Design of a Highly Dynamic Hydraulic Actuator?for Active Damping Systems in Machine Tools

2012 ◽  
Vol 2 (4) ◽  
pp. 15-26 ◽  
Author(s):  
C. Brecher ◽  
S. Bäumler ◽  
B. Brockmann
Keyword(s):  
Machine Tools ◽  
Active Damping ◽  
Linear Actuator ◽  
Hydraulic Actuator ◽  
New Approach ◽  
Hydraulic Cylinders ◽  
Multi Body ◽  
Actuator Design ◽  
Damping Systems

The positioning accuracy of conventional servo hydraulic cylinders is limited by oil compressibility, leak oil, nonlinearities, hysteresis effects, etc. This affects the control quality of the actuator, which is essential for a use in high dynamic positioning tasks, such as applications in active damping systems for machine tools. The presented hydraulic actuator design is a new approach to extend those limitations by using membrane based piston guidance and casing of pressure chambers. The actuator design is based on a linear mathematical model and FE-Simulations. The developed linear actuator model is integrated into a coupled multi body simulation of an existing active damping system. As the results of the coupled multi body simulation were promising, the actuator was manufactured and put into operation. A first insight into the behavior of the actuator and the verification of the linear actuator model is provided.

Experimental Estimation of Friction and Friction Coefficient of a Lightweight Hydraulic Cylinder Intended for Robotics Applications

2018 ◽  
Vol 10 (08) ◽  
pp. 1850080 ◽  
Author(s):  
Mohamad El Asswad ◽  
Samer AlFayad ◽  
Khaled Khalil
Keyword(s):  
Composite Materials ◽  
Friction Coefficient ◽  
Hydraulic Cylinder ◽  
Hydraulic Actuator ◽  
Engineering Applications ◽  
Average Value ◽  
Material Choice ◽  
Hydraulic Cylinders ◽  
Actuator Design ◽  
And Robotics

Recently, hydraulic actuator has been used in several engineering applications such as: aeronautics, construction and robotics. This is due to the need of high torque and power density in such engineering applications. Despite these advantages, hydraulic actuators are fabricated from metallic materials, which provoke their heavy weight, which necessitate the development of a lightweight hydraulic actuator, fabricated of composite materials. Using composite materials in hydraulic cylinders, it is important to study the friction force characteristics and to estimate the friction coefficient between composites and O-rings, which is presented in this paper. This paper deals with the estimation of Coulomb friction and friction coefficient in the lightweight hydraulic cylinder fabricated mainly of composite materials. The actuator is presented by its dynamic equation of motion, where each term is discussed including the stiffness coefficient, the viscous damping coefficient, the kinematics and the pressure parameters. Meanwhile, these coefficients and parameters are obtained according to data recorded from conducted experiments. As a result, the new methodology which uses the experimental measurements combined the dynamic model has succeeded to evaluate the friction inside the hydraulic cylinder which has been estimated and found to be around 166[Formula: see text]N, while the corresponding coefficient of friction is computed (about 0.61 as average value). These results will be important for further optimization of the material choice and actuator design, which will help in the amelioration of the hydraulic cylinder.

Dynamics of the processes in metal machining

1998 ◽  
Vol 2 ◽  
pp. 115-122
Author(s):  
Donatas Švitra ◽  
Jolanta Janutėnienė
Keyword(s):  
High Frequency ◽  
Machine Tools ◽  
Metal Cutting ◽  
Cutting Tool ◽  
Low Frequency ◽  
Metal Cutting Machine ◽  
Cutting Machine ◽  
Metal Machining

In the practice of processing of metals by cutting it is necessary to overcome the vibration of the cutting tool, the processed detail and units of the machine tool. These vibrations in many cases are an obstacle to increase the productivity and quality of treatment of details on metal-cutting machine tools. Vibration at cutting of metals is a very diverse phenomenon due to both it’s nature and the form of oscillatory motion. The most general classification of vibrations at cutting is a division them into forced vibration and autovibrations. The most difficult to remove and poorly investigated are the autovibrations, i.e. vibrations arising at the absence of external periodic forces. The autovibrations, stipulated by the process of cutting on metalcutting machine are of two types: the low-frequency autovibrations and high-frequency autovibrations. When the low-frequency autovibration there appear, the cutting process ought to be terminated and the cause of the vibrations eliminated. Otherwise, there is a danger of a break of both machine and tool. In the case of high-frequency vibration the machine operates apparently quiently, but the processed surface feature small-sized roughness. The frequency of autovibrations can reach 5000 Hz and more.

Guideline for the management of long tunnelled external ventricular drains in chronic hydrocephalus

2021 ◽  
Vol 30 (7) ◽  
pp. 416-421
Author(s):  
Phillip Correia Copley ◽  
John Emelifeonwu ◽  
Pasquale Gallo ◽  
Drahoslav Sokol ◽  
Jothy Kandasamy ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Nursing Care ◽  
Pilocytic Astrocytoma ◽  
Parental Education ◽  
Chronic Hydrocephalus ◽  
Treatment Protocols ◽  
New Approach ◽  
Viable Treatment

This article reports on the journey of a child with an inoperable hypothalamic-origin pilocytic astrocytoma causing hydrocephalus, which was refractory to treatment with shunts, and required a new approach. With multidisciplinary support, excellent nursing care and parental education, the child's hydrocephalus was managed long term in the community with bilateral long-tunnelled external ventricular drains (LTEVDs). This article describes the patient's journey and highlights the treatment protocols that were created to achieve this feat. Despite the difficulties in initially setting up these protocols, they proved successful and thus the team managing the patient proposed that LTEVDs are a viable treatment option for children with hydrocephalus in the context of inoperable tumours to help maximise quality of life.

Analyzing of UVLC system considering the effect of water depth

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Mustafa B. Al-Deen ◽  
Mazin Ali A. Ali ◽  
Zeyad A. Saleh
Keyword(s):  
Coastal Water ◽  
Water Depth ◽  
Bit Error Rate ◽  
Multiple Input Multiple Output ◽  
Visible Light Communications ◽  
New Approach ◽  
Multiple Input ◽  
Input Multiple Output ◽  
Depth Water

Abstract This paper presents a new approach to discover the effect of depth water for underwater visible light communications (UVLC). The quality of the optical link was investigated with varying water depth under coastal water types. The performance of the UVLC with multiple input–multiple output (MIMO) techniques was examined in terms of bit error rate (BER) and data rate. The theoretical result explains that there is a good performance for UVLC system under coastal water.

A new approach based on graph matching and evolutionary approach for sport scheduling problem

2020 ◽  
pp. 1-16
Author(s):  
Meriem Khelifa ◽  
Dalila Boughaci ◽  
Esma Aïmeur
Keyword(s):  
Graph Matching ◽  
State Of The Art ◽  
Travel Cost ◽  
Round Robin ◽  
New Approach ◽  
Traveling Tournament Problem ◽  
Significant Interest ◽  
National League ◽  
Better Than

The Traveling Tournament Problem (TTP) is concerned with finding a double round-robin tournament schedule that minimizes the total distances traveled by the teams. It has attracted significant interest recently since a favorable TTP schedule can result in significant savings for the league. This paper proposes an original evolutionary algorithm for TTP. We first propose a quick and effective constructive algorithm to construct a Double Round Robin Tournament (DRRT) schedule with low travel cost. We then describe an enhanced genetic algorithm with a new crossover operator to improve the travel cost of the generated schedules. A new heuristic for ordering efficiently the scheduled rounds is also proposed. The latter leads to significant enhancement in the quality of the schedules. The overall method is evaluated on publicly available standard benchmarks and compared with other techniques for TTP and UTTP (Unconstrained Traveling Tournament Problem). The computational experiment shows that the proposed approach could build very good solutions comparable to other state-of-the-art approaches or better than the current best solutions on UTTP. Further, our method provides new valuable solutions to some unsolved UTTP instances and outperforms prior methods for all US National League (NL) instances.

scholarly journals A New Approach to Assess the Quality of Small High-Speed Centrifugal Fans Using Noise Measurement

1999 ◽  
Vol 5 (2) ◽  
pp. 147-153 ◽  
Author(s):  
Dingjun Cui ◽  
Ian A. Craighead
Keyword(s):  
Signal Processing ◽  
Quality Assessment ◽  
Condition Monitoring ◽  
High Speed ◽  
Noise Levels ◽  
New Approach ◽  
Commercial Market ◽  
Centrifugal Fans ◽  
Special Approach

The requirements for a special approach for the quality assessment of small high-speed centrifugal fans are outlined and a new parameter designating the noise levels from the product in comprehensive form will be discussed and described as a criterion for such quality assessment.By applying techniques of signal processing and condition monitoring, the sources of the vibration and noise in different sections of the product can be identified, then the noise from each source from different components can be determined. Using this criterion, more aspects of the quality of the products can be assessed and suggestions to improve the quality of the products can be made. Finally, the assessment of a number ofvacuum cleaner motor/fan units available in the commercial market will be presented and compared with conventional specifications. It will be shown that the new parameter provides a more useful indication of appliance quality.

Dynamisches Verhalten von Gestellwerkstoffen in Werkzeugmaschinen*/Dynamic behavior of different machine frame materials

2015 ◽  
Vol 105 (05) ◽  
pp. 263-268
Author(s):  
P. H. Nebeling
Keyword(s):  
Dynamic Behavior ◽  
Machine Tools ◽  
Dynamic Behaviour ◽  
Influencing Factor ◽  
Complex Structures ◽  
Geometric Properties ◽  
Long Time

Das dynamische Verhalten von Werkzeugmaschinen ist für die Stabilität während der Bearbeitung sowie die Qualität der erzeugten Werkstücke von besonderer Bedeutung. Ein Einflussfaktor darauf ist die Dämpfung. Im Bereich der Maschinengestelle kommen seit langer Zeit unterschiedliche Materialien zum Einsatz. In diesem Fachbeitrag werden die Dämpfungskennwerte unterschiedlicher Gestellwerkstoffe an geometrisch gleichen Proben vergleichend gegenübergestellt. Als weitere Kenngröße wurde die Lage der (1. Biege-) Eigenfrequenz als Maß für die massebezogene dynamische Steifigkeit verwendet. Die Effekte beim Übergang von einfachen Bauteilen zu komplexen Strukturen runden den Fachartikel ab.   The dynamic behaviour of machine tools is of great importance for stability and quality of the machined work pieces. One influencing factor in this area is damping. In the field of machine bases different materials have been use since long time. In this article the damping values of different materials with equal geometric properties are compared. As further parameter the first bending Eigenfrequency as dimension for mass related stiffness is use. The transition from simple components to complex structures is touched at the end of the paper.

Measurement of cortical plate volume based on CBCT of frontal teeth in studies with retrusion and normality

2021 ◽  
pp. 17-21
Author(s):  
N. G. Meskhiya ◽  
I. S. Kopetskiy ◽  
I. A. Nikolskaya ◽  
D. A. Eremin ◽  
O. N. Kovaleva
Keyword(s):  
Orthodontic Treatment ◽  
Soft Tissues ◽  
Three Dimensions ◽  
Cone Beam ◽  
Cortical Plate ◽  
Imaging Method ◽  
New Approach ◽  
Accuracy Of Measurements ◽  
Bone Structures

Cone Beam Computed Tomography (CBCT) is the preferred imaging method for a comprehensive orthodontic examination. Thanks to the development of this technique, clinicians today can make most accurate measurements without fear of errors associated with projection distortion or localization of landmarks on radiographs. The quality of CBCT images gives to orthodontists the ability to analyze bone structures, teeth (even impacted teeth), and soft tissue in three dimensions. The accuracy of measurements of hard and soft tissues from CBCT images determines the accuracy of diagnosis and treatment planning. A fundamentally new approach has been proposed, which makes it possible to thoroughly study the bone tissue surrounding the tooth at the stages of planning orthodontic treatment. Аnalysis of radiation studies of patients with dentoalveolar anomalies was carried out to select the optimal treatment tactics and to control its effectiveness.

Research of actual information on well casing using machine learning and neural networks

2021 ◽  
pp. 108-119
Author(s):  
D. V. Shalyapin ◽  
D. L. Bakirov ◽  
M. M. Fattahov ◽  
A. D. Shalyapina ◽  
V. G. Kuznetsov
Keyword(s):  
Machine Learning ◽  
Probabilistic Models ◽  
Western Siberia ◽  
Network Modeling ◽  
Horizontal Wells ◽  
Categorical Variables ◽  
Neural Network Modeling ◽  
New Approach ◽  
Attachment Process

In domestic and world practice, despite the measures applied and developed to improve the quality of well casing, there is a problem of leaky structures in almost 50 % of completed wells. The study of actual data using classical methods of statistical analysis (regression and variance analyses) doesn't allow us to model the process with sufficient accuracy that requires the development of a new approach to the study of the attachment process. It is proposed to use the methods of machine learning and neural network modeling to identify the most important parameters and their synergistic impact on the target variables that affect the quality of well casing. The formulas necessary for translating the numerical values of the results of acoustic and gamma-gamma cementometry into categorical variables to improve the quality of probabilistic models are determined. A database consisting of 93 parameters for 934 wells of fields located in Western Siberia has been formed. The analysis of fastening of production columns of horizontal wells of four stratigraphic arches is carried out, the most weighty variables and regularities of their influence on target indicators are established. Recommendations are formulated to improve the quality of well casing by correcting the effects of acoustic and gamma-gamma logging on the results.

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