Snake-Like Locomotions of Multilink Mechanisms

2003 ◽  
Vol 9 (1-2) ◽  
pp. 235-256 ◽  
Author(s):  
F. L. Chernousko
Keyword(s):  
Dry Friction ◽  
Horizontal Plane ◽  
Sufficient Conditions ◽  
Numerical Results ◽  
Mechanical Parameters ◽  
Average Speed ◽  
Optimal Values ◽  
Rotational Motions

Snake-like locomotions of a three-member linkage equipped with actuators are modeled and investigated. Longitudinal, lateral, and rotational motions of the mechanism along a horizontal plane in the presence of the dry friction are analyzed. The desired motions are presented as a combination of more simple elementary motions. Sufficient conditions are deduced under which these motions are possible. The dependence of the average speed of motions on various geometrical and mechanical parameters is investigated. The optimal values of the parameters which maximize the speed are obtained. The numerical results are presented and discussed.

scholarly journals Free Interfaces at the Tips of the Cilia in the One-Dimensional Periciliary Layer

Mathematics ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1961
Author(s):  
Kanognudge Wuttanachamsri
Keyword(s):  
Mathematical Model ◽  
Exact Solution ◽  
Free Boundary ◽  
Horizontal Plane ◽  
Numerical Solutions ◽  
Numerical Results ◽  
Brinkman Equation ◽  
Average Height ◽  
Free Interface ◽  
The Mathematical Model

Cilia on the surface of ciliated cells in the respiratory system are organelles that beat forward and backward to generate metachronal waves to propel mucus out of lungs. The layer that contains the cilia, coating the interior epithelial surface of the bronchi and bronchiolesis, is called the periciliary layer (PCL). With fluid nourishment, cilia can move efficiently. The fluid in this region is named the PCL fluid and is considered to be an incompressible, viscous, Newtonian fluid. We propose there to be a free boundary at the tips of cilia underlining a gas phase while the cilia are moving forward. The Brinkman equation on a macroscopic scale, in which bundles of cilia are considered rather than individuals, with the Stefan condition was used in the PCL to determine the velocity of the PCL fluid and the height/shape of the free boundary. Regarding the numerical methods, the boundary immobilization technique was applied to immobilize the moving boundaries using coordinate transformation (working with a fixed domain). A finite element method was employed to discretize the mathematical model and a finite difference approach was applied to the Stefan problem to determine the free interface. In this study, an effective stroke is assumed to start when the cilia make a 140∘ angle to the horizontal plane and the velocitiesof cilia increase until the cilia are perpendicular to the horizontal plane. Then, the velocities of the cilia decrease until the cilia make a 40∘ angle with the horizontal plane. From the numerical results, we can see that although the velocities of the cilia increase and then decrease, the free interface at the tips of the cilia continues increasing for the full forward phase. The numerical results are verified and compared with an exact solution and experimental data from the literature. Regarding the fixed boundary, the numerical results converge to the exact solution. Regarding the free interface, the numerical solutions were compared with the average height of the PCL in non-cystic fibrosis (CF) human tissues and were in excellent agreement. This research also proposes possible values of parameters in the mathematical model in order to determine the free interface. Applications of these fluid flows include animal hair, fibers and filter pads, and rice fields.

On Motion of Chaplygin Sleigh on a Horizontal Plane with Dry Friction

2019 ◽  
Vol 54 (5) ◽  
pp. 632-637
Author(s):  
A. V. Karapetyan ◽  
A. Yu. Shamin
Keyword(s):  
Dry Friction ◽  
Horizontal Plane ◽  
Chaplygin Sleigh

Laboratory Study of Tribological Characteristics of Innovative Lubricant Coolants

2020 ◽  
Vol 992 ◽  
pp. 590-597
Author(s):  
S.M. Gaidar ◽  
A.V. Pydrin ◽  
M.Yu. Karelina ◽  
M.S. Gaidar ◽  
A.V. Sukhodolya
Keyword(s):  
Mathematical Models ◽  
Influence Factors ◽  
Sufficient Conditions ◽  
Mathematical Methods ◽  
Processing Methods ◽  
Qualitative Level ◽  
Optimal Values ◽  
Necessary And Sufficient ◽  
Technical And Economic Indicators ◽  
Combined Methods

In the article researches mathematical models that ensure effectiveness of use combined methods for parts processing. The use of combined processing methods is always associated with the search for technological compromise and boils down to technical and economic indicators comparative assessment. In this case, it is necessary to rely on mathematical models that objectively reflect manufacturing parts technological processes. Mathematical methods and models for optimizing production processes for manufacturing parts that are applicable in combined methods for processing parts are a complex formalized scientific abstraction that describes production functioning process at all stages of its implementation. In the synthesis of various processing methods, it is necessary to ensure that a number of conditions are met that determine necessary and sufficient conditions for implementing feasibility a particular technology in the combined method of processing parts. Multiple regression analysis methods allow minimizing experiments number in mathematical model determining which adequate to processes under study and form the baseline data for the transition from multi-factor to multi-criteria models. Using this approach, it is necessary to determine objective function optimal values parameters and influence factors in each specific technological process, which will allow us to bring the uncertainty removal in the processing materials technology to a new qualitative level.

scholarly journals Theoretical studies of the technological process of a rod elevator with an adjustable inclination angle of the apron

2020 ◽  
Vol 21 (1) ◽  
pp. 52-61
Author(s):  
A. S. Dorokhov ◽  
A. V. Sibiriev ◽  
A. G. Aksenov
Keyword(s):  
Inclination Angle ◽  
Horizontal Plane ◽  
Relative Velocity ◽  
Longitudinal Change ◽  
Theoretical Studies ◽  
Relative Speed ◽  
Technological Parameters ◽  
Average Speed ◽  
Root Crops ◽  
Maximum Separation

The article presents the design of a rod elevator with an adjustable inclination angle of the apron, which reduces damage to marketable products of root crops and bulbs with maximum separation. The results of theoretical studies of a rod elevator on substantiation of the structural and technological parameters during its interaction with a heap of onion sets are presented. The constructive-technological scheme of the separating rod elevator with an adjustable inclination angle of the apron which improves the quality indicators of harvesting onion sets is substantiated and developed. It has been established that with increasing angle of the longitudinal inclination of the apron, the relative speed of movement of the heap of onion sets decreases. In the absence of air flow, the relative velocity of the onion set heap with a longitudinal change in the inclination of the rod elevator apron in the considered range varies from 0.34 to 0.47 m / s. Changing the angle of the longitudinal inclination of the rod elevator by 5º significantly changes the relative average speed of movement of the heap of onion sets. A mathematical model of the movement of a heap of onion sets along the surface of the rod elevator with a change in the direction of its oscillations in the horizontal plane is developed

scholarly journals Observations on the reciprocal influence which magnetic needles exercise over each other, when placed at a given distance within their respective spheres of action, at different positions on the earth; with tables of numerical results obtained at separate stations. Also a method of discovering where certain local influences are acting on the needle, from which may be obtained a proportional correction to be applied to magnetic observations in general

1837 ◽  
Vol 3 ◽  
pp. 282-282
Keyword(s):  
Horizontal Plane ◽  
Numerical Results ◽  
Tabular Form ◽  
Reciprocal Influence ◽  
Material Change ◽  
The Earth ◽  
Freely Suspended

The author, considering it probable that two or more magnetic needles freely suspended at a certain distance in given positions with respect to each other, would develope certain proportionate deflections determined by their position on the earth, made a set of experiments, with a few common compass needles, at Yarmouth, London, and Clifton, which so far confirmed the truth of his conjecture, as to induce him to fix on stations at a greater distance from one another, and to multiply his observations; ascertaining, from time to time, that the magnetic powers of his apparatus had undergone no material change. The results of these observations are given in a tabular form. The author conceives that comparative observations of the amount of deflection produced by one magnet on another, placed in various situations, relative to the meridian, on an horizontal plane, will afford the means of determining the peculiar local influences of the particular situation in which the experiment is made, as distinguished from the general magnetic influence; because the former will act unequally on each magnet, while the latter acts equally on all.

scholarly journals Standardized Comparison of 40 Local Driving Cycles: Energy and Kinematics

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5434
Author(s):  
Guilherme Medeiros Soares de Andrade ◽  
Fernando Wesley Cavalcanti de Araújo ◽  
Maurício Pereira Magalhães de Novaes Santos ◽  
Fabio Santana Magnani
Keyword(s):  
Fuel Economy ◽  
Numerical Results ◽  
Average Speed ◽  
Traffic Characteristics ◽  
Driving Cycles ◽  
The Difference

Local driving cycles (LDCs) capture local traffic characteristics, while standard driving cycles (SDCs) compare vehicles in distinct regions. There is a plethora of LDCs, raising the question as to how distinct they are. To quantify it, we first organized a collection of 77 LDCs. From the speed—time images, it was possible to extract numerical vectors of 40 cycles in a standardized way. Comparing the LDCs developed for cars, we found that their parameters fluctuate significantly: the average speed varies from 14.7 to 44.7 km/h, and the fuel economy varies from 10.8 to 20.5 km/L. Comparing the LDCs with FTP-75 cycle, the difference in speed is 7 km/h, and in fuel economy is 1.5 km/L. For WLTC, the difference is 19.4 km/h and 3 km/L, respectively. Thus, given the deviations found between the analyzed LDCs, and between LDCs and SDCs, the numerical results reinforce the relevance of using LDCs for each region.

scholarly journals Oscillations Control of Rocking-Block-Type Buildings by the Addition of a Tuned Pendulum

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Luca Collini ◽  
Rinaldo Garziera ◽  
Kseniia Riabova ◽  
Mariya Munitsyna ◽  
Alessandro Tasora
Keyword(s):  
Numerical Simulations ◽  
Approximation Method ◽  
Dry Friction ◽  
Mechanical Model ◽  
Horizontal Plane ◽  
Galerkin Approximation ◽  
Block Type ◽  
Theoretical Part ◽  
Lagrange Formulation ◽  
Rocking Block

This study deals with the dynamical evolutions exhibited by a simple mechanical model of building, comprising a parallelepiped standing on a horizontal plane. The main goal is the introduction of a pendulum in order to reduce oscillations. The theoretical part of the work consists of a Lagrange formulation and Galerkin approximation method, and dry friction has also been considered. From the analytical/numerical simulations, we derive some important conclusions, providing us with the tools suitable for the design of absorbers in practical cases.

Study on the Evaluation Method of Subgrade Settlement Caused by Structure Layer of the High-Speed Railway

2012 ◽  
Vol 188 ◽  
pp. 72-77
Author(s):  
Ling Fa Jiang ◽  
Shu Dan Xiong ◽  
Xi Chang Xu ◽  
Shan Xiong Chen
Keyword(s):  
Numerical Calculation ◽  
High Speed ◽  
Evaluation Method ◽  
Functional Relationship ◽  
Numerical Results ◽  
Measure Data ◽  
Mechanical Parameters ◽  
High Speed Railway ◽  
Structure Layer

Based to the geometric and mechanical parameters of the typical high-speed railway, the settlement values on the foundation and the subgrade face with different structure layer load are obtained by the numerical calculation. According to these numerical results, the power functional relationship between Sst / S∞ and Pst /hγ is found, and a new evaluation method of the subgrade face settlement caused by the structure layer using the measure data is put forward. Through analyzing the settlement data of different conditions, the parameters of the formula are discussed, and some conclusions and suggestions are given. This new evaluation method will provide some reference for the design and the evaluation of the subgrade settlement caused by the structure layer of the high-speed railway.

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