DYNAMIC CHARACTERISTICS OF A VIBRATIONAL TREE UPROOTING MACHINE

2018 ◽  
Vol 45 (2) ◽  
pp. 149-157
Author(s):  
A. R. Mikhitarov ◽  
V. L. Savich ◽  
V. K. Khegai
Keyword(s):  
Mathematical Model ◽  
Root System ◽  
Dynamic Characteristics ◽  
Mutual Influence ◽  
Frequency Characteristics ◽  
Frequency Range ◽  
System A ◽  
Forest Sites ◽  
Tree Uprooting ◽  
The Mathematical Model

Objectives Following logging operations, tree stumps remain in the site of the former forest.While these may be uprooted by special machines in the course of forestry operations, the use of heavy forestry machines operated repeatedly on the forest sites not only lead to soil erosion, but also to considerable financial expense. Consequently, the development of machines combining cutting (logging) and uprooting operations – that is, uprooting the trees along with their roots – are of a great interest. As research has shown, the main disadvantages of the use of such technology by “conventional” logging or forestry machines are their excessive loading and energy intensity. The aim of the research is to investigate means of eliminating these drawbacks by using vibration.Methods The article deals with theproblem of ensuring the effectiveness of the vibration application – in particular, torsional vibrations, used to stub trees together with their roots. To solve this problem, a mathematical model of the “machine-tree-soil-root system” system was developed, which takes into account the mutual influence of the dynamic characteristics of the machine’s technological equipment and tree and soil-root system, which allows a rational (optimal) frequency range of vibration equipment to be selected by analysing the amplitude-frequency characteristics of a given system. To analyse the amplitude-frequency characteristics of a mechanical system, the Euler-Lagrange equationswere used.Results Based on the mathematical model of the “machine-tree-soil-root system (SRS)” system and an analysis of the amplitude-frequency characteristics of a given system, a rational range of vibration frequencies was determined. As shown by analysis, the work of vibrational equipment in a given frequency range can significantly reduce the dynamic loading of the machine and at the same time create appropriate conditions for the effective destruction of the soil-root system.Conclusion The proposed method allows the rational values of the frequency characteristic of vibration equipment for each calculated tree to be found depending on the soil type and the basic machine.

Coupling Effects of Double Lungs on Dynamic Characteristics of Volume-Controlled Mechanical Insufflation-Exsufflation Secretion Clearance System

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Dongkai Shen ◽  
Yanjun Zhou ◽  
Yan Shi
Keyword(s):  
Mathematical Model ◽  
Dynamic Characteristics ◽  
Orthogonal Experiment ◽  
Coupling Effects ◽  
System A ◽  
The Impact ◽  
The Mathematical Model ◽  
Volume Controlled ◽  
Secretion Clearance

Mechanical insufflation-exsufflation (MI-E) secretion clearance system is usually utilized to help patients to clear secretion. In this paper, to obtain the essential dynamic characteristics of volume-controlled (VC) MI-E secretion clearance system with double lungs, a dimensionless model of the MI-E secretion clearance system is derived. Furthermore, for the validation of the mathematical model, a prototype VC MI-E secretion clearance system is proposed. Finally, to reveal the impact of key parameters on VC MI-E secretion clearance system, a dimensionless orthogonal experiment with four factors and five levels was processed. And then, coupling effects of two lungs on VC MI-E secretion clearance system were illustrated. This paper can be referred to in treatment of secretion clearance with VC secretion clearance system.

scholarly journals Determination of the Vertical Load on the Carrying Structure of a Flat Wagon with the 18–100 and Y25 Bogies

2021 ◽  
Vol 11 (9) ◽  
pp. 4130
Author(s):  
Oleksij Fomin ◽  
Alyona Lovska ◽  
Václav Píštěk ◽  
Pavel Kučera
Keyword(s):  
Mathematical Model ◽  
Fatigue Strength ◽  
Service Life ◽  
Dynamic Characteristics ◽  
Dynamic Load ◽  
Field Tests ◽  
Vertical Load ◽  
Mathcad Software ◽  
The Mathematical Model

The study deals with determination of the vertical load on the carrying structure of a flat wagon on the 18–100 and Y25 bogies using mathematic modelling. The study was made for an empty wagon passing over a joint irregularity. The authors calculated the carrying structure of a flat wagon with the designed parameters and the actual features recorded during field tests. The mathematical model was solved in MathCad software. The study found that application of the Y25 bogie for a flat wagon with the designed parameters can decrease the dynamic load by 41.1% in comparison to that with the 18–100 bogie. Therefore, application of the Y25 bogie under a flat wagon with the actual parameters allows decreasing the dynamic loading by 41.4% in comparison to that with the 18–100 bogie. The study also looks at the service life of the supporting structure of a flat wagon with the Y25 bogie, which can be more than twice as long as the 18–100 bogie. The research can be of interest for specialists concerned with improvements in the dynamic characteristics and the fatigue strength of freight cars, safe rail operation, freight security, and the results of the research can be used for development of innovative wagon structures.

The static and dynamic characteristics of a pressure relief valve with a proportional solenoid-controlled pilot stage

2002 ◽  
Vol 216 (2) ◽  
pp. 143-156 ◽  
Author(s):  
R Maiti ◽  
R Saha ◽  
J Watton
Keyword(s):  
Mathematical Model ◽  
Dynamic Characteristics ◽  
Dynamic Behaviour ◽  
Practical Experience ◽  
Pressure Relief Valve ◽  
Relief Valve ◽  
Pressure Relief ◽  
Static And Dynamic Characteristics ◽  
Good Comparison ◽  
The Mathematical Model

The steady state and dynamic characteristics of a two-stage pressure relief valve with proportional solenoid control of the pilot stage is studied theoretically as well as experimentally. The mathematical model is studied within the MATLAB-SIMULINK environment and the non-linearities have been considered via the use of appropriate SIMULINK blocks. The detailed modelling has resulted in a good comparison between simulation and measurement, albeit assumptions had to be made regarding the solenoid dynamic characteristic based upon practical experience. The use of this characteristic combined with additional dynamic terms not previously considered allows new estimations of internal characteristics to be made such as the damping flowrate. The overall dynamic behaviour has been shown to be dominated by the solenoid characteristic relating force to applied voltage.

A guaranteed deterministic approach to margining on exchange-traded derivatives market: Numerical experiment

2021 ◽  
Vol 57 (4) ◽  
pp. 76
Author(s):  
Sergey Smirnov
Keyword(s):  
Mathematical Model ◽  
Risk Management ◽  
Critical Role ◽  
Deterministic Approach ◽  
Computational Framework ◽  
Modern Approach ◽  
System A ◽  
Lipschitz Constants ◽  
Isaacs Equations ◽  
The Mathematical Model

The article discusses a modern approach to risk management of the central counterparty,primarily the issue of the sufficiency of its financial resources, including the provision of clearingmembers, the capital of the central counterparty and the mutual liability fund. The main subject is the margining system, responsible for an adequate level of collateral for clearing members, that plays critical role in risk management, being the vanguard in protecting against losses associated with default by clearing members and the most sensitive to market risk part of the central counterparty’s skin of the game. A system of margining a portfolio of options and futures in the derivatives market is described, with default management based on the methodology proposed by a number of inventors, registered in 2004. For this system, a mathematical model of margining (i.e. determining the required level of the collateral) is built, based on the ideology of a guaranteed deterministic approach to superhedging: Bellman–Isaacs equations are derived from the economic meaning of the problem. A form of these equations, convenient for calculations, is obtained. Lipschitz constants for the solutions of Bellman–Isaacs equations are estimated. A computational framework for efficient numerical solution of these equations is created. Numerical experiments are carried out on some model examples to demonstrate the efficiency of the system. These experiments also show practical implications of marginsubadditivity — a crucial property of the mathematical model.

Exact Solutions of the Vibration Problem of Beam Structures

2013 ◽  
Vol 390 ◽  
pp. 242-245 ◽  
Author(s):  
Alexander V. Chekanin
Keyword(s):  
Mathematical Model ◽  
Exact Solutions ◽  
Dynamic Characteristics ◽  
Natural Frequencies ◽  
Numerical Solutions ◽  
High Accuracy ◽  
Displacement Method ◽  
Actual Problem ◽  
Beam Structures ◽  
The Mathematical Model

The article deals with the actual problem of improving the accuracy of determining the dynamic characteristics of beam structures. To solve such problems the displacement method is used. Defining matrices are calculated with the Godunovs scheme. Numerical solutions in this case can be obtained practically with any accuracy within accepted hypotheses of the mathematical model of the calculated object. This suggests that the resulting solutions are standard. The examples of determining the natural frequencies of vibrations of beam structures that demonstrate an extremely high accuracy of the proposed algorithm are given.

Parameters Determination of PID in MAX1978

2012 ◽  
Vol 588-589 ◽  
pp. 1458-1461
Author(s):  
Mei Mei Lv ◽  
Tie Liang Lv ◽  
Guo Feng Ou
Keyword(s):  
Mathematical Model ◽  
Measurement Method ◽  
Frequency Measurement ◽  
Frequency Characteristics ◽  
Working Principle ◽  
The Mathematical Model

The system based on the working principle of MAX1978 and TEC, using multi-point at different frequency measurement method, and establishing corresponding mathematical model. Confirmed the pole-zero plot of the PID, according to the amplitude-frequency and phase-frequency characteristics of the mathematical model, and then, adjusted the corresponding resistance and capacitance of the circuit to make the accuracy of the temperature adjustment to 1E-3centigrade.

Study on Control Characteristics of Driving and Lifting System for Logistics and Loading Machinery

2012 ◽  
Vol 268-270 ◽  
pp. 1517-1522 ◽  
Author(s):  
Guo Jin Chen ◽  
Ting Ting Liu ◽  
Ni Jin ◽  
You Ping Gong ◽  
Huo Qing Feng
Keyword(s):  
Mathematical Model ◽  
Dynamic Characteristics ◽  
Optimization Design ◽  
Integrated System ◽  
Operating Conditions ◽  
Control Methods ◽  
Lifting System ◽  
The Mathematical Model ◽  
Power Match

The logistics and loading machinery is the typical hydromechatronics integrated system. How to solve the reasonable power match in the driving and lifting process of the logistics and loading machinery, we need to establish the mathematical model of the driving and lifting system, and analyze their control characteristics. Aiming at the load requirements for different operating conditions, this paper studies respectively the dynamic characteristics of the driving and lifting system. Through simulation and computation, the control methods and strategies based on the best performance are proposed. That lays the foundation for the optimization design of the logistics and loading machinery.

scholarly journals Improving the Dynamic Characteristics of Precision Lathes Used in the Repair of Agricultural Machinery

2021 ◽  
pp. 36-39
Author(s):  
D.E. Molochnikov ◽  
◽  
R.Sh. Halimov ◽  
N.P. Ayugin ◽  
I.R. Salakhutdinov ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Dynamic Characteristics ◽  
Low Frequency ◽  
Frequency Component ◽  
Honeycomb Structure ◽  
Friction Unit ◽  
Agricultural Machinery ◽  
Longitudinal Vibrations ◽  
Model Of Friction ◽  
The Mathematical Model

A model of a friction unit of a lathe in the form of a thin layer of material of a honeycomb structure is described to determine the dynamic characteristics of a movable carriage to guide joint. The analysis of the mathematical model of friction for different sliding pairs with varying load and sliding speed is performed. It is shown that the presence of an abrasive impurity in the lubrication of the guide enhances the effect of the low-frequency component of the carriage vibrations on the dynamics of the machine tool and the presence of pockets for retaining the lubricant in the joint of the guide makes it possible to reduce the amplitude of the longitudinal vibrations of the carriage to 30-50 %.

scholarly journals Melacak Dampak Perubahan Iklim Terhadap Kondisi Makroekonomi dengan Teori Permainan Dinamis

2018 ◽  
Vol 7 (2) ◽  
pp. 57-62
Author(s):  
Muhammad Wakhid Musthofa
Keyword(s):  
Climate Change ◽  
Economic Growth ◽  
Mathematical Model ◽  
Equation System ◽  
Output Function ◽  
Macroeconomic Conditions ◽  
System A ◽  
Economic Growth Model ◽  
The Impact ◽  
The Mathematical Model

Makalah ini membahas tentang model matematika dampak perubahan iklim terhadap kondisi makroekonomi suatu negara. Dengan mengacu pada model pertumbuhan ekonomi endogen pada suatu negara, dengan fungsi output berbentuk fungsi Cobb-Douglas akan diturunkan model matematika yang mendeskripsikan dampak perubahan iklim terhadap kondisi makroekonomi suatu negara. Selanjutnya, akan dikonstruksikan pula fungsi ongkos yang berhubungan dengan model matematika yang telah diturunkan. Mengingat model matematika tersebut masih dalam bentuk sistem persamaan nonlinear, maka diperlukan proses linearisasi untuk menghasilkan model matematika yang linear sehingga memudahkan untuk dianalisis maupun diaplikasikan. [This paper discusses the mathematical model of the impact of climate change on the macroeconomic conditions of a country. By referring to an endogenous economic growth model in a country, with the output function in the form of a Cobb-Douglas function, a mathematical model will be described that describes the effects of climate change on the macroeconomic conditions of a country. Furthermore, it will also construct cost functions related to mathematical models that have been derived. Considering that the mathematical model is still in the form of a nonlinear equation system, a linearisation process is needed to produce a linear mathematical model that makes it easy to analyze and apply.]

Mathematical modeling of articulated passenger train spatial vibrations

2021 ◽  
Vol 2021 (2) ◽  
pp. 91-99
Author(s):  
O. Markova ◽  
◽  
H. Kovtun ◽  
V. Maliy ◽  
◽  
...  
Keyword(s):  
Mathematical Model ◽  
Differential Equations ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Ride Quality ◽  
Railway Transport ◽  
Passenger Train ◽  
Wide Range ◽  
Random Track Irregularities ◽  
The Mathematical Model

The problem of high-speed railway transport development is important for Ukraine. In many countries articulated trains are used for this purpose. As the connections between cars in such a train differ from each other, to investigate its dynamic characteristics not a separate car, but a full train vibrations model is necessary. The article is devoted to the development of the mathematical model for articulated passenger train spatial vibrations. The considered train consists of 7 cars: one motor-car, one transitional car, three articulated cars, one more transitional car and again one motor-car. Differential equations of the train motion along the track of arbitrary shape are set in the form of Lagrange’s equations of the second kind. All the necessary design features of the vehicles are taken into account. Articulated cars have common bogies with adjoining cars and a transfer car and the cars are united by the hinge. The operation of the central hinge between two cars is modeled using springs and dampers acting in the horizontal and vertical directions. Four dampers between two adjacent car-bodies act as dampers for pitching and hunting and are represented in the model by viscous damping. The system of 257 differential equations of the second order is set, which describes the articulated train motion along straight, curved, and transitional track segments with taking into account random track irregularities. On the basis of the obtained mathematical model the algorithm and computational software has been developed to simulate a wide range of cases including all possible combinations of parameters for the train elements and track technical state. The study of the train self-exited vibrations has shown the stable motion in all the range of the considered speeds (40 km/h – 180 km/h). The results obtained at the train motion along the track maintained for the speedy motion have shown that all the dynamic characteristics and ride quality index insure train safe motion and comfortable conditions for the travelling passengers.

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