scholarly journals The Question of Drawing a Design Scheme of a Wagon with a Non-Symmetrically Located Freight

2021 ◽  
Vol 1 (2) ◽  
pp. 76-87
Author(s):  
Vladimir Solonenko ◽  
◽  
Janat Musayev ◽  
Algazy Zhauyt ◽  
Valikhan Kuparov ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Center Of Mass ◽  
Forced Vibrations ◽  
Operating Conditions ◽  
Transverse Displacement ◽  
Design Scheme ◽  
Design Diagram ◽  
The Stability

Violations of the stability of a wagon with an asymmetrically positioned freight can lead to a threat to the safety of train traffic, the safety of freight on the route and transport facilities. The design diagram of a wagon with an asymmetrically located freight drawn up in the article and the equations obtained in an analytical way, oscillations of the sprung mass of a wagon with an asymmetric arrangement of the freight, characterizing the longitudinal and transverse displacement of the center of mass of the freight, can be used for mathematical modeling of forced vibrations and impact on the track of a wagon with asymmetrically located freight in various operating conditions.

scholarly journals OPTIMIZATION OF CALCULATION SCHEMES

2021 ◽  
pp. 85-91
Author(s):  
I. Medved ◽  
Keyword(s):  
Linear Programming ◽  
Operating Conditions ◽  
Real Structure ◽  
Building Structures ◽  
Optimal Parameters ◽  
Microsoft Excel ◽  
Efficiency Criterion ◽  
Design Scheme ◽  
Design Diagram ◽  
Complete Calculation

Any calculation is preceded by the stage of creating a design diagram of a real structure, which would most accurately correspond to real operating conditions. The more optimally the design scheme is drawn up, the less laborious the stages of calculation and design of the corresponding structure will be. There are practically no results of using this approach when calculating building structures. This article attempts to show the possibility and expediency of using the "Search for solutions" (add-on for Microsoft Excel) at the stage of choosing the optimal parameters of the design design schemeAny calculation is preceded by the stage of creating a design diagram of a real structure, which would most closely correspond to real operating conditions. The more optimally the design scheme is drawn up, the less laborious the stages of calculation and design of the corresponding structure will be. If the efficiency criterion is a linear function, and the variables in the constraint system are also linear, then such a problem is a linear programming problem. Of the listed methods of mathematical programming, the most common and developed is linear programming. To illustrate the idea of the proposed approach, a simple statically definable truss on two supports was deliberately chosen. This is done so that the idea of the proposed approach is not lost due to the complexity and cumbersomeness of the calculations. This article shows the possibility and feasibility of using the "Search for solutions" at the stage of choosing the optimal parameters of the design design scheme. After the design scheme has been defined, more powerful conventional means of calculating building structures can be involved for its complete calculation.

scholarly journals A Mathematical Model of the Plane-Parallel Movement of an Asymmetric Machine-and-Tractor Aggregate

Agriculture ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 151 ◽  
Author(s):  
Volodymyr Bulgakov ◽  
Simone Pascuzzi ◽  
Volodymyr Nadykto ◽  
Semjons Ivanovs
Keyword(s):  
Differential Equations ◽  
Center Of Mass ◽  
Longitudinal Axis ◽  
Design Parameters ◽  
Transverse Displacement ◽  
Parallel Movement ◽  
Axis Of Symmetry ◽  
Being There ◽  
Linear Differential ◽  
The Stability

Technological peculiarities of cultivation and harvesting of some agricultural crops make it necessary to use asymmetric machine-and-tractor aggregates. However, for the time being there is no sufficiently complete, analytical study of the steady movement of such machine-and-tractor aggregates. This necessitates the development of a theory of stable movement of the aggregates which would allow choosing their optimal kinematic and design parameters. On the basis of the results of mathematical simulation, a system of linear differential equations of the second order is obtained describing transverse displacement of the center of masses of the aggregating wheeled tractor and turning of its longitudinal axis of symmetry by some angle around the indicated center of mass, as well as the deviation angle of the rear-trailed harvester from the longitudinal axis of the tractor at any arbitrary moment of time. This system of differential equations can be applied for numerical calculations on the PC, which will make it possible to evaluate the stability of the movement of the asymmetric machine-and-tractor aggregate when it performs the technological process.

scholarly journals Influence of the position of the center of mass of a trailer category O1 on the stability of the road train

2022 ◽  
Vol 14 (2) ◽  
pp. 111-120
Author(s):  
Volodymyr Sakhno ◽  
◽  
Victor Poljakov ◽  
Svitlana Sharai ◽  
Iruna Tchovcha ◽  
...  
Keyword(s):  
Critical Speed ◽  
Center Of Mass ◽  
Design Parameters ◽  
Steering Wheel ◽  
Transverse Displacement ◽  
Maximum Displacement ◽  
The Road ◽  
Course Stability ◽  
The Stability ◽  
Oscillation Instability

In a number of operational properties of motor vehicle (ATZ) at the tendency of increase of speeds of movement the most important indicators of the kept quality, in any modes, are stability and controllability. The choice of constructive parameters of ATZ providing these properties increases active safety of operation and reduces probability of road accidents during the execution of transport operations. From the point of view of practical purposes at operation of ATZ not only the reason of infringement of stability becomes important, and reaction of ATZ to it and control actions of the driver which are ambiguous and unstable. Therefore, it is assumed that the stability and controllability of the ATZ movement should be provided by the design parameters of the machine itself. The result of the analysis of the course stability of the road train was the expression of the critical speed of rectilinear motion. According to the developed mathematical model, the critical velocity is determined. Calculations were made for a road train consisting of a VAZ-2107 car and the uniaxial trailer for different loads of the trailer and different location of its center of mass. According to the initial data inherent in the nominal load of the car and the maximum load of the trailer and the location of the center of mass of the trailer on the longitudinal axis and in the center of mass of the loading platform, the critical speed is about 36 m/s (129.6 km/h). In transient modes of movement, such as "entering the circle and moving in a circle", "jerk of the steering wheel", "shift", "snake", displacement of the center of mass of the trailer in both the longitudinal and transverse planes, the critical speed decreases, and more significantly reduction occurs when the transverse displacement of the center of mass. Thus, if at the maximum displacement of the center of mass of the trailer on the x-axis (x = -0.75 m) the rate of oscillation instability decreases by 36.4% (Gn = 350 kg), 38.4% (Gn = 500 kg) and 44.3% (Gn = 750 kg) in comparison with this speed in the absence of displacement, then at the maximum displacement along the y -axis in the rate of oscillation instability decreases by 45.4%, 55.2% and 63.6%, respectively. In the case of such a trailer loading, the center of mass of the trailer shifts along both the x-axis and the y-axis, there is a further decrease in both the critical speed of the road train and the rate of oscillation instability. This must be taken into account when loading the trailer.

TO THE STABILITY OF TANK VEHICLES IN THE BRAKE MODE

2019 ◽  
pp. 27-32
Author(s):  
Denys Popelysh ◽  
Yurii Seluk ◽  
Sergyi Tomchuk
Keyword(s):  
Mathematical Model ◽  
Control Systems ◽  
Distribution Systems ◽  
Traffic Accidents ◽  
Road Traffic ◽  
Center Of Mass ◽  
Dynamic Processes ◽  
Course Stability ◽  
The Stability ◽  
Tank Vehicles

This article discusses the question of the possibility of improving the roll stability of partially filled tank vehicles while braking. We consider the dangers associated with partially filled tank vehicles. We give examples of the severe consequences of road traffic accidents that have occurred with tank vehicles carrying dangerous goods. We conducted an analysis of the dynamic processes of fluid flow in the tank and their influence on the basic parameters of the stability of vehicle. When transporting a partially filled tank due to the comparability of the mass of the empty tank with the mass of the fluid being transported, the dynamic qualities of the vehicle change so that they differ significantly from the dynamic characteristics of other vehicles. Due to large displacements of the center of mass of cargo in the tank there are additional loads that act vehicle and significantly reduce the course stability and the drivability. We consider the dynamics of liquid sloshing in moving containers, and give examples of building a mechanical model of an oscillating fluid in a tank and a mathematical model of a vehicle with a tank. We also considered the method of improving the vehicle’s stability, which is based on the prediction of the moment of action and the nature of the dynamic processes of liquid cargo and the implementation of preventive actions by executive mechanisms. Modern automated control systems (anti-lock brake system, anti-slip control systems, stabilization systems, braking forces distribution systems, floor level systems, etc.) use a certain list of elements for collecting necessary parameters and actuators for their work. This gives the ability to influence the course stability properties without interfering with the design of the vehicle only by making changes to the software of these systems. Keywords: tank vehicle, roll stability, mathematical model, vehicle control systems.

Coverage and Stability of NHx Terminated Cobalt and Ruthenium Surfaces: a First Principles Investigation

2019 ◽  
Author(s):  
Ji Liu ◽  
Michael Nolan
Keyword(s):  
Metal Surfaces ◽  
High Vacuum ◽  
Atomic Layer ◽  
Nitrogen Plasma ◽  
Operating Conditions ◽  
Ultra High Vacuum ◽  
Bridge Site ◽  
Stable Surface ◽  
Saturation Coverage ◽  
The Stability

<div>In the atomic layer deposition (ALD) of Cobalt (Co) and Ruthenium (Ru) metal using nitrogen plasma, the structure and composition of the post N-plasma NHx terminated (x = 1 or 2) metal surfaces are not well known but are important in the subsequent metal containing pulse. In this paper, we use the low-index (001) and (100) surfaces of Co and Ru as models of the metal polycrystalline thin films. The (001) surface with a hexagonal surface structure is the most stable surface and the (100) surface with a zigzag structure is the least stable surface but has high reactivity. We investigate the stability of NH and NH2 terminations on these surfaces to determine the saturation coverage of NHx on Co and Ru. NH is most stable in the hollow hcp site on (001) surface and the bridge site on the (100) surface, while NH2 prefers the bridge site on both (001) and (100) surfaces. The differential energy is calculated to find the saturation coverage of NH and NH2. We also present results on mixed NH/NH2-terminations. The results are analyzed by thermodynamics using Gibbs free energies (ΔG) to reveal temperature effects on the stability of NH and NH2 terminations. Ultra-high vacuum (UHV) and standard ALD</div><div>operating conditions are considered. Under typical ALD operating conditions we find that the most stable NHx terminated metal surfaces are 1 ML NH on Ru (001) surface (350K-550K), 5/9 ML NH on Co (001) surface (400K-650K) and a mixture of NH and NH2 on both Ru (100) and Co (100) surfaces.</div>

Application of the method of mathematical modeling for forecasting channel deformations at the underwater crossing of the main pipeline

2020 ◽  
Vol 10 (6) ◽  
pp. 599-609
Author(s):  
Valery А. Gruzdev ◽  
◽  
Georgy V. Mosolov ◽  
Ekaterina A. Sabayda ◽  
◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Roughness Coefficient ◽  
Computational Domain ◽  
Channel Deformations ◽  
Geological Surveys ◽  
Kuban River ◽  
The Stability ◽  
Protective Structures

In order to determine the possibility of using the method of mathematical modeling for making long-term forecasts of channel deformations of trunk line underwater crossing (TLUC) through water obstacles, a methodology for performing and analyzing the results of mathematical modeling of channel deformations in the TLUC zone across the Kuban River is considered. Within the framework of the work, the following tasks were solved: 1) the format and composition of the initial data necessary for mathematical modeling were determined; 2) the procedure for assigning the boundaries of the computational domain of the model was considered, the computational domain was broken down into the computational grid, the zoning of the computational domain was performed by the value of the roughness coefficient; 3) the analysis of the results of modeling the water flow was carried out without taking the bottom deformations into account, as well as modeling the bottom deformations, the specifics of the verification and calibration calculations were determined to build a reliable mathematical model; 4) considered the possibility of using the method of mathematical modeling to check the stability of the bottom in the area of TLUC in the presence of man-made dumping or protective structure. It has been established that modeling the flow hydraulics and structure of currents, making short-term forecasts of local high-altitude reshaping of the bottom, determining the tendencies of erosion and accumulation of sediments upstream and downstream of protective structures are applicable for predicting channel deformations in the zone of the TLUC. In all these cases, it is mandatory to have materials from engineering-hydro-meteorological and engineering-geological surveys in an amount sufficient to compile a reliable mathematical model.

scholarly journals Performance of Iron-Functionalized Activated Carbon Catalysts (Fe/AC-f) on CWPO Wastewater Treatment

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 337
Author(s):  
Sara Mesa Medina ◽  
Ana Rey ◽  
Carlos Durán-Valle ◽  
Ana Bahamonde ◽  
Marisol Faraldos
Keyword(s):  
Wastewater Treatment ◽  
Activated Carbon ◽  
Landfill Leachate ◽  
Surface Composition ◽  
Treatment Plant ◽  
Reaction Medium ◽  
Pollutant Removal ◽  
Operating Conditions ◽  
Water Matrix ◽  
The Stability

Two commercial activated carbon were functionalized with nitric acid, sulfuric acid, and ethylenediamine to induce the modification of their surface functional groups and facilitate the stability of corresponding AC-supported iron catalysts (Fe/AC-f). Synthetized Fe/AC-f catalysts were characterized to determine bulk and surface composition (elemental analysis, emission spectroscopy, XPS), textural (N2 isotherms), and structural characteristics (XRD). All the Fe/AC-f catalysts were evaluated in the degradation of phenol in ultrapure water matrix by catalytic wet peroxide oxidation (CWPO). Complete pollutant removal at short reaction times (30–60 min) and high TOC reduction (XTOC = 80 % at ≤ 120 min) were always achieved at the conditions tested (500 mg·L−1 catalyst loading, 100 mg·L−1 phenol concentration, stoichiometric H2O2 dose, pH 3, 50 °C and 200 rpm), improving the results found with bare activated carbon supports. The lability of the interactions of iron with functionalized carbon support jeopardizes the stability of some catalysts. This fact could be associated to modifications of the induced surface chemistry after functionalization as a consequence of the iron immobilization procedure. The reusability was demonstrated by four consecutive CWPO cycles where the activity decreased from 1st to 3rd, to become recovered in the 4th run. Fe/AC-f catalysts were applied to treat two real water matrices: the effluent of a wastewater treatment plant with a membrane biological reactor (WWTP-MBR) and a landfill leachate, opening the opportunity to extend the use of these Fe/AC-f catalysts for complex wastewater matrices remediation. The degradation of phenol spiked WWTP-MBR effluent by CWPO using Fe/AC-f catalysts revealed pH of the reaction medium as a critical parameter to obtain complete elimination of the pollutant, only reached at pH 3. On the contrary, significant TOC removal, naturally found in complex landfill leachate, was obtained at natural pH 9 and half stoichiometric H2O2 dose. This highlights the importance of the water matrix in the optimization of the CWPO operating conditions.

scholarly journals A Unified Control Strategy of Distributed Generation for Grid-Connected and Islanded Operation Conditions Using an Artificial Neural Network

2021 ◽  
Vol 13 (11) ◽  
pp. 6388
Author(s):  
Karim M. El-Sharawy ◽  
Hatem Y. Diab ◽  
Mahmoud O. Abdelsalam ◽  
Mostafa I. Marei
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Control System ◽  
Distributed Generation ◽  
Control Strategy ◽  
Current Control ◽  
Operating Conditions ◽  
Pi Controllers ◽  
Artificial Neural ◽  
The Stability

This article presents a control strategy that enables both islanded and grid-tied operations of a three-phase inverter in distributed generation. This distributed generation (DG) is based on a dramatically evolved direct current (DC) source. A unified control strategy is introduced to operate the interface in either the isolated or grid-connected modes. The proposed control system is based on the instantaneous tracking of the active power flow in order to achieve current control in the grid-connected mode and retain the stability of the frequency using phase-locked loop (PLL) circuits at the point of common coupling (PCC), in addition to managing the reactive power supplied to the grid. On the other side, the proposed control system is also based on the instantaneous tracking of the voltage to achieve the voltage control in the standalone mode and retain the stability of the frequency by using another circuit including a special equation (wt = 2πft, f = 50 Hz). This utilization provides the ability to obtain voltage stability across the critical load. One benefit of the proposed control strategy is that the design of the controller remains unconverted for other operating conditions. The simulation results are added to evaluate the performance of the proposed control technology using a different method; the first method used basic proportional integration (PI) controllers, and the second method used adaptive proportional integration (PI) controllers, i.e., an Artificial Neural Network (ANN).

Stability of Ring-Type MEMS Gyroscopes Subjected to Stochastic Angular Speed Fluctuation

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Samuel F. Asokanthan ◽  
Soroush Arghavan ◽  
Mohamed Bognash
Keyword(s):  
Angular Velocity ◽  
Degrees Of Freedom ◽  
Microelectromechanical Systems ◽  
Damping Ratio ◽  
Operating Conditions ◽  
System Stability ◽  
System Response ◽  
Ring Type ◽  
Mems Gyroscopes ◽  
The Stability

Effect of stochastic fluctuations in angular velocity on the stability of two degrees-of-freedom ring-type microelectromechanical systems (MEMS) gyroscopes is investigated. The governing stochastic differential equations (SDEs) are discretized using the higher-order Milstein scheme in order to numerically predict the system response assuming the fluctuations to be white noise. Simulations via Euler scheme as well as a measure of largest Lyapunov exponents (LLEs) are employed for validation purposes due to lack of similar analytical or experimental data. The response of the gyroscope under different noise fluctuation magnitudes has been computed to ascertain the stability behavior of the system. External noise that affect the gyroscope dynamic behavior typically results from environment factors and the nature of the system operation can be exerted on the system at any frequency range depending on the source. Hence, a parametric study is performed to assess the noise intensity stability threshold for a number of damping ratio values. The stability investigation predicts the form of threshold fluctuation intensity dependence on damping ratio. Under typical gyroscope operating conditions, nominal input angular velocity magnitude and mass mismatch appear to have minimal influence on system stability.

Nonlinear Free and Forced Vibrations of Symmetric Laminated Panels

2011 ◽  
Vol 471-472 ◽  
pp. 616-621 ◽  
Author(s):  
Alireza Shooshtari ◽  
Soheil Razavi ◽  
Hadi Ghashochi Bargh ◽  
Mohammad Homayoun Sadr-Lahidjani
Keyword(s):  
Perturbation Method ◽  
External Force ◽  
Laminated Composite ◽  
Composite Plates ◽  
Forced Vibrations ◽  
Numerical Results ◽  
Transverse Displacement ◽  
Laminated Composite Plates ◽  
Free And Forced Vibrations ◽  
Laminated Panels

In this paper, free and forced vibrations of symmetric laminated composite plates are studied analytically by using a perturbation method where the analytical results for transverse displacement are compared with the numerical results. The external force is taken to be harmonic in time and having uniform amplitude.

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