Roughness-Induced Shear- and Squeeze-Film Effects in Magnetic Recording—Part I: Analysis

1989 ◽  
Vol 111 (2) ◽  
pp. 220-227 ◽  
Author(s):  
Bharat Bhushan ◽  
Kristian To̸nder
Keyword(s):  
Magnetic Recording ◽  
Design Guidelines ◽  
Squeeze Film ◽  
Operating Parameters ◽  
Periodic Motions ◽  
Average Flow ◽  
Thickness Standard ◽  
Orientation Parameters ◽  
Rarefaction Effects

General analyses are developed to predict the role of surface roughness, rarefaction effects, and various operating parameters in thin-film gas lubrication. Both shear- and squeeze-film effects are considered. The squeeze-film analysis is developed for transient and periodic motions. The analyses are based on average flow (roughness) factors. The results are presented in terms of Knudsen number, h/σ (film thickness/standard deviations of composite roughness) and roughness-orientation parameters. The appropriate analyses presented in this paper are simple and can be applied to magnetic recording and other applications to provide design guidelines.

The Role of Flexibility on Center of Mass Oscillations of Self Propelled Flapping Fins

2015 ◽  
Author(s):  
Ashok K. Kancharala ◽  
Michael K. Philen
Keyword(s):  
Theoretical Investigation ◽  
Center Of Mass ◽  
Design Guidelines ◽  
Operating Frequency ◽  
Operating Parameters ◽  
Optimal Operating ◽  
Propulsive Performance ◽  
Robotic Vehicles

Flexibility is known to improve the propulsive performance of flapping fins. Flapping fins generate forces oscillatory in nature and this paper reports an investigation on the effect of flexibility and other parameters such as heaving, pitching amplitudes and operating frequency in reducing the center of mass oscillations of bodies attached to flapping fins. A detailed theoretical investigation has been carried out to predict the optimal operating parameters along with the fin stiffness to reduce the COM oscillations for a given self-propelled speed (SPS). Some design guidelines have been proposed which reduce COM oscillations that aid in the development of aerial and underwater robotic vehicles.

Transmission Electron Microscopy studies of texture of Cr underlayer of magnetic recording hard disk

1991 ◽  
Vol 49 ◽  
pp. 580-581
Author(s):  
L. Tang ◽  
G. Thomas ◽  
M. R. Khan ◽  
S. L. Duan
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Magnetic Recording ◽  
Magnetic Thin Films ◽  
Magnetic Films ◽  
Substrate Bias ◽  
Epitaxial Relationship ◽  
Transmission Electron

Cr thin films are often used as underlayers for Co alloy magnetic thin films, such as Co1, CoNi2, and CoNiCr3, for high density longitudinal magnetic recording. It is belived that the role of the Cr underlayer is to control the growth and texture of the Co alloy magnetic thin films, and, then, to increase the in plane coercivity of the films. Although many epitaxial relationship between the Cr underlayer and the magnetic films, such as ﹛1010﹜Co/ {110﹜Cr4, ﹛2110﹜Co/ ﹛001﹜Cr5, ﹛0002﹜Co/﹛110﹜Cr6, have been suggested and appear to be related to the Cr thickness, the texture of the Cr underlayer itself is still not understood very well. In this study, the texture of a 2000 Å thick Cr underlayer on Nip/Al substrate for thin films of (Co75Ni25)1-xTix dc-sputtered with - 200 V substrate bias is investigated by electron microscopy.

Design guidelines for thermo-photo-voltaic generator: The critical role of the emitter size

2013 ◽  
Vol 103 ◽  
pp. 618-626 ◽  
Author(s):  
G. Attolini ◽  
M. Bosi ◽  
C. Ferrari ◽  
F. Melino
Keyword(s):  
Critical Role ◽  
Design Guidelines ◽  
Photo Voltaic

scholarly journals The Nature and Role of User Beliefs Regarding a Website's Design Quality

2020 ◽  
Vol 32 (1) ◽  
pp. 75-96 ◽  
Author(s):  
Camille Grange ◽  
Henri Barki
Keyword(s):  
Information Quality ◽  
Past Research ◽  
Design Guidelines ◽  
Ease Of Use ◽  
Research Model ◽  
System Quality ◽  
Design Quality ◽  
It Acceptance

Researchers and practitioners have long been interested in identifying the criteria that users consider important in assessing whether a system is worth using. However, past research in this domain has not taken into account the characteristics of a system's design and their quality in a systematic and comprehensive manner, which is likely to have limited the development of actionable design guidelines. The article addresses this issue by suggesting a research model that links user beliefs—which have traditionally been used in IT acceptance and success research (i.e., information quality, system quality, usefulness, and ease of use)—to their beliefs regarding the quality of three categories of a system's design (i.e., visual quality, page layout quality, and navigation quality) and testing it in the context of organizational intranets. The analysis of data collected from 159 intranet website users in three organizations supported the model, suggesting that the three categories of design quality beliefs significantly influenced users' assessment of their system's information quality and system quality.

Analytical Dynamics of a Ball Bouncing on a Vibrating Table

2012 ◽  
Author(s):  
Yu Guo ◽  
Albert C. J. Luo
Keyword(s):  
Dynamical Systems ◽  
Numerical Simulations ◽  
Analytical Dynamics ◽  
Periodic Motions ◽  
Chaotic Motions ◽  
Theory Of Flow ◽  
Mapping Structures ◽  
Ball Bouncing ◽  
Vibrating Table

In this paper, the theory of flow switchability for discontinuous dynamical systems is applied. Domains and boundaries for such a discontinuous problem are defined and analytical conditions for motion switching are developed. The conditions explain the important role of switching phase on the motion switchability in such a system. To describe different motions, the generic mappings and mapping structures are introduced. Bifurcation scenarios for periodic and chaotic motions are presented for different motions and switchability. Numerical simulations are provided for periodic motions with impacts only and with impact chatter to stick in the system.

Effects of Electron-ion Recombination on Contrast in ESEM Images

2001 ◽  
Vol 7 (S2) ◽  
pp. 794-795
Author(s):  
M. Toth ◽  
B. L. Thiel ◽  
A. M. Donald
Keyword(s):  
Secondary Electron ◽  
Image Formation ◽  
Environmental Scanning ◽  
Operating Parameters ◽  
Ion Recombination ◽  
Conventional Models ◽  
Working Distance ◽  
Present Experimental Evidence ◽  
Scanning Electron

We present experimental evidence for the effects of electron-ion recombination on contrast formation in secondary electron (SE) images obtained using an environmental scanning electron microscope (ESEM). Inclusion of the effects of SE-ion recombination in the theory of ESEM image formation accounts for contrast reversal observed, under appropriate conditions, in SE images of conductors (ie, in the absence of localized specimen charging) and of insulators that exhibit localized charging. Previously unexplained dynamic contrast caused by temporal charging can be understood if both conventional models of the effects of charging on SE emission, and the proposed role of SEion recombination in ESEM image formation are accounted for.In an ESEM, the extent of charging exhibited by insulating specimens can be controlled by varying the type and pressure (P) of the imaging gas, and operating parameters that determine the extent to which the gas is ionized (eg, detector bias, VGSED, and working distance, WD).

The saliency of geographical landmarks for community navigation: A photovoice study with persons living with dementia

Dementia ◽  
2020 ◽  
pp. 147130122092723 ◽  
Author(s):  
Kishore Seetharaman ◽  
Mardelle M Shepley ◽  
Cayce Cheairs
Keyword(s):  
Group Discussion ◽  
Design Guidelines ◽  
Community Dwelling ◽  
Visual Aids ◽  
Walking Program ◽  
Care Partners ◽  
Moderate Dementia ◽  
Community Navigation ◽  
Emic Perspective

This study uses the photovoice method to explore how persons living with mild-to-moderate dementia perceive neighborhood landmarks and identify characteristics that render these landmarks salient for outdoor navigation. Previous research has highlighted the role of well-designed, stable geographical landmarks in improving the navigability of neighborhoods for persons living with dementia. However, the specific attributes that render landmarks salient have not yet been sufficiently explored, resulting in inadequate evidence-based environmental design guidelines for dementia-friendly communities. To address this gap, a photovoice study was conducted with five community-dwelling persons living with dementia and their care partners, as part of a dementia-friendly neighborhood walking program in the city of Seattle, USA. Photovoice facilitated the exploration of saliency of neighborhood landmarks from an emic perspective by (i) empowering persons living with dementia to identify and take photos of salient landmarks during the group walk and (ii) interpret and reflect on attributes that contributed to saliency using the photos as visual aids in a focus group discussion and survey questionnaire. Participants associated the saliency of landmarks with two groups of attributes: (i) visual distinctiveness, which encompassed physical aspects, such as size, shape, color, texture; and (ii) meaningfulness, which included subjective factors of personal and emotional significance that linked the landmarks to participants’ pasts, passions, hobbies, and emotions related to having dementia. Findings suggest that outdoor landmarks should be designed for maximum legibility and noticeability, as well as familiarity, recognizability, and memorability. The evidence from this research also points to the likely positive effect of salient neighborhood landmarks on the community navigation of persons living with dementia.

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