scholarly journals Soil Resistance and its Impact on Tillage Depth

2013 ◽  
Vol 16 (1) ◽  
pp. 26-30 ◽  
Author(s):  
František Varga ◽  
Miroslav Mojžiš ◽  
Rudolf Abrahám
Keyword(s):  
Theoretical Analysis ◽  
Control Systems ◽  
Force Control ◽  
Initial Conditions ◽  
The Other ◽  
Experimental Measurements ◽  
Soil Resistance ◽  
Research Development ◽  
Advantages And Disadvantages ◽  
Tillage Depth

Abstract Currently manufactured tractors are equipped with a three-point hitch, which is used to connect semi-mounted implements to the tractor. The tractor three-point hitch is operated hydraulically, using various types of control. The most commonly used control is a force, positional and a mixed one. Each of these types of control has its specific characteristics and some advantages and disadvantages. Finally, each type of control is suitable for certain soil and terrain conditions. Particular attention was paid to a force control, which is improving the use of the tractor with a mounted implement, but on the other hand, adversely affects the uniformity of working depth of implements on soils with variable resistance. Based on theoretical analysis and experimental measurements, there has been determined the effect of soil resistance on the tillage depth, depending on initial conditions for implement deepening. Initial conditions for implement deepening are given by the tillage depth, soil resistance, and the cutting width of a plough. It was found that soil resistance strongly affects the tillage depth, and with increasing soil resistance the tillage depth decreases non-linearly. A gradual increasing of soil resistance is associated with a less-marked decreasing of the tillage depth. These facts will be further used in research, development and experimental verification of new control systems of the three-point hitch of tractors.

scholarly journals A bistable structural element

2008 ◽  
Vol 222 (11) ◽  
pp. 2045-2051 ◽  
Author(s):  
T Schioler ◽  
S Pellegrino
Keyword(s):  
Theoretical Analysis ◽  
Analytical Model ◽  
Mechanical Behaviour ◽  
The Other ◽  
Experimental Measurements ◽  
Structural Element ◽  
High Stiffness ◽  
Revolute Joints ◽  
Prototype Structure ◽  
Good Agreement

This article presents a novel bistable structural element that has high stiffness in stable configurations, but requires only a small amount of energy to be switched from one configuration to the other. The element is based on a planar linkage of four bars connected by revolute joints, braced by tape-spring diagonals. A description of the concept is presented, along with a detailed theoretical analysis of its mechanical behaviour. Experimental measurements obtained from a prototype structure are found to be in very good agreement with the predictions from this analytical model.

Hybrid polymer composite materials. Part 2. Preparation technology

2020 ◽  
pp. 8-13
Keyword(s):  
Composite Materials ◽  
Impact Toughness ◽  
Polymer Composites ◽  
The Other ◽  
Polymer Materials ◽  
Hybrid Polymer ◽  
Preparation Technology ◽  
Advantages And Disadvantages ◽  
Hybrid Polymer Composite ◽  
The One

The main methods (pressing and winding) of the processing of hybrid polymer composites to obtain items were examined. Advantages and disadvantages of the methods were noted. Good combinations of different-module fibers (carbon, glass, boron, organic) in hybrid polymer materials are described, which allow one to prepare materials with high compression strength on the one hand, and to increase fracture energy of samples and impact toughness on the other hand.

scholarly journals COVID-19 Shutdown: A Qualitative Study on Pearls and Pitfalls

Proceedings ◽  
2021 ◽  
Vol 74 (1) ◽  
pp. 4
Author(s):  
Naciye Güliz Uğur
Keyword(s):  
Qualitative Study ◽  
Human Health ◽  
Social Distance ◽  
The Other ◽  
Adoption Of Technology ◽  
Family Ties ◽  
Advantages And Disadvantages ◽  
Modern Period ◽  
Long Term Impact

The extraordinary and tragic conditions that humanity has not experienced before in the modern period have become ordinary, namely, a “new normal” with the presence of the COVID-19 pandemic. COVID-19 has had frightening consequences for human health and has caused one million deaths as of September 2020. On the other hand, it has set a new standard of good habits, approaches, and benefits. Due to its global and long-term impact, this unique virus has laid the groundwork for unprecedented helping and sharing behaviors between people and countries. In this study, findings are compiled from the open-ended responses of 626 individuals, all of whom live in Turkey. Within the study’s scope, individuals were asked about the unique advantages and disadvantages of the restrictions imposed under COVID-19. While the categories of economy, social distance, and health came to the fore among the harms, the strengthening of family ties, adoption of technology, and the spread of solidarity culture were mentioned among the advantages.

A Low-Cost Hexa Platform for Efficient Force Control Systems Using Industrial Manipulators

2009 ◽  
Vol 147-149 ◽  
pp. 1-6 ◽  
Author(s):  
Rafal Osypiuk ◽  
Torsten Kröger
Keyword(s):  
Control Systems ◽  
Force Control ◽  
Execution Time ◽  
Low Cost ◽  
Degree Of Freedom ◽  
Industrial Manipulators ◽  
Control Concept ◽  
Six Dof ◽  
Parallel Platform ◽  
Six Degree Of Freedom

This contribution presents a new force control concept for industrial six-degree of freedom (DOF) manipulators, which uses a Hexa platform that provides an active environmental stiffness for all six DOFs. The paper focuses on the Hexa platform and is split into two essential parts: (i) parallel platform construction, and (ii) application of force control with industrial manipulators using a six-DOF environmental stiffness. This mechatronic solution almost gives one hundred percent robustness for stiffness changes in the environment, what guaranties a significant shortening of execution time.

Signature change in p-adic and noncommutative FRW cosmology

2014 ◽  
Vol 29 (27) ◽  
pp. 1450155 ◽  
Author(s):  
Goran S. Djordjevic ◽  
Ljubisa Nesic ◽  
Darko Radovancevic
Keyword(s):  
Loop Quantum Gravity ◽  
Initial Conditions ◽  
Planck Scale ◽  
The Other ◽  
Frw Cosmology ◽  
Signature Change ◽  
Discrete Nature ◽  
Frw Metric ◽  
The Universe ◽  
Friedmann Robertson Walker

The significant matter for the construction of the so-called no-boundary proposal is the assumption of signature transition, which has been a way to deal with the problem of initial conditions of the universe. On the other hand, results of Loop Quantum Gravity indicate that the signature change is related to the discrete nature of space at the Planck scale. Motivated by possibility of non-Archimedean and/or noncommutative structure of space–time at the Planck scale, in this work we consider the classical, p-adic and (spatial) noncommutative form of a cosmological model with Friedmann–Robertson–Walker (FRW) metric coupled with a self-interacting scalar field.

scholarly journals On Existence of Stabilizing Switching Laws within a Class of Unstable Linear Systems

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Sendren Sheng-Dong Xu ◽  
Chih-Chiang Chen
Keyword(s):  
Control Systems ◽  
Linear Systems ◽  
Switched Systems ◽  
The Other ◽  
Linear Control ◽  
Linear Control Systems ◽  
Problem Statement ◽  
Theoretical Derivation ◽  
Control Laws ◽  
Numerical Examples

The equivalence of two conditions, condition (3) and condition (4) stated in Problem Statement section, regarding the existence of stabilizing switching laws between two unstable linear systems first appeared in (Feron 1996). Although Feron never published this result, it has been referenced in almost every survey on switched systems; see, for example, (Liberzon and Morse 1999). This paper proposes another way to prove the equivalence of two conditions regarding the existence of stabilizing switching laws between two unstable linear systems. One is effective for theoretical derivation, while the other is implementable, and a class of stabilizing switching laws have been explicitly constructed by Wicks et al. (1994). With the help of the equivalent relation, a condition for the existence of controllers and stabilizing switching laws between two unstabilizable linear control systems is then proposed. Then, the study is further extended to the issue concerning the construction of quadratically stabilizing switching laws among unstable linear systems and unstabilizable linear control systems. The obtained results are employed to study the existence of control laws and quadratically stabilizing switching laws within a class of unstabilizable linear control systems. The numerical examples are illustrated and simulated to show the feasibility and effectiveness of the proposed methods.

scholarly journals Interaction of buoyant plumes in open-channel flow

1992 ◽  
Vol 33 (4) ◽  
pp. 451-473
Author(s):  
P. J. Wicks
Keyword(s):  
Diffusion Equation ◽  
Channel Flow ◽  
Open Channel ◽  
Nonlinear Term ◽  
Initial Conditions ◽  
Hermite Polynomials ◽  
Open Channel Flow ◽  
The Other ◽  
Buoyant Plumes ◽  
Rich Variety

AbstractIn this paper, a model for lateral dispersion in open-channel flow is studied involving a diffusion equation which has a nonlinear term describing the effect of buoyancy. The model is used to investigate the interaction of two buoyant pollutant plumes. An approximate analytic technique involving Hermite polynomials is applied to the resulting PDEs to reduce them to a system of ODEs for the centroids and widths of the two plumes. The ODEs are then solved numerically. A rich variety of behaviour occurs depending on the relative positions, widths and strengths of the initial discharges. It is found that for two plumes of equal strength and width discharged side-by-side, the plumes move apart and the rate of spreading is inhibited by their interaction, whereas when one plume is initially much wider than the other, both plumes tend to drift to the side of the narrower plume. Finally, the PDEs are solved numerically for two sets of initial conditions and a comparison is made with the ODE solutions. Agreement is found to be good.

THEORETICAL ANALYSIS AND EXPERIMENT OF A NOVEL DEP CHIP WITH 3-D SILICON ELECTRODES

2005 ◽  
Vol 15 (02) ◽  
pp. 231-236 ◽  
Author(s):  
LIMING YU ◽  
FRANCIS E. H. TAY ◽  
GUOLIN XU ◽  
CIPRIAN ILIESCU ◽  
MARIOARA AVRAM
Keyword(s):  
Theoretical Analysis ◽  
Applied Voltage ◽  
Microfluidic Channel ◽  
The Other ◽  
Yeast Cells ◽  
Applied Potential ◽  
Dielectrophoretic Force ◽  
Joule Effect ◽  
Doped Silicon ◽  
Planar Electrodes

This paper presents a novel dielectrophoresis (DEP) device where the DEP electrodes define the channel walls. This is achieved by fabricating microfluidic channel walls from highly doped silicon so that they can also function as DEP electrodes. Compared with planar electrodes, this device increases the exhibited dielectrophoretic force on the particle, therefore decreases the applied potential and reduces the heating of the solution. A DEP device with triangle electrodes has been designed and fabricated. Compared with the other two configurations, semi-circular and square, triangle electrode presents an increased force, which can decrease the applied voltage and reduce the Joule effect. Yeast cells have been used to for testing the performance of the device.

Second Paper: Failure-Survival Automatic Flight Control Systems for Aircraft with Particular Reference to a High Reliability Electrohydraulic Actuator

1965 ◽  
Vol 180 (1) ◽  
pp. 246-259
Author(s):  
R. Ruggles
Keyword(s):  
Control System ◽  
Control Systems ◽  
Flight Control ◽  
High Reliability ◽  
Supply System ◽  
Design Criteria ◽  
Flight Control System ◽  
Advantages And Disadvantages ◽  
System Configurations ◽  
Very High

The author discusses some of the problems of failure-survival automatic flight control systems and suggests some basic ground rules as design criteria. The advantages and disadvantages of some of the main types of system are discussed: duplex, triplex, triple component, duplicate-monitored and quadruplex systems being covered. In particular, a quadruplex actuator is described which has been designed and developed mainly for automatic flight control system applications where a very high degrees of failure-survival capability is required. A detailed failure analysis of the various systems is carried out and the importance of the electrical and hydraulic supply system configurations and failure rates is brought out.

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