Design of user interfaces and information graphics is poorly
understood, and somewhat hit-or-miss in terms of effectiveness.
A number of issues influence the success of a
design, and these run the gamut of the underlying human
behavior. A design must be good cognitively (can the user
easily understand the semantic structure of the design?),
perceptually (can they effortlessly interpret the visual information
present in the design?), and socially (does the
design fit into the user’s workflow? will they want to use
it?). Here we focus on perceptual aspects of design.
Perhaps the most important aspect of human vision for design
is perceptual organization. Perceptual organization
refers to phenomena in which the visual system quickly and
seemingly effortlessly transforms individual feature estimates
into perception of coherent regions, structures, and
objects. These phenomena were first studied in detail by
the Gestalt psychologists, who produced a set of qualitative
Gestalt principles that govern pattern perception [1, 2], including
but not limited to: the tendency of things to group if
they are nearby (the Gestalt law of proximity); if they share
similar features (the law of similarity), or are smooth and
continuous (the law of good continuation). The duals of perceptual
grouping are important phenomena in their own right:

we quickly and effortlessly perceive boundaries between

certain visual textures, perceive edges between coherent regions
in an image, and quickly detect unusual items that
seem to “pop out” from the background. Examples of perceptual
grouping phenomena are given in Figure 1.
Following the visual system’s “rules” of visual organization
makes interpretation of visual aspects of designs effortless:
a user easily sees which labels refer to which parts of a diaa
b
c
d
e
f
Figure 1: Perceptual grouping examples, including
grouping by proximity & similarity (a, b), and grouping

by good continuation (c, d). (e) A user interface; what

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is the percept? (f) A graph, from [5]. Will a user
perceive the trend of the data?

widely adopted approaches to handle this rather complicated
situation are time-hardening and strain-hardening
rules@71. In general, predictions based on these two
approaches are quite different, and a choice between
them should depend on the comparison of their predictions
with experimental data.
Another key element is initial imperfections which, on
many occasions, are directly resulted from the unavoidable
inaccuracy of manufacturing process. It has been
shown that initial imperfections have a great impact on
reducing buckling pressures of spherical shells in both
static and dynamic responses[8-IO]. As to their influence
in the creep buckling analysis, there has been an indication
that the collapse time of cylindrical shells is

very much affected by the imperfection

magnitude [ 11,121.
In an earlier creep buckling analysis of shallow
tThe research reported on here was supported by the Office of

Naval Research, Contract Number NAVY 00014-75-C-0946.

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spherical shells[2], a huge discrepancy was found between
theoretical predictions and experimental results on

time in such analyses is usually defined in terms of infinite deformations or infinite deformation
rates. Comprehensive reviews of these studies are given by Hoffll, 21 and
Kurshin[3].
In recent years an increasing interest has been attracted by applications of the classical

bifurcation theory to the creep-stability research. In particular, creep stability of cylindrical

shells is treated in many publications[4-81 as an instantaneous process which involves
time-dependent constitutive terms and is characterized as branching into a different
equilibrium configuration. Respectively, the critical time is associated with the instant at
which bifurcation first becomes possible. The results from these studies depend upon the
basic assumptions as to the creep properties of the structure.
The present paper is concerned with the stability analysis of circular cylindrical shells

whose material properties are defined by the constitutive equations of the linear viscoelastic

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theory. Using the concept of bifurcation the exact linear eigenvalue problem is
formulated in terms of two destabilizing parameters: the compressive load and time. The
problem is treated by means of the quasi-elastic solution technique which utilizes the
concept of a time-dependent elastic material as a model of the actual viscoelastic response.

occupancy rates of hotels in Malaysia have fluctuated between 2005 and 2012
The current issue and full text archive of this journal is available at
www.emeraldinsight.com/1757-9880.htm
Received 8 January 2013
Revised 14 April 2013

Accepted 19 June 2013

Journal of Hospitality and Tourism
Technology
Vol. 4 No. 3, 2013
pp. 228-247
q Emerald Group Publishing Limited
1757-9880

DOI 10.1108/JHTT-01-2013-0002

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JHTT
4,3
228
(Malaysia Tourism, 2012). This also indicates that hotel performance in Malaysia needs

Christensen, Kasper Hansen, Johannes Raaballe, an anonymous referee, and workshop
participants at the 2004 European Accounting Association Conference and the University of
Aarhus.
IJMF
4,1

4

International Journal of Managerial
Finance
Vol. 4 No. 1, 2008
pp. 4-36
q Emerald Group Publishing Limited
1743-9132

DOI 10.1108/17439130810837366

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since there are several aspects where it is likely that small and large stock markets
differ with respect to their information environment.With regard to pre-announcement
information it can be argued that the smaller size leads to a less developed market with
less investor sophistication and therefore less pre-announcement information. On the
other hand, one could argue that the smaller size leads to a more transparent market