Externally Pressurized Bearings as Servomechanisms. I—The Simple Thrust Bearing

1967 ◽  
Vol 89 (4) ◽  
pp. 418-424 ◽  
Author(s):  
Donald F. Wilcock
Keyword(s):  
Transfer Function ◽  
Film Thickness ◽  
Closed Loop ◽  
Thrust Bearing ◽  
The Other ◽  
Time Dependent ◽  
Dependent Flow ◽  
Bearing Behavior ◽  
Fresh Insight ◽  
Insight Into

The externally pressurized bearing may be considered and analyzed as an hydraulic closed-loop servomechanism. The use of restrictor feed devices introduces an inner loop that reduces the gain. The time-dependent flow due to the change in volume with film thickness creates a “lead” break frequency favorable to stability. Fluid compressibility, on the other hand, leads to a “lag” break frequency which, if it approaches or becomes less than the “lead” frequency, results in bearing instability. Analysis by transfer function furnishes fresh insight into EP bearing behavior.

Optimum Design of a Dynamic Micro-Mixer for Multiphase Flow

2007 ◽  
Vol 353-358 ◽  
pp. 2836-2838
Author(s):  
Seok Young Han ◽  
J.Y. Park ◽  
Y.D. Kim ◽  
S.J. An ◽  
J.S. Maeng
Keyword(s):  
Optimum Design ◽  
Lattice Boltzmann ◽  
The Other ◽  
Time Dependent ◽  
Index Formula ◽  
Lattice Boltzmann Methods ◽  
Design Variables ◽  
Karman Vortex ◽  
Dependent Flow ◽  
Micro Mixer

An active micro-mixer equipped with an oscillating stirrer is considered by analyzing the mixing behaviors, i.e. the effect of the Karman vortex, the flow structure after the stirrer, etc. The mixing was calculated by the D2Q9 model of Lattice Boltzmann methods. In this study, the time– averaged mixing index formula, I D , is newly proposed for time dependent flow. Three models are tested and the mixing indices are compared. From the results, it was found that the mixing of Model III is enhanced and stabilized much more than the other models. Therefore, an optimum design for a dynamic micro-mixer with an oscillating stirrer was performed. The design variables were established as the length, the angle and frequency of the stirrer. It is found that the optimal design variables are determined by 0.66, 107.9 o and 0.49 Hz.

scholarly journals Asymptotic behaviour of Stokes flow in a thin domain with a moving rough boundary

2014 ◽  
Vol 470 (2167) ◽  
pp. 20130735 ◽  
Author(s):  
J. Fabricius ◽  
Y. O. Koroleva ◽  
A. Tsandzana ◽  
P. Wall
Keyword(s):  
Fluid Flow ◽  
Film Thickness ◽  
Stokes Flow ◽  
High Frequency ◽  
The Other ◽  
Time Dependent ◽  
Rough Boundary ◽  
Thin Domain ◽  
Small Parameters ◽  
Zero Time

We consider a problem that models fluid flow in a thin domain bounded by two surfaces. One of the surfaces is rough and moving, whereas the other is flat and stationary. The problem involves two small parameters ϵ and μ that describe film thickness and roughness wavelength, respectively. Depending on the ratio λ= ϵ / μ , three different flow regimes are obtained in the limit as both of them tend to zero. Time-dependent equations of Reynolds type are obtained in all three cases (Stokes roughness, Reynolds roughness and high-frequency roughness regime). The derivations of the limiting equations are based on formal expansions in the parameters ϵ  and  μ .

Evaluation of Various Approximate Solutions for Fluid Inertia Effects on the Dynamic Performance of a Stepped Thrust Bearing

1985 ◽  
Vol 107 (1) ◽  
pp. 39-45 ◽  
Author(s):  
Y. Haruyama ◽  
T. Kazamaki ◽  
A. Mori ◽  
H. Mori
Keyword(s):  
Film Thickness ◽  
Thrust Bearing ◽  
Stokes Equations ◽  
Dynamic Performance ◽  
Approximate Solutions ◽  
Time Dependent ◽  
Fluid Inertia ◽  
Inertia Effects ◽  
Dependent Term ◽  
Wide Range

Based on the Navier-Stokes equations in which the pressure is assumed to be constant across the film thickness, various approximate solutions and the exact one for the dynamic performance of an infinitely wide, stepped thrust bearing in a laminar flow regime are presented under the assumption of a small harmonic vibration. From comparison of the approximate solutions with the exact one, it is concluded that some kind of averaging approach in which the time dependent term is treated exactly while the convective inertia terms are averaged out across the film thickness gives close approximations in a wide range of designing conditions, and that the other kind of averaging approach in which all the inertia terms including the time dependent term are averaged out across the film thickness gives fairly good approximations.

scholarly journals Effect of Bolts on Flow and Heat Transfer in a Rotor-Stator Disc Cavity

2016 ◽  
Author(s):  
Sulfickerali Noor Mohamed ◽  
John W. Chew ◽  
Nicholas J. Hills
Keyword(s):  
Heat Transfer ◽  
Flow Rate ◽  
Parametric Study ◽  
Time Dependent ◽  
Navier Stokes ◽  
Cfd Simulations ◽  
Flow And Heat Transfer ◽  
Gap Ratio ◽  
Dependent Flow ◽  
Insight Into

Previous studies have indicated some differences between steady CFD predictions of flow in a rotor-stator disc cavity with rotating bolts compared to measurements. Recently time-dependent CFD simulations have revealed the unsteadiness present in the flow and have given improved agreement with measurements. In this paper unsteady Reynolds averaged Navier-Stokes (URANS) 360° model CFD calculations of a rotor-stator cavity with rotor bolts were performed in order to better understand the flow and heat transfer within a disc cavity previously studied experimentally by other workers. It is shown that the rotating bolts generate unsteadiness due to wake shedding which creates time-dependent flow patterns within the cavity. At low throughflow conditions, the unsteady flow significantly increases the average disc temperature. A systematic parametric study is presented giving insight into the influence of number of bolts, mass flow rate, cavity gap ratio and the bolts-to-shroud gap ratio on the time depended flow within the cavity.

scholarly journals Effect of Bolts on Flow and Heat Transfer in a Rotor–Stator Disk Cavity

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Sulfickerali Noor Mohamed ◽  
John W. Chew ◽  
Nicholas J. Hills
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Time Dependent ◽  
Navier Stokes ◽  
Cfd Simulations ◽  
Flow And Heat Transfer ◽  
Gap Ratio ◽  
Computational Fluid Dynamics Cfd ◽  
Dependent Flow ◽  
Insight Into

Previous studies have indicated some differences between steady computational fluid dynamics (CFD) predictions of flow in a rotor–stator disk cavity with rotating bolts compared to measurements. Recently, time-dependent CFD simulations have revealed the unsteadiness present in the flow and have given improved agreement with measurements. In this paper, unsteady Reynolds averaged Navier–Stokes (URANS) 360 deg model CFD calculations of a rotor–stator cavity with rotor bolts were performed in order to better understand the flow and heat transfer within a disk cavity previously studied experimentally by other workers. It is shown that the rotating bolts generate unsteadiness due to wake shedding which creates time-dependent flow patterns within the cavity. At low throughflow conditions, the unsteady flow significantly increases the average disk temperature. A systematic parametric study is presented giving insight into the influence of number of bolts, mass flow rate, cavity gap ratio, and the bolts-to-shroud gap ratio on the time-dependent flow within the cavity.

A Bird in the Hand Isn’t Good for Long

2018 ◽  
Vol 65 (1) ◽  
pp. 23-31 ◽  
Author(s):  
Stefan Scherbaum ◽  
Simon Frisch ◽  
Maja Dshemuchadse
Keyword(s):  
Decision Making ◽  
Cognitive Control ◽  
The Other ◽  
Decision Task ◽  
Short Term ◽  
Additional Time ◽  
Control Processes ◽  
Folk Wisdom ◽  
Study Participants ◽  
Insight Into

Abstract. Folk wisdom tells us that additional time to make a decision helps us to refrain from the first impulse to take the bird in the hand. However, the question why the time to decide plays an important role is still unanswered. Here we distinguish two explanations, one based on a bias in value accumulation that has to be overcome with time, the other based on cognitive control processes that need time to set in. In an intertemporal decision task, we use mouse tracking to study participants’ responses to options’ values and delays which were presented sequentially. We find that the information about options’ delays does indeed lead to an immediate bias that is controlled afterwards, matching the prediction of control processes needed to counter initial impulses. Hence, by using a dynamic measure, we provide insight into the processes underlying short-term oriented choices in intertemporal decision making.

Correlational Methods for Analysis of Dance Movements

2011 ◽  
Vol 29 (supplement) ◽  
pp. 283-304 ◽  
Author(s):  
Timothy R. Brick ◽  
Steven M. Boker
Keyword(s):  
Motion Capture ◽  
Mirror Symmetry ◽  
Cross Correlation ◽  
The Other ◽  
Free Form ◽  
Motion Capture Data ◽  
Complex Interactions ◽  
Dance Movements ◽  
Time Lagged ◽  
Insight Into

Among the qualities that distinguish dance from other types of human behavior and interaction are the creation and breaking of synchrony and symmetry. The combination of symmetry and synchrony can provide complex interactions. For example, two dancers might make very different movements, slowing each time the other sped up: a mirror symmetry of velocity. Examining patterns of synchrony and symmetry can provide insight into both the artistic nature of the dance, and the nature of the perceptions and responses of the dancers. However, such complex symmetries are often difficult to quantify. This paper presents three methods – Generalized Local Linear Approximation, Time-lagged Autocorrelation, and Windowed Cross-correlation – for the exploration of symmetry and synchrony in motion-capture data as is it applied to dance and illustrate these with examples from a study of free-form dance. Combined, these techniques provide powerful tools for the examination of the structure of symmetry and synchrony in dance.

Marx, Silk Poems, and the Pretext of Qualities

2020 ◽  
Vol 151 (1) ◽  
pp. 96-126
Author(s):  
Kathryn Crim
Keyword(s):  
The Other ◽  
Use Value ◽  
Working Day ◽  
The One ◽  
Insight Into

Karl Marx’s comments on silk manufacture in “The Working Day” chapter of Capital, volume 1, demonstrate how “quality”—usually associated with “use value”—has been mobilized by capital to naturalize industrialized labor. Putting his insight into conversation with a recent multimedia poetic project, Jen Bervin’s Silk Poems (2016–17), this essay examines the homology between, on the one hand, poetry’s avowed task of fitting form to content and, on the other, the ideology of labor that fits specific bodies to certain materials and tasks.

Spiritualism in Raymond Carver’s Work

2015 ◽  
Vol 3 (1) ◽  
pp. 214
Author(s):  
Viola Kita
Keyword(s):  
The Other ◽  
Good Thing ◽  
Raymond Carver ◽  
The Bible ◽  
Other Hand ◽  
Christian Writer ◽  
Spiritual Reading ◽  
Insight Into

Raymond Carver’s work provides the opportunity for a spiritual reading. The article that offers the greatest insight into spirituality is William Stull’s “Beyond Hopelessville: Another Side of Raymond Carver.” In it we can notice the darkness which is dominant in Carver’s early works with the optimism that is an essential part of Carver’s work “Cathedral”. A careful reading of “A Small Good Thing” and “The Bath” can give the idea that they are based on the allegory of spiritual rebirth which can be interpreted as a “symbol of Resurrection”. Despite Stull’s insisting in Carver’s stories allusions based on the Bible, it cannot be proved that the writer has made use of Christian imagery. Therefore, it can be concluded that spirituality in Carver’s work is one of the most confusing topics so far in the literary world because on one hand literary critics find a lot of biblical elements and on the other hand Carver himself refuses to be analyzed as a Christian writer.

Intimacy as Transgression and the Problem of Freedom

2018 ◽  
Vol 1 (1) ◽  
pp. 18
Author(s):  
Kym Maclaren
Keyword(s):  
Intimate Relationships ◽  
Critical Analysis ◽  
Mutual Recognition ◽  
Public Institutions ◽  
The Other ◽  
Social Forces ◽  
Critical Insight ◽  
Insight Into ◽  
What Matters

“To consent to love or be loved,” said Merleau-Ponty, “is to consent also to influence someone else, to decide to a certain extent on behalf of the other.” This essay explicates that idea through a meditation on intimacy. I propose, first, that, on Merleau-Ponty’s account, we are always transgressing into each other’s experience, whether we are strangers or familiars; I call this “ontological intimacy.” Concrete experiences of intimacy are based upon this ontological intimacy, and can take place at two levels: (1) at-this-moment (such that we can experience intimacy even with strangers, by sharing a momentary but extra-ordinary mutual recognition) and (2) in shared interpersonal institutions, or habitual, enduring, and co-enacted visions of who we are, how to live, and what matters. Through particular examples of dynamics within these layers of intimacy (drawing upon work by Berne and by Russon), I claim that we are always, inevitably, imposing an “unfreedom” upon our intimate others. Freedom, then, can only develop from within and by virtue of this “unfreedom.” Thus, what distinguishes empowering or emancipating relationships from oppressive ones is not the removal of transgressive normative social forces; it is rather the particular character of those transgressive forces. Some transgressions upon others’ experience—some forms of “unfreedom”—will tend to promote freedom; others will tend to hinder it. This amounts to a call for promoting agency and freedom not only through critical analysis of public institutions, practices and discourses, but also through critical insight into and transformation of our most private and intimate relationships.

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