Simulation of Airflow in an Idealized Emphysematous Human Acinus

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Amitvikram Dutta ◽  
Dragos M. Vasilescu ◽  
James C. Hogg ◽  
A. B. Phillion ◽  
J. R. Brinkerhoff
Keyword(s):  
Wall Motion ◽  
Computational Domain ◽  
Airway Wall ◽  
Flow Rates ◽  
Pulmonary Acinus ◽  
Two Generations ◽  
Recirculatory Flow ◽  
Parametric Studies ◽  
The Individual ◽  
Alveolar Septa

Emphysema is the permanent enlargement of air spaces in the respiratory regions of the lung due to destruction of the inter-alveolar septa. The progressive coalescence of alveoli and alveolar ducts into larger airspaces leads to the disruption of normal airway wall motion and airflow rates within the pulmonary acinus. To contribute to the understanding of the individual effects of emphysema during its earliest stages, computational fluid dynamics (CFD) simulations of airflow in mathematically derived models of the pulmonary acinus were performed. The here generated computational domain consists of two generations of alveolar ducts within the pulmonary acinus, with alveolar geometries approximated as closely packed, 14-sided polygons. Physiologically realistic airflow rates and wall motions were used to study airflow patterns within subsequent generations of alveolar ducts during the inspiratory and expiratory phases of the breathing cycle. The effects of progressive emphysema on the airway wall motion and flow rates were simulated by sequentially removing all alveolar septa within each alveolar duct. Parametric studies were presented to independently assess the relative influence of progressive septal destruction of airway motion and flow rates. The results illustrate that septal destruction lowers the flow resistance through the alveolar ducts but has little influence on the mass transport of oxygen into the alveoli. Septal destruction has a net effect on the flow field by favoring the development of recirculatory flow patterns in individual alveoli.

Sisterhood and After

2019 ◽  
Author(s):  
Margaretta Jolly
Keyword(s):  
Oral History ◽  
Women's Liberation ◽  
Equal Rights ◽  
Collective Memories ◽  
Women’S Liberation ◽  
Two Generations ◽  
Personal Accounts ◽  
The Individual ◽  
The Uk ◽  
Cultural Taste

This ground-breaking history of the UK Women’s Liberation Movement explores the individual and collective memories of women at its heart. Spanning at least two generations and four nations, and moving through the tumultuous decades from the 1970s to the present, the narrative is powered by feminist oral history, notably the British Library’s Sisterhood and After: The Women’s Liberation Oral History Project. The book mines these precious archives to bring fresh insight into the lives of activists and the campaigns and ideas they mobilised. It navigates still-contested questions of class, race, violence, and upbringing—as well as the intimacies, sexualities and passions that helped fire women’s liberation—and shows why many feminists still regard notions of ‘equality’ or even ‘equal rights’ as insufficient. It casts new light on iconic campaigns and actions in what is sometimes simplified as feminism’s ‘second wave’, and enlivens a narrative too easily framed by ideological abstraction with candid, insightful, sometimes painful personal accounts of national and less well-known women activists. They describe lives shaped not only by structures of race, class, gender, sexuality and physical ability, but by education, age, love and cultural taste. At the same time, they offer extraordinary insights into feminist lifestyles and domestic pleasures, and the crossovers and conflicts between feminists. The work draws on oral history’s strength as creative method, as seen with its conclusion, where readers are urged to enter the archives of feminist memory and use what they find there to shape their own political futures.

Performance Prediction for Automotive Turbocharger Compressors

1975 ◽  
Vol 189 (1) ◽  
pp. 557-565 ◽  
Author(s):  
A. Whitfield ◽  
F. J. Wallace
Keyword(s):  
Performance Prediction ◽  
Flow Analysis ◽  
Compressor Stage ◽  
Thermodynamic Models ◽  
Flow Rates ◽  
Design Point ◽  
One Dimensional ◽  
Dimensional Flow ◽  
Performance Map ◽  
The Individual

A procedure to predict the complete performance map of turbocharger centrifugal compressors is presented. This is based on a one-dimensional flow analysis using existing published loss correlations that were available and thermodynamic models to describe the incidence loss and slip factor variation at flow rates which differ from the design point. To predict the losses within the complete compressor stage using a one-dimensional flow procedure, it is necessary to introduce a number of empirical parameters. The uncertainty associated with these empirical parameters is assessed by studying the effect of varying them upon the individual losses and upon the overall predicted performance.

Critical examination of various approaches used for analysing helical cables

1994 ◽  
Vol 29 (1) ◽  
pp. 43-55 ◽  
Author(s):  
M Raoof ◽  
I Kraincanic
Keyword(s):  
Large Diameter ◽  
Numerical Results ◽  
Hertzian Contact ◽  
Critical Examination ◽  
First Order ◽  
Wide Range ◽  
End Conditions ◽  
Parametric Studies ◽  
The Individual ◽  
Fixed End

Using theoretical parametric studies covering a wide range of cable (and wire) diameters and lay angles, the range of validity of various approaches used for analysing helical cables are critically examined. Numerical results strongly suggest that for multi-layered steel strands with small wire/cable diameter ratios, the bending and torsional stiffnesses of the individual wires may safely be ignored when calculating the 2 × 2 matrix for strand axial/torsional stiffnesses. However, such bending and torsional wire stiffnesses are shown to be first order parameters in analysing the overall axial and torsional stiffnesses of, say, seven wire stands, especially under free-fixed end conditions with respect to torsional movements. Interwire contact deformations are shown to be of great importance in evaluating the axial and torsional stiffnesses of large diameter multi-layered steel strands. Their importance diminishes as the number of wires associated with smaller diameter cables decreases. Using a modified version of a previously reported theoretical model for analysing multilayered instrumentation cables, the importance of allowing for the influence of contact deformations in compliant layers on cable overall characteristics such as axial or torsional stiffnesses is demonstrated by theoretical numerical results. In particular, non-Hertzian contact formulations are used to obtain the interlayer compliances in instrumentation cables in preference to a previously reported model employing Hertzian theory with its associated limitations.

Turbulence Measurements in a Centrifugal Pump With a Synchronously Orbiting Impeller

1991 ◽  
Author(s):  
Ronald D. Flack ◽  
Steven M. Miner ◽  
Ronald J. Beaudoin
Keyword(s):  
Centrifugal Pump ◽  
Reynolds Stress ◽  
Flow Rate ◽  
Cross Product ◽  
Design Flow ◽  
Low Flow ◽  
Rate Variation ◽  
Flow Rates ◽  
The Individual ◽  
Design Flow Rate

Turbulence profiles were measured in a centrifugal pump with an impeller with backswept blades using a two directional laser velocimeter. Data presented includes radial, tangential, and cross product Reynolds stresses. Blade to blade profiles were measured at four circumferential positions and four radii within and one radius outside the four bladed impeller. The pump was tested in two configurations; with the impeller running centered within the volute, and with the impeller orbiting with a synchronous motion (ε/r2 = 0.016). Flow rates ranged from 40% to 106% of the design flow rate. Variation in profiles among the individual passages in the orbiting impeller were found. For several regions the turbulence was isotropic so that the cross product Reynolds stress was low. At low flow rates the highest cross product Reynolds stress was near the exit. At near design conditions the lowest cross product stress was near the exit, where uniform flow was also observed. Also, near the exit of the impeller the highest turbulence levels were seen near the tongue. For the design flow rate, inlet turbulence intensities were typically 9% and exit turbulence intensities were 6%. For 40% flow capacity the values increased to 18% and 19%, respectively. Large local turbulence intensities correlated with separated regions. The synchronous orbit did not increase the random turbulence, but did affect the turbulence in the individual channels in a systematic pattern.

Turbulence Measurements in a Centrifugal Pump With a Synchronously Orbiting Impeller

1992 ◽  
Vol 114 (2) ◽  
pp. 350-358 ◽  
Author(s):  
R. D. Flack ◽  
S. M. Miner ◽  
R. J. Beaudoin
Keyword(s):  
Centrifugal Pump ◽  
Reynolds Stress ◽  
Flow Rate ◽  
Cross Product ◽  
Design Flow ◽  
Low Flow ◽  
Rate Variation ◽  
Flow Rates ◽  
The Individual ◽  
Design Flow Rate

Turbulence profiles were measured in a centrifugal pump with an impeller with backswept blades using a two-directional laser velocimeter. Data presented include radial, tangential, and cross product Reynolds stresses. Blade-to-blade profiles were measured at four circumferential positions and four radii within and one radius outside the four-bladed impeller. The pump was tested in two configurations: with the impeller running centered within the volute, and with the impeller orbiting with a synchronous motion (ε/r2 = 0.016). Flow rates ranged from 40 to 106 percent of the design flow rate. Variation in profiles among the individual passages in the oribiting impeller were found. For several regions the turbulence was isotropic so that the cross product Reynolds stress was low. At low flow rates the highest cross product Reynolds stress was near the exit. At near-design conditions the lowest cross product stress was near the exit, where uniform flow was also observed. Also, near the exit of the impeller the highest turbulence levels were seen near the tongue. For the design flow rate, inlet turbulence intensities were typically 9 percent and exit turbulence intensities were 6 percent. For 40 percent flow capacity the values increased to 18 and 19 percent, respectively. Large local turbulence intensities correlated with separated regions. The synchronous orbit did not increase the random turbulence, but did affect the turbulence in the individual channels in a systematic pattern.

Wire Stress Calculations in Helical Strands Undergoing Bending

1992 ◽  
Vol 114 (3) ◽  
pp. 212-219 ◽  
Author(s):  
M. Raoof ◽  
Y. P. Huang
Keyword(s):  
Theoretical Model ◽  
Axial Stress ◽  
Operating Conditions ◽  
Radius Of Curvature ◽  
Axial Component ◽  
Practical Applications ◽  
Bending Stresses ◽  
Parametric Studies ◽  
Steel Cables ◽  
The Individual

Steel cables play an important role in many offshore applications. In many cases, an understanding of the magnitude and pattern of bending stresses in the individual component wires of a bent strand is essential for minimizing the risk of their failure under operating conditions. Following previously reported experimental observations, a theoretical model is proposed for obtaining the magnitude of wire bending stresses in a multi-layered and axially preloaded spiral strand fixed at one end and subsequently bent to a constant radius of curvature. The individual wire bending stresses are shown to be composed of two components. The first component is the axial stress generated in the wires due to interwire/interlayer shear interactions between the wires in a bent cable, and the second component is associated with the wires bending about their own axes. Using the theoretical model, which includes the effects of interwire friction, parametric studies on a number of realistic helical strands with widely different cable (and wire) diameters and lay angles subjected to a range of practical mean axial loads, and subsequently bent to a range of radii of curvature with one end of the cable fixed against rotation, have been carried out. It is shown that for most practical applications, the axial component of wire stresses due to friction is much greater than the second component of bending stresses associated with the individual wires bending about their own axes.

scholarly journals Selection for leukocyte counts in mice

1966 ◽  
Vol 8 (2) ◽  
pp. 125-142 ◽  
Author(s):  
C. K. Chai
Keyword(s):  
Body Weight ◽  
Coat Color ◽  
Leukocyte Count ◽  
Individual Cell ◽  
Cell Types ◽  
Two Generations ◽  
X Irradiation ◽  
Leukocyte Counts ◽  
Selection For ◽  
The Individual

By directional selection for total leukocyte counts from a hybrid mouse stock we have gradually established two lines of mice, LLC (Low Leukocyte Count) and HLC (High Leukocyte Count), which differ both in total and in differential leukocyte counts. A randombred line (RLC) is also being concurrently maintained. Other variations between these lines of mice are in body weight, in the frequencies of coat color genes, reproductive performance, and resistance to X-irradiation. The LLC line was comparatively low in the latter two physiological parameters, and high in variation of body weight.Responses to selection for high and low leukocyte counts were asymmetrical. In the first two generations, responses were irregular; thereafter they were large in the low line (LLC) for two or three generations and then became small in comparison with those of the high line (HLC). At eleven generations of selection, the mean leukocyte count of HLC is about three times that of LLC Responses of the different cell types were proportional to their individual percentages of the total counts. There were sexual differences in the counts of total and individual cell types. Selection for total leukocyte counts affected the proportions of the individual cell types. Heritability estimates based on selection differential and response and on sib relationships yielded values ranging from 0·15 to 0·39.

Aerodynamic Performance of Turbine Center Frames With Purge Flows—Part I: The Influence of Turbine Purge Flow Rates

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Stefan Zerobin ◽  
Andreas Peters ◽  
Sabine Bauinger ◽  
Ashwini Bhadravati Ramesh ◽  
Michael Steiner ◽  
...  
Keyword(s):  
Measurement Data ◽  
Leading Edge ◽  
Aerodynamic Performance ◽  
Flow Structures ◽  
Flow Rates ◽  
Purge Flow ◽  
Mass Flows ◽  
The Individual ◽  
The Impact ◽  
First Time

This two-part paper deals with the influence of high-pressure turbine (HPT) purge flows on the aerodynamic performance of turbine center frames (TCF). Measurements were carried out in a product-representative one and a half-stage turbine test setup. Four individual purge mass flows differing in flow rate, pressure, and temperature were injected through the hub and tip, forward and aft cavities of the unshrouded HPT rotor. Two TCF designs, equipped with nonturning struts, were tested and compared. In this first part of the paper, the influence of different purge flow rates (PFR) is discussed, while in the second part of the paper, the impact of the individual hub and tip purge flows on the TCF aerodynamics is investigated. The acquired measurement data illustrate that the interaction of the ejected purge flow with the main flow enhances the secondary flow structures through the TCF duct. Depending on the PFR, the radial migration of purge air onto the strut surfaces directly impacts the loss behavior of the duct. The losses associated with the flow close to the struts and in the strut wakes are highly dependent on the relative position between the HPT vane and the strut leading edge (LE), as well as the interaction between vane wake and ejected purge flow. This first-time experimental assessment demonstrates that a reduction in the purge air requirement benefits the engine system performance by lowering the TCF total pressure loss.

The Effects of a Parametric Variation of the Rim Seal Geometry on the Interaction Between Hub Leakage and Mainstream Flows in HP Turbines

2012 ◽  
Author(s):  
I. Popović ◽  
H. P. Hodson
Keyword(s):  
Large Scale ◽  
Full Range ◽  
The Other ◽  
Flow Uniformity ◽  
Flow Rates ◽  
Linear Cascade ◽  
Parametric Variation ◽  
Optimum Geometry ◽  
Parametric Studies ◽  
Mass Flow Rates

The objective of this work was to assess and understand the effects of parametric variation performed on a typical overlapping rim seal geometry. The datum geometry has been focus of a detailed experimental investigation employing a large-scale linear cascade subjected to a range of the mass flow rates and swirl velocities of the leakage air. The parametric variations described in this paper were examined using validated CFD. As a part of the parametric studies, both the axial and the radial seal clearance between the rotor fin (angel wing) and stator platform were varied as well as the length of the overlap between stator and rotor platforms. In addition, the effects of forward and backward facing annulus steps were also investigated. It has been found that a backward facing annulus step was detrimental for all conditions considered, while a forward facing step offered improvements for smaller step heights and/or lower leakage fractions. Tightening of the seal clearances closer to the annulus line improved the sealing effectiveness, but often at the expense of increased losses. On the other hand, increasing the overlap length led to improvements in the sealing effectiveness with very small effects on the overall losses. Moving the rim seal away from the blade leading edges reduced the pressure asymmetry at the rim seal and increased the flow uniformity of the leakage air. However, this led to an increased cross-passage flow (more negative skew) and higher losses at all but lowest leakage fractions. The results presented in this paper highlight the fact that there may not be an optimum rim seal solution that would offer an improvement for the full range of leakage fractions and that for different rim sealing flows there may be a different optimum geometry. In addition, rotor disc movements in radial and axial directions at various off-design conditions should be considered as a part of the design process. Based on the presented results it may be of a benefit to the turbine designer to consider rotor disc designs which would be more biased towards the upstream and outward disc movements that would result in tightening of the seal clearances and avoidance of a backward facing annulus step.

scholarly journals Pola Pewarisan Nilai yang Berimplikasi Bimbingan pada Pancakaki Bani Nuryayi

2017 ◽  
Vol 1 (1) ◽  
pp. 99
Author(s):  
Ade Hidayat
Keyword(s):  
Cultural Values ◽  
Family System ◽  
Personality Development ◽  
Historical Period ◽  
Guidance And Counseling ◽  
Next Generation ◽  
Kinship System ◽  
Two Generations ◽  
The Individual ◽  
Maintain Relationship

One of family functions is to maintain relationship among generations, where the prior generation leaves the influence to the next generation. The family system built then become widespread, not only has two generations but unfold to many generation in building kinship system. The kinship system in Sundanese culture is known as Pancakaki. The individual and social function of pancakaki varies in each period, so that in historical period, society of Sundanese are able to keep values of Sundanese established by their own social system. Pancakaki not only strengthens cultural identity of ancestor heritage, but also as a means for preparing, maintaining and developing a collaboration relation among members based on their values. As an example of the implementation of the pancakaki, Bani Nuryayi kept strongly maintains tradition that was taught by Kyai Nuryayi. This inheritance is sustainable by using patron-client approach. Therefore, pancakaki becomes an effective education pattern for inheritance of cultural values and tradition to the next generation. The implication on Guidance and Counseling that Pancakaki system as an exclusive means of family as coordinate institution for school in order to support optimalitation of personality development and integrity of student identity.

Sign in / Sign up

Export Citation Format

Share Document