bluuebunny/crossref_metadata_2025 huggingface dataset:
The Work of Performativity: Staging Social Justice at the University of Southern California
Authors: Houston Donna , Pulido Laura
Published: August 2002

In this paper we offer an alternative reading of the role of performativity and everyday forms of resistance in current geographic literature. We make a case for thinking about performativity as a form of embodied dialectical praxis via a discussion of the ways in which performativity has been recently understood in geography. Turning to the tradition of Marxist revolutionary theater, we argue for the continued importance of thinking about the power of performativity as a socially transformative, imaginative, and collective political engagement that works simultaneously as a space of social critique and as a space for creating social change. We illustrate our point by examining two different performative strategies employed by food service workers at the University of Southern California in their struggle for a fair work contract and justice on the job.
Remoralising Landscapes of Care
Authors: Gleeson Brendan , Kearns Robin
Published: August 2002

The policy and theoretical discourses of deinstitutionalisation have been centred on a fundamental normative polarity that opposes the ‘dehumanising’ institution to the more humane environment of community care. We reconsider this moral polarity by drawing upon three philosophical currents that emphasise the need for inclusive and compassionate governance. We argue that there are strong political — ethical and practical reasons why inclusive governance can improve human-services planning and delivery. First, by recognising and addressing the vulnerabilities of nonservice users, an inclusive ethics is most likely to maximise the welfare of all groups with interests in community care. Following from this, an inclusive ethics is more likely to foster the broad social support that we argue is necessary for successful community care. Third, an inclusionary outlook has the potential to broaden the design of community-care services and facilities. An inclusive ethics would radically open up policy design to a range of other service options that account for the complexities of place, policy context, and the needs of key interest groups, such as service users, workers, relatives/advocates, and local communities.
Masculine Discourses and Dissonances: Strutting ‘Lads’, Protest Masculinity, and Domestic Respectability
Authors: McDowell Linda
Published: August 2002

In this paper I explore the social construction of masculinities among white working-class youth in contemporary Britain. The literatures of urban sociology, cultural studies, and education have been remarkably ambivalent about ‘lads’, both celebrating and criticising the anti-authority young men who have strutted across the pages of numerous books, papers, and reports. Policymakers, on the other hand, have feared rather than envied this group, representing them as a danger to respectable society. First, through an analysis of these discourses and, second, through an empirical study of two groups of young men, one in a northern English city, the other in a southern city, over a twelve-month period, I explore contemporary versions of masculinity, assessing the extent to which the attitudes and behaviour of the young men whom I interviewed reflect hegemonic notions of working-class masculinity. I suggest that this version of masculinity is itself complex and variable, combining not only protest and resistance but also respectability and domestic aspirations. These latter attributes have generally been ignored in studies of lads'.
Development of Infants' Sensitivity to Surface Contour Information for Spatial Layout
Authors: Sen Maya G , Yonas Albert , Knill David C
Published: August 2002

The development of sensitivity to a recently discovered static-monocular depth cue to surface shape, surface contours, was investigated. Twenty infants in each of three age groups (5, 5½, and 7 months) viewed a display that creates an illusion, for adult viewers, that what is in fact a frontoparallel cylinder is slanted away in depth, so that one end appears closer than the other. Preferential reaching was recorded in both monocular and binocular conditions. More reaching to the apparently closer end in the monocular than in the binocular condition is evidence of sensitivity. Infants aged 7 months responded to surface contour information, but infants aged 5 and 5 months did not. In a control study, twenty 5-month-old infants reached consistently for the closer ends of cylinders that were actually rotated in depth. As findings with other static-monocular depth information suggest, infants' sensitivity to surface contour information appears to develop at approximately 6 months.
Global-Perspective Jitter Improves Vection in Central Vision
Authors: Palmisano Stephen , Gillam Barbara J , Blackburn Shane G
Published: August 2002

Previous vection research has tended to minimise visual – vestibular conflict by using optic-flow patterns which simulate self-motions of constant velocity. Here, experiments are reported on the effect of adding ‘global-perspective jitter’ to these displays—simulating forward motion of the observer on a platform oscillating in horizontal and/or vertical dimensions. Unlike non-jittering displays, jittering displays produced a situation of sustained visual–vestibular conflict. Contrary to the prevailing notion that visual – vestibular conflict impairs vection, jittering optic flow was found to produce shorter vection onsets and longer vection durations than non-jittering optic flow for all of jitter magnitudes and temporal frequencies examined. On the basis of these findings, it would appear that purely radial patterns of optic flow are not the optimal inducing stimuli for vection. Rather, flow patterns which contain both regular and random-oscillating components appear to produce the most compelling subjective experiences of self-motion.
The Role of the Centre of Projection in the Estimation of Slant from Texture of Planar Surfaces
Authors: Tibau Stefaan , Willems Bert , Van Den Bergh Erik , Wagemans Johan
Published: August 2002

Displays were presented consisting of a perspective projection of a regular square grid, made up of vertical and horizontal equally spaced white lines, that was slanted in depth. The surface was viewed monocularly, through a circular aperture. A range of slants was shown (0°, 10°, 20°, 30°, 40°, 50°, or 60°) and the observers' task was to match the slant by means of a mouse-driven probe. The viewing distance (50, 75, or 100 cm) as well as the focal distance (25, 50, 75, 100, or 125 cm) were varied. We expected the estimation error to be smallest when the viewing distance and the focal distance coincided. This was not the case. Instead, subjects seemed to use the perspective deformation of the texture elements in the stimulus display to make a slant estimation, regardless of the specific combination of viewing distance and focal distance.
The Face-Inversion Effect as a Deficit in the Encoding of Configural Information: Direct Evidence
Authors: Freire Alejo , Lee Kang , Symons Lawrence A
Published: August 2002

We report four experiments leading to conclusions that: (i) the face-inversion effect is mainly due to the deficits in processing of configural information from inverted faces; and (ii) this effect occurs primarily at the encoding stage of face processing, rather than at the storage stage. In experiment 1, participants discriminated upright faces differing primarily in configuration with 81% accuracy. Participants viewing the same faces presented upside down scored only 55%. In experiment 2, the corresponding discrimination rates for faces differing mainly in featural information were 91% (upright) and 90% (inverted). In experiments 3 and 4, the same faces were used in a memory paradigm. In experiment 3, a delayed matching-to-sample task was used, in which upright-face pairs differed either in configuration or features. Recognition rates were comparable to those for the corresponding upright faces in the discrimination tasks in experiments 1 and 2. However, there was no effect of delay (1 s, 5 s, or 10 s). In experiment 4, we repeated experiment 3, this time with inverted faces. Results were comparable to those of inverted conditions in experiments 1 and 2, and again there was no effect of delay. Together these results suggest that an ‘encoding bottleneck’ for configural information may be responsible for the face-inversion effect in particular, and memory for faces in general.
The Role of Visual and Auditory Temporal Processing in Reading Irregular and Nonsense Words
Authors: Au Agnes , Lovegrove Bill
Published: August 2002

In the present study, the role of rapid visual and auditory temporal processing in reading irregular and nonsense words was investigated with a group of normal readers. One hundred and five undergraduates participated in various visual and auditory temporal-processing tasks. Readers who primarily adopted the phonological route in reading (nonsense-word readers) showed a trend for better auditory temporal resolution but readers who primarily adopted sight word skills (irregular-word readers) did not exhibit better visual temporal resolution. Both the correlation and stepwise multiple-regression analyses, however, revealed a relationship between visual temporal processing and irregular-word reading as well as a relationship between auditory temporal processing and nonsense-word reading. The results support the involvement of visual and auditory processing in reading irregular and nonsense words respectively, and were discussed with respect to recent findings that only dyslexics with phonological impairment will display temporal deficits. Further, the temporal measures were not effective discriminants for the reading groups, suggesting a lack of association between reading ability and the choice of reading strategy.
Characterising the Visual Buffer: Real-World Evidence for Overwriting Early in Each Fixation
Authors: Tatler Benjamin W
Published: August 2002

What happens to the pictorial content of fixations when we move our eyes? Previous studies demonstrate that observers are very poor at detecting changes in natural scenes that occur across saccades, blinks, and artificial interruptions (‘change blindness’). They suggest that the visual ‘snapshots’ of what is on the retina during a fixation are not retained and fused over successive fixations. I find similar results when volunteers are performing the complex real-life task of making a cup of tea. Volunteers can access the snapshot of the current fixation but not those of previous fixations. I suggest that volunteers are reporting the content of a low-level visual store that holds a veridical snapshot of the current fixation, rather than the retina itself. The snapshots are not ‘wiped’ by the saccade and remain in the buffer until they are overwritten by a new snapshot. The overwrite occurs in an all-or-none manner and can be at any time within the first 400 ms of each new fixation, with 50% of overwrites being within the first 100 ms.
Attractiveness of Facial Averageness and Symmetry in Non-Western Cultures: In Search of Biologically Based Standards of Beauty
Authors: Rhodes Gillian , Yoshikawa Sakiko , Clark Alison , Lee Kieran , McKay Ryan , Akamatsu Shigeru
Published: August 2002

Averageness and symmetry are attractive in Western faces and are good candidates for biologically based standards of beauty. A hallmark of such standards is that they are shared across cultures. We examined whether facial averageness and symmetry are attractive in non-Western cultures. Increasing the averageness of individual faces, by warping those faces towards an averaged composite of the same race and sex, increased the attractiveness of both Chinese (experiment 1) and Japanese (experiment 2) faces, for Chinese and Japanese participants, respectively. Decreasing averageness by moving the faces away from an average shape decreased attractiveness. We also manipulated the symmetry of Japanese faces by blending each original face with its mirror image to create perfectly symmetric versions. Japanese raters preferred the perfectly symmetric versions to the original faces (experiment 2). These findings show that preferences for facial averageness and symmetry are not restricted to Western cultures, consistent with the view that they are biologically based. Interestingly, it made little difference whether averageness was manipulated by using own-race or other-race averaged composites and there was no preference for own-race averaged composites over other-race or mixed-race composites (experiment 1). We discuss the implications of these results for understanding what makes average faces attractive. We also discuss some limitations of our studies, and consider other lines of converging evidence that may help determine whether preferences for average and symmetric faces are biologically based.
Is Lightness Induction a Pictorial Illusion?
Authors: Logvinenko Alexander D , Kane John , Ross Deborah A
Published: August 2002

Lightness induction, or simultaneous lightness contrast (we prefer the term lightness induction since contrast has another meaning in the visual literature, namely, the relative intensity of the stimulation), was studied for a 3-D object (Adelson's wall of blocks) and its 2-D pictorial representations. A statistically significant lightness induction effect was found only for the pictures but not for the 3-D object. No lightness induction effect was found for the 3-D object under either monocular or binocular viewing conditions.
The Influence of Verbal Labeling on the Perception of Odors: Evidence for Olfactory Illusions?
Authors: Herz Rachel S , von Clef Julia
Published: August 2002

Using the definition that an illusion is observed when a stimulus is invariant but context alters its perception, we examined whether verbal context could produce olfactory illusions. To test this effect, we chose five odors with minimally fixed sources and that could be interpreted with various hedonic connotations. The odors were violet leaf, patchouli, pine oil, menthol, and a 1:1 mixture of isovaleric and butyric acids. Subjects individually sniffed each odor at two different sessions separated by one week. At each session an odor was given a different verbal label (either positive or negative) and subjects rated the odors on several hedonic scales and provided perceptual and interpretative responses to them. Results showed that the perception of an odor could be significantly influenced by the label provided for it. We propose that the cases where verbal labels inverted odor perception are the first empirical demonstrations of olfactory illusions.
The Perception of Texture on Folded Surfaces
Authors: Bravo Mary J , Farid Hany
Published: August 2002

Do judgments of texture similarity reflect surface texture or image texture? To find out, we had observers view a rectangular surface that was folded into three panels, much like a brochure. Each panel was textured with an oriented noise pattern and the observers' task was to determine which side panel matched the center panel in surface texture. Information about surface geometry was conveyed by binocular disparity and by the boundaries of the rectangular surface. We found that observers were often consistently wrong, selecting the texture that differed in the image and not on the surface. In sharp contrast, when observers judged the texture orientation on each panel individually, their judgments were accurate reflections of the surface texture. So even when observers can recover surface texture, their judgments of texture similarity may still be based on image texture.
Detection Performance in Pop-Out Tasks: Nonmonotonic Changes with Display Size and Eccentricity
Authors: Meinecke Cristina , Donk Mieke
Published: August 2002

We carried out three experiments to investigate detection performance in pop-out tasks and analysed how performance varied as a function of display size (number of elements) and retinal eccentricity of the target. Results showed that when display size was increased from 2 to 81 elements performance first decreased and then increased (replicating Sagi and Julesz, 1987 Spatial Vision2 39–49). Performance variations differed as a function of eccentricity and often were more pronounced in the periphery than in the foveal area. This retinal-eccentricity influence suggests that processes underlying detection performance in small display sizes are different from those in large display sizes. One should be careful when using the variation of display size as an instrument to analyse visual-search processes because this analysis could be based on a comparison between non-equivalent conditions.
Is Visual Search Really like Foraging?
Authors: Gilchrist Iain D , North Alice , Hood Bruce
Published: August 2002

The visual-search paradigm provides a controlled and easy to implement experimental situation in which to study the search process. However, little work has been carried out in humans to investigate the extent to which traditional visual-search tasks are similar to more general search or foraging. Here we report results from a task in which search involves walking around a room and leaning down to inspect individual locations. Consistent with more traditional search tasks, search time increases linearly with display size, and the target-present to target-absent search slope is 1:2. However, although rechecking of locations did occur, compared to more traditional search it was relatively rare, suggesting an increased role for memory.
The Priming of Face Recognition after Metric Transformations
Authors: Brooks Brian E , Rosielle Luke J , Cooper Eric E
Published: August 2002

Four experiments were performed to test whether the perceptual priming of face recognition would show invariance to changes in size, position, reflectional orientation (mirror reversal), and picture-plane rotation. In all experiments, subjects recognized faces in two blocks of trials; in the second block, some of the faces were identical to those in the first, and others had undergone metric transformations. The results show that subjects were equally fast to recognize faces whether or not the faces had changed in size, position, or reflectional orientation between the first and second presentations of the faces. In contrast, subjects were slower to recognize both faces and objects when they were planar-rotated between the first and second presentations. The results suggest that the same metric invariances are shown by both face recognition and basic-level object recognition.
Configural Face Processing Develops more Slowly than Featural Face Processing
Authors: Mondloch Catherine J , Le Grand Richard , Maurer Daphne
Published: August 2002

Expertise in face processing takes many years to develop. To determine the contribution of different face-processing skills to this slow development, we altered a single face so as to create sets of faces designed to measure featural, configural, and contour processing. Within each set, faces differed only in the shape of the eyes and mouth (featural set), only in the spacing of the eyes and mouth (spacing set), or only in the shape of the external contour (contour set). We presented adults, and children aged 6, 8, and 10 years, with pairs of upright and inverted faces and instructed them to indicate whether the two faces were the same or different. Adults showed a larger inversion effect for the spacing set than for the featural and external contour sets, confirming that the spacing set taps configural processing. On the spacing set, all groups of children made more errors than adults. In contrast, on the external contour and featural sets, children at all ages were almost as accurate as adults, with no significant difference beginning at age 6 on the external contour set and beginning at age 10 on the featural set. Overall, the results indicate that adult expertise in configural processing is especially slow to develop.
Structural Studies of Complexes Containing the Peroxodisulfate Anion. II. The Crystal and Molecular Structure of Cd(S2O8) (bpy)2.H2O and Hg2(S2O8)(terpy)2(acet)2 (bpy: 2,2′-bipyridine, terpy: 2,2′,2′′-terpyridine, acet: acetate)
Authors: Harvey Miguel A. , Baggio Sergio , Garland María T. , Baggio Ricardo
Published: August 2002

The crystal structures of two transition-metal complexes with different dinitrogenated bases, and the unusual peroxodisulfate anion are presented, Cd(S2O8)(bpy)2·H2O (1) and Hg2(S2O8)(terpy)2(acet)2 (2) (where bpy represents 2,2′-bipyridine, terpy represents 2,2′,2′′-terpyridine, and acet represents acetate). In both structures, though in different ways, the peroxodisulfate group acts as a bridge, giving rise to polymeric linear chains. To our knowledge these are the first structures reported wherein the anion displays such behaviour. The cadmium compound crystallizes with one water molecule of hydration, which intervenes in medium-strength H-bonds, stabilizing the structure. The mercury complex is built up of similar, though independent, chains displaying double Hg–O–Hg bridges spanning Hg···Hg distances of 4.214(1) and 3.911(1) Å. The inter-chain link is achieved through weak C–H···O contacts. Compound (1) is triclinic P1–; a 7.213(3), b 9.841(6), c16.371(5) Å; α 82.94(4), β 82.31(3), γ 86.32(4)˚; V 1141.6(9) Å3; Z 2; conventional R (on F) being 0.0315 for 4019 No observed reflections (I> 2σ(I)). Compound (2) is also triclinic P1–; a 10.653(2), b 12.195(3), c 14.641(3) Å; α 88.295(19), β 83.553(18), γ 73.921(19)˚; V 1816.0(7) Å3; Z 2; R0.0498; No 6179.
Effects of insulin-like growth factors I and II on tumour-necrosis-factor-a-induced apoptosis in early murine embryos
Authors: Byrne A. T. , Southgate J. , Brison D. R. , Leese H. J.
Published: August 2002

The proposition that members of the insulin-like growth factor superfamily act
as rescue factors from apoptosis in murine preimplantation embryos was tested.
The cytokine tumour necrosis factor α (TNFα) was used to induce
apoptosis. Zygotes were cultured for 5 days to the blastocyst stage in the
presence or absence of TNFα and in the presence or absence of the
insulin-like growth factors, IGF-I or IGF-II. Tumour necrosis factor α
significantly increased the percentage of apoptotic cells and reduced the
total cell count in Day 5 blastocysts. When IGF-I or IGF-II were added to the
culture medium in the presence of TNFα, the cell number and apoptotic
dead cell index (DCI) were restored to control values. Insulin-like growth
factor-I alone had a greater effect on total cell number than IGF-II alone,
but did not significantly decrease the apoptotic DCI. In contrast, IGF-II
significantly reduced the number of apoptotic cells. This study shows that
IGFs may play a role as apoptotic survival factors in the early mouse embryo.
Lightning and lightning fire, central cordillera, Canada
Authors: Wierzchowski Jack , Heathcott Mark , Flannigan Michael D.
Published: August 2002

This study examines the influences of fuel, weather and topography on
lightning-caused forest fires in portions of southern British Columbia and
Alberta, Canada. The results show a significant difference in lightning and
lightning-caused fires east and west of the Continental Divide. In British
Columbia, on average there was one fire for every 50 lightning discharges
whereas in Alberta there was one fire for every 1400 lightning discharges.
Elevation, the distribution of lightning strikes, the Daily Severity Rating (a
component of the Canadian Forest Fire Weather Index System) and vegetation
composition were identified as primary agents controlling lightning fire
occurrence. However, the multivariate analysis does suggest that there are
other factors influencing fire occurrence other than the biophysical factors
we tested. The implications of the lightning and lightning-ignited fires for
land managers are discussed.
Growth and condition in Australian fur seals (Arctocephalus pusillus doriferus) (Carnivora : Pinnipedia)
Authors: Arnould J. P. Y. , Warneke R. M.
Published: August 2002

Mass and length growth models were determined for male
(n = 69) and female (n
= 163) Australian fur seals
(Arctocephalus pusillus doriferus) collected at a
breeding colony on Seal Rocks (38˚31′S, 145˚06′E), Bass
Strait, in south-east Australia, between February and November during
1970–72. Growth was best described by the logistic model in males and
the von Bertalanffy model in females. Asymptotic mass and length were 229 kg
and 221 cm for males, and 85 kg and 163 cm for females. In all, 95% of
asymptotic mass and length were attained by 11 years and 11 years,
respectively, in males compared with 9 years and 5 years, respectively, in
females. Males grew in length faster than females and experienced a growth
spurt in mass coinciding with the onset of puberty (4–5 years). The
onset of puberty in females occurs when approximately 86% of asymptotic
length is attained. The rate of growth and sexual development in Australian
fur seals is similar to (if not faster than) that in the conspecific Cape fur
seal (A. p. pusillus), which inhabits the nutrient-rich
Benguela current. This suggests that the low marine productivity of Bass
Strait may not be cause of the slow rate of recovery of the Australian fur
seal population following the severe over-exploitation of the commercial
sealing era. Sternal blubber depth was positively correlated in adult animals
with a body condition index derived from the residuals of the
mass–length relationship (males:
r2 = 0.38,
n = 19, P < 0.001;
females: r2 = 0.22,
n = 92, P < 0.001),
confirming the validity of using such indices on otariids. Sternal blubber
depth varied significantly with season in adult animals. In males it was
lowest in winter and increased during spring prior to the breeding season
(r2 = 0.39,
n = 19, P < 0.03)
whereas in females it was greatest during winter
(r2 = 0.05,
n = 122, P< 0.05).
Effect of Insulation Location on Initial Transient Thermal Response of Building Walls
Authors: Al-Sanea Sami A. , Zedan M. F.
Published: August 2002

The effect of insulation location on the heat transfer characteristics of building wall elements under initial transient conditions is studied. Thermal performance with an insulation layer placed on the inside of a wall is compared to that when the insulation layer is placed on the outside. The investigation is carried out for the climatic conditions of Riyadh, Saudi Arabia, during representative days for July and January using a finite-volume implicit procedure. The initial temperature distribution across the wall is assumed to be uniform and equal to the daily mean external air temperature. The numerical model is validated against a semi-analytic solution developed for a simple test case. The results of model application under the present conditions show that placing the insulation on the inside gives an instantaneous load that is about 20% of the value for outside insulation during the first few hours in the initial transient process. Besides, the duration of the transient process which leads to steady periodic state, and thus, the period of thermal discomfort due to radiation exchange is much shorter for the inside insulation. The average heat transmission over the first 24 hours of air-conditioning operation with the inside insulation is about one-third of that with the outside insulation. The dynamic R-values are averaged over the first 24 hours and compared for various wall orientations, seasons and insulation locations. It is recommended that for spaces where the air-conditioning system is switched on and off intermittently, the insulation should be placed on the inside.
Modification of NBR by Addition of Phenol-CNSL Formaldehyde Copolymer
Authors: Lubi C. Mary , Thachil Eby Thomas
Published: August 2002

This paper reports the results of employing a Cashew Nut Shell Liquid (CNSL) based resin for modifying the properties of NBR. The resin is a copolymer obtained by condensing a mixture of phenol and CNSL with hexamethylene tetramine (hexa) at a stoichiometric ratio of 1:2.9 between total phenol and formaldehyde generated from hexa. The synthesis procedure, characterization and method of incorporation into the NBR compound are described. Sheets moulded from the compound have been subjected to different aging periods viz. 24 hrs, 48 hrs, 72 hrs and 96 hrs at 100°C and various properties were evaluated. Comparison of the properties of the aged material containing resin with those of NBR specimens not containing the resin show improved aging characteristics with respect to tensile strength, modulus and tear strength at aging periods in excess of 72 hours.
A Dynamical Systems Approach to Bifurcation and Instability of Constitutive Relations for Brittle Damage Materials
Authors: Sun Xin , Karr Dale G.
Published: August 2002

A methodology based on stability theory of dynamical systems is proposed to study the stability of the constitutive relations for brittle damage materials. The bifurcation conditions and the subsequent stability issues of the equilibrium paths are examined in the framework of bifurcation and stability theories of nonlinear dynamical systems. This framework also demonstrates that stability is not only a constitutive property, it also depends on the imposed traction and displacement boundary conditions. Moreover, the loss of uniqueness and stability of the primary equilibrium path does not necessarily imply failure in the dynamical sense since there may exist a stable secondary equilibrium path. Stability criteria for both stress-controlled and displacement-controlled conditions are formulated and an equivalent stability condition for the corresponding statical system is also presented.
Numerical Analysis and Experimental Studies on the Role of Rheological Properties in Effecting Die Swell of Low Density Polyethylene, Polypropylene and Polystyrene: A Predictive Model Based on Newtonian Fluid
Authors: Kar Kamal K. , Otaigbe Joshua U.
Published: August 2002

Die swell measurements were performed on low density polyethylene, polypropylene, and polystyrene, in a Randcastle microtruder over a range of shear rate, length/diameter ratio (Li/Di) of die, and polymer melt temperature to accelerate efforts to develop reliable quantitative description of die swell phenomena observed in practical polymer processing operations. Die swell of these polymers increased with increasing shear rates. An increase in polymer melt temperature and the length/diameter ratio of the Microtruder die decreased the die swell of the polymers. A comparison of the experimental data with predictions from various existing models such as the ones reported by Bagley and Duffey, Mendelson et al., Tanner, White and Roman, Vinogradov and Malkin, Macosko and Kumar et al. revealed that existing models are not capable of accurately predicting the die swell of the materials. Therefore, a theoretical model based on strain energy density function, Gaussian network theory, and first normal stress difference with no adjustable parameters appropriate for determining die swell has been developed for Newtonian fluid. The experimental data for the polymers studied conformed excellently well with predictions from this proposed model. Thus for the first time a suitable quantitative model for exploring die swell phenomena in actual polymer processing equipment, such as an extruder, is established. Further, a special linear relationship between die swell and maximum recoverable deformation and a nonlinear relationship between die swell, storage and loss moduli have been established for these polymers. The first normal stress difference, calculated from the maximum recoverable deformation, has been found to vary strongly with shear stress and shear rate but independent of temperature for a specific polymer. Flow activation energies of the polymer melts decrease with increasing frequencies, indicating increased mobility of polymer chains at such frequencies.
The Interlaminar Stresses of Symmetric Composite Laminates
Authors: Tong J. W. , Xie M. Y. , Shen M. , Li H. Q.
Published: August 2002

Three-dimensional finite element interlaminar stress solutions of composite laminates with resin layers under uniform axial strain are presented. Their three-dimensional distributions are plotted. In the cross-ply laminate, interlaminar normal and shear stresses are shown to be of free-edge effect. But shear stresses are found to be significantly reduced in the free-edge region, which show some conformity to the boundary stress conditions. In the angle-ply laminate, the stress distributions all vary significantly along both extension and width directions. There exists free-edge effects and end-edge effects in this case; however, the peaky interlaminar stresses are not exactly at the edges, but are near the edge regions.
Comparison of Field-Controlled Characteristics between ER and MR Clutches
Authors: Choi Seung-Bok , Hong Sung-Ryong , Cheong Chae-Cheon , Park Yong-Kun
Published: August 2002

This paper presents torque control characteristics of ER (electro-rheological) and MR (magneto-rheological) clutches. As a first step, Bingham properties of ER and MR fluids are experimentally distilled under the shear mode. A nondimensional model of the clutches is established for reasonable comparison. Two clutches have the same principal design parameters such as outer radius of the disc and electrode gap size. Following the manufacturing of two clutches on the basis of the nondimensional model, field-dependent torque levels are experimentally evaluated. A PID (proportional-integral-derivative) controller is then designed and experimentally realized to achieve desired torque. Both regulating and tracking torque control responses of the two clutches are evaluated and compared. In addition, control durability for torque tracking is undertaken to provide a practical feasibility of the proposed clutches.
Design, Modeling, and Performance of a High Force Piezoelectric Inchworm Motor
Authors: Galante Timothy , Frank Jeremy , Bernard Julien , Chen Weiching , Lesieutre George A. , Koopmann Gary H.
Published: August 2002

A linear inchworm motor was developed for structural shape control applications. One motivation for this development was the desire for higher speed alternatives to shape memory alloy based devices. Features of the subject device include compactness (60 x 40 x 20 mm), large displacement range (6 mm), and large holding force capability (200 N). There are three active piezoelectric elements within the inchworm: two "clamps" and one "pusher." Large displacements are achieved by repetitively advancing and clamping the pushing element. Although each pusher step is small, on the order of 10 microns, if the step rate is high enough, substantial speeds may be obtained (8 mm/s). In the past, inchworm devices have been used primarily for precision positioning. The development of a robust clamping mechanism is essential to the attainment of high force capability, and considerable design effort focused on improving this mechanism. To guide the design, a lumped parameter model of the inchworm was developed. This model included the dynamics of the moving shaft and the frictional clamping devices, and used a variable friction coefficient. It enabled the simulation of the time response of the actuator under typical loading conditions. The effects of the step drive frequency, the pre-load applied on the clamps, and the phase shifts of the clamp signals to the main pusher signal were investigated. Using this tool, the frequency bandwidth, the optimal pre-load and phase shifts which result in maximum speed were explored. Measured rates of motion agreed well with predictions, but the measured dynamic force was lower than expected.
Experimental and Numerical Activities on Damage Detection Using Magnetostrictive Actuators and Statistical Analysis
Authors: Monaco Ernesto , Franco Francesco , Lecce Leonardo
Published: August 2002

The purpose of this work is to present the formulation of a new experimental procedure to employ in problems of damage analysis of structural elements. The proposed method is based on the acquisition and comparison of Frequency Response Functions (FRFs) of the monitored structure before and after damage occurred. Structural damages modify the dynamic behaviour of the structure and consequently its FRFs making possible calculation of a representative “Damage Index.” The experimental activity was carried on using two prototypes of magnetostrictive actuators developed within the European Commission funded project named MADAVIC (Magnetostrictive Actuators for Damage Analysis and VIbration Control). Three kinds of damages have been simulated on two beam-like structures: little mass disturbances, partial cuts of the beam sections and constraint yielding. Two expressions of damage indices were calculated and analysed. The main target of the work was to assess the reliability of the damage identification by using a “repetitiveness index.” This index is related to the lowest measurable damage extension and the statistical t-test, in order to verify if each calculated index was really representative of a structural damage, rather than of unforeseen differences between the FRFs. A simple Finite Element Model (F.E.M.) of the second test-article has also been developed for numerically simulating the experimental tests and comparing the corresponding results.
Electrorheological Effects of ER Gels Containing Iron Particles
Authors: Liu Bo , SHAW Montgomery T.
Published: August 2002

Electrorheological (ER) gels were prepared by aligning 5-mm iron particles in liquid-like silicone RTV prepolymers in magnetic fields while the silicone cured. The pre-cured composite was then swollen with oil to reduce the conductivity. The iron content was held at 3% by volume, while the oil content ranged up to 20% by weight. In general, the dynamic shear moduli of the aligned ER gels increased quadratically with the electric field intensity, following the empirical equation G = G0 [1 + (E/E0)α], with α≈ 2. Observed values of G/G0 ranged up to 2.5. When the iron-particle chains were tilted with respect to the electrical field direction, the electrorheological effect decreased. While the rate of decrease was in approximate accord with the prediction of the point-dipole assumption, the magnitudes of the ER effect were under predicted by two orders of magnitude.
Reinforcing Masonry Walls with Composite Materials-Model
Authors: Jai John , Springer George S. , Kollar Laszlo P. , Krawinkler Helmut
Published: August 2002

In this investigation, a procedure is developed for determining the effectiveness of composite materials in retrofitting masonry buildings to reduce seismic damage. The reinforcement considered is a thin layer of fiber-reinforced composite applied to the wall in a wallpaper-like fashion. Models were developed which predict the behavior of masonry walls reinforced in such a fashion and subjected to static, in-plane normal and shear loads. Solid walls, as well as walls with openings (such as windows and doors), were considered. The models estimate the load-deflection characteristic of the wall, the load set at which the wall fails, and the deflection of the wall at the instant of failure. Numerical results were also generated which indicate that composite reinforcement applied in a wallpaper-like fashion may increase substantially the load carrying capacities of masonry walls.
The Effect of Woven, Chopped and Longitudinal Glass Fibers Reinforcement on the Transverse Strength of a Repair Resin
Authors: Uzun Gülay , Keyf Filiz
Published: August 2002

Fracture resistance of prosthesis is an important clinical concern. This property is directly related to transverse strength. Strengthening of prostheses may result from reinforcement with various fiber types. This study evaluated the effect of fiber type on the transversestrength of a commercially available autopolymerizing resin that is used for repairing prosthesis. The resin was reinforced with woven form, chopped form and longitudinal form, and no reinforcement was used.Uniform samples were made from autopolymerizing resin. In total, twenty-four bar-shaped specimens (60 × 10 × 4 mm) were reinforced with glass fibers. Nine specimens were prepared without fiber. Athree-point loading test was used to measure transverse strength, maximal deflection, and modulus of elasticity. The Kruskal-Wallis analysis of variance was used to examine differences between the four groups. Although the results of the analysis between these groups showed no statistical significances, the transverse strength, maximal deflection and modulus of elasticity increased more with fiber than without the fiber group. This finding may be of clinical significance. Because the addition of fiber reinforcement enhanced the physical properties of the processed material, specially woven form glass fiber was superior to the other forms.
Studies on Polyurethane Potting Compound Based on Isocyanurate of Aliphatic Diisocyanate for Fabrication of a Haemodialyser
Authors: Thomas Vinoy , Jayabalan M. , Sandhya S.
Published: August 2002

Polyurethane potting compounds based on multifunctional isocyanurate of aliphatic diisocyanate, hexamethylene diisocyanate (HDI-IC) as Component A and polypropylene glycol, polyethylene glycol and castor oil (Component B) were prepared as potential potting compounds for the fabrication of a haemodialyser. The setting characteristics of the potting compounds having isocyanate index 2.54 are better than those of the compounds having 1.77. The ageing stability of castor oil and PPG-based potting compounds having isocyanate index 2.54 is better than that of PEG oil-based potting compounds. Appreciable hydrolytic, oxidative and chemical stability could be observed with HDI-IC/PPG/2.54 potting compounds for development of haemodialyser, oxygenator, etc.
Effect of Cigarette Variables on Ignition Propensity of Various Fabrics
Authors: Wanna Joseph T. , Zelius Peggy
Published: August 2002

A factorial matrix consisting of 25 cigarette samples, where tobacco density, circumference, paper porosity and paper citrate were varied at three levels was tested on cotton duck, treated sailcloth and four commercial fabrics. Duck fabrics are heavy canvas-type fabrics that have very high levels of potassium ions. Treated sailcloth is a light areal density fabric treated with potassium sulfate and hydroxide salts to produce ignition results that mimic those obtained with light areal density commercial fabrics. The chosen commercial fabrics had light, heavy and mid-range areal densities. The results underscore the fact that changing tobacco column parameters does not produce cigarette designs that perform consistently well on all fabric types. Lower cigarette density and reduced circumference levels reduce ignitions on duck fabrics but increase ignitions on treated sailcloth and the light areal density commercial fabric. Reducing paper porosity reduced ignitions on duck fabric, had little effect on treated sailcloth and increased ignitions on the light areal density commercial fabric. Paper citrate had the smallest effect.

Ignition results on duck fabrics correlated with each other but were in contrast to those obtained with treated sailcloth. The heavy and light areal density fabrics produced similar ignition results to the duck fabrics and treated sailcloth, respectively. The two mid-weight commercial fabrics produced ignition results dissimilar to the other fabrics.
Impact Response of Unidirectional Carbon Fibre Rod Elements with and without an Impact Protection Layer
Authors: Potter K. D. , Schweickhardt F. , Wisnom M. R.
Published: August 2002

Rods of unidirectional CFRP offer outstanding performance in terms of strength to weight ratio. Their performance is, however, expected to be limited by their resistance to in-service impact threats, especially with regard to compressive loadings. The work reported here has verified that damage is done to unprotected rods at relatively minor impact levels and that a substantial reduction in compressive strength is experienced after impact. Identical rods have been overwound with high modulus aramid fibre under tension to act as a protective layer and subsequently impacted. These rods are much more resistant to impact than the unprotected rods; the best case studied to date being more than three times as strong after impact as the unprotected rods and more than twice as strong when taking the mass of aramid fibre into account. The longitudinal splitting seen in the impacted, unprotected rods has been completely suppressed by the tensioned overwind. This novel approach to reducing the influence of impact on the post-impact properties of composite rods has been validated by these tests.
Double Adjustable Shock Absorbers Using Electrorheological Fluid
Authors: Lindler J. E. , Wereley N. M.
Published: August 2002

Double adjustable shock absorbers allow for adjustment of their yield force and post-yield damping. To emulate the performance of a conventional double adjustable shock absorber, an electrorheological (ER) automotive shock absorber was designed and fabricated at the University of Maryland. An applied electric field between two tubular electrodes, located in the piston head, increases the force required for a given piston rod velocity. Two different shaped gaps between the electrodes, meet the controllable performance requirements of a double adjustable shock. A uniform gap primarily adjust the yield force of the shock absorber, as opposed to a non-uniform gap which allow for control of the post-yield damping. Force measurements from sinusoidal displacement cycles, recorded on a 5 HP mechanical dynamometer, validate the performance of uniform and non-uniform gaps for yield force and post-yield damping adjustments.
Out-of-Plane Coupling Effects on Stress Intensity Factors at Interface Cracks in Composite Lap Joints
Authors: Penado F. Ernesto
Published: August 2002

The existence of off-axis plies in adhesively bonded lap joints leads to anisotropic stress-strain relationships where the in-plane and out-of-plane components of stress and deformation (in a plane perpendicular to the width of the joint) are coupled. In this paper, the anisotropic elasticity solution near a bimaterial crack tip is formulated using an eigenfunction expansion of the stresses and displacements. This elasticity solution is subsequently used in conjunction with finite elements in a global/local method in order to determine mode I, mode II, and mode III stress intensity factors. Numerical results for [(±θ)2] s layups indicated that an out-of-plane mode III stress intensity factor, KIII, arises when off-axis plies are present even though the loading is in-plane. Depending on the layup angle and crack location, KIII can be as large as 43% of KI and 55% of KII. It was also found that, in addition to producing a mode III intensity factor, out-of-plane coupling affects the magnitude of the in-plane stress intensity factors, KI and KII. Comparison of the 3D results with a 2D solution indicated that, depending on the layup angle, the 2D solution can either overpredict or underpredict the values of KI and KII by as much as 35%. Finally, the use of an effective stress intensity factor with thermoplastic or thermoset composites indicated that the 2D solution can overestimate failure loads by as much as 36% and corroborated the experimental observation that failure in composite bonded joints generally occurs as a first-ply failure of the adherends.