Dynamic Behavior of a Hydraulically Actuated Mechanism. Part 1: Small Perturbations

1986 ◽  
Vol 108 (2) ◽  
pp. 245-249 ◽  
Author(s):  
V. Venkatraman ◽  
R. W. Mayne
Keyword(s):  
Dynamic Behavior ◽  
Transient Response ◽  
Hydraulic Cylinder ◽  
Design Guidelines ◽  
System Behavior ◽  
Small Perturbations ◽  
Wide Range ◽  
Hydraulically Actuated ◽  
Quantitative Design ◽  
Parameter Values

This paper considers the dynamic behavior of a mechanism actuated by an oscillating hydraulic cylinder. The analysis is generalized by introducing nondimensional parameters. In this first portion of the paper, linearization is applied to explore the basic nature of the system transient response. A wide range of parameter values is considered to illustrate the effects of fluid capacitance, fluid inertance, load, leakage and friction on the system behavior and quantitative design guidelines are indicated. Part 2 of the paper deals with nonlinear aspects of the actuator-mechanism system.

Transient response of the 1-st order dynamic system with fluctuating parameters

1979 ◽  
Vol 44 (7) ◽  
pp. 2184-2195
Author(s):  
Vladimír Herles ◽  
Jan Čermák ◽  
Antonín Havlíček
Keyword(s):  
Dynamic System ◽  
Dynamic Behavior ◽  
Transient Response ◽  
Flow Model ◽  
Stirred Tank ◽  
Order System ◽  
Random Parameters ◽  
Stirred Tank Reactor ◽  
Tank Reactor ◽  
Theoretical Results

The paper deals with the analysis of the dynamic behavior of the 1st order system with two random parameters. The theoretical results have been compared with experiments on flow model of a stirred tank reactor.

scholarly journals β-Lactoglobulin Adsorption Layers at the Water/Air Surface: 5. Adsorption Isotherm and Equation of State Revisited, Impact of pH

2021 ◽  
Vol 5 (1) ◽  
pp. 14
Author(s):  
Georgi G. Gochev ◽  
Volodymyr I. Kovalchuk ◽  
Eugene V. Aksenenko ◽  
Valentin B. Fainerman ◽  
Reinhard Miller
Keyword(s):  
Theoretical Description ◽  
Fluid Interfaces ◽  
Interfacial Behavior ◽  
Current State ◽  
Air Interface ◽  
Direct Measurements ◽  
Wide Range ◽  
Dilational Viscoelasticity ◽  
Parameter Values ◽  
Β Lactoglobulin

The theoretical description of the adsorption of proteins at liquid/fluid interfaces suffers from the inapplicability of classical formalisms, which soundly calls for the development of more complicated adsorption models. A Frumkin-type thermodynamic 2-d solution model that accounts for nonidealities of interface enthalpy and entropy was proposed about two decades ago and has been continuously developed in the course of comparisons with experimental data. In a previous paper we investigated the adsorption of the globular protein β-lactoglobulin at the water/air interface and used such a model to analyze the experimental isotherms of the surface pressure, Π(c), and the frequency-, f-, dependent surface dilational viscoelasticity modulus, E(c)f, in a wide range of protein concentrations, c, and at pH 7. However, the best fit between theory and experiment proposed in that paper appeared incompatible with new data on the surface excess, Γ, obtained from direct measurements with neutron reflectometry. Therefore, in this work, the same model is simultaneously applied to a larger set of experimental dependences, e.g., Π(c), Γ(c), E(Π)f, etc., with E-values measured strictly in the linear viscoelasticity regime. Despite this ambitious complication, a best global fit was elaborated using a single set of parameter values, which well describes all experimental dependencies, thus corroborating the validity of the chosen thermodynamic model. Furthermore, we applied the model in the same manner to experimental results obtained at pH 3 and pH 5 in order to explain the well-pronounced effect of pH on the interfacial behavior of β-lactoglobulin. The results revealed that the propensity of β-lactoglobulin globules to unfold upon adsorption and stretch at the interface decreases in the order pH 3 > pH 7 > pH 5, i.e., with decreasing protein net charge. Finally, we discuss advantages and limitations in the current state of the model.

scholarly journals A New Statistic for Detecting Genetic Differentiation

Genetics ◽  
2000 ◽  
Vol 155 (4) ◽  
pp. 2011-2014 ◽  
Author(s):  
Richard R Hudson
Keyword(s):  
Genetic Differentiation ◽  
Dna Sequences ◽  
Genetic Data ◽  
Island Model ◽  
Wide Range ◽  
Infinite Sites Model ◽  
Parameter Values

Abstract A new statistic for detecting genetic differentiation of subpopulations is described. The statistic can be calculated when genetic data are collected on individuals sampled from two or more localities. It is assumed that haplotypic data are obtained, either in the form of DNA sequences or data on many tightly linked markers. Using a symmetric island model, and assuming an infinite-sites model of mutation, it is found that the new statistic is as powerful or more powerful than previously proposed statistics for a wide range of parameter values.

Dynamic Behavior of a Hydraulically Actuated Mechanism. Part 2: Nonlinear Character

1986 ◽  
Vol 108 (2) ◽  
pp. 250-254
Author(s):  
V. Venkatraman ◽  
R. W. Mayne
Keyword(s):  
Dynamic Response ◽  
Transient Response ◽  
Adequate Description ◽  
Linear Behavior ◽  
Transmission Angle ◽  
Dimensionless Groups ◽  
Hydraulically Actuated ◽  
Nonlinear Character ◽  
The Common ◽  
Nonlinear Nature

The first of these papers considering a hydraulically actuated mechanism presents the common oscillating cylinder arrangement and sets of equations which describe the dynamic system. It then defines dimensionless groups that characterize the actuator-mechanism and explores the quasi-linear behavior of the system. This present paper focuses on the nonlinear nature of the system. Effects of transmission angle, mechanism geometry and loading are considered as well as the range of operation in which the small perturbation behavior provides an adequate description of the dynamic response. The paper closes by identifying a new parameter which plays an important role in characterizing the dependence of the system transient response on mechanism geometry.

Motion of slender bodies in unsteady Stokes flow

2011 ◽  
Vol 688 ◽  
pp. 66-87 ◽  
Author(s):  
Efrath Barta
Keyword(s):  
Stokes Flow ◽  
Slenderness Ratio ◽  
Creeping Flow ◽  
Slender Body Theory ◽  
Wide Range ◽  
Unsteady Stokes Flow ◽  
Slender Bodies ◽  
Set Up ◽  
Micro Organisms ◽  
Parameter Values

AbstractThe flow regime in the vicinity of oscillatory slender bodies, either an isolated one or a row of many bodies, immersed in viscous fluid (i.e. under creeping flow conditions) is studied. Applying the slender-body theory by distributing proper singularities on the bodies’ major axes yields reasonably accurate and easily computed solutions. The effect of the oscillations is revealed by comparisons with known Stokes flow solutions and is found to be most significant for motion along the normal direction. Streamline patterns associated with motion of a single body are characterized by formation and evolution of eddies. The motion of adjacent bodies results, with a reduction or an increase of the drag force exerted by each body depending on the direction of motion and the specific geometrical set-up. This dependence is demonstrated by parametric results for frequency of oscillations, number of bodies, their slenderness ratio and the spacing between them. Our method, being valid for a wide range of parameter values and for densely packed arrays of rods, enables simulation of realistic flapping of bristled wings of some tiny insects and of locomotion of flagella and ciliated micro-organisms, and might serve as an efficient tool in the design of minuscule vehicles. Its potency is demonstrated by a solution for the flapping of thrips.

Ein semiaktiver Ansatz zur Verbesserung des dynamischen Verhaltens/Vibration damping on industrial robots – A semi-active approach to improve the dynamic behavior

2021 ◽  
Vol 111 (09) ◽  
pp. 622-627
Author(s):  
Michael Neubauer ◽  
Patrick Mesmer ◽  
Armin Lechler ◽  
Alexander Verl
Keyword(s):  
Dynamic Behavior ◽  
Disturbance Rejection ◽  
Vibration Damping ◽  
Active Damping ◽  
Drive Train ◽  
Industrial Robots ◽  
System Behavior ◽  
Eine Hohe ◽  
Damped System ◽  
Active Approach

Von Industrierobotern wird zunehmend eine hohe Bahn genauigkeit und ein gutes Störunterdrückungsverhalten gefordert. Um dem gerecht zu werden, wird hier ein semiaktiver Dämpfungsansatz vorgestellt, der Antriebsstrangschwingungen aktorbasiert dämpft. Damit geht ein stärker gedämpftes Systemverhalten einher, wodurch sich die Regelverstärkungsfaktoren erhöhen lassen. Das Resultat ist ein verbessertes Gesamtverhalten, das an einem „Kr210–2“ von Kuka mit semiaktiver Dämpfung an Achse 1 nachgewiesen wird.   Industrial robots are increasingly required to provide high path accuracy and good disturbance rejection behavior. In order to achieve this, a semi-active damping approach is presented, which damps drive train vibrations actuator-based. This leads to a more damped system behavior, allowing control gains to be increased. The result is an improved overall behavior, which is demonstrated on a Kuka Kr210–2 with semi-active damping on axis 1.

Convective and turbulent motions in non-precipitating Cu. Part 1: Method of separation of convective and turbulent motions

2021 ◽  
Author(s):  
Mark Pinsky ◽  
Eshkol Eytan ◽  
Ilan Koren ◽  
Orit Altaratz ◽  
Alexander Khain
Keyword(s):  
Velocity Field ◽  
Vertical Velocity ◽  
Isotropic Turbulence ◽  
Convective Velocity ◽  
Cloud Dynamics ◽  
Wide Range ◽  
Homogeneous And Isotropic Turbulence ◽  
Microphysical Processes ◽  
Bin Microphysics ◽  
Parameter Values

AbstractAtmospheric motions in clouds and cloud surrounding have a wide range of scales, from several kilometers to centimeters. These motions have different impacts on cloud dynamics and microphysics. Larger-scale motions (hereafter referred to as convective motions) are responsible for mass transport over distances comparable with cloud scale, while motions of smaller scales (hereafter referred to as turbulent motions) are stochastic and responsible for mixing and cloud dilution. This distinction substantially simplifies the analysis of dynamic and microphysical processes in clouds. The present research is Part 1 of the study aimed at describing the method for separating the motion scale into a convective component and a turbulent component. An idealized flow is constructed, which is a sum of an initially prescribed field of the convective velocity with updrafts in the cloud core and downdrafts outside the core, and a stochastic turbulent velocity field obeying the turbulent properties, including the -5/3 law and the 2/3 structure function law. A wavelet method is developed allowing separation of the velocity field into the convective and turbulent components, with parameter values being in a good agreement with those prescribed initially. The efficiency of the method is demonstrated by an example of a vertical velocity field of a cumulus cloud simulated using SAM with bin-microphysics and resolution of 10 m. It is shown that vertical velocity in clouds indeed can be represented as a sum of convective velocity (forming zone of cloud updrafts and subsiding shell) and a stochastic velocity obeying laws of homogeneous and isotropic turbulence.

scholarly journals Signaling pathways have an inherent need for noise to acquire information

2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Eugenio Azpeitia ◽  
Eugenio P. Balanzario ◽  
Andreas Wagner
Keyword(s):  
Signaling Pathways ◽  
Information Acquisition ◽  
Cellular Level ◽  
Kinetic Properties ◽  
Positive Role ◽  
Binding Interactions ◽  
Reversible Binding ◽  
Wide Range ◽  
The One ◽  
Parameter Values

Abstract Background All living systems acquire information about their environment. At the cellular level, they do so through signaling pathways. Such pathways rely on reversible binding interactions between molecules that detect and transmit the presence of an extracellular cue or signal to the cell’s interior. These interactions are inherently stochastic and thus noisy. On the one hand, noise can cause a signaling pathway to produce the same response for different stimuli, which reduces the amount of information a pathway acquires. On the other hand, in processes such as stochastic resonance, noise can improve the detection of weak stimuli and thus the acquisition of information. It is not clear whether the kinetic parameters that determine a pathway’s operation cause noise to reduce or increase the acquisition of information. Results We analyze how the kinetic properties of the reversible binding interactions used by signaling pathways affect the relationship between noise, the response to a signal, and information acquisition. Our results show that, under a wide range of biologically sensible parameter values, a noisy dynamic of reversible binding interactions is necessary to produce distinct responses to different stimuli. As a consequence, noise is indispensable for the acquisition of information in signaling pathways. Conclusions Our observations go beyond previous work by showing that noise plays a positive role in signaling pathways, demonstrating that noise is essential when such pathways acquire information.

scholarly journals Monte Carlo ice flow modeling projects a new stable configuration for Columbia Glacier, Alaska, by c. 2020

2012 ◽  
Vol 6 (2) ◽  
pp. 893-930 ◽  
Author(s):  
W. Colgan ◽  
W. T. Pfeffer ◽  
H. Rajaram ◽  
W. Abdalati
Keyword(s):  
Monte Carlo ◽  
Dynamic Equilibrium ◽  
Stable Configuration ◽  
Ice Flow ◽  
Wide Range ◽  
Ensemble Mean ◽  
Iceberg Calving ◽  
Calving Rate ◽  
Parameter Values

Abstract. Due to the abundance of observational datasets collected since the onset of its retreat (c. 1983), Columbia Glacier, Alaska, provides an exciting modeling target. We perform Monte Carlo simulations of the form and flow of Columbia Glacier, using a 1-D (depth-integrated) flowline model, over a wide range of parameter values and forcings. An ensemble filter is imposed following spin-up to ensure that only simulations which accurately reproduce observed pre-retreat glacier geometry are retained; all other simulations are discarded. The selected ensemble of simulations reasonably reproduces numerous highly transient post-retreat observed datasets with a minimum of parameterizations. The selected ensemble mean projection suggests that Columbia Glacier will achieve a new dynamic equilibrium (i.e. "stable") ice geometry c. 2020, by which time iceberg calving rate will have returned to approximately pre-retreat values. Comparison of the observed 1957 and 2007 glacier geometries with the projected 2100 glacier geometry suggests that, by 2007, Columbia Glacier had already discharged ∼83 % of its total sea level rise contribution expected by 2100. This case study therefore highlights the difficulties associated with the future extrapolation of observed glacier mass loss rates that are dominated by iceberg calving.

Discussion of Calculation of Power Function with Special Reference to Respiratory Metabolism in Fish

1969 ◽  
Vol 26 (10) ◽  
pp. 2643-2650 ◽  
Author(s):  
Norman R. Glass
Keyword(s):  
Body Weight ◽  
Oxygen Consumption ◽  
Power Function ◽  
Body Weight Data ◽  
Fitting Method ◽  
Wide Range ◽  
Curve Fitting Method ◽  
Parameter Values ◽  
Weight Data ◽  
Range Of Values

The rationale for employing a nonlinear iterative least-squares technique for fitting the well-known power function to oxygen consumption–body weight data is set forth. Twenty-six sets of routine or standard metabolism data from six authors were used to demonstrate the relative merits of two methods of calculating parameter values for the power function. The conclusion was reached that if accuracy in predicting oxygen consumption over a wide range of values of body weight is desired, an iterative curve fitting method may be superior to the much used technique of performing a linear regression on logarithmically transformed data.

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